dos_jul_2017

Patrons Subhash C. Dadeya, Editor-in-chief Volume 23 No. 1, July-August, 2017
A.K. Gupta G. Mukherjee
Gurbax Singh L.D. Sota Savleen Kaur Shibal Bhartiya Sonal Dangda Sumit Monga
Madan Mohan M.S. Boparai, P.K. Khosla Executive Editor Executive Editor Executive Editor Executive Editor

Chief Advisory Board Editorial 73 What is New in Treatment of
Atul Kumar Cyrus Shroff 5 A New Beginning Amblyopia?
Harbansh Lal Kamlesh, Lalit Verma 78 Do you want to be a Pediatric
Mahipal Sachdev Rajendra Khanna Featuring Sections Ophthalmologist?

Rishi Mohan, R.V. Azad S. Bharti, Y.R. Sharma Expert Corner Techniques
9 Controversies in Intermittent 80 Botulinum Toxin in Strabismus
Editor-in-chief
Exotropia 82 Hang-Back Muscle Recession
Subhash C. Dadeya
Review Articles Snapshot
Editors 23 Duane’s Retraction Syndrome: 85 One and a Half Syndrome
Anuj Mehta, Kirti Singh Ritu Arora
Radhika Tandon Sudarshan Khokhar Diagnosis and Management 87 Myopic Strabismus Fixus

Executive Editors 26 Retinoblastoma: Diagnosis and Photo Essay
Savleen Kaur, Shibal Bhartiya Sonal Dangda, Sumit Monga Management 90 An Interesting case of Head Tilt
31 Superior Oblique Palsy: 93 Glioma Masquerading as
Associate Editors Diagnosis and Management Acquired Non-Accommodative
Aditi Manudhane Vineet Sehgal 37 Diagnosis and Management of Comitant Esotropia in a Child
Retinopathy of Prematurity
Assistant Editors
Monica Lohchab Pallavi Dhokania 41 Diagnosis and Management of Case Reports
Prateek Kakkar Pulak Agarwal Abducens Palsy 97 Is there an Age Limit While
International Advisory Board 47 Diagnosis and Management of Treating Amblyopia in Adults?
Arvind Chandna Derek Sprunger, Frank Martin Third Nerve Palsy 99 Utility of Ice Pack Test in
Larson Scott, Saurabh Jain Seyhan Obzkon
Sonal Ferzavandi Surabhi Shalini Perspective Diagnosis of Myasthenia Gravis
National Advisory Board 50 Lost Muscle in Strabismus 102 A Case of Congenital Third
A.K. Khurana B.N. Gupta, B.S. Goel Cranial Nerve Palsy
Barun Nayak, Chaitra Jaidev Chand Singh Dhull Surgery – How to Handle the
Deepak Mishra D. Ramamurthy
Gursatinder Singh Hemalini Samant, Jagat Ram Problem? News Watch
Jai Kelkar, Kamaljeet Singh Krishna Prasad Kundlu 55 Squint Surgery is not just 105 DOS Times Quiz
Manisha Rathi, Mangat Dogra Ragini Parekh, Rakesh Porwal “Cosmetic”, but Functional and 107 DOS Crossword
S.P. Singh, Sandeep Saxena Sanjeev Nainiwal Restorative Procedure 108 Academic Calendar of Meeting &
Sudesh Arya, Santhan Gopal Santosh Honavar 57 Skew Deviations: The Brain Conferences 2017 - 18
Shreya Shah, Sudhir Kumar T.S. Surendran Throws a Wild Pitch 109 DOS Membership Form
V. Saharanamam Vandana Jain
Virendra Agarwal Yogesh Shukla Recent Trends and Advance 111 Instruction to Authors

Delhi Advisory Board 61 Pediatric Cataract: Evaluation Tear Sheet
A.K. Grover Ajay Aurora, Ajay Sharma, Alkesh Chaudhary and Management 113 Amblyopia Treatment Study
Amit Chopra, Amit Khosla, Anju Rastogi, Anup Goswami 67 Intraocular Lens Power
Arun Baweja, Arun Sangal Ashwini Ghai, Ashu Agarwal, Calculation for Pediatric Cataract Reports
B.P. Guliani, Bhavna Chawla Dinesh Talwar
D.K. Mehta, G.K. Das H.S. Sethi, H.S. Trehan 69 Pediatric Cataract in Difficult
J.K.S. Parihar, J.S. Titiyal Jatinder Bali, J.L. Goyal
Jolly Rohatgi, K.P.S. Malik K.R. Kuldeep, Kamal Kapoor Situations
Lopa Sarkar, M. Vanathi M.C. Agarwal, M.L. Bharti
Mahesh Chandra Manisha Agarwal www. dos-times.org 1
Meenakshi Thakkar Mohita Sharma
Mukesh Sharma N.Z. Farooqui, Nabin Pattnaik
N amrata Sharma, Noshir Shroff Om Prakash, O.P. Anand
P .K. Pandey, P.K. Sahu, P.N. Seth Pawan Goyal, Piyush Kapur
Poonam Jain, Pradeep Sharma Praveen Malik, Punita K. Sodhi
Rajendra Prasad, Rajesh Sinha Rajiv Bajaj, Rajiv Garg,
Rajiv Mohan, Rajiv Sudan Rajpal, Rakesh Bhardwaj
R.B. Jain, Ramanjit Sihota Rakesh Mahajan, Rohit Saxena
Sagarika Patyal Sandhya Makhija
Sanjay Chaudhary Sangeeta Abrol, Sarita Beri
Sarika Jindal, Satish Mehta Shashi Vashisht
Sunil Chakravarty, S.N. Jha Suma Ganesh, S.M. Betharia
Sushil Kumar, Tanuj Dada Taru Dewan, Tushar Agarwal
Tinku Bali, Umang Mathur Usha K. Raina, V.K. Dada
V.P. Gupta, V. Rajsekhar V.S. Gupta, Vinay Garodia
Viney Gupta, Vipul Nayar Yogesh Gupta

Section Editors
Strabismus & Oculoplasty
Paediatric Hardeep Singh
Ophthalmology Mridula Mehta
Abhishek Sharma Rachna Meel
Anirudh Singh Seema Das
Deepali Mathur Sumita Sethi
Geetha Srinivasan Neuro-ophthalmology
Rasheena Bansal Satya Karna
Renu Grover Swati Phuljhele, V. Krishna
Glaucoma Retina
Deven Tuli, J.S. Bhalla Bhumika Sharma
Mainak Bhattacharya Bhuvan Chanana
Manavdeep Singh Darius Shroff
Reena Chaudhary Deependra Vikram Singh
Cataract & Refractive Devesh Kumawat
Abhishek Dagar Koushik Tripathy
Charu Khurana Naginder Vashisht
Reena Sethi Raghav Ravani
Ritika Sachdev R.P. Singh, Ritesh Narula
Sanjiv Mohan Vinod Kumar Agarwal
DOS Correspondents Cornea & Oular Surface
Annu Joon Noopur Gupta
Divya Kishore Pranita Sahay
Prateeksha Sharma Rajat Jain
R icha Agarwal, Shweta Dhiman Uma Sridhar
Sumit Grover, Yashpal Goel Vikas Veerwal

DOS TIMES
Editorial Assistance & Layout: Sunil Kumar

Cover Design: Aman Dua

DOS Times will hitherto be published once every two months by Dr. Subhash C.

Dadeya, on behalf of Delhi Ophthalmological Society, DOS Secretariat, Guru Nanak

Eye Centre, New Delhi. Printed by Pushpak Press Pvt. Ltd. (Registration No. F-1P-

1Press CCS, 2011). All solicited & unsolicited manuscripts submitted to Dos Times

are subject to editorial review before acceptance. DOS Times is not responsible for

the statements made by the contributors. All advertising material is expected to

conform to ethical standards and acceptance does not imply endorsement by DOS

Times. ISSN 0972-0723

DOS EXECUTIVE MEMBERS

Executive Committee: DOS 2017-2019

DOS Office Bearers

Prof. Kamlesh Dr. Sudarshan Kumar Khokhar Dr. Subhash C. Dadeya
President Vice President Secretary

Dr. Manav Deep Singh Dr. Arun Baweja Dr. Bhavna Chawla Dr. Jatinder Singh Bhalla
Joint Secretary Treasurer Editor Library Officer

Executive Members DOS Representative to AIOS

Dr. Radhika Tandon Dr. Hardeep Singh Dr. Alkesh Chaudhary Dr. Naginder Vashisht Dr. Rohit Saxena

Dr. Vinod Kumar Dr. Sandhya Makhija Dr. Pawan Goyal Dr. M.C. Agarwal Dr. Ashu Agarwal

Ex-Officio Members

Dr. Rishi Mohan Dr. M. Vanathi Dr. Vipul Nayar
Ex-President Ex-Secretary Ex-Treasurer

DOS Hall of Fame Satish Sabharwal J.C. Das Dos General Secretaries
DOS Presidents N.C. Singhal Gurbax Singh
Madan Mohan Noshir M. Shroff Hari Mohan R.V. Azad
S.N. Mitter A.C. Chadha Pratap Narain Mahipal S. Sachdev R.S. Garkal B. Ghosh
H.S. Trehan M.S. Boparai (Brig.) R.C. Sharma Lalit Verma S.R.K. Malik Mahipal Sachdev
Tej Pal Saini N.N. Sood B.N. Khanna S. Bharti Madan Mohan Atul Kumar
L.P. Agarwal P.K. Jain R.N. Sabharwal Sharad Lakhotia J.C. Bhutani Lalit Verma
D.C. Bhutani L.D. Sota N.L. Bajaj P.V. Chadha S.C. Sabharwal Dinesh Talwar
R.C. Aggarwal L.D. Sota Mathew M. Krishna B.P. Guliani A.C. Chadha Harsh Kumar
S.N. Kaul S.K. Angra Prem Prakash Harbansh Lal Pratap Narain J S. Titiyal
S.N. Kaul D.K. Mehta D.K. Sen J S. Titiyal S.K. Angra Harbansh Lal
H.S. Trehan Y. Dayal P.K. Khosla Rajendra Khanna G. Mukherjee Namrata Sharma
Hari Mohan K.P.S. Malik K. Lall Cyrus Shroff H.K. Tewari Amit Khosla
R.S. Garkal R.B. Jain A.K. Gupta Rishi Mohan R. Kalsi Rohit Saxena
J.C. Bhutani G. Mukherjee B. Pattnaik Kamlesh D.K. Mehta Rajesh Sinha
S.R.K. Malik R.V. Azad A.K. Grover P.C. Bhatia M. Vanathi
Tejpal Saini Satinder Sabharwal K.P.S. Malik Subhash Dadeya
Arun Sangal

Sincere thanks to all DOS Office Staff : Office Secretary: Parveen Kumar w DOS Accountant: Sandeep Kumar w DOS Times Assistant: Sunil Kumar
DJO Assistant: Varun Kumar w Library Attendant: Niyaj Ahmad w Office Attendant: Harshpal

3 DOS Times - July-August 2017

Editorial

A New Beginning

Dear DOS Members,

New beginnings can sometimes be daunting, everything is alien and yet fraught

with possibility. Interacting with new people, taking on new responsibilities of

an organisation as dynamic as DOS, could have been overwhelming. Instead,

thanks to the absolutely rock-solid support of my mentors, friends, students

and readers like you, I am looking forward to the colossal task.

The past editorial board added many feathers to the cap of DOS with an
excellent amalgam of scientific papers, discussions and reports. We begin as

a new team, but strive towards academic excellence; the ultimate goal of the

DOS. We attempt to extend and spearhead this educational brilliance through

the various issues of DOS times in the coming months. We promise to deliver
scientific discussions which increase our understanding, knowledge and

management of ophthalmic problems.

We are trying to transform DOS Times to make it more standardised, unique,

resourceful and relevant. We hope that you will soon begin to see a change in

our perspective and accomplishments. We plan to change some of our patterns Dr. (Prof.) Subhash C. Dadeya

and guidelines. We wish to make the articles more informative and recent. We

also endeavour to offer you access to original research from the various subspecialties in ophthalmology. Having

spent most of my career studying and mastering the art of childhood eye diseases, I venture to bring before you the
first ‘focus’ issue of the DOS times – a special edition in paediatric ophthalmology.

Children are not small adults. Although this subspecialty is as vast as ophthalmology itself, there are only a handful

of dedicated paediatric ophthalmologists in India today. Unhealthy children are a burden in terms of budget and

energy to the society. Various screening programs can prevent many causes of reversible blindness which are low

in cost as compared to other sub-specialities. Hence, we dedicate this issue to paediatric ophthalmology. This issue

is an assortment of cases, reviews and reports from across the world in paediatric ophthalmology. We expand the

spectrum of this domain to include excellent write ups from the stalwarts of paediatric ophthalmology. We welcome

any pointers and feedbacks to make DOS times outshine and progress even more.

I also take this opportunity to welcome you all to the joint DOS-SPOSI International Congress on 9th and 10th

December at India Habitat Centre, Delhi. The congress will focus on the global perspectives in strabismus and

paediatric ophthalmology with symposiums by AAPOS, ESA, ISA, APSPOS, IPOSC and IOA, AOIS, OPAI, APSOOP,
ACOIN, QOIC. I am sure it will be an academic fiesta with an opportunity to interact with the glitterati in paediatric

ophthalmology and strabismus from around the world.

The preparations for I-DOS-QOIC Joint International Conference from 4-7 January, 2018 at Dubai are in full swing.

On behalf of the Executive, it gives us great pleasure to invite you and your family to participate in this wonderful
academic and fun filled International Conference.

We are a union of thousands of ophthalmologists, who strive for better clinical outcomes. Yet we are divided by

choices, subspecialties, regions and personal agendas. Let us all aim to work towards our objective. To promote

healthy teaching, surgical skill transfer, ethical conduct and state of the art cutting edge information should be our

purpose and ambition. I have imagined and re-imagined what my ideas of DOS are. I had a dream and vision for

DOS. I will ensure that DOS grows from strength to strength and scales great heights as an organization committed
to academic excellence,fulfill everything we were founded for; reform our existing norms; provide you with the best

of best.

I ask for your help and support, as always, because it is only with your cooperation that I have managed to achieve

whatever little that I have. The affection and regard that I have received from all of you gives me the courage to

stand up for our collective rights and responsibilities. I look forward to our continued association

Wishing you all a pleasant reading

Warm regards

Dr. (Prof.) Subhash C. Dadeya
Secretary - Delhi Ophthalmological Society
Room No 205, 2nd Floor, OPD Block,
Guru Nanak Eye Centre, Maharaja Ranjit Singh Marg,
New Delhi - 110002
Email: [email protected]
Mobile: 9968604336, 9810575899

www. dos-times.org 5





Expert Corner

Controversies in Intermittent Exotropia

Dr. Seyhan B. Özkan, Turkey Dr. Michael X. Repka, USA Dr. Frank Martin, Australia Dr. Scott A. Larson, USA

Dr. Federico G. Velez, USA Dr. Kamlesh, India Dr. Subhash Dadeya, India Dr. Savleen Kaur, India

Intermittent exotropia (IXT) is an entity that every strabismologist comes across in their day to day clinic. The incidence is estimated
to be 32 per 100 000; ranging from 1 in every 30 cases in the eastern countries to about 1 in every 100 in the western countries.
It is first noted as an intermittent strabismus or exophoria in children and the patients can usually control their deviation at this
stage. The ability to do so can be measured based on various described control scores. Although assessment of control can facilitate
management decisions, yet intermittent exotropia is a difficult condition to master because of its variability and uncertain natural
history. There are a variety of conservative options available as well surgical treatment strategies in cases of progression. However,

even surgical options are known to cause recurrence. Dunlap has stated that few problems in ophthalmology are more frustrating

than surgical treatment of intermittent exotropia. To correct an exotropic child for few months or a few years, only to watch his

eyes turn to their divergent state is an unpleasant experience for both the child’s parents and the ophthalmologist. It is especially

distressing to observe such a failure even after the second surgical procedure, which involves the remaining two horizontal recti.

As randomised prospective trials on intermittent exotropia are rare, we asked a panel of eminent strabismologists from around

the globe about their opinion and views on various aspects of the diagnosis and management of IXT through this questionnaire.

(SBO); Dr. Seyhan B. Özkan, Professor, Adnan Menderes University Medical School, Department of Ophthalmology, Aydin, Turkey
and President International Strabismus Association.
(MR); Dr. Michael X. Repka, Wilmer Eye Institute, Johns Hopkins School of Medicine Baltimore, Maryland, USA.
(FM); Dr. Frank Martin, Clinical Professor. Medical officer at the Sydney Children’s Hospitals Network, Australia and President
International Pediatric Ophthalmology and Strabismus Council.
(SL); Dr. Scott A. Larson, Professor of Paediatric Ophthalmology, Department of Ophthalmology and Visual Sciences, University of
Iowa, USA.
(FV); Dr. Federico G. Velez. Associate Clinical Professor of Ophthalmology. (Pediatric Ophthalmology and Adult Strabismus- Jules
Stein Eye Institute; Doheny Eye Institute; Olive View-UCLA Medical Center). UCLA School of Medicine. Los Angeles, California, USA.
(K); Dr. Kamlesh, Director and Head of Ophthalmology, Guru Nanak Eye Center, Maulana Azad Medical College, New Delhi, India and
President, Delhi Ophthalmological Society.
(SD); Dr. Subhash Dadeya, Director Professor of Ophthalmology, Guru Nanak Eye Center, Maulana Azad Medical College, New Delhi,
India. President Strabismus and Pediatric Oph Society of India and Secretary, Delhi Ophthalmological Society).
(SK); Dr. Savleen Kaur, Senior Research Associate, Advanced Eye Center, Post Graduate Institute of Medical Education and Research,
Chandigarh, India. Executive Editor DOS Times.

www. dos-times.org 9

Expert Corner by classmates come later. The key examination points
are visual acuity, pupils and optic nerve to exclude
SK: How many cases of IXT do you routinely see in vision loss and optic neuropathy.
your clinic? Lastly, refractive error needs to be measured with
cycloplegia and any myopia corrected with spectacles,
SBO: We did not make a statistical survey in our clinic on before making plans for further interventions. In
the number of the cases with IXT but on observational some cases, manipulation of the glasses power with
basis the routine number of IXT is not different than some minus sphere or reducing the plus sphere for
that of the literature results as 1:3 of esodeviations. the hyperopic patient may be helpful.
The Turkish population represents Caucasians and FM: The most common presenting complaint is parents
the incidence of exodeviations are not as high as in noticing that one of their child’s eyes intermittently
some Asian countries. becomes exotropic. This particularly tends to
occur when they are outdoors or when the child is
MR: There are probably 4-5 patients per session with IXT, daydreaming. Children also present with a tendency
and probably one new IXT patient every clinical day. to close one eye.
Many of the children are seen for a second opinion on In examining these children, it is extremely important
what treatment to do as I suspect this discussion will to perform the cover test, not only at near and distance
demonstrate that the decision is not simple. There is but also at far distance as otherwise some cases of
also possibly one adult with the phenomenon at least intermittent exotropia will not be diagnosed at the
weekly in search of care. initial consultation. If exotropia is not seen at the
examination, it is important to review the child as the
FM: I conduct six clinics per week and would see at least parents are rarely wrong about their observations.
five children with IXT in each clinic. SL: Most of the complaints are from the parents. They
notice the eye drifting and they are concerned that the
SL: Approximately 30-40% of all our strabismus cases vision is being damaged. Other children and adults
are IXT. This represents about 8-12 per day. We cover complain of their appearance, eye strain, headaches
a referral area of 3 million people. This problem is the and intermittent diplopia.
second most common strabismus problem seen in The examination should first include an assessment
our university clinic after accommodative esotropia. of the stereovision and fusional capability. We do
this with Randot or stereo fly testing and the Worth
FV: About 20% of my patient population is IXT. 4 dot test. The examiner should then asses the level
K: We routinely see about 8-10 cases of intermittent of control of the deviation. This is incorporated in the
cover testing. With the patient fixating on an object,
exotropia per clinic. the testing occurs at both distance and near. The
SD: IXT accounts for majority of cases of childhood examiner occludes an eye and after uncovering the eye
assess the facility and rapidity with which the patient
strabismus in our setting, approximately 25 to 30 recovers from the exotropia. Then ocular alignment
percent of patients seen by me in my clinic are IXT. (in the 9 cardinal gaze positions plus head tilts if
there is any vertical deviation) and an assessment of
SK: What is the most common presenting complaint ocular ductions can be performed. This is followed
in your setting and what are the most essential by visual acuity testing at both distance and near.
points for examination in such patients? Next one would do a cycloplegic refraction and an
assessment of ocular health including an examination
SBO: The most common presenting symptom in children of the anterior and posterior segments of the eye with
is the complaint of parents about the appearance of attention to the macula and optic nerve. Other testing
their child. In adults, the main complaint is again the for distance/near disparity could include the use of
appearance and problems of eye contact in social life. 45-minute occlusion test and ocular alignment at
As the patients with IXT suppresses while squinting, near with plus 3.00 lenses.
most of the time they do not have asthenopic FV: Most commonly; the parents see the drifting and
symptoms as the patients do with decompensating squinting.
exophorias who present with diplopia. However, some K: Most common complaints are intermittent outward
patients learn to control their deviation by voluntary deviation of eyes followed by asthenopic symptoms.
convergence and this group is highly bothered with Children often present with diplophotophobia.
asthenopic symptoms and visual blur. As in all patients of strabismus, complete and thorough
examination should be done in all the patients of IXT.
The most essential points for examination are same as However, few important points of examination in these
the routine evaluation of any patient with strabismus patients are: a) BCVA should be given after cycloplegic
that includes visual acuity, cover test prism cover refraction, and deviation should be measured with
test, ocular motility, evaluation of alphabetical glasses. b) Deviation measured should be the ‘static
pattern, measurement of near point of convergence, one’ i.e. that measured by breaking the fusion and
assessment of fusion and stereopsis, dynamic suspending the accommodation. At our institute, we
retinoscopy, cycloplegic refraction and fundus
examination. The additional points to assess are: how
well the deviation is controlled at near/distance and
far distance, binocular visual acuity, the prism cover
test at far distance, measurement of the deviation on
side gazes and one hour patch test followed by plus
3 diopters lens test. We perform the last two tests on
subsequent visits.

MR: The most common complaint is a wandering eye
noted by parents, grandparents or other adults.
Typically, diplopia, squinting an eye, or observations

10 DOS Times - July-August 2017

SD: use overnight patching of one eye for this purpose. Expert Corner
c) Deviation should be measured in all the gazes to
look for any pattern and lateral incomitance. d) Both examination. The voluntary convergence, which
near and distance deviation should be measured. e) is highly bothersome, should not be confused by a
Binocular status must be checked. good control. Post patch test is essential to unmask
Patients of IXT are usually asymptomatic. This can the real near deviation by eliminating the fusional
be explained due to the presence of well-developed convergence and plus 3 diopters test to unmask the
sensory adaptations. As the age of onset period of accommodative convergence. Plus 3 diopters lens
intermittent exotropia (2-5 years of age) is the period test must be done following monocular occlusion
of visual function maturation for children, binocular and the patients should not be allowed to remain
function is often affected. As a rule, during the phoric binocular during these evaluations. The existence of
phase of intermittent exotropia, the eyes are perfectly the exodeviation similar with the distance deviation
aligned and the patient has excellent bifoveal fusion indicates a normal AC/A ratio and the need for a
with excellent stereo acuity ranging between 40 and recess-resect surgery. The increase of near deviation
60 seconds of arc. with plus 3 lenses indicates a high AC/A ratio and
During the tropic phase, when the exodeviation these patients may need bifocals after surgery.
manifests itself, outward drifting of eye is the most MR: Prior to performing any strabismus measurements
common complaint. or even measure visual acuity, it is ideal to watch
Patients with late onset exotropia, after the age of 6-7 the patient for a few minutes to see if there is
years, may experience diplopia because the exotropia spontaneous deviation of the eyes and how much of
develops after the loss of plasticity that allows the time it occurs under casual viewing. Also noting
suppression. what maneuvers with the eyes or the head that a child
The various symptoms seen in IXT are: asthenopic uses to restore alignment can be informative. I would
symptoms, transient diplopia, micropsia and assess control at distance based on the control score
diplophotophobia. The examination, in addition we have used in PEDIG studies and described by
to routine examination of visual acuity, refraction, Mohney and Holmes. It is important to recognize that
cover test for near and distance, motility examination there is tremendous variability of the measurements
and tests for stereopsis, following special tests are of control during the day, so this should not be
required in relation to IXT. an absolute determinant. It is also important to
Measuring the angle of deviation by a prolonged remember that far distance (or remote) viewing will
alternate cover. If there is significant angle variability unmask many intermittent exotropias.
or a significant distance/near discrepancy after Post patch test is used to determine the maximum
prolonged alternate cover testing, only then a patch distance angle as well as to determine if the smaller
test is indicated. We must understand the basic near angle when present is due to tenacious proximal
principles that plus 3.00 lenses suspend normal fusion. It is reassuring to go forward with the surgery
accommodative convergence, whereas monocular and not fear an overcorrection. The plus 3.00 diopter
occlusion relaxes fusional convergence mechanisms, test is used when the deviation at near does not
therefore monocular occlusion should be used before increase with the patch to see, if the small near angle
plus 3.00 D lenses to measure near deviation, to avoid is due to a high AC/A ratio. If that is found, caution
misdiagnosing a high AC/A ratio. is needed when deciding to operate on such patients
I rely on Kushner’s Method for assessment of control. as they are at risk for a postoperative overcorrection
It is very important to carry out repeated examination and diplopia.
in these children. FM: The deviation is measured with the prism bar cover /
uncover test. It is difficult to perform this test in very
SK: How do you measure deviation in such patients young children as they will not fixate in the distance
and what is the role of Post patch test and plus 3 or far distance. The post patch test differentiates
dioptre lens test? true divergence excess intermittent exotropia from
pseudo divergence excess intermittent exotropia.
SBO: The deviation is measured with and without glasses This test is performed when the child is old enough
at near and distance as well as far distance. I first ask to cooperate for accurate prism bar measurements.
the patient to look at far distance before dissociating The 3 dioptre lens test unmasks the deviation that is
the patients’ eyes with cover test. The first thing controlled by convergence / accommodation. We do
that I do is to evaluate the control level first with a not place much emphasis on this test.
quick cover test without much dissociation effect. SL: We have orthoptists assisting the physicians in
the evaluation of all strabismus patients. They
Then I make a more dissociative cover test and make begin with a cover-uncover test to determine the
amount of tropia present and to assess the level of
prism cover measurements at near, distance and far control. If there is a large latent component, then a
simultaneous prism and cover test is used to quantify
distance. The near point of convergence is measured the alignment. This is followed by an alternate prism
and cover test. If there is a variable alignment or a
in all patients. Especially in adult patients I also larger deviation at distance, the deviation at near is
measured with a plus 3.00 lens before each eye. The
measure the visual acuity binocularly. Those who
www. dos-times.org 11
use voluntary convergence have a decrease in visual

acuity when they control their deviation and that can

easily be observed during binocular visual acuity

Expert Corner

FV: 45-minute occlusion of one eye is then done next different times of the day. We do not use any scoring
K: with care not to allow the child to have binocular system to decide on surgery, but we certainly look
vision when the patch is removed. The alternate for all the aspects in clinical scoring systems. The
prism and cover test is repeated after 45 minutes of control level is documented as ‘spontaneous control’,
SD: monocular patching. The examination is finished with ‘control with blinking’ and ‘control with refixation’
a cycloplegic refraction. at near, distance and far distance in all the patients.
Diagnosis can be made by the alternate prism cover The general rule is to document the worsening of
test. Patching and plus 3 D tests are very helpful, but the control of deviation in three consecutive visits. If
time consuming as well as hard to do for all patients. there is a decrease in stereoacuity or conversion into
As mentioned above, we measure deviation after a constant exotropia, the decision for surgery is more
patching one of the eyes. Deviation is measured in rapid and verification of the decompensation is done
all the gazes. Also, both near and distance deviations in more frequent visits.
are measured. Post patch test is the single most MR: I would recommend monitoring the IXT patient with
important test for measuring exact deviation in good visual acuity about every 6 months. Always
such cases to determine Full (static) deviation to consider that this patient might have an optic
determine distance/ near disparity (True /Simulated neuropathy. We use the PEDIG control score (0 to 5),
divergence excess and to determine the type of but also recognize the remarkable variability of this
surgical procedure. measurement and perhaps do not make a surgical
Plus 3.0 D test has been devised to diagnose the decision based on a single observation, but rather
patients of divergence excess type who have true examine a couple of times.
divergence excess due to high AC/A ratio. This test FM: The best way to monitor progression in these
uses the lens gradient method to measure the AC/A patients is to listen to the parents and ask them
ratio. These patients are the ones who will continue how much of the time they are aware of their child’s
to have a distance-near disparity post-operatively, exotropic deviation. In children who are old enough
and may require bifocal spectacles after surgery for to cooperate, we also use the Lang stereopsis test as a
a consecutive esotropia at near. This test should be monitor of control of the deviation. If the child starts
resorted to in patients who have a distance deviation to lose stereopsis, this is generally an indication that
greater than near deviation of 10 prism diopters or control is deteriorating. We do not use any particular
more after the patch test. After the patch test while scoring system. We, however, do note in the records
still dissociated, re-measure the deviation at near with where the children have good, fair or poor control,
a plus 3.0 add. If the exodeviation at near increases by depending on whether the deviation after being
20 prism diopters or more the diagnosis of high AC/A unmasked with the cover test recovers spontaneously,
ratio true divergence excess intermittent exotropia is with a blink or fails to recover.
made. SL: I use the parent’s assessment of control as the
Routine alternate cover prism testing gives variable prime factor in deciding in when to proceed to more
results in IXT; therefore, it is important to carry out a treatment. If there is a disparity in the assessment
prolonged alternate cover. It suspends tonic fusional level of control between my assessment and the
convergence. If there is significant angle variability parent’s assessment, particularly when I believe
or a significant distance/near discrepancy after the child has worse control than the parents see, I
prolonged alternate cover testing, only then a patch work to come to common ground with the parents
test is indicated. by teaching them to monitor their children closely. I
Patch Test - It is used for differencing cases of true don’t record a formal scoring system in the patient
divergence excess from pseudo-divergence excess. chart. However, I use most of the elements from
It’s another use is to control the tonic fusional formal scoring system which include the rapidity
convergence. We do the patch test after 24 hours of of recovery from the exotropia and the behaviours
mono-occlusion to get the best results. that were needed to recover from the exotropia. This
Plus 3.0 D near add test (lens gradient method) - This could include spontaneous recovery, blinking or near
test is useful in cases of true divergence excess due fixation.
to high AC/A ratio. This test uses the lens gradient FV: Control reported by parents is the best way to monitor
method to measure the AC/A ratio. After the mono- progression. Measuring the near and distance
occlusion patch test, we measure the deviation at stereopsis is also very essential.
near with a plus 3.0 D add. In cases of high AC/A ratio K: Signs of progression of Intermittent Exotropia are:
true divergence excess intermittent exotropia, the Progression of tropic phase, exotropia occurs more
deviation at near increases by 15 diopter or more. than 50% of waking hours, secondary convergence
insufficiency, increase in size of basic deviation,
SK: What is the best way to monitor progression in development of suppression (no diplopia).
these patients? Do you routinely use any scoring We routinely use the following system to judge the
system for these patients? control.
Good Control: Patient “breaks” only after cover
SBO: It was recently demonstrated that the evaluation testing and resumes fusion rapidly without need
of the ‘control’ of the deviation was not consistent for a blink or refixation. Fair Control: Patient blinks

even with the same examiner on the same patient at

12 DOS Times - July-August 2017

Expert Corner

or refixes to control the deviation after disruption FV: this study have significantly changed my behaviour
with cover testing. Poor Control: Patient who breaks K: and I do not recommend patching very often any
spontaneously without any form of fusion disruption. more. I am part of the minus lens glasses study for
SD: Best way is to take the information provided by SD: IXT with PEDIG as well. We will have those results in a
parents in account. Recently Kushner et al have few years. I have been less impressed with minus lens
introduced the concept of assessment of control of therapy in kids that don’t have a high AC/A ratio than
intermittent exotropia. It a very good method and it I was for patching and I am concerned about inducing
helps to evaluate the patients in a better way and acts myopia in a minority of kids. I discuss patching and
as a guide to monitor deterioration and progression glasses with families, but they often move to surgery.
of intermittent exotropia. The first line of treatment can be both conservative
Subjective Methods and surgical depending on the presentation of the
Home Control: The parents may be told to keep a chart patient.
noting the control of deviation at home in terms of the Non-surgical treatment for intermittent exotropia
percentage of waking hours the manifest deviation is is not very effective but it may be preferred in
noticed at home. patients with small deviations (<15 PD), convergence
Office Control: Good Control: Patient “breaks” only insufficiency type of IXT, very young patients in whom
after cover testing and resumes fusion rapidly surgical overcorrection could lead to amblyopia
without need for a blink or refixation. Fair Control: or loss of bifixation and in patients who otherwise
Patient blinks or refixes to control the deviation after cannot be taken up for surgery. Any patient showing
disruption with cover testing. Poor Control: Patient signs of progression should be operated.
who breaks spontaneously without any form of fusion The treatment for IDS is primarily surgical, non-
disruption. surgical methods can be tried as a temporary measure
Objective Methods include measurement of Distance in the following situations. 1. Patients with small
and near stereopsis. Distance Stereo acuity: It (<20 PD) deviations 2. Very young patients in whom
provides an objective assessment of both control surgical overcorrection could lead to amblyopia or
of the deviation and the deterioration of fusion loss of bifoveal fixation 3. Patients waiting for surgery
that occurs early in this disorder. Normal distance or in whom surgery is contraindicated 4. Patients
stereoacuity indicates good control with little or with a high AC/A ratio may be responsive to non-
no suppression. The Mentor B-Vat II BVS assesses surgical methods.
distance stereoacuity using both contour circles and
the random dot E test from 240 to 15 seconds of arc SK: What are the conservative measures that you
disparity. advise for IXT when the control is good- orthoptic
exercises, occlusion, botulinum toxin A therapy,
SK: What is your first line of management in these binocular vision training or watchful waiting?
patients-conservative or surgical?
SBO: The first major step is the correction of refractive
SBO: In all patients as a first line of management, I prefer error. Refractive correction is the major tool to
to be on the conservative side and try to increase the control the level of accommodation and convergence
control of the deviation. The first golden rule is not to as well as obtaining good and equal visual acuity. The
make the patient worse. Most of these patients may first step is to balance the fixation preference. Any
develop and keep good level of stereopsis despite level of amblyopia provokes decompensation and
that they have day-fatigue exotropia at distance. Post- requires occlusion of the dominant eye. Even though I
surgical monofixation syndrome is my major concern find an equal level of visual acuity, if there is a fixation
in childhood. preference, I prescribe patching which most of the
time helps to control the deviation. As the orthoptic
MR: I tend to be conservative and observe for a few months exercise, I only use pencil push up exercises if the near
at least. I also want to be sure that there is no evidence point of convergence is remote or if there is difficulty
of an optic neuropathy. It looks bad if you rush to to maintain convergence. I tell the parents about the
surgery and this was for a sensory exotropia from possible scenarios and inform the necessity of follow
optic nerve compression or developing oculomotor up and the necessity of parental observation. The
nerve paresis. collaboration with the teachers usually give reliable
observational results as they have the opportunity to
FM: We tend to adopt a conservative management in observe the child during the whole day from distance.
children with intermittent exotropia. At the initial If the control is getting worse in an adult patient with
consultation, we outline to the child’s parents that moderate angle of deviation, I advise botulinum toxin
the child may require glasses if there is significant injection before considering any surgery. In children,
refractive error, part-time occlusion or orthoptic because of the off-label use of botulinum toxin, we
treatment. Generally, we do not commence orthoptic prefer to use it to rescue over/undercorrections in
treatment until the child is aged 4½-5½ years and IXT.
old enough to cooperate as otherwise, it becomes a
frustrating experience. MR: Monitoring is foremost and probably what I use most
often with patients. I would suggest home orthoptic
SL: In the past, I believed patching helped IXT. I prescribed exercises for school age children that are interested
it to many. I was a participant in the PEDIG trial for
alternate patching of IXT in children. The results of

www. dos-times.org 13

Expert Corner These measures can delay surgery or can be beneficial
for smaller deviations, but are not a substitute for
in computer-based activities, although the data are surgery. Botulinum toxin injection into the lateral
sparse to confirm a benefit. I do patching only if there recti has been reported as an alternative to surgery
is evidence of amblyopia, but I do tell patients about but with varying success rates.
the PEDIG trial which showed a minor benefit in a few
patients SK: Do you believe and prescribe alternate patching or
FM: Where there is good control, we generally use over minus lenses as a substitute for surgery? Do
orthoptic eye exercises to improve the control. If the you prefer giving pencil pushups and convergence
child can learn to recognise when the eye has deviated exercises in all types of IXT?
and spontaneously recovers from the exotropic
position, then we feel we have made great progress SBO: I use part time alternate patching during infancy to
and are well on the way to longstanding good results increase the chance for equal ocular preference. I use
without the need for surgery. over minus lenses in case of a recent worsening of a
SL: My impression with orthoptic exercises or binocular well-controlled IXT, in residual exodeviations or in
vision training is that they don’t help. Although I think consecutive exodeviations in an attempt to rebuild
there is a need for more studies in this area. I don’t the control. It is not a substitute for surgery but
use Botox for this problem, so most often the decision may work well in some patients. The troublesome
is to observe or do surgery. group on deciding the prescription of over minus, is
FV: For non-surgical management, we observe; followed the hypermetropic patients as they carry the risk of
by patching for one hour and glasses development of ametropic amblyopia. In preverbal
K: We regularly follow up such cases. 1. Measure amount period, my decision of how much to under correct
of deviation at distance and near. 2. Record frequency a hypermetropic child is dependent on the result
of deviation. 3. Lateral incomitance is checked for. 4. of dynamic retinoscopy and I believe that it is a
Any pattern if present crucial evaluation for hypermetropic children with
SD: Non-surgical treatment consists of following options: IXT. The patients with high hypermetropia may
Correction of Refractive error, Overcorrecting minus have a total relaxation of accommodation and that
lens therapy, Part time occlusion, Prismotherapy, group requires full hypermetropic correction for
Orthoptics and botulinum toxin injection. amblyopia treatment. In this group with amblyogenic
Anisometropia, astigmatism, myopia and even hypermetropia, the correction of the hypermetropic
hyperopia can impair fusion and can leads to refractive error should not be reduced with the concern
occurrence of manifest deviation, therefore it is of increasing the exodeviation. Hypermetropic
mandatory to do a proper cycloplegic refraction in correction does not always worsen the exodeviation
each and every case. It is particularly useful in myopes as expected. In contrast, once the accommodation
as correction of refractive error keeps the deviation in ability is increased, the accommodative convergence
control in few patients. In cases of high AC/A ratio, may help to control the exodeviation. Because of the
overcorrecting with minus lenses is helpful because increase of the accommodative effort some patients
stimulating accommodative convergence can reduce may even convert into an accommodative esotropia.
an exodeviation. Part time occlusion is temporary We use convergence exercises only if the patient has
method and useful in young children or can be used remote near point of convergence or has difficulty
to postpone surgical intervention in responsive in maintaining convergence. I do not think that all
patients. In some cases, part time occlusion of the non- patients with IXT need to perform convergence
deviating eye for four to six hours daily may convert exercises.
an intermittent exotropia to a phoria. Alternate
occlusion may be used in patients with equal fixation MR: Some patients are interested in trying exercises
preferences. If the angle of deviation is decreased, the and those will try vergence exercises (e.g., pencil
occlusion should be continued and assessment should pushups) for a period of time. I am unimpressed with
be made every 4 months until no further change their outcome in most cases. Over minus lenses are
occurs. In case there is no improvement for 4 months, an interesting option and seem to help a few patients.
it is discontinued. Prisms are rarely a long-term There is some evidence that it can work, often with
solution in patients with intermittent exotropia, but about minus 3.00D added to the cycloplegic refraction.
can be used to improve fusional control. For smaller PEDIG is currently conducting a randomized trial
deviations of up to 20 PD, base in prisms may be used of over minus by minus 2.50D in children when the
to assist control and relieve asthenopic symptoms. hyperopia is 1.00 or less after an earlier pilot study
Convergence exercises are indicated for symptomatic showed some potential for this dose.
patients with convergence insufficiency because of
the high risk of overcorrection with surgery. The goal FM: We do prescribe patching. The patching generally
is to increase the ranges of fusional convergence and involves occluding the fixing eye for 1-2 hours a day.
divergence. This is a form of passive orthoptics. We do not use
Some ophthalmologists use occlusion therapy for minus lenses. We do not give pencil push-ups and
preoperative antisuppression but the efficiency convergence exercises in all types of IXT.
remains debatable. Alternate patching has been
advised to improve control and reduce suppression. SL: I have nearly stopped doing patching for IXT since
our PEDIG trial results became available. I do use
14 DOS Times - July-August 2017 minus lenses in cases of High AC/A but not in true

divergence excess type IXT. I haven’t seen benefit in Expert Corner
my patients with convergence exercises.
FV: These modalities cannot be used as a substitute. Yes, I than 50% of the time, asthenopic symptoms from
do prescribe pencil push up exercises. the child trying to control the IXT, the child is being
K: No, we do not use these methods as a substitute teased at school about the IXT and at times we will
for the surgery. Rather these methods are used go ahead with surgery if the parents are extremely
as temporary measures till surgery is performed. concerned about the child’s strabismus (cosmesis).
Convergence exercises are prescribed by us in At each consultation we monitor the child, not only
convergence insufficiency type of IXT. Orthoptics are for control of the IXT but also for amblyopia and
not a substitute for surgery. Orthoptics don’t make loss of stereopsis. The goal of surgery is to achieve a
any significant difference to surgical outcome but may good cosmetic outcome, even after surgery children
be useful pre/post operatively for: Antisuppression still break down to exophoria or IXT. The most stable
therapy, diplopia awareness and fusional convergence postsurgical results are children who end up with a
training micro esotropia. This, however, can sacrifice their
SD: Treatment of IXT is surgical and only surgical. There previously good stereopsis.
is no substitute for surgery. Knapp summarized the SL: The decision to go to surgery is a cooperative one
opinion of most strabismologists by stating that between the parents and myself. I rarely push
orthoptics should not be used as a substitute for surgery if the family is not keen to do it. The goal
surgery but rather as a supplement. The aim is to of course would be to eliminate the IXT completely.
make the patient aware of manifest deviation and to However, often the result is much better control with
improve the patient’s control over it. Convergence very infrequent exotropia. I believe this could be a
exercises are preferred in convergence insufficiency successful outcome even though cover testing shows
type of IXT. a recurrent IXT.
FV: The indications for surgery are poor control; diplopia
SK: How do you decide which patient needs surgery and worsening stereopsis. The goal of surgery is an
and what are the goals of surgery? initial overcorrection.
K: As mentioned earlier a patient who shows signs of
SBO: In children, my major concern is to avoid amblyopia progression or in other words when a patient shows
and to preserve stereopsis. If I see any risk about loss of control, he/she should be operated. The goal
losing the binocularity which is usually manifested by of strabismus surgery for intermittent exotropia
decreased control of near deviation or in cooperative is to restore alignment and to preserve or restore
ones with the documentation of diminished binocular function. We target overcorrection of 8-10
stereopsis scores, I suggest surgery. The goal of PD in all patients above 4 years of age.
surgery is to correct the alignment by preserving SD: Following may be the indications for surgical
binocular function. The worst scenario is to end intervention:
up with monofixation syndrome, loss of stereopsis • Poor control: Poor control may be judged both by
and development of amblyopia in a child who had home control and office control. Exotropia occurring
stereopsis despite moderately controlled IXT. The at least 50% of waking hours may be a manifestation
goals of surgery in adult patients are again to correct of poor control calling for surgical intervention.
the alignment, to reduce the asthenopic symptoms • Deterioration of control: Serial observations are
related to the convergence effort and to increase required to assess deterioration/progression.
their quality of life by eliminating the psychosocial Following are the sign of progression:
impact of squint. In case of a recent decompensation • a) Increase in the frequency of the manifest phase
of a well-controlled IXT, my first choice is botulinum of squint b) Development of secondary convergence
toxin injection in adult patients. If botulinum toxin insufficiency c) Increase in size of the basic deviation
treatment does not provide a satisfactory result, or if d) Development of suppression as indicated by
the patient does not accept botulinum toxin injection absence of diplopia during manifest phase e)
for any reason, surgery is planned. Progressive deterioration of distance & near
stereopsis.
MR: Symptoms are my key determinant of when surgery • Severe asthenopia: Most patients are usually
is needed. Diplopia, squinting, covering an eye or asymptomatic because of the development of
children in school commenting about the patient hemiretinal suppression. In some cases, however,
and having difficulty with social issues. If we knew such as in the convergence insufficiency type of
the surgery to be always successful I might lower exodeviation, severe asthenopic symptoms are
my threshold but IXT surgery does not always have especially bothersome at near. Asthenopia may be
a perfect outcome with very frequent recurrences. a consequence of deteriorating control. If a trial
The goal of surgery is functional binocularity plus an of vigorous orthoptic exercises is unsuccessful,
angle that stays small or completely controlled. definitive surgery will be required.
• Bothersome diplopia is usually an indication for
FM: Generally, we try to avoid surgery until the child is surgical correction.
out of the amblyogenic age group (5-6 years). At By surgical intervention in intermittent exotropia,
times, we do need to perform earlier surgery if the we aim to achieve both cosmetic as well as functional
child meets our indications and criteria for surgery. success. We should aim for short term over correction
The indications include: exotropia present more
www. dos-times.org 15

Expert Corner we operate that patient irrespective of age.
SD: Intermittent exotropia is as such a controversial topic.
for long term desirable results in children (4-10 PD),
to counter the tendency of eyes to drift over time. Among all the factors, the most confusing and most
In young adults, we should aim for orthophoria so controversial is the age of patient at the time of surgery.
as to restore alignment and to preserve or restore Opinions vary widely about the appropriate timing of
binocular function. surgical intervention for patients with intermittent
exotropia. Knapp and many other workers advocated
SK: Do you believe there is a relation between age and early surgical intervention to prevent development
response to surgery and thus do you have any age of sensory changes that may prove intractable later.
preference for surgery? What is the best age to However, we must keep in mind that in visually
operate these patients? immature children a slight under correction should
be attempted to prevent occurrence of monofixation
SBO: The general tendency is not to operate IXT before 4 syndrome from consecutive esotropia. On the other
years. However, there is a group that may certainly hand, Jampolsky advocates delayed surgery, citing
require surgery below 4 years of age with signs advantages like accurate diagnosis and quantification
of converting into a constant exotropia. In those of the amount of deviation and to avoid consecutive
cases, waiting too long may result with the loss of esotropia and development of amblyopia. Success
binocular capacity. Unless early surgery is required, rate from surgery is more in the younger patients
the rule of thumb is to allow the necessary time for as compared to adult patients. We believe patients
the visual system to recover by providing the optimal should be operated around four years of age and the
circumstances with refractive correction, amblyopia surgery in less than age 4 is reserved for patients in
treatment or convergence exercises where necessary. whom rapid loss of control is documented.
The correct timing for surgery depends on the patient
and it is the time to operate when deterioration of the SK: What is your surgical preference in terms of
control of the deviation occurs. type of surgical procedure-unilateral or bilateral
surgery? Does your surgical procedure differ
MR: I do not know, but there are many opinions. There for basic type; convergence insufficiency and
are arguments for delay until older ages in childhood divergence type of IXT?
to preserve binocularity and avoid a postoperative
permanent monofixation syndrome that may result SBO: I prefer unilateral recess-resect surgery unless
from an overcorrection compared with earlier to there is a clear-cut indication of a divergence excess
preserve binocularity before it withers away. It would IXT. In small differences between near and distance
be nice to study this question but the randomization deviation, I manipulate the amount of surgery on a
between early surgery and delay in surgery is difficult. recess-resect basis. In pure convergence insufficiency
Physicians in the UK (Clarke M et al) tried but had where the patients are orthophoric at distance, I
trouble with recruitment. A key finding in their study prefer botulinum toxin injection instead of surgery
however was the remarkable benefit to quality of life because of the high risk of carrying the problem
which was much improved with surgery compared at distance. If the near deviation is more than the
with a mild decrement in those being monitored. far deviation but there is still manifest deviation at
distance I manipulate the surgery by decreasing the
FM: Our practice has been to try to defer surgery until lateral rectus recession and increasing the medial
the child is out of the amblyogenic age group. Our rectus resection. The presence of lateral incomitance,
preference for surgery is around 5-6 years. We do the results of patch test and +3 diopters test influence
not believe there is any relation between age and the planning of surgery
response to surgery.
MR: I tend to prefer bilateral lateral rectus recessions
SL: I have seen a higher success rate from surgery in the because they are less painful in my experience,
younger patients compared with older patients. I less red, and heal quickly. Recess-resects are done
believe the PEDIG study on surgery for IXT will also whenever there is a visual difference with surgery
report on their findings in this regard. Stay tuned for in the poorer seeing eye, when there is a real strong
that information. fixation preference, and in all of my adult patients.
A PEDIG trial exploring this question failed to
FV: Age is not a direct influence. Any patient who is find a difference in outcome with the two surgical
doing poorly or deteriorating regardless of age is a approaches 3 years after surgery.
candidate for surgery.
FM: Our preference is for recession-resection for basic
K: Small children are uncooperative for examination; type IXT. For divergence excess and pseudo divergence
thus, true deviation is not measured. Thus, surgery excess IXT, we prefer to do bilateral lateral rectus
often results in under/overcorrection. Timing recession. For IXT that occurs at near, the preference
of surgery is controversial. Surgery should be is for bimedial resection.
delayed in visually immature infants to avoid over
correction. It can be delayed up to 4 years for proper SL: I have moved more and more to unilateral Recess/
preoperative assessment and to avoid amblyopia and Resect for IXT without a distance near/disparity up to
loss of stereopsis due to desired initial consecutive 35 prism diopters. Even in younger children. I believe
esotropia. Early surgery under 4 years only if I am seeing better long-term outcomes with this
deterioration occurs in phase of intermittency to
maintain binocularity-to avoid intractable sensory
changes. If there are significant signs of progression

16 DOS Times - July-August 2017

approach. I still use bilateral lateral rectus recessions Expert Corner
for true and pseudo-divergence excess types but
the under-correction rates are significant with this need more data and the PEDIG data will help to clarify
procedure. I may do a recess/resect or bilateral this information.
medial rectus resection for convergence insufficiency FV: I believe timely surgery prevents further deterioration
type but I have been humbled by the difficulty with SD: Yes, the success rate of surgery varies from 60 to
this sub-set of patients. In my hands operating on a 90 percent. Surgery at appropriate time helps the
convergence insufficiency problem in an adult is one patients to maintain fusion as well as stereopsis.
fraught with poor outcomes from overcorrection at
distance. For this, I use a procedure that is weaker in SK: How do you determine the target angle for
my hands, medial rectus plications. This has reduced surgery and do you aim for overcorrection as your
the distance overcorrections and in theory may be early post-operative goal? Do you routinely do the
easier to fully or partially reverse. prism adaptation test before surgery?
FV: For basic type I prefer unilateral surgery and for all
other types bilateral surgery. SBO: We do not perform prism adaptation test in our clinic
K: We decide for surgery depending on distance-near as it costs high and is too much time consuming.
relationship: A. Basic type -1. Monocular recession The early post-operative goal is to have and
and resection. 2. Bilateral recession - if deviation is overcorrection of 10 prism diopters. I am also glad
less than 35pd. B. Distance exodeviation more than to see an overcorrection up to 15 prism diopters
near: Bilateral LR recession is the choice of surgery. but larger esodeviations make me concerned. If the
C. Exo more at near than distance: Bilateral MR overcorrection persists with decrease of stereopsis
resection. I first adjust refractive correction and if it does not
SD: For all types of exotropia except the convergence work, inject botulinum toxin into the medial rectus
insufficiency type we advise bilateral lateral rectus muscle.
recessions. To avoid lateral incomitance, it is advisable
to perform symmetric surgery rather than monocular MR: I measure the distance deviation with prism and
recession/resection procedures. For convergence alternate cover test. I expect a slight over correction
insufficiency type our preference is for bimedial in children with bilateral lateral rectus muscle
resection. 8-mm unilateral lateral rectus recession is recessions based on my tables for surgery. For
an attractive alternative procedure in the treatment adults when I do unilateral recess-resect I aim at
of intermittent exotropia with a deviation of 25 to 30 the adjustment to have them aligned at near and a
PD. very slight to no deviation at distance. I do not use
preoperative prism adaptation in the management of
SK: Do you think treatment in IXT changes the natural IXT or exotropia.
course of the disease? Does surgery correct the
central and peripheral fusion as well as stereopsis FM: In the preoperative workup, it is important to unmask
in a patient? the maximal angle of the IXT. Surgery aims to correct
the maximal angle and even though it is not what
SBO: Yes, I think it changes the natural course, these one aims for, there is often a small overcorrection
patients go back and forth in good stereopsis and immediately after the surgery. We do not routine use
suppression and the aim is to increase the balance the prism adaptation test before surgery.
towards the binocularly well controlled state. Lack
of appropriate follow up or treatment, leads many of SL: I aim for a small amount of esotropia, less than 15
those patients to convert into constant exotropia with PD for the post op angle in the first week in children
amblyopia and loss of binocular vision. and in adults that can handle it. I do not routinely do
prism adaptation for this condition.
MR: Yes, in some patients, the deviation is cured and
cannot be found during long term follow up with FV: We rarely use the prisms adaptation test. We aim for
very normal binocularity. However, in many patients overcorrection as long term recurrent drifting occurs
there is a recurrence of the deviation over time, while in 30%.
in others the eyes are aligned but the stereo is not
improved. K: We perform post patch test at least 3 times before
proceeding to surgery. Maximum deviation measured
FM: The short-term results from surgery for IXT are for distance after patching is taken as target angle. As
reasonably good, however, long term results are mentioned earlier, we aim for 8-10 PD over correction
disappointing. Surgery may help the child maintain in all our patients except very small children. No, we
central and peripheral fusion as well as stereopsis. don’t perform prism adaptation test routinely before
Surgery does not correct abnormal sensory function. surgery in our cases.

SL: I think if we do this young enough, we may prevent SD: Measurements should be performed at fixation
peripheral suppression from becoming so habitual distances greater than 6m after unilateral occlusion
that we can change the course of the condition. We do for 24 hours. We aim for overcorrection of 10 prism
diopters. Prism adaptation testing is considered by
some to be useful in determining the target angle of
surgery whereas others have found no differences in
surgical results with their use. We do not perform this
test routinely.

www. dos-times.org 17

Expert Corner poor preoperative stereo is a factor associated with
poorer outcomes, but large studies are needed to
SK: What is the long-term stability of surgery in these confirm that impression. Future analyses of PEDIG
patients? How do you prognosticate your patients IXT surgical trial data may help but the study was
in terms of longevity of your surgical success? Do not large enough to have sufficient power to look at
you believe some patient/ surgical factors make important risk factors in a definitive manner.
them prone to an exotropic drift? FM: The poor prognostic indicators are the presence
of amblyopia. Children who refuse to wear their
SBO: Amblyopia, lack of stereopsis or fusion and remote glasses to correct significant refractive error. Poor
near point of convergence are the high-risk factors preoperative assessment and planning leads to poor
for the recurrence of the deviation. Coexisting prognosis.
vertical deviations and especially the presence of ‘A’ SL: Large angle intermittent exotropia in obese myopic
pattern deviation are also the major risk factors for adults are the patients that seem to be the hardest
recurrence. patients for us to treat in my part of the world. They
require more surgery than other patients.
MR: About 60% will do well with no significant deviation FV: Absence of stereopsis and presence of amblyopia are
recurring, but the remainder will have a residual poor prognostic factors.
deviation which may grow with time. I do not know K: Some poor prognostic factors are Large deviations,
which factors are significant. hyperopia, deviation angle at the initial post-
operative period and amblyopia. High AC/A ratio is
FM: Patients with intermittent exotropia often have a also a poor prognostic factor as these patients tend to
strong family history of the condition. The long- have consecutive esotropia at near.
term results are disappointing. We estimate that SD: A high AC/A is an indicator of a poor surgical prognosis
approximately 50% of patients who undergo a and most of these patients have a consecutive
surgery within 5 years have a recurrence of the IXT. esotropia at near. Also, larger angle deviations with
We have found it is important to correct refractive amblyopia are poor candidates for surgery.
error, especially myopia as this helps maintain control
of the IXT. We have not been aware of any patient/ SK: Do you modify your surgical plan in cases with
surgical factors that make patients more prone to an lateral incomitance?
exotropic drift.
SBO: Yes, we evaluate lateral incomitance before surgery in
SL: The majority of patients will drift back towards all of our cases and modify the surgical plan where
exotropia. If we have < 15 PD of esotropia in the first necessary. The lateral incomitance which is defined
week or two and a small esophoria a month later, then as 20% decrease of the deviation on side gazes, may
I believe we will have a better long-term success. If be due to underacting lateral rectus or a tight medial
they have any exotropia on either of those visits, then rectus muscle. Depending on the forced duction test,
there will likely be more exotropia in the future. If the lateral rectus recession or the medial rectus
they have good alignment a year out from surgery resection needs to be reduced to avoid overcorrection.
then they will unlikely break down later but you can
never be sure. I try to never label anyone a “cure”. MR: I do not adjust. Some of these are measurement
artefacts and some are real but I have not reduced the
FV: I believe that patients with basic type of IXT operated surgical dosage.
with only lateral recessions drift out again even more
FM: We have found lateral incomitance to be a rare
K: We believe that if pre-operative work up of the patient phenomenon. Sometimes we slightly reduce the dose
is thorough, and the surgery has been done for the of the surgery.
largest measured angle of deviation with a target of
5-10 PD of overcorrection, then most of these patients SL: Yes. If there is more than 5 prism diopters of lateral
maintain correction over a long period of time. incomitance, and the lateral gaze usually has a
smaller angle. I would reduce my surgical dose down
SD: Dunlap has stated that few problems in by a millimetre or two.
ophthalmology are more frustrating than surgical
treatment of intermittent exotropia. To correct an FV: Yes. I do modify my surgical plan.
exotropic child for few months or a few years, only K: In cases of lateral incomitance, one might do either:
to watch his eyes turn to their divergent state is an
unpleasant experience for both the child’s parents 1. Recess each LR, more on the side where deviation
and the ophthalmologist. It is especially distressing is greater- for greater reduction of action of LR in that
to observe such a failure even after second surgical gaze 2. Recess LR on the side of greater deviation and
procedure, which involves remaining two horizontal Resect MR of opposite side- for greater effect of MR in
recti. Around 60 to 70 percent will drift back towards that gaze
exotropia after 5 years. We don’t associate any SD: In cases of lateral incomitance, a reduction in surgical
particular patient/ surgical factor that make them dosage is advisable.
more prone to an exotropic drift.
SK: How do you treat a case of IXT with V
SK: What are the poor prognostic indicators for PHENOMENON?
surgical treatment?
SBO: The correction of any alphabetical pattern is a must
SBO: Preoperative lack of stereopsis and amblyopia are the in IXT. Although in V pattern the patients may have a
poor prognostic indicators for IXT.

MR: It is difficult to have long term success with
unilateral or bilateral sensory exotropia. I think

18 DOS Times - July-August 2017

MR: better control in downgaze, this is usually associate Expert Corner
with torsional abnormalities which has a negative
FM: influence on control of the deviation. These patients This choice affects the postoperative interval to be
SL: may develop abnormal head posture in an attempt to chosen for that dashboard. Many might choose 3
K: control their deviation. months as the primary effect of the surgery, while
I repair the IXT with lateral rectus muscle recessions. excluding many late healing and patient factors that
SD: Rarely is there a reason to perform inferior oblique have impact during long term follow up.
surgery as some of these are pseudo-overaction of FM: The short-term success rate is 70-80%. The long-term
the inferior oblique as described many years ago success rate (over 5 years is approximately 50%).
by Capo et al. They noted the higher position of the We firmly believe that in managing intermittent
fellow eye when not fully adducted because there was exotropia the ophthalmologist when considering
more room for ocular elevation. However, if there is surgery should operate as late as possible and do as
torsion in a V pattern, and clear overaction when the little as possible.
eye is completely in adduction then a weakening of SL: Success can be defined in multiple ways and at
the inferior oblique muscle can be performed. multiple points in time. Most cases will have improved
This depends on whether there is associated inferior control of the misalignment. Post-op ocular alignment
oblique overaction. If the inferior obliques are of <10 Prism diopters occurs in 75% of my cases
overacting, then these are weakened at the time of on the 2-month post op visit. About 25% are under
the surgery for IXT. If V exotropia is present without corrected and 1- 5% of my cases are overcorrected
overaction of the inferior oblique muscles, then the at this time point. Most of the under corrections will
pattern is corrected by supraplacing the lateral recti go on to have additional surgery. If I include all cases
muscles at the time of surgery. where I have operated one or two times, > 90% have
Without oblique muscle dysfunction, I use vertical good alignment 2 months post-surgery. I am in the
offset of the horizontal rectus muscles. Any oblique process of looking at my outcomes 4-5 years out but I
muscle dysfunction will lead me to address them don’t have that data currently.
directly. FV: Cure rate is approximately 40% but improvement is
Surgical considerations in such cases are: A. seen in 80% in my experience.
Large A or V patterns will have significant oblique K: Based on a case series of 325 cases over a period of 3
muscle dysfunction. B. Surgery is selected to years, our immediate success rate in these cases was
reduce horizontal deviation in primary position. C. 92.8%.
Horizontal Muscle Transposition works well if no SD: Immediate post op success (Ortho ± 8 PD) is
oblique dysfunction, but it is not substitute for it. D. approximately 95 % in my cases. Three months post
Inferior oblique weakening or SO tucking correct op success is 85- 90 %; one year success is 70-80 %
15-25 PD of V-pattern. E. Bilateral superior oblique and 5-year success is around 50 %.
tenotomies correct 35-45 PD of A-pattern. F. Primary
& reading positions are functionally the most SK: How do you treat cases of Post-operative under
important positions of gazes. and over corrections?
V pattern may or may not be associated with primary
inferior oblique overreaction (IOOA). In the absence SBO: In post-operative, over and under corrections, my first
of IOOA, the lateral recti may be shifted upwards or tool is glasses. In those cases with overcorrection, I
the medial recti may be shifted downwards. If IOOA prescribe full hypermetropic correction and use
is present, then one of the various inferior oblique bifocal glasses if there is a high AC/A ratio. If the
weakening procedures may be performed along with problem is under correction, I use over minus glasses.
horizontal muscle surgery. If it does not seem to work I consider botulinum toxin
injection during the early post-operative period.
SK: What is the overall success rate in your cases?
MR: Overcorrections are patched and occasionally placed
SBO: We did not make a recent survey for IXT in our in prism for about 6 months, trying to wean over
department but I think it is consistent with the time. A small reoperation is done if the problem does
general literature results. not resolve. Clearly patience seems very important
with overcorrections as many will resolve. Under
MR: Since our move to the electronic medical record in corrections are watched for 6 months or more, and
2013, I have not been able to search and review the surgery is offered at that time for large and socially
data. That is clearly a deficiency in our practice and unacceptable residual deviations. I do not think this
I think we , for now, only have the ability to access resolves very often, if ever.
our patient lists by procedure and diagnosis. This
data can be used to create a dashboard that show the FM: In the preoperative informed consent progress, it
success rate of surgery being constantly updated over is explained to parents that approximately 30% of
time. This would make it much easier to examine the children will require more than one procedure to
impact of practice modifications. One problem I note correct the strabismus. We stress to the parents that
with any outcome measure is what we want to know. the need for further surgery may occur soon after
For instance, is surgery the key variable OR healing the operation if there is significant over and under-
or other patient variables the important question? correction or may occur years later if the deviation
should recur. If there is overcorrection immediately
after the surgery, it is important that the surgeon and
the team remain calm and reassure the parents that

www. dos-times.org 19

Expert Corner rectus is indicated. Otherwise, bimedial recession
is usually the procedure of choice for a consecutive
most of these correct spontaneously over a period esotropia, especially if the esotropia is greater at
of 6 weeks. If the child is complaining of diplopia near the possibility of lost or slipped lateral rectus
then we use part-time occlusion. If the child has any muscle should be kept in mind if there is an unusually
significant hyperopia, then it is worth correcting large over correction with gross limitation of ocular
this with glasses to help relax accommodation. motility on the first postoperative day and surgery
We have found that most overcorrections resolve should not be delayed in such cases. In adults; up-
spontaneously with an excellent long-term outcome. to 25 PD deviation, nonsurgical measures should be
If overcorrection persists, then we have found tried till 6-8 weeks, if there is no improvement, re-
that performing a unilateral medial rectus muscle surgery should be planned.
recession tends to correct the esotropia. Under correction: For Small residual exotropia (20
Under corrections are more difficult to manage. PD): Nonsurgical treatment should be tried for 6-8
If there is significant under correction then more weeks in such cases. However, in cases with large
surgery can be performed on the muscles that have residual exotropia (>20 PD), it is better to wait 8-12
already been operated on, depending on how much weeks before re-operating. If the primary surgery
has been done to the muscle. If there is no scope was bilateral lateral rectus recession of 7 mm or less,
for further surgery on the operated muscles, then re-recession of the lateral rectus may be resorted
the patient is managed as an intermittent exotropia to. If the primary recession was greater than 7 mm,
with a dose of surgery depending on the angle of the then perform bilateral medial rectus resections with
strabismus. a conservative approach, as over corrections are
SL: My under-corrections will go on to have one or two common after resecting against a large recession.
muscle surgery, typically on the unoperated horizontal
rectus muscles. Typically, if I have an overcorrection, SK: Which is your preferred surgical technique in
I will recess the previously resected muscle. It is such cases, adjustable hangback or nonadjustable
rare for me to have large persistent over-corrections surgery, Hangback or conventional surgery?
however those people are usually unhappy and have
diplopia. I would consider re-operating in a few SBO: If the surgical field is convenient and if the patient is
months if no improvement is measured. If there is any a child I prefer conventional sutures. In adults, I use
improvement in the over-correction, I try to convince adjustable suture surgery as a routine.
the patient to wait for more surgery as an exotropic
drift is so common. MR: I use adjustable sutures in all adults and most teens.
FV: We begin trial with glasses followed by patching and I use hang back surgery for most lateral rectus
then surgery. recessions.
K: Over correction: Small consecutive Esotropia 10-12
PD is desired, Patient may have diplopia-resolves FM: In children we do not use adjustable sutures. We tend
within 2 weeks, If Esotropia persists for > 2 weeks use to perform recessions using a Hangback technique
of base out prisms is recommended, Persistence after and conventional resection surgery although we are
8 weeks –resurgery- B/L LR advancement , If residual now starting to think about the use of publications.
Esotropia for near only- Bifocals, miotics or base out
prisms or bimedial recession with Faden SL: I use adjustable sutures less often now than when I
Under correction: A small residual exotropia (<15 PD) was younger. One reason is the difficulty I have found
should be managed by non-surgical measures such as in predicting where the muscle needs to be left before
orthoptics. Patients with a residual exotropia over 15 tying it down. I work to leave them about 10-15 ET
PD in the first postoperative week will probably not if they can tolerate it for larger pre-op deviations
improve. These patients require additional surgery. It and 5-10 ET for smaller pre-op deviations. I will
is better to wait 8-12 weeks before re-operating on more often use adjustable sutures with very large
the residual exotropia. If the primary surgery was angle exotropia in adults even on the first surgery.
bilateral lateral rectus recession of 6 mm or less, re- Unfortunately, this type of patient is even harder to
recession of the lateral rectus may be performed. If predict. I like to sew the muscle in the position I want
the primary recession was greater than 6 mm, then to leave it even though the hangback technique has
perform bilateral medial rectus resections with been shown to be equivalent. I like to know where I
a conservative approach, as over corrections are left the muscle.
common after resecting against a large recession.
SD: Small over correction is a desirable outcome. If FV: I prefer adjustable suture in adults and scleral fixation
there is over correction up to 20 PD, we should wait in young patients.
and watch as there is high chance of spontaneous
resolution. The possibility of postoperative diplopia K: We generally do conventional surgery as well as
must be explained to parents of child. Nonsurgical non-adjustable hang-back surgery. However, in
treatment should be tried for 6-8 weeks. If after 6-8 certain cases such as high myopes, children & large
weeks the esotropia persists, then a reoperation recessions, hangback recession is preferred.
should be considered. In case of a limited adduction
or lateral incomitance, advancement of the lateral SD: The adjustable hangback technique is my choice in
such cases.
20 DOS Times - July-August 2017
SK: Any indications for Hangback surgery? What are
the advantages and disadvantages of Hangback
Surgery in such cases?

SBO: Large lateral rectus recessions in a small eye is an
indication for me for hang back surgery as well as the

ones who will undergo adjustable suture surgery. Too Expert Corner
large recessions carry the potential risk of anterior
migration of the lateral rectus muscle but this is hangback surgery until I can see they have improved
usually a problem in restrictive strabismus cases. their technique. I like to clean the muscle capsule as
In IXT we did not face anterior migration in any of little as possible so the muscles are harder to hang
the reoperations. The major advantage of hangback back in that setting. I believe, there is faster healing
surgery is to avoid scleral sutures in close proximity but the muscles tend to get hung up on the supporting
with the macular area. We use adjustable suture tissue if they are minimally cleaned and therefore
surgery in adult patients as a routine procedure and they need to be sewn in the desired location.
we have not faced any problem about the effect of FV: Difficult surgery, when using adjustable sutures
surgery. and in cases of high myopia we can use hangback
MR: Lateral rectus recession being performed. I do use technique. Final position of the muscle however may
conventional surgery for some smaller deviations. move forward.
I tend to use most of the time for safety and facility, K: We do hangback recession in high myopes, children,
recognizing that different tables are necessary. My recessions more than 8 mm, and while doing adjustable
feeling is that I use this approach with adjustable recessions. Advantages of hangback surgery include
surgery and thus feel it can be effective at other minimal chances of scleral perforation, adjustable
times. I recognize others are concerned about where surgery can be done and less chances of tenons
the muscle migrates, typically forward, but I find that capsule snaring in large recessions. Disadvantages of
effect is also fairly predictable. hangback surgery include Central posterior muscle
FM: We use hangback surgery on all horizontal muscle bowing and Chances of late over-corrections if muscle
weakening procedures. We find Hangback surgery is reattachment lags suture hydrolysis.
safer with a lower risk of perforation of the sclera. We SD: I perform hangback squint surgery in most of
are meticulous with our surgical procedure and the my patients. Advantages of hang-back recession
knot to ensure that we do not end up with a slipped include decreased incidence of globe perforation,
or lost muscle. To date, we have been very happy with shorter surgical time, better exposure of surgical
this form of surgery. field and decreased amount of surgically induced
SL: I would use Hangback surgery for trainees that are astigmatism. Disadvantages include unpredictable
just starting out or who are less skilled. For example, results in especially large angle deviations, difficulty
if a trainee perforates the sclera, I have them move to in performing recessions of more than 7 mm and
occurrence of possible late over corrections.

Compiled by:
Dr Savleen Kaur
Senior Research Associate, PGIMER, Chandigarh
Email: [email protected]

www. dos-times.org 21

Review Articles

Duane’s Retraction Syndrome:
Diagnosis and Management

Nripen Gaur MD, Pradeep Sharma MD
Dr Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India

Abstract: Duane’s retraction syndrome (DRS) is a form of complex strabismus. This clinical entity can have a varied presentation
and may be a part of syndromic association as well. Numerous theories have been proposed regarding the etiopathogenesis
of this clinical entity, however, the clinical findings are best explained by the paradoxical innervations of the lateral rectus
secondary to maldevelopment of sixth nerve nucleus. Apart from this, the genetic basis of this disease is also being unravelled
with the ongoing research. The diagnosis and management of this disease require an astute observation and surgical planning
and the treatment plan must be individualised. In this article, the authors discuss the management strategies for various
clinical forms of DRS.

Duane’s retraction syndrome (DRS) is an unusual Figure 1: showing bilateral eso-DRS in a patient with Klippel-Feil
congenital form of strabismus. This condition syndrome, (1B, C) showing clinical photograph of the patient depicting
was initially described by Stilling (1887) and short neck and low hairline.
Turk (1896) and was later made popular by
Alexander Duane. Its frequency in the general shown to be the causative factor in the development of this
population of strabismus patients is 1–4%1. disease process3. The branches of the third nerve, in turn, are
The ophthalmic manifestations and associated non-ocular redirected to the lateral rectus. This abnormal or paradoxical
anomalies, as well as the demographic and epidemiologic innervational impulses to the horizontal recti are the basic
aspects of the syndrome, have all been extensively studied pathology of this disease. The lateral rectus (LR) may exhibit an
in affected cases and their relatives. It is suggested that array of affection. It may have a normal, subnormal or absent
certain characteristics of the syndrome may vary in different activity along with an anomalous third nerve innervation. In a
populations. DRS is included in a group of disorders called few cases, even the medial rectus (MR) may have subnormal
Congenital Cranial Dysinnervation Disorders (CCDDs)2. These innervations owing to the redirection of developing nerve
are secondary to some neurologic pathology of congenital fibres to the sixth nerve. Secondary muscle changes may occur
origin and have a wide spectrum of phenotypic presentation. in form of contracture of medial rectus and superior rectus as a
This wide spectrum results due to either primary or secondary result of constant esotropia and upshoots respectively.
dysinnervation. The concept of CCDDs was proposed in 2002.
Recent studies have supported this concept and the focus is Diagnosis
now on identifying the genes that cause CCDDs.
The diagnosis of DRS is usually clinical. Molecular genetic
Clinical characteristics testing is being investigated for this disease, however, it remains
in infancy. It involves single gene testing using sequential and
DRS is characterised by the limitation of abduction and / deletion/duplication analysis of the CHN1 gene4. This disease
or adduction along with a narrowing of palpebral aperture and has been differentiated into three subtypes on the basis of
retraction of the globe and variable upshoot and downshoot of myography by Huber5. (Table 1) Apart from these it can also be
the globe on attempted adduction (Figure 1). Apart from these, classified based on the primary position deviation into eso DRS,
the patients may also have a face turn to achieve binocularity. exo DRS and ortho DRS. MRI imaging has shown the absence of
Other ocular findings include nystagmus, anisocoria, ptosis, abducens in many studies6,7.
and epibulbar dermoid. Other findings may include congenital
cataract, heterochromia and optic nerve hypoplasia. DRS has Differential diagnosis
also been shown to be associated with gustatory lacrimal reflex
or crocodile tears. The clinical features may vary case to case Major differentials of this condition include sixth nerve
and one may see a myriad of presentations. Several syndromic palsy, Moebius syndrome, infantile esotropia and congenital
associations of DRS have been noted out of which the most
common ones include Goldenhar syndrome, Klippel – Feil
anomaly and Wildervanck syndrome.

Etiopathogenesis

A maldevelopment or any insult to the development of
the sixth nerve nucleus at 4 to 8 week of gestation has been

Gaur N et al. Duane’s Retraction Syndrome www. dosonline.org 23

Review Articles

Table 1: Huber’s classification of DRS rule out MR contracture in the affected eye
as a tight MR should always be recessed.
Types Innervation Clinical presentation One must take care to never resect lateral
rectus or medial rectus in the involved
I On abduction – LR innervation absent Abduction limited eye. Superior rectus transposition (SRT)
On adduction – LR innervation present Adduction limited due to or vertical recti transposition (VRT) to
resistance with retraction lateral rectus to achieve an abduction
force can be done if there is no anomalous
II On abduction – LR innervation present Abduction may be normal. LR recruitment. The combination of
On adduction – LR innervation present Adduction limited with SRT and MR recession has been found
retraction. to be more effective than MR recession
or bilateral MR recession at improving
III On abduction – LR + MR innervation Limited abduction with abduction while allowing for a smaller
recession to align the eyes and eliminate a
present retraction compensatory head posture8. However, in
cases with uncorrected severe anomalous
On adduction – LR + MR innervation Limited adduction with LR recruitment, any transposition
procedures are not indicated. And in case
present retraction the MR and LR are both to be operated
adding the SRT is fraught with the danger
LR= Lateral Rectus; MR=Medial Rectus of anterior segment ischemia.

oculomotor apraxia. However, these position deviation and face turn. Apart In cases with minimal anomalous
conditions can be ruled out based on from this, surgery can also be done to LR activity and normal LR abducting
the absence of characteristics like globe ward off cosmetically unacceptable globe force, a MR recession in the affected
retraction, narrowing of the palpebral retraction, upshoots or downshoots eye may suffice. Those with anomalous
aperture on attempted adduction and which are present because of severe co- LR activity should be tackled by LR
upshoots or downshoots. A simple patch contraction of LR and MR on attempted weakening procedures. The abduction
test can rule out the presence of infantile adduction. If binocular vision is deficit can be tackled by transposition
esotropia. present with cosmetically acceptable procedures like SRT (Figure 2) and
ocular appearance, surgery must not VRT, however we prefer a balanced
Work up of a case of DRS be undertaken just for improving the partial VRT to SRT as the latter has risk
abduction limitation. of vertical incomitance and inducing
A complete work up of DRS includes torsion. In cases with significant upshoot
a good history recording along with a Eso DRS or downshoot, the co-contraction can be
comprehensive ocular examination. The countered by the recession of both LR and
patient must also be investigated for the Cases of classic eso DRS do not MR of the affected eye. Another strategy
concurrent systemic anomalies which can have normal LR function, but anomalous is lateral rectus recession with Y split9.
be a part of this disease. Any abnormal action occurs during adduction. These In this procedure the LR is split from its
head posture must be recorded. DRS is patients have an esodeviation in the insertion to 18-20 mm posteriorly and
usually associated with the presence primary position and as such, they the two halves are placed at a distance
of a face turn that the patient assumes assume a corrective face turn. The of 20 mm apart. This procedure has been
to gain binocularity. The degree of face treatment options include asymmetric shown to be effective in tackling severe
turn be recorded. Ocular movements MR recessions or transposition surgeries upshoot and downshoot.
must be examined carefully to record any in form of vertical rectus transpositions.
globe retraction and palpebral aperture Asymmetric MR recession can be done Exo- DRS
narrowing on attempted adduction and in the good fellow eye to produce a
the presence or absence of upshoots fixation duress without fearing adduction These patients present with a
and downshoots must be recorded. The deficiency in the good eye. This not only primary position exotropia and may
primary, as well as secondary deviations, corrects the primary position esotropia have upshoots or downshoots along with
should be recorded in all the nine gazes. but it also decreases the likelihood of deviation. Such patients can be tackled by
A sensory examination must be done to contracture of the medial rectus in the a LR weakening in form of supramaximal.
check for binocularity and stereopsis. affected eye through the fixation duress in
Hess charting can be done to record the right eye which leads to a continuous
the field of binocular field of vision. It is inhibition on affected eye’s MR. However,
important to look for any contracture in before planning any surgery in DRS, it is
medial and lateral rectus by doing force imperative to check force duction test to
duction tests. The presence of anomalous
lateral rectus activity can be detected
by the help of force degeneration test
of Romero-Apis. This test is extremely
useful in confirming cocontraction in
adduction and the missing LR innervation
on abduction and thus helps in deciding
the plan of surgery.

Management Figure 2A: Showing abduction deficit in patient of left eso-DRS tackled by SRT(2B)

The primary indication for surgery
in DRS is the correction of primary

24 DOS Times - July-August 2017 Gaur N et al. Duane’s Retraction Syndrome

Review Articles

LR recession or a periosteal fixation (PF) Figure 3A: Showing severe upshoots in a patient with exo-DRS tackled effectively by LR recession
of lateral rectus to the medial rectus. An with Y-split(3B)
LR recession with Y split is also an option
is cases with normal LR activity where the Table 2: DRS management summary
upshoots and downshoots are a problem
(Figure 3). It may be noted that the LR 1. Eso DRS
recession should be substantial to correct
the retraction in adduction, as the Y split A Minimal anomalous action of LR MR recession as per FDT, SRT/pVRT
per se does not affect the retraction. The (cocontraction) with normal LR
PF wards off the anomalous LR activity action in abduction
most substantially. Some authors have
even advocated extirpation of the lateral B Anomalous LR present (moderate MR recession as per FDT, LR weakening
rectus! The resultant lack of abduction
can be taken care of by transposition cocontraction) with Y split
procedures to LR. A study done at our
centre has shown LR periosteal fixation C With upshoot and downshoot MR recession as per FDT and LR
to be effective surgery to correct the 2 A Exo DRS recession / LR recession with Y split
exodeviation, anomalous head posture
and improving adduction in Exo DRS and LR weakening (periosteal fixation/
partial VRT in addition to be effective in supramaximal recession with pVRT
improving abduction and binocular single
visual field10. B Exo DRS with normal LR activity LR recession with Y split, with pVRT
with upshoot and downshoot
Ortho DRS
3. Ortho DRS Symmetrical recession of MR (with
These patients are orthophoric in adjustable sutures) and LR with Y split
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7. Yonghong J, Kanxing Z, Zhenchang W,
Xiao W, Xuehan Q, Fengyuan M, et al.
Detailed magnetic resonance imaging
findings of the ocular motor nerves in
Duane’s retraction syndrome. J Pediatr

Gaur N et al. Duane’s Retraction Syndrome www. dosonline.org 25

Review Articles

Retinoblastoma: Diagnosis and Management

Raksha Rao MS1, Santosh G Honavar MD2

1. Chaithanya Eye Hospital and Research Institute, Trivandrum.
2. National Retinoblastoma Foundation, Ocular Oncology Service, Centre for Sight, Hyderabad, India.

Abstract: Retinoblastoma is the most common intraocular malignancy of childhood. The treatment of retinoblastoma is
multimodal. Since the introduction of intravenous chemotherapy in the mid-90’s, it has been the most extensively used eye-
saving modality of treatment. Periocular and intravitreal chemotherapy have emerged as treatment for recurrent seeds in
retinoblastoma. Intra-arterial chemotherapy is a alternative for advanced and refractory retinoblastoma. Radiation in the
form of external beam radiotherapy and plaque radiotherapy are also used in refractory retinoblastoma. Enucleation still
continues to play a role in advanced cases in eyes with no useful vision. The management of retinoblastoma is thus aimed at
not only to save life, but also to preserve eye, and optimize residual vision.

Retinoblastoma is an ocular malignancy with visualize, it grows to become opaque and white. In the exophytic
a well-established genetic mutation. RB1 is a growth pattern, the tumor causes diffuse retinal detachment
tumor suppressor gene, implicated in the genesis (Figure 1A), and is frequently associated with small subretinal
of retinoblastoma, located in the long arm of seeds. In contrast, an endophytic retinoblastoma progressively
chromosome 13 (13q). Heritable retinoblastoma fills the vitreous cavity to cause vitreous seeding (Figure 1B).
constitutes 30-40% of all retinoblastomas, while At times, the tumor maybe a combination of these two growth
the rest 60-70% are non-heritable. In heritable retinoblastoma, patterns. Diffuse infiltrating retinoblastoma is a rare pattern of
the mutation is present in the germ cell which is carried in presentation where there is no obvious mass, only a flat retinal
every cell in the body, making the patients prone for, apart infiltration, and is acalcific. It is generally seen in older children,
from retinoblastoma, other second cancers (most commonly and the incidence is less than 2%.
pinealoblastoma, osteosarcoma and soft tissue sarcomas)1.
The incidence of retinoblastoma is 1 in every 15000 to 18000 Patients with advanced tumor can have anterior extension
live births2. There are an estimated 5000 new cases worldwide of the tumor with anterior chamber cells, neovascularization of
annually, with India alone contributing to 1500-2000 cases. iris and glaucoma (Figure 1C), or an orbital cellulitis-like picture
(Figure 1D). Retinoblastoma which has extended outside the
Clinical Features confines of the eye is known as orbital retinoblastoma and this
can occur when the tumor invades either the optic nerve, or full
Retinoblastoma is usually diagnosed at an average age thickness of the sclera and beyond, and the patient generally
of 18 months, with 95% of children diagnosed by 5 years of age. presents with proptosis.
Germline retinoblastomas can present as early as first month
and sporadic retinoblastomas are detected at an average age Grouping and Staging
of 24 months2. Retinoblastoma can be unilateral or bilateral.
The most common presenting symptom and sign is leukocoria, The grouping system is for retinoblastoma confined
and strabismus is the second most common sign. The other to the eye, where eye salvage is the end-point, whereas
common clinical features are as listed in Table 1. the staging system is for predicting survival in patients

A child with a suspicious retinoblastoma is best
examined under anesthesia for a detailed fundus evaluation.
Retinoblastoma typically manifests as a unifocal or multifocal,
well-circumscribed, dome-shaped retinal mass with dilated
retinal vessels. Although initially transparent and difficult to

Table 1: Clinical features of Retinoblastoma Figure 1: Clinical presentation of retinoblastoma (A) Exophytic growth
Leukocoria pattern with diffuse subretinal fluid (B) Endophytic growth pattern with
Strabismus diffuse vitreous seeds (C) Advanced retinoblastoma with neovascular
Poor vision glaucoma (D) Advanced retinoblastoma presenting as sterile orbital
Red painful eye cellulitis.
Vitreous hemorrhage
Phthisis bulbi Rao R et al. Retinoblastoma
Sterile orbital cellulitis
Proptosis

26 DOS Times - July-August 2017

Review Articles

with retinoblastoma. International Table 2: International Classification of Retinoblastoma
Classification of Retinoblastoma (ICRB) Group A: Small tumor Retinoblastoma (Rb) ≤3 mm in size
was devised in 2003 and includes both
grouping and staging3. The grouping is Group B: Larger tumor Rb >3 mm,
based on the tumor size, location, severity Group C: Focal seeds
and presence of subretinal and vitreous Macular location (≤3 mm to foveola),
seeds (Table 2). Juxtapapillary location (≤1.5 mm to disc)
Clear subretinal fluid ≤3 mm from margin
Management
Subretinal seeds ≤3 mm from retinal tumor
The management of a child with Vitreous seeds ≤3 mm from retinal tumor
retinoblastoma is aimed at achieving Subretinal & Vitreous seeds ≤3 mm from retinal tumor
the three sequential goals of life salvage,
eye salvage, and optimal vision. The Group D: Diffuse seeds Subretinal seeds >3 mm from retinal tumor
management involves the identification Vitreous seeds > 3 mm from retinal tumor
of the tumor group and stage, decision- Subretinal & Vitreous seeds >3 mm from retinal tumor
making regarding the appropriate
therapeutic measure, and meticulous Group E: Extensive Rb occupying 50% globe
follow-up for monitoring the treatment retinoblastoma Neovascular glaucoma,
progress and detection of any recurrence. Opaque media (from hemorrhage in anterior chamber,
vitreous, or subretinal space)
Imaging Invasion of postlaminar optic nerve, choroid (2 mm), sclera,
orbit, anterior chamber
While the diagnosis of retinoblastoma
is mostly clinical, ancillary tests like Staging:
ultrasonography, fluorescein angiography
(FA), optical coherence tomography Stage 0 Unilateral or bilateral retinoblastoma and no enucleation
(OCT), computed tomography (CT) and
magnetic resonance imaging (MRI) aid Stage I Enucleation with complete histological resection
in the documentation of the disease and
differentiation of pseudoretinoblastomas Stage II Enucleation with microscopic tumor residual (anterior
from retinoblastoma. CT scan also helps chamber, choroid, optic nerve, sclera)
to diagnose extraocular extension,
while MRI is most appropriate to Stage III Regional extension
detect optic nerve invasion and to A. Overt orbital disease
screen for pinealoblastoma in heritable B. Preauricular or cervical lymph node extension
retinoblastoma.
Stage IV Metastatic disease
Intravenous Chemotherapy A. Hematogenous metastasis
1. Single lesion
Currently, IVC is the most widely 2. Multiple lesions
used treatment in India (Table 3). Used B. CNS extension
as a combination triple drug therapy of 1. Prechiasmatic lesion
vincristine, etoposide and carboplatin, 2. CNS mass
chemotherapy with focal consolidation 3. Leptomeningeal disease
achieves excellent success rates in the
primary management of retinoblastoma. Figure 2: Standard-dose chemotherapy in retinoblastoma (A) A group B eye (B) After 6 cycles of
Chemotherapy alone can achieve standard-dose chemotherapy (C) A group C eye with focal vitreous seeds (D) After 6 cycles of
an impressive tumor control in less standard-dose chemotherapy.
advanced cases, with success rates of
100%, 93% and 90% in ICRB groups A,
B and C, respectively (Figures 2A-D)4,5,6.
Rates of regression of retinoblastoma
and eye salvage with standard triple-drug
chemotherapy have been suboptimal for
ICRB group D and E tumors.

Periocular injection of carboplatin
or topotecan injection results in higher
intravitreal drug level. Transscleral
penetration of posterior sub-Tenon
carboplatin leads to augmented vitreous
concentration. High-dose chemotherapy
with concurrent periocular chemotherapy
can lead to higher eye salvage in group D
and E eyes.

Rao R et al. Retinoblastoma www. dosonline.org 27

Review Articles

Table 3: Intravenous Chemotherapy Intravitreal Chemotherapy

Procedure: Vitreous seeds are aggregates
IVC when given as a primary treatment for retinoblastoma causes reduction in tumor of tumor cells found in the avascular
volume, and this is known as chemoreduction (CRD). Most commonly, a combination vitreous, which are relatively resistant to
of three drugs of standard dose (SD) is used, although high dose (HD) may be the effect of intravenous chemotherapy
necessary in advanced cases or tumors not responding to SD. due to lack of blood supply. Intravitreal
chemotherapy (IVitC) provides a high
Drugs: concentration of the chemotherapeutic
Triple drug combination therapy of vincristine, etoposide and carboplatin (VEC) is drug in the vitreous. Melphalan is now
employed, generally given 4 weekly for 6 cycles. the most extensively used drug to control
Day 1: Vincristine + Etoposide + Carboplatin the vitreous disease in retinoblastoma
Day 2: Etoposide by a potentially safe technique to
perform intravitreal injections to prevent
Drug SD-VEC SD-VEC HD-VEC extraocular extension of the tumor
(≥3 years of age) (< 3 years of age) (Figure 4A-D)10. The authors have used
topotecan in achieving vitreous seed
Vincristine* 1.5 mg/m2 0.05 mg/kg 0.025 mg/Kg regression in 36 eyes.
Etoposide 150 mg/m2 5 mg/kg 12 mg/Kg
Carboplatin 560 mg/m2 18.6 mg/kg 28 mg/Kg

*maximum dose < 2 mg Radiation Therapy

Indications: Retinoblastoma is a highly
(1) Primary tumor (2) Recurrent tumor (3) Recurrent subretinal seeds (4) As adjuvant radiosensitive tumor, and radiation
therapy in post-enucleation patients with high-risk features (discussed elsewhere) therapy can be curative. Radiation in the
(5) Orbital retinoblastoma (6) As palliative therapy in metastatic retinoblastoma form of External Beam Radiotherapy
(EBRT) was the most popular globe-
Advantages: salvage therapy in retinoblastoma before
(1) Long-term tumor control (2) Reduces incidence of pinealoblastoma (3) Reduces the introduction of chemotherapy in
incidence of second cancers (4) Reduces incidence of systemic metastasis

Disadvantages: 1990s. Although it is no longer the primary

(1) Systemic side-effects including thrombocytopenia, leucopenia and anemia (2) modality of treatment for retinoblastoma

Allergic reactions to carboplatin and etoposide (3) Long-term effects include hearing due to the associated complications, it is

loss, renal toxicity and secondary leukemia used as a part of multimodal treatment

for advanced retinoblastoma.

Intra-arterial Chemotherapy responded adequately to IVC. Shields et Episcleral plaque radiotherapy is

Suzuki and Kaneko described the al observed 94% globe salvage in group D a form of brachytherapy wherein the
technique of ‘selective ophthalmic artery eyes8,9. IAC also seems to be more effective source of radiation is placed on the
infusion’ (SOAI) of the chemotherapeutic in eyes that have failed to respond to episclera adjacent to the tumor, and
previous therapies. the tumor absorbs radiation, sparing
drugs in 2004 by the balloon technique.

In 2006, Abramson and Gobin pioneered

direct intra-arterial (ophthalmic artery)

infusion or superselective intra-arterial

chemotherapy or “chemosurgery”7. The

decision to treat with IAC is undertaken

in consultation with an ocular oncology

team, an endovascular neurosurgeon and

a paediatric oncologist. The procedure

is performed under general anesthesia

using a sterile technique (Figures 3A-

D). Through a transfemoral approach,

the ipsilateral internal carotid artery

is catheterized with a 4F pediatric

guide catheter. The arterial anatomy is

visualized with serial angiography runs,

and the ostium of the ophthalmic artery

is super selectively catheterized. Each

chemotherapy dose is administered in a

pulsatile fashion over 30 minutes.

IAC has emerged as an effective

treatment for advanced retinoblastoma.

It is increasingly being used in tumors Figure 3: Intra-arterial chemotherapy: Procedure in the Cath lab (A) Patient under general
as a primary treatment, especially in anesthesia with a transfemoral catheter (B) An angiography performed at the beginning of the
unilateral retinoblastoma. It can be procedure, showing a patent internal carotid artery (C) An angiography performed with the
used as a secondary therapy for those microcatheter at the ostium of the ophthalmic artery, showing a patent ophthalmic artery (D)
cases which have recurred or have not Infusion of the chemotherapeutic drug through the transfemoral catheter.

28 DOS Times - July-August 2017 Rao R et al. Retinoblastoma

Review Articles

Figure 4: Intravitreal chemotherapy: Safety-enhanced technique (A) Figure 5: Multimodal management in orbital retinoblastoma (A)
Pars plana intravitreal injection of topotecan at a dose of 30 μg in 0.15 External photograph of primary orbital retinoblastoma taken during
ml with a 30-gauge needle (B) Needle is withdrawn through the first examination under anesthesia (B) Axial computed tomography image
ice ball of the cryotherapy (C) Triple freeze-thaw cryotherapy at the displaying extraocular extension of the intraocular tumor (C) After 12
injection site (D) Forceps-assisted jiggling of the eyeball following the cycles of doses of high-dose chemotherapy, external beam radiotherapy
injection for an even dispersion of the chemotherapeutic drug. and enucleation (D) Healthy child cured of orbital retinoblastoma,
with a well-fitting prosthesis.

other healthy ocular tissues from the ill- chemotherapy has been emphasized poor prognosis. Orbital disease increases
effects of radiation11. Radioisotopes like to reduce the risk of secondary orbital the risk of systemic metastasis by 10-27
Iodine-125 and Ruthenium-106 that emit recurrence and systemic metastasis12. times and the mortality rates range from
radiation are used for the treatment of The incidence of metastasis was 4% in 25 to 100%. However, with an intensive
small recurrent retinoblastoma. those who received adjuvant therapy, multimodal management and careful
compared with 24% in those who did not. monitoring, patients with orbital disease
Focal Therapy Hence when HRF is positive, adjuvant are known to do well (Figures 5A-D).
treatment with chemotherapy and/ or
The use of cryotherapy, EBRT is indicated (Table 4). Adjuvant Prenatal Genetics
Transpupillary thermotherapy (TTT), chemotherapy consists of a combination
and laser therapy in the treatment of of vincristine, etoposide and carboplatin To prevent transmission of the
retinoblastoma is for consolidation of given 4-weekly for 6 cycles. disease from parents to offspring,
the tumor, once it attains a considerably genetic testing for germline mutations
lower volume after chemoreduction. Orbital Retinoblastoma can be done at specialized laboratories.
Transscleral cryotherapy involves RB1 is the only gene that is implicated
freezing the tumor under visualization Orbital retinoblastoma is an in retinoblastoma. Peripheral blood
using indirect ophthalmoscopy. In TTT, advanced form of retinoblastoma seen lymphocytes or tumor tissue, when
the hyperthermia generated by infrared mostly in developing countries of Asia available, are sampled for the detection
radiation at sub-photocoagulation levels and Africa. The incidence varies among of the mutation. Preimplantation genetic
destroys the tumor. Photocoagulation different countries, and is in the range testing for carriers of mutation involves
using argon green laser (532 nm) of 18-40%13. The presence of orbital the identification of RB1 mutation in
delivered with an indirect laser delivery disease is generally known to carry a a blastomere (8-cell embryo) which is
system causes tumor apoptosis. obtained by in vitro fertilization (IVF)
Table 4: High Risk Features on technique. The small material is amplified
Enucleation pathology where adjuvant therapy by polymerase chain reaction (PCR) and
the blastomere without the RB1 mutation
Enucleation is the oldest form of is indicated maybe implanted for a successful
treatment for retinoblastoma, and is still pregnancy.
indicated in advanced cases. Unilateral Anterior segment invasion
disease with no salvageable vision is Ciliary body infiltration Conclusion
best treated by enucleation and the Massive choroidal invasion (invasion ≥
patient can be cured of the disease for 3 mm in basal diameter or thickness) The management of retinoblastoma
life. Enucleation is a simple procedure, revolves around having a sound
although special precautions need to Full thickness scleral extension knowledge of the disease, choosing the
be taken when handling an eye with best treatment for the patient among
retinoblastoma to avoid accidental Extra-scleral extension the various available options and
perforation that can potentially cause careful monitoring for recurrences.
orbital seeding of the tumor. Retrolaminar optic nerve invasion Retinoblastoma has a very high cure rate,
and is best managed in an integrated
An enucleated eyeball is always Optic nerve invasion at line of retinoblastoma clinic under the watchful
submitted for pathology to assess for high transection monitoring of an expert ocular oncologist.
risk factors (HRF). In a landmark paper Combination of optic nerve infiltration
by Honavar et al, the need for adjuvant till any level (pre-laminar/ laminar/
retrolaminar) and choroidal infiltration
(any thickness)

Rao R et al. Retinoblastoma www. dosonline.org 29

Review Articles

References intravenous chemoreduction, and of the needle track. Br J Ophthalmol
2012;96:1084-1087.
1. Nichols KE, Walther S, Chao E, Shields intra-arterial chemotherapy. Curr Opin 11. Shields CL, Shields JA, Cater J,
C, Ganguly A. Recent advances in Othmane I, Singh AD, Micaily B. Plaque
retinoblastoma genetic research. Curr Ophthalmol. 2010;21:203-12 radiotherapy for retinoblastoma: long-
Opin Ophthalmol 2009;20:351-5. term tumor control and treatment
7. Abramson DH, Marr BP, Dunkel IJ, complications in 208 tumors.
2. Shields J, Shields C: Retinoblastoma: Ophthalmology 2001;108:2116-21.
introduction, genetics, clinical features, Brodie S, Zabor EC, Driscoll SJ, Gobin 12. Honavar SG, Singh AD, Shields CL,
classification. In Shields J, Shields Demirci H, Smith AF, Shields JA. Post-
C, Atlas of intraocular tumors, 3ed. YP. Intra-arterial chemotherapy for enucleation prophylactic chemotherapy
Philadelphia, PA: Lippinoctt, Wolters in high-risk retinoblastoma. Arch
Kluwer; 2016. retinoblastoma in eyes with vitreous Ophthalmol 2002;120:923-31.
13. Honavar SG. Orbital retinoblastoma.
3. Chantada G, Doz F, Antoneli CB, and/or subretinal seeding: 2-year In Singh AD, Murphee LA, Damato
Grundy R, Clare Stannard FF, Dunkel BE. Clinical Ophthalmic Oncology-
IJ et al. A proposal for an international results. Br J Ophthalmol 2012;96:499- Retinoblastoma, 2ed. NY: Springer;
retinoblastoma staging system. Pediatr 2015.
Blood Cancer. 2006;47:801-5. 502.
Correspondence to:
4. Shields CL, Mashayekhi A, Au 8. Shields CL, Jorge R, Say EA, Magrath Dr. Santosh Honavar
AK, Czyz C, Leahey A, Meadows National Retinoblastoma Foundation,
AT, Shields JA. The International G, Alset A, Caywood E et al. Unilateral Ocular Oncology Service, Centre for Sight,
Classification of Retinoblastoma Banjara Hills, Hyderabad, India
predicts chemoreduction success. retinoblastoma managed with
Ophthalmology. 2006;113:2276-80
intravenous chemotherapy versus
5. Shields CL, Fulco EM, Arias JD,
Alarcon C, Pellegrini M, Rishi P et intra-arterial chemotherapy:
al. Retinoblastoma frontiers with
intravenous, intra-arterial, periocular, outcomes based on the international
and intravitreal chemotherapy. Eye classification of retinoblastoma. Asia
(Lond). 2013;27:253-64.
Pac J Ophthalmol 2016;5:97-103.
6. Shields CL, Shields JA. Retinoblastoma
management: advances in enucleation, 9. Shields CL, Kaliki S, Al-Dahmash
S, Rojanaporn D, Leahey A, Griffin

G et al. Management of advanced

retinoblastoma with intravenous

chemotherapy then intra-arterial

chemotherapy as alternative to

enucleation. Retina 2013;33:2103-9.

10. Munier FL, Soliman S, Moulin AP,

Gaillard MC, Balmer A, Beck-Popovic
M. Profiling safety of intravitreal

injections for retinoblastoma using an
anti-reflux procedure and sterilisation

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30 DOS Times - July-August 2017 Rao R et al. Retinoblastoma

Review Articles

Superior Oblique Palsy: Diagnosis and
Management

Rebika Dhiman MD, Anita Ganger MD, Mayank Jain MBBS, Rohit Saxena MD
Dr Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India

Abstract: Superior oblique palsy (SOP) is the most common cyclovertical muscle palsy encountered in ophthalmic practice.
All cases of acute onset SOP need to be thoroughly evaluated for the underlying etiology. Neuroimaging should be advised in
young onset SOP, and/or as deemed necessary by the treating ophthalmologist. Superior oblique surgery is one of the most
challenging surgeries. However, when performed with appropriate clinical indication may result in optimal clinical outcome.

Superior oblique palsy (SOP) is the most common brainstem contralaterally just past the vertical midline.
cause of ocular torticollis in children, and the most Subarachnoid space- The subarachnoid segment of the
frequent cyclo-vertical muscle palsy encountered
in ophthalmic practice1. It may be congenital or trochlear nerve then courses around the midbrain and passes
acquired. Superior oblique muscle (SO) is supplied anteriorly along the edge of the cerebellar tentorium.
by the fourth cranial nerve, also known as the
trochlear nerve, that is purely motor in function. Superior Cavernous sinus (Intracavernous)- It then travels in the
oblique muscle is primarily an intorter, a depressor and lateral wall of the contralateral cavernous sinus, below the
abductor. Hence, a superior oblique palsy causes oculomotor nerve and above the first division of the fifth cranial
• Excyclotorsion, nerve, on its way to the superior orbital fissure.
• Hypertropia, and
• Esotropia of the involved eye. Orbit (Infraorbital)- After entering the orbit through the
There is a considerable variation in the treatment of lateral part of the superior orbital fissure, the nerve passes
this disorder. High-definition radiological studies have given medially and ends by supplying the superior oblique muscle2-5.
us a better understanding of the patho-physiology of SOP,
influencing its diagnosis and treatment. Hence, in the light of The involvement of the fourth cranial nerve anywhere
recent literature, this article highlights the current perspective along its course or of the superior oblique muscle causes
in the diagnosis and management of superior oblique palsy. superior oblique palsy.
The search of published literature for this review article
had been completed using Ovid, Medline, Embase, Pubmed over Etiology
the last 5 decades along with the checking of cross references. • Congenital- Congenital fourth nerve palsies are particularly
English language articles with full text access were included and
electronic literature search was performed using fourth nerve common in clinical practice due to the slender size and
palsy, trochlear nerve, superior oblique palsy and management long circuitous anatomical course taken by the developing
as key words. While reviewing the literature, parameters fourth cranial nerve6,7. High definition magnetic resonance
evaluated were: applied neuroanatomy, etiology, medical and imaging (MRI) studies have identified two groups of
surgical management for trochlear nerve palsy. congenital SOP. The most frequent type, present in 73%
of cases, is a Congenital Cranial Dysinnervation Syndrome
Applied Neuroanatomy (CCDS) where the trochlear nerve is absent and results
in secondary atrophy of the superior oblique muscle
Trochlear nerve is the longest and the thinnest of all (Figure 1). The second type has a normal trochlear nerve
cranial nerves. Unlike the other cranial nerves, trochlear nerve and size of the superior oblique muscle, but presumably
crosses completely to the opposite side during its course and has an abnormal superior oblique tendon (e.g., tendon
arises from the dorsal aspect of the midbrain. laxity)8.
• Traumatic- Trauma frequently causes bilateral SOP due to
Nucleus- The fourth nerve nucleus lies in the lower an impact in the anterior medullary velum, where the two
midbrain at the level of the inferior colliculus, near the midline,
just anterior to the cerebral aqueduct. There is one nucleus Figure 1: MRI image of the orbit (coronal section) showing a reduced
on each side corresponding to the cell bodies of the neurons bulk of the muscle on the affected side as compared to the fellow eye
comprising each trochlear nerve. in a case of a congenital left SOP.

Fasciculus- In contrast to the third nerve fascicles, which
course anteriorly, the fourth nerve fascicles course posteriorly
around the cerebral aqueduct, decussate in the anterior
medullary velum and cross the midline to emerge from the

Dhiman R et al. Superior oblique palsy www. dosonline.org 31

Review Articles (A) (C)
(B) (E)
nerves decussate. It could be a mild concussion or a direct (D)
trauma to the trochlea.
• Idiopathic Figure 2: Parks 3-step test: (A) Left hypertropia in primary position;
• Vascular- Microvascular palsies are thought to occur (B&C) Hypertropia increases on dextroversion; (D&E) Hypertropia
most often in adults 50 years of age or older with existing increases on left head tilt, suggestive of left SOP.
vascular risk factors.
• Neurologic Figure 3: Clinical photographs of a patient with a bilateral SOP showing
alternating hypertropia and superior oblique underaction in both eyes.
Clinical features
need neuroimaging to identify the underlying cause.
Symptoms-In acquired SOP, patient complains of vertical Although the presence of vasculopathic risk factors in
or torsional diplopia maximum in downgaze. If the chief patients >50 years is a significant predictor for a presumed
complaint is torsion, bilateral palsy should be considered. Other microvascular cause, a substantial proportion of patients
non-specific complaints may include asthenopia or cervical with other causes were found in a recent study regardless
discomfort. of vasculopathic risk factors. Hence, neuroimaging is now
recommended in all patients presenting with acute onset
Signs- Superior oblique palsy is characterized by ocular motor neuropathy16,17,18.
hypertropia of the involved eye that increases in the opposite Bilateral superior oblique palsy: Bilateral SOP
field of gaze (i.e., in adduction of the paretic eye), and during (Figure 3) should be suspected in a patient with one or more of
ipsilateral head tilt. Consequently, patients maintain a head the following features:
tilt to the opposite side that enables them to compensate for • SOP following closed head trauma
the hypertropia9. The abnormalities in the version movement • Subjective complain of torsion
observed are underaction of ipsilateral superior oblique and • Alternating hypertropia on head tilt
overaction of ipsilateral inferior oblique with correlative • V-pattern esotropia
excyclotorsion. • Chin down head posture
• Objective torsion ≥10 degrees
Diagnosis
Congenital superior oblique palsy
I. Park’s three-step test. Bielschowsky described Despite its congenital origin, this condition may first
characteristic changes in the hypertropia with head tilt
as a means of diagnosing paresis of the superior oblique come to medical attention during teenage or adult years, when
muscle10. Parks later described his 3-step test that used diplopia, asthenopia, or headache develops from a combination
this phenomenon in a broader sense to help the clinician of spontaneous decompensation and superior rectus
identify which paretic cyclovertical muscle could cause contracture19. A characteristic facial asymmetry, especially
such a hyperdeviation11. For left SOP (Figure 2), shallowing of the mid-facial region, is usually seen on the side
of the tilt (Figure 4). Table 1 shows the differentiating points
1. Left hypertropia in primary position between congenital and acquired SOP.
2. Hypertropia increases on dextroversion (worse on
Dhiman R et al. Superior oblique palsy
opposite gaze)
3. Hypertropia increases on left tilt (worse on ipsilateral

tilt)
However, several limitations of these tests have become
apparent over time. Various studies have indicated the lack
of specificity of 3-step test in diagnosing SOP12,13 especially
bilateral SOP14. A recent study has reported 40% sensitivity
for Beilschowsky’s head tilt test and 24% sensitivity for Parks
3-step test in diagnosing bilateral superior oblique palsy15.
II. Torsion- Torsion can be assessed subjectively (Double
Maddox Rod, Synoptophore), or objectively (Indirect
ophthalmoscopy; Fundus photograph. Important points to
consider are:
1. Congenital SOP frequently has little or no measurable

subjective torsion.
2. Complain of torsional diplopia or a torsion ≥10 degree

is suggestive of a bilateral SOP.
III. Diplopia charting
IV. Hess/Lees’ Charting
V. Oblique traction test (Exaggerated forced duction test) is

an important clinical test to identify lax superior oblique
tendon in SOP that may be corrected by superior oblique
tuck.
VI. Neuroimaging- The decision to perform neuroimaging in
patients who present acutely with ocular motor cranial
palsy is based on age at presentation, which nerve is
involved and pertinent past medical history. All patients <50
years with acute ocular motor cranial nerve involvement

32 DOS Times - July-August 2017

Review Articles

Table 1: Differences between congenital and acquired SOP

Congenital Acquired

Onset Since Birth Any age

Etiology CCDS, abnormal SO tendon Traumatic, Idiopathic,
Vascular, Neurologic

Facial asymmetry Present on the side of the tilt Absent
from contracture of facial
muscles

Head tilt Present since infancy (old Anytime later following the
photographs) onset

Subjective torsion Absent Usually Present

Diplopia Absent Usually Present
Fusional amplitude
Figure 4: Clinical photograph of a patient with Significantly increased (16-30 Normal (2-3 prism diopters)
congenital right SOP with left sided head tilt
and a characteristic facial asymmetry on the prism diopters)
side of the tilt.
Neuroimaging SO muscle volume may be Normal to slightly reduced
There are significant clinical
differences between the two groups of significantly reduced muscle volume
congenital SOP. In the first type with
an absent trochlear nerve, a greater Amblyopia in the May be present Usually absent
percentage have a head tilt, which is involved eye
present within the first year of life,
significant facial asymmetry, and more CCDS: Congenital Cranial Dysinnervation Syndromes; SO=Superior Oblique
hypertropia on ipsilateral head tilt.
Conversely, the second type of congenital Occlusion of the normal eye during two eyes in the primary gaze. The goals
SOP with a normal trochlear nerve the period of observation eliminates the and limitations of the surgery should
and muscle have more overaction of troublesome diplopia and past-pointing be clearly understood by the patient to
the inferior oblique muscle and higher associated with acute palsies. In children avoid disappointment. Several staged
frequency of dissociated vertical under the age of 6 sustained patching can procedures may be required to achieve
deviation. result in amblyopia, hence close follow- an optimal correction. Figure 5 describes
up is recommended23. Adult patients can the various types of surgical intervention
Differential diagnosis safely patch either eye without concern for SOP and their indications.
for amblyopia. Ocular motility exercises 1. Ipsilateral superior oblique tuck-
1. Primary inferior oblique overaction are sometimes recommended following
2. Brown syndrome an ischemic palsy, but there is no clinical Several studies advocate the
3. Skew deviation data to support the same24. strengthening of the SO muscle as the
4. Thyroid associated ophthalmopathy primary procedure to correct SOP
In non-recovering or residual when a lax SO tendon is identified,
Management trochlear nerve palsies, with a stable or when there is significant head
Medical management deviation for at least 6-12 months, tilt. SO tuck is titrated based on
surgical intervention may be considered. the intraoperative tension of the
Treatment initially involves medical superior oblique muscle with
management of systemic predisposing Surgical management an end point of inducing mild
factors and conservative measures to post-operative Brown syndrome,
obviate symptoms followed later by Superior oblique surgery is one which subsequently is expected
surgical intervention in non-resolving of the most challenging surgeries and to either disappears or becomes
trochlear nerve palsy. The patient should requires thorough knowledge of anatomy, insignificant over time27,28,29. Bhola et
be evaluated at each follow up with extensive experience, and appropriate al recommended isolated SO tendon
a complete squint work-up, diplopia preoperative decision-making in tuck for unilateral SOP and less than
charting and Hess-charting. view of possible complications and 15 Δ deviation in primary position30.
unpredictable outcomes. Its management Yet, many surgeons have reported
Ischemic neuropathies usually has been systematized by Von secondary Brown syndrome post-
resolve in 6 weeks to 3 months22 Noorden’s modification of the Knapp’s operatively. Currently this procedure
and can be treated conservatively. classification25,26. Main indications for is preferred in congenital SOP with a
Underlying systemic conditions should surgery in a fourth nerve palsy are a lax tendon.
be adequately controlled and managed significant head tilt, diplopia, decrease 2. Harada-Ito procedure is also a
to prevent further ocular morbidity. in binocular vision and dissociated strengthening procedure for SO,
Mononeuropathies with aneurysmal vertical deviation. A significant head employed for the correction of
compressions or other compressive tilt is the main indication for surgery excyclotorsion especially in bilateral
lesions require neurosurgical referral and in children younger than age 5, as it is SOP (Figure 6). The original method
intervention. thought that the uncorrected torticollis of correction was to anteriorize
will lead to progressive facial asymmetry. the anterior half of the SO tendon
The surgical procedure employed aims without disinsertion31. Fells modified
at achieving adequate alignment of the

Dhiman R et al. Superior oblique palsy www. dosonline.org 33

Review Articles

Figure 7: (A)Pre-operative 9 gaze clinical
photographs of the patient with right SOP
(B) Post-operative photograph of the patient
following IOANT in the right eye. (C) Pre-
operative fundus photograph of the right eye
showing excyclotorsion. (D) Post-operative
fundus photograph of the same eye showing
improvement in excyclotorsion.

Figure 5: Surgical management protocol for superior oblique palsy.

Figure 6: (A) Pre-operative 9 gaze clinical photographs of the patient with post-traumatic bilateral iatrogenic Brown syndrome.
superior oblique palsy and marked excyclotorsion; (B) Post-operative photograph of the patient 4. Anterior and nasal transposition
following bilateral Harada-Ito procedure.
(ANT) of ipsilateral IO (Figure 7).
this technique in 1974, whereby 3. Ipsilateral inferior oblique recession In the absence of significant vertical
the anterior half of the tendon was (IOR) can be performed especially deviation in the primary gaze
disinserted and moved forward and in the absence of SO tendon laxity, but significant torsional diplopia,
laterally32. Metz and Lerner33 later and in the presence of ipsilateral IO anterior and nasal transposition
reported using the adjustable suture overaction. In their retrospective of the inferior oblique may be
technique with this procedure. series, Kaeser et al35 compared the undertaken as described by Stager36.
Harada-Ito procedure is on the basis surgical results of inferior oblique This procedure converts the IO
that the anterior fibers of the SO recession alone, with those of inferior muscle from an extorter and elevator
contribute to the torsional action oblique recession combined with in adduction to an intorter and tonic
while the posterior fibers contribute superior oblique tuck in patients depressor in adduction. Extreme
to the vertical action34. It corrects with congenital superior oblique ANT may induce exotropia in the
around 10 degrees of excyclotorsion palsy and found that inferior oblique primary position. Adjustable ANT
in primary gaze and 15-20 degrees recession alone is an appropriate has been described for a case of SOP
in downgaze. procedure with a low incidence of to obviate torsional diplopia37.
5. Recession of ipsilateral superior
rectus (SR) can be considered in
cases where the superior rectus
is tight due to long standing
hypertropia.
6. Recession of contralateral inferior
rectus (IR) is an effective treatment
for superior oblique palsy with
hypertropia greatest across the
lower fields of gaze (Knapp Class V
SOP)38.
The critical surgical step for patients
with fourth nerve palsy is to decide
whether to perform a single-muscle
or two-muscle surgery. The decision
depends on the magnitude of hypertropia
in primary position and side gaze, and the
presence of torsion39,40.

Conclusion

Superior oblique palsy is a common
occurrence in clinical practice. It is

34 DOS Times - July-August 2017 Dhiman R et al. Superior oblique palsy

Review Articles

essential to rule out an underlying 14. Sydnor CF, Seaber JH, Buckley EG. 29. Li Y, Zhao K. Superior oblique tucking
etiology in acute onset SOP followed
by the adequate referral for the same. Traumatic superior obliquepalsies. for treatment of superior oblique palsy.
One should not hesitate to order
neuroimaging at the slightest doubt of Ophthalmology 1982;89:134–138. J Pediatr Ophthalmol Strabismus.
an intracranial lesion. Superior oblique
muscle surgery may result in good 15. Muthusamy B, Irsch K, Chang HP, 2014;51:249–254.
clinical outcomes when performed with
appropriate clinical indications and for DAVID L. Guyton DL. The Sensitivity 30. Bhola R, Velez FG, Rosenbaum AL.
selected cases. The choice of surgical
method should be individualized in order of the Bielschowsky Head-Tilt Test in Isolated superior oblique tucking: an
to avoid complications.
Diagnosing Acquired Bilateral Superior effective procedure for superior oblique

Oblique Paresis. Am J Ophthalmol. palsy with profound superior oblique

2014;157:901–907. underaction. JAAPOS. 2005;9:243-249.

16. Chou KL, Galetta SL, Liu GT, Volpe NJ, 31. Harada M, Ito Y. Surgical Correction

Bennett JL, Asbury AK, Balcer LJ. Acute of Cyclotropia. Japan Journal

ocular motor mononeuropathies: Ophthalmology. 1964;8:88-96.

prospective study of the roles of 32. Fells P. Management of Paralytic

neuroimaging and clinical assessment. Strabismus. British Journal

J Neurol Sci. 2004;219:35–39. Ophthalmology. 1974; 58:255-265.

References 17. Tamhankar MA, Volpe NJ. Management 33. Metz HS, Lerner H. The adjustable

of acute cranial nerve 3, 4 and 6 palsies: Harada-Ito procedure. Arch

1. Helveston EM, Mora JS, Lipsky SN, role of neuroimaging. Curr Opin Ophthalmol. 1981;99:624-626.

Plager DA, Ellis FD, Sprunger DT, Sondhi Ophthalmol. 2015;26:464-468. 34. Fink WH. Surgery of the Oblique

N. Surgical treatment of superior 18. Ray D, Gupta A, Sachdeva V, Muscles of the Eye. Am J Ophthalmol.

oblique palsy. Trans Am Ophthalmol Kekunnaya R. Superior Oblique Palsy: 1951;34:261-281.

Soc. 1996;94:315–328. Epidemiology and Clinical Spectrum 35. Kaeser PF, Klainguti G, Kolling GH.

2. Prasad S, Volpe NJ. Paralytic strabismus: From a Tertiary Eye Care Center in Inferior oblique muscle recession

third, fourth, and sixth nerve palsy. South India. Asia Pac J Ophthalmol with and without superior oblique

Neurol Clin. 2010;28:803–833. (Phila). 2014;3:158-163. tendon tuck for treatment of unilateral

3. Adams ME, Linn J, Yousry I. Pathology 19. Brodsky MC. Ocular motor nerve congenital superior oblique palsy.

of the ocular motor nerves III, IV, palsies in children. In: Pediatric neuro- JAAPOS 2012;16:26-31.

and VI. Neuroimaging Clin N Am. ophthalmology. 2nd ed. New York: 36. Stager DR Jr, Beauchamp GR, Wright

2008;18:261–282. Springer; 2010. p. 253–308. WW, Felius J, Stager D Sr. Anterior

4. Bennett JL, Pelak VS. Palsies of the 20. Wallace DK, Von Noorden GK. and nasal transposition of the inferior

third, fourth, and sixth cranialnerves. Clinical characteristics and oblique muscles. JAAPOS 2003;7:167-

Ophthalmol Clin North Am. surgicalmanagement of congenital 73.

2001;14:169–185. absence of the superior obliquetendon. 37. Saxena R, Singh D, Chandra A, Sharma

5. Brazis PW, Masdeu JC, Biller J. Am J Ophthalmol. 1994;118:63–69. P. Adjustable anterior and nasal

Localization in Clinical Neurology. 21. Mottier ME, Mets MB. Vertical fusional transposition of inferior oblique

Philadelphia, PA: Lippincott Williams & vergences in patients with superior muscle in case of torsional diplopia in

Wilkins; 2011:173–303. oblique palsies. Am Orthopt J. superior oblique palsy. Indian J Clinical

6. Holmes JM, Mutyala S, Mous TL, 1990;40:88–93. and Experimental Ophthalmology.

Grill R, Hodge DO, Gray DT. Pediatric 22. Jacobson DM. Progressive 2015;1:104-106.

third, fourth, andsixth nerve palsies: ophthalmoplegia with acute ischemic 38. Mahmoud TA, Flanders M. Treatment

a population-based study. Am J abducens nerve palsies. Am J of Knapp Class V superior oblique

Opthtalmol.1999;127:388–92. Ophthalmol. 1996;122:278–279. palsy with contralateral inferior rectus

7. Von Noorden GK, Campos EC. Binocular 23. Levi DM, Knill DC, Bavelier D. Stereopsis muscle recession. Can J Ophthalmol.

vision andocular motility. 6th ed. New and amblyopia: A mini-review. Vision 2009;44(3):320-322.

York: C.V. Mosby; 2002. Res. 2015;114:17-30. 39. Saunders RA. When and how to

8. Yang HK, Kim JH, Hwang JM. 24. Rawstron JA, Burley CD, Elder MJ. A strengthen the superior oblique

Congenital superior oblique palsy and systematic review of theapplicability muscle. JAAPOS. 2009;13:430–437.
and efficacy of eye exercises. J Pediatr
trochlearnerve absence. A clinical and 40. Knapp P, Moore S. Diagnosis and

radiological study. Ophthalmology Ophthalmol Strabismus. 2005;42:82– surgical options in superior oblique

2012;119:170–177. 88. surgery. Int Ophthalmol Clin.

9. Von Noorden GK, Murray E, Wong 25. Knapp P, Moore S. Diagnosis and 1976;16:137–149.

SY. Superior oblique paralysis. A Surgical options in superior oblique

review of 270 cases. Arch Ophthalmol. surgery. Int Ophthalmol Clin.

1986;104:1771–6. 1976;16:137-149.

10. Bielschowsky A. Lectures on motor 26. Von Noorden G.K, Murray E, Wong SY.

anomalies of the eye. Arch Ophthalmol. Superior oblique paralysis. A review

1935;13:33–59. of 270 cases. Arch. Ophthalmol.

11. Parks MM. Isolated 1986;104:1771-1776.

cyclovertical muscle palsy. Arch 27. Saunders RA. When and how to

Ophthalmol.1958;60:1027-1035. strengthen the superior oblique

12. Kushner BJ. Errors in the three-step test muscle. JAAPOS 2009;13:430–437. Correspondence to:
Dr. Rohit Saxena,
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Dr. R. P. Centre for Ophthalmic Sciences,
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New Delhi, India.
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superior oblique palsy. Ann of superior oblique palsy. JAAPOS.

Ophthalmol.1981;13:337–343. 2013;17:e10.

Dhiman R et al. Superior oblique palsy www. dosonline.org 35

Review Articles

Diagnosis and Management of Retinopathy of
Prematurity

Parijat Chandra MD, Devesh Kumawat MD, Atul Kumar MD
Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences New Delhi, India

Abstract: Retinopathy of prematurity (ROP) is an important cause of preventable childhood blindness in our country. The
ROP classification, screening and treatment guidelines are well established. High quality neonatal care can prevent ROP and
effective ROP screening programs are essential to detect treatable ROP in time. Laser treatment of avascular retina ensures
good disease regression. Anti-VEGF drugs have proven useful in selected cases of ROP, though safety concerns still exist. Early
referral of advancing ROP for surgical management can give good outcomes. Though it is essential to establish a ROP screening
program in every NICU, yet lack of awareness/services for screening and treatment compounded with poor neonatal care is
leading to a huge increase in ROP blindness in India.

Retinopathy of prematurity (ROP) is an important Stages of ROP (Figure 2)
cause of childhood blindness in our country.
ROP occurs due to incomplete development • Stage 1 – Demarcation line between the vascular and
of retinal vasculature in preterm low birth avascular retina
weight babies. Though the important risk
factors for development of ROP are low birth • Stage 2- Demarcation ridge between the vascular and
weight and prematurity, other common risk factors include avascular retina
respiratory distress syndrome, apnea, hypotension, patent
ductus arteriosus (PDA), sepsis, necrotizing enterocolitis, • Stage 3–Extraretinal neovascularization and proliferation
pneumonia, meningitis, intraventricular hemorrhage, packed • Stage 4A – Subtotal retinal detachment not involving
cell transfusion, use of oxygen, continuous positive airway
pressure and positive pressure ventilation1. macula
While timely screening and treatment of ROP leads to • Stage 4B – Subtotal retinal detachment involving macula
good outcomes in these babies, yet lack of awareness among • Stage 5 – Total retinal detachment
ophthalmologists and neonatologists about ROP is leading to
huge ROP-related blindness2. India is now having the largest Plus disease- It is characterized by dilated tortuous
number of preterm births in the world which predisposes
a large number of babies to high risk of developing ROP3. In posterior pole vessels, iris vascular engorgement, pupillary
developing countries like India, while smaller babies develop
ROP due to advancement of neonatal care, now even larger rigidity and vitreous haze (Figure 3). Plus disease is a good
babies develop ROP due to poor neonatal practices4. Thus,
high quality neonatology care, an effective ROP screening and indicator of the activity of the disease and worsening plus
treatment programme is essential to prevent ROP-related
blindness5. disease can signify disease progression, while reduction of

plus disease may signify disease regression. Poor pupillary

ROP classification Figure 1: Zones of ROP.

The international classification of retinopathy of
prematurity (ICROP) group6 classifies ROP into zones and
stages on the basis of location of disease on retina and extent of

vascular proliferation.

Zones of ROP (Figure 1) Figure 2: Stages of ROP.

• Zone 1 - Circle drawn from centre of disc with a radius of
twice the distance from disc to macula.

• Zone 2 - From nasal edge of zone 1 to ora nasally and upto
equator temporally.

• Zone 3 –Temporal crescent of retina anterior to zone II.
Typically, smaller the zone, more severe is the disease

which occurs as there is a large area of avascular retina. The

disease is most commonly seen in zone 2.

Chandra P et al. Retinopathy of prematurity www. dosonline.org 37

Review Articles

Figure 3: APROP with Plus disease. weeks of age, primarily to detect APROP. Figure 4: Retcam digital screening.
Where to screen?– The ideal
dilation must always raise suspicion of Its diagnostic accuracy compares
plus disease. setting is always the NICU where the well with indirect ophthalmoscopy,
baby is admitted or comes for routine and many successful tele-screening
Pre-plus disease– The dilation and follow-up visits. The pediatrician can programs are running globally where
tortuosity of the posterior pole vessels is monitor vitals of the baby and deal with screening can be performed at peripheral
lesser than that observed in classical plus any emergency. However, in many eye centres and experts in a reading centre
disease, but is more than normal. Pre- hospitals, screening is being done on an can opine about treatment and follow-
plus disease can progress to plus disease outpatient basis as well - though in such up. The Stanford University Network
if the disease worsens. a scenario emergency equipment should for Diagnosis of Retinopathy of
be kept ready and a pediatrician on call Prematurity (SUNDROP) program8 and
Aggressive Posterior ROP (AP- should be available. Karnataka Internet Assisted Diagnosis
ROP)– This is a severe variant of ROP of Retinopathy of Prematurity (KIDROP)
which has an unpredictable course and How to Screen?- Screening is a program9 are successful examples of such
can often lead to rapid progression and stressful procedure for the baby and digital tele-screening programs.
blindness. It is characteristically seen in proper preparation is necessary. It is
smaller zones (zone 1 - zone 2 posterior), very important to take written informed How long to follow-up?- Long
with a featureless junction between consent from the parents and provide term follow up is essential, regardless of
the vascular and avascular retina, often them details of the procedure. The babies whether they have undergone treatment,
associated with multiple avascular loops, are kept fasting for 30-60 minutes prior to as these babies are at risk for developing
which can confuse beginners about the procedure. Pupillary dilatation should visual disorders later in life such as
the disease stage. However, notably be started an hour prior to screening strabismus, amblyopia, myopia and
plus disease is out of proportion to the using a combination of tropicamide cataract. The importance of follow-up and
severity seen at the junction. A high (0.5%) and phenylephrine (2.5%) drops, visual rehabilitation must be stressed to
index of suspicion for APROP should instilled 2-3 times about 10 minutes the parents.
be maintained and it should be treated apart. Beware of the non-dilating pupil,
promptly. which should raise suspicion of severe ROP treatment
plus disease and APROP.
ROP screening It is very important to treat ROP in
Screening is performed under a timely manner to prevent blindness. A
Since ROP has a well-defined topical anesthesia, assisted by a pediatric screening programme is the only way to
course and can occur in many high risk speculum and pediatric scleral depressor. detect treatable ROP in time
premature babies, an effective screening The procedure is to examine the anterior
program is the only way to detect ROP in segment (especially for pupillary dilation When to treat?- The Early Treatment
time and ensure prompt treatment. It is and tunica vasculosa lentis) and then For Retinopathy of Prematurity
essential that every neonatal intensive the posterior segment, starting with the Cooperative Group (ETROP) study10
care unit (NICU) should have a screening posterior pole (to look for plus disease) divided ROP into two types.
programme. and then identify the disease in all clock
hours of the retinal periphery. It is very
When to Screen?– Most screening essential to properly document all the
programs now follow the National ROP findings correctly in a record sheet.
Neonatology Forum (NNF) of India ROP
screening guidelines, which suggest that Further follow-up screening is done
we should screen all preterm babies <34 at 1-2 weeks (or lesser) depending on the
weeks gestational age or <1750 g birth zone, stage of ROP and post-conceptional
weight. Bigger babies of 34–36 weeks age. ROP screening is usually stopped
gestational age or 1750–2000g birth when complete retinal vascularization
weight should also be screened if they occurs (mature retina) or complete
have risk factors for developing ROP. regression of ROP is noted.

Whom to Screen?- NNF suggests Role of Digital ROP screening?-
that first retinal examination should be Digital screening has become popular
performed at not later than 4 weeks of now due to the relative ease of performing
age or 30 days of life. In infants born <28 ROP screening by trained technicians/
weeks gestation age or <1200 grams birth nurses, without the need for an
weight, they should be screened by 2-3 ophthalmologist. The main advantage is
photo documentation which can be used
for training, referral and tele-screening
purposes. These hand-held cameras (e.g.
Retcam; Figure 4) provide wide field
angle retinal imaging up to 130 degrees,
and can be easily transported to areas
like NICU or OT. It is also easier to explain
to the parents the disease of their child
using these photos. It provides advantage
of performing fundus fluorescein
angiography7 in select cases as well.

38 DOS Times - July-August 2017 Chandra P et al. Retinopathy of prematurity

Review Articles

• Type 1 ROP - defined as to perform surgery on very small
eyes. An experienced anesthesia
zone I, any stage ROP team and reliable NICU backup
are very essential.
with plus disease; zone I,
Though previously scleral
stage 3 ROP without plus buckling was performed, now
modern 25/27G lens sparing
disease; or zone II, stage 2 small gauge vitrectomy has
good anatomical and functional
or 3 ROP with plus disease. results in stage IV ROP. Lens
sparing vitrectomy is the
This disease needs prompt procedure of choice in stage 4A
and subtypes of 4B. Surgery in
treatment. bilateral cases of Stage 5 ROP
• Type 2 ROP - defined as is performed with the hope
of obtaining some navigable
zone I, stage 1 or 2 ROP vision, but often the results are
poor14.
without plus disease or
Conclusion
zone II, stage 3 ROP without
Retinopathy of prematurity is
plus disease. This can be rapidly emerging as an important cause
of childhood blindness in India. The
followed up and treated if it poor awareness about ROP among the
pediatricians, ophthalmologists and
converts to type 1 ROP. parents, is leading to an uncontrolled
epidemic of ROP blindness. It is essential
How to treat?- Various Figure 5: Lasered regressed ROP. that an ROP program is established in
treatment options are available every NICU with partnership between
ophthalmologists and pediatricians.
for management of ROP like pupillary dilation allowing complete We need to remember that the child
laser, Anti-VEGF drugs and vitreoretinal laser treatment. is not born with ROP, therefore timely
surgery. • In severe zone 1 disease with screening, referral and laser treatment
A) Laser Treatment – Laser treatment by extensive neovascularization which are the key to success in preventing ROP-
might not be controlled by laser related blindness.
indirect ophthalmoscopic delivery is alone - these drugs can serve as
the gold standard for treatment and useful adjunct to laser treatment. References
is very effective in causing disease • In very small zone 1 disease with
regression (Figure 5). The aim of macular non-perfusion - these drugs 1. Kumar P, Sankar MJ, Deorari A, Azad R,
treatment is to ablate entire anterior might provide benefit of progressive Chandra P, Agarwal R, et al. Risk factors
avascular retina up to ora serrata in vascularization into the periphery, for severe retinopathy of prematurity
a near confluent burn pattern. Some improving visual fields. in preterm low birth weight neonates.
disadvantages of the laser treatment Though it is a quick procedure, with Indian J Pediatr. 2011;78:812–6.
are pain experienced during the benefits of better visual field and lesser
procedure, visual field loss in lasered myopia, its long term safety still needs 2. Azad R, Chandra P, Gangwe A, Kumar
area, induction of significant myopia further evaluation13. There is proof of V. Lack of Screening Underlies Most
and sometimes poor results in zone systemic absorption of the drug, and Stage-5 Retinopathy of Prematurity
1 aggressive disease. Moreover, laser it might prevent normal angiogenesis among Cases Presenting to a Tertiary
treatment of ROP requires properly of organs which are still developing in Eye Center in India. Indian Pediatr.
trained ophthalmologist, who can preterm babies. There is still lack of 2016 Nov 7;53 Suppl 2:S103–6.
perform the procedure quickly and evidence about the correct dose and
adequately, with minimal systemic number of injections which can be given. 3. Gilbert C. Retinopathy of prematurity:
stress to the baby11. There is a high chance of late recurrence, a global perspective of the epidemics,
B) Anti-VEGF drugs - Recently anti- which might need prompt treatment, population of babies at risk and
VEGF drugs like Bevacizumab thus longer follow-up is warranted. Thus, implications for control. Early Hum
and Ranibizumab have emerged its indiscriminate use is not warranted Dev. 2008 F;84:77–82.
as a popular treatment modality, and proper consent and case selection
especially for Zone 1 APROP. are essential. 4. Vinekar A, Dogra MR, Sangtam T,
The Bevacizumab Eliminates the C. ROP Surgery - Advanced ROP with Narang A, Gupta A. Retinopathy of
Angiogenic Threat of Retinopathy retinal detachment (stage 4-5) needs prematurity in Asian Indian babies
of Prematurity (BEAT ROP) study12 surgical intervention. This further weighing greater than 1250 grams at
has shown the benefits of these highlights the importance of timely birth: ten-year data from a tertiary care
drugs in zone 1 stage 3 plus disease. detection and treatment to prevent center in a developing country. Indian J
Intravitreal Anti-VEGF drugs disease progression. Timely surgery Ophthalmol. 2007;55:331–6.
(usually given in half adult dose) in stage 4 ROP can have excellent
help to quickly dilate the pupils, outcomes, therefore in cases of 5. Sivanandan S, Chandra P, Deorari AK,
reduce neovascularization inducing progressive ROP despite laser/ Agarwal R. Retinopathy of Prematurity:
effective disease regression, and AntiVEGF, prompt early referral to a AIIMS, New Delhi Experience. Indian
allows normal vascularization to higher surgical centre is necessary. Pediatr. 2016 Nov 7;53 Suppl 2:S123–8.
proceed into the periphery. ROP surgery needs high-risk
Some possible indications where informed consent, preoperative clearance 6. International Committee for the
these drugs may be used are – by pediatric and anesthesia team (since Classification of Retinopathy of
• In cases with severe iris new vessels, these babies are often very sick and
plus disease and poor pupillary preterm) and experienced surgical teams
dilation preventing laser treatment
- these drugs can ensure early

Chandra P et al. Retinopathy of prematurity www. dosonline.org 39

Review Articles

Prematurity. The International Ophthalmol. 2014;62:41–9. Endothelial Growth Factor (VEGF)
Retinopathy 10. Good WV, Early Treatment for Inhibitors for the Treatment of
Classification of Retinopathy of Prematurity. PloS One.
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of Prematurity revisited. Arch Cooperative Group. Final results of 14. Cusick M, Charles MK, Agrón E,
the Early Treatment for Retinopathy Sangiovanni JP, Ferris FL, Charles
Ophthalmol. 2005;123:991–9. of Prematurity (ETROP) randomized S. Anatomical and visual results of
trial. Trans Am Ophthalmol Soc. vitreoretinal surgery for stage 5
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A. Role of intravenous fluorescein 250. Phila Pa. 2006;26:729–35.
11. Jalali S, Azad R, Trehan HS, Dogra
angiography in early detection MR, Gopal L, Narendran V. Technical Correspondence to:
aspects of laser treatment for acute Dr. Parijat Chandra,
and regression of retinopathy of retinopathy of prematurity under Additional Professor of Ophthalmology,
topical anesthesia. Indian J Ophthalmol. Dr. R. P. Centre for Ophthalmic Sciences,
prematurity. J Pediatr Ophthalmol 2010;58:509–15. All India Institute of Medical Sciences,
12. Mintz-Hittner HA, Kennedy KA, Chuang New Delhi, India
Strabismus. 2008;45:36–9. AZ, BEAT-ROP Cooperative Group.
Efficacy of intravitreal bevacizumab for
8. Wang SK, Callaway NF, Wallenstein stage 3+ retinopathy of prematurity. N
Engl J Med. 2011;364:603–15.
MB, Henderson MT, Leng T, Moshfeghi 13. Pertl L, Steinwender G, Mayer C,
Hausberger S, Pöschl E-M, Wackernagel
DM. SUNDROP: six years of screening W, et al. A Systematic Review and Meta-
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telemedicine. Can J Ophthalmol J Can

Ophtalmol. 2015;50:101–6.

9. Vinekar A, Gilbert C, Dogra M, Kurian M,

Shainesh G, Shetty B, et al. The KIDROP

model of combining strategies for

providing retinopathy of prematurity

screening in underserved areas in
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medicine, non-physician graders

and smart phone reporting. Indian J

40 DOS Times - July-August 2017 Chandra P et al. Retinopathy of prematurity

Review Articles

Diagnosis and Management of
Abducens Palsy

Geetha Srinivasan MS
ICARE Eye Hospital and Research Centre, Noida, India

Abstract: Sixth cranial nerve palsy is the most common of the extra ocular muscle palsies. The incidence is reported as
11.1/ 100000. A patient with an isolated 6th Nerve palsy presents with a complaint of diplopia in primary position or on
abduction of the paretic eye, depending on the magnitude of limitation of movement. While in the elderly the cause is very often
vasculopathies like diabetes, hypertension and atherosclerosis, viral and unknown etiologies are common in young adults and
in children brain infections and neoplasms like a brainstem glioma must be ruled out.

Sixth cranial nerve palsy is the most common of Attempting to abduct the eye maximally increases the
the extra ocular muscle palsies. The incidence is innervational effort and may widen the palpebral fissure.
reported as 11.1/ 1000001. (Figure 3) There may be a V pattern strabismus due to

It is also the most common cause of decrease in abduction and unopposed action of medial rectus
an abduction deficit, though restrictive and
inflammatory conditions among others can also in downgaze.
cause abduction deficits. The long tortuous course of the nerve
intracranially from the pons to the orbit and the peripheral part In bilateral involvement, there may be no change in the
esodeviation with either eye fixing.
of the nerve near the clivus makes it a target of intracranial
A compensatory head posture to negate or decrease the
lesions and high intracranial pressure. (Figure 1). So a lateral
diplopia is often seen. The face turn is typically towards the
rectus paresis calls for a thorough evaluation of the fundus to
direction of the paralyzed muscle and away from the action of
rule out papilloedema. Sixth nerve palsy can occur at any age.
the lateral rectus. (Figure 4). However, this is not a consistent
However, the causes and the approach to management of sixth sign and may be missed if not specifically looked for. This is
associated with horizontal diplopia, which is worse on levo/
nerve palsy vary with age.

The nerve may be involved in isolation or may be affected

with other structures along its path leading to a variety of

syndromes.

Clinical characteristics Figure 1: Note the long tortuous course of the sixth CN and its relation
to the clivus and cavernous sinus
A patient with an isolated Sixth Nerve palsy presents with Figure 2: Right Lateral Rectus palsy. Note esotropia in primary position
a complaint of diplopia in primary position or on abduction and limitation of abduction in Right Eye.
of the paretic eye, depending on the magnitude of limitation
of movement. In mild lateral rectus paresis, the patient may
have an intermittent diplopia with esophoria. The symptoms
are usually of acute onset. However, very young children rarely
complain of double vision. The parents observe that the child’s
eye is squinting or that he is shutting one eye during visual
tasks.

A history of trauma, systemic illness, fever, vomiting,
weakness of arms or limbs, neurosurgery, headache etc should
be elicited. This is important because involvement of the nerve
due to neurological and other systemic causes should be
excluded before arriving at a diagnosis of idiopathic palsy. An
idiopathic palsy should always be a diagnosis of exclusion.

Evaluation of a case Figure 3: Left Eye Lateral rectus palsy. Relative lid fissure widening on
abduction of Left eye and mild esotropia in primary position.
After recording visual acuity and assessing the pupils,
cover and alternate cover testing would reveal an esotropia
more for distance than near, with limitation of abduction in the
paretic eye (Figure 2). The greatest esotropia is seen when the
patient attempts to abduct the paretic eye. As mentioned, in
mild cases only a latent deviation (esophoria) is seen.

Srinivasan G et al. Sixth Nerve Palsy www. dosonline.org 41

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Table 2: Causes of 6 Cranial Nerve
Palsy in children

Infections Cytomegalovirus

Figure 4: Note Right Lateral rectus palsy and compensatory face turn to right. Ebstein Barr virus
Influenza virus

dextroversion, depending on the eye Lyme disease
affected. Involvement of other extraocular
muscles should be looked for. Table 1: Causes of 6 Cranial nerve Meningoencephalitis
palsies in adults4
Hess and diplopia charting Streptococcal disease
corroborate the clinical findings and the Infections Arachnoiditis
former quantifies the weakness in the Head trauma
nerve (Figure 5a, 5b). Lyme disease
Neoplasms Astrocytoma
Causes: While in the elderly the cause Varicella zoster
is very often vasculopathies like diabetes, Chondrosarcoma
hypertension and atherosclerosis, viral Trauma Head injury
and unknown etiologies are common Craniopharyngioma
in young adults and in children brain Spinal injury
infections and neoplasms like a brainstem Ependymoma
glioma (commonest) must be ruled out. Neoplasm Chondroma
(Table 1 and 2). Posterior fossa tumors Glioma
like ependymoma and medulloblastoma, Sarcoma
clivus chordoma, parasellar tumors with Pinealoma
cavernous sinus involvement are some of Meningioma
the causes of sixth nerve palsy in children. Neuroblastoma
metastasis (secondary)
Newborns can have a transient 6th
Nerve paresis, which usually resolves Pituitary adenoma Systemic Leukemia
spontaneously (Figure 6). The incidence disease
has been reported to be 0.4% by Galbraith Nasopharyngeal
et al2. However, Duane’s retraction carcinoma Aneurysm
syndrome and infantile esotropia must
be kept in mind and excluded while Pontine glioma Arterio- venous
evaluating these infants. Overall, the malformation
incidence according to etiology3 has been Systemic Atherosclerosis
reported variously as Idiopathic 8-30%; disorders
Miscellaneous 10-30%; Trauma 3-30%; Neurological Arnold Chiari
Aneurysm 0-6%; and Ischemia 0-36%.
Diabetes mellitus disorders malformation
Non-Isolated sixth nerve palsy:
The sixth cranial nerve can be affected Hypertension Demyelinating
along its course in the brainstem, disease
subarachnoid space, petrous apex, Preeclampsia
cavernous sinus or orbit. Involvement
in each of these locations would have Leukemia Increased
different manifestations that help localise intracranial pressure
the lesion. Collagen vascular
disease Migraine
Brainstem
Sarcoidosis Others Congenital
1. Millard Gublar syndrome: associated
with ipsilateral 7th nerve paralysis Other vascular Aneurysm Idiopathic
and contralateral hemiparesis. causes
Immunological
2. Raymond syndrome: Sixth Arterio- venous Inflammatory
nerve paresis with contralateral malformations
hemiparesis
Associated Cluster headache haemorrhage and infiltration of the
3. Foville syndrome. neurologic subarachnoid space can also affect the
diseases sixth nerve.
Subarachnoid space
Demyelinating Petrous apex
Any condition that raises intracranial disease Inflammatory or infective
pressure can lead to downward
displacement of the brainstem and Increased lesions of the petrous apex due to ear
compression of the nerve at its exit from intracranial infections lead to 6th Nerve palsy with
the pons and in Dorello’s canal. This pressure ipsilateral hearing loss with facial nerve
involvement. Trauma, Cerebellopontine
Idiopathic tumors, nasopharyngeal carcinoma with
spread to cavernous sinus are some other
Inflammatory conditions that involve the 6th nerve
causes palsy (Figure 7).

Miscellaneous High myopia Cavernous sinus: The palsy is
causes unlikely to be isolated if the cause is
a lesion in the cavernous sinus. The
manifests as a sixth nerve palsy. This is other oculomotor nerves, carotid
oculosympathetic plexus are also involved
quite commonly seen in pseudotumor in most cases.

cerebrii with associated papilloedema
and visual field changes.

Any infection, inflammation,

42 DOS Times - July-August 2017 Srinivasan G et al. Sixth Nerve Palsy

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(a) (b) and diagnosed vasculopathic
illness, imaging is not indicated

at initial visit
• In patients who do not show

any improvement in 3 months

or if there are associated

neurological symptoms,

whatever the age, imaging is

indicated. Non vasculopathic

Figure 5a: Diplopia charting of RE LR palsy. Figure 5b: Hess charting of RE LR palsy. Note smaller causes need to be ruled out in
field of RE and underaction of RE Lateral rectus and overaction of LE medial rectus. these cases. It is important to

Figure 7: Patient with nasopharyngeal carcinoma with Right 3CN palsy and 6CN palsy.

Figure 8: LR palsy Most common cause of an abduction deficit. However, rule out restrictive
pathology.

Figure 6: An infant with Left 6 CN paresis. Figure 9: Elderly patient with diplopia and minimal limitation of abduction both eyes

Orbit: Orbital lesions are associated Ophthalmologic remember that even patients
with proptosis. There may be associated with history of vasculopathic
congestion of the conjunctival vessels and Hess charting: Serial charting gives disease may be harbouring
chemosis. Other oculomotor nerves may us an objective record of the amount of a neoplastic or infiltrative
also be involved. weakness in the lateral rectus muscle. disease. Any progression of
the abduction deficit even in a
Recurrence: Isolated palsies are Diplopia charting: Shows maximum patient with a microvascular
known to recur, though the incidence uncrossed horizontal diplopia in the disease should be investigated
of recurrence is not high. In one series direction of paretic lateral rectus. thoroughly and imaging is to be
of 782 patients more than 50 years, 7 done.
patients showed a recurrence. The main While these tests are usually not • In younger patients with
causes identified in those patients were needed to establish the diagnosis, having acquired isolated 6th Nerve
mass lesions in the parasellar or petrous a baseline helps to monitor progress palsy imaging is indicated in all
apex cavernous sinus regions. objectively. and urgent imaging is indicated
if there is papilloedema.
Benign 6th nerve palsy of childhood Imaging of the orbit (when
may be recurrent either on the same indicated): In cases where orbital Differential diagnosis
side or contralateral eye. However, restrictive pathology is suspected.
any recurrence should be viewed with (Figure 8). Though the diagnosis is often
suspicion and an indicator of an etiology straightforward, few conditions may
that can increase morbidity and mortality. Systemic mimic 6th Nerve palsy
Imaging is mandatory. 1. Duane’s retraction syndrome Type
In the elderly, the following
Investigations investigations are indicated. 1 needs exclusion. Assessment of
1. A hemogram with sedimentation extraocular movements to detect the
The work up of a patient with an limitation of movement can pose a
isolated 6th Nerve palsy depends on the rate challenge in infants sometimes. Of
age and the clinical circumstances of the 2. Blood pressure, course, the lid and palpebral changes
patient. 3. Blood sugar
4. Serum lipid profile
• In patients, older than 50 years

with isolated 6th Nerve palsy

Srinivasan G et al. Sixth Nerve Palsy www. dosonline.org 43

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Practice pathway recommendations for Sixth Cranial Palsy8 for imaging. Initially the follow up is 2
weekly and later monthly till it resolves.
Modified from Miller RW, Lee GW et al (Med Decis Making 1999) The standard dictum is to wait for 6
months to allow spontaneous recovery if
Sixth Cranial Nerve Palsy the aetiology/ pathology so allows.

Non-Isolated Isolated Treatment

Neuroimaging mandatory + Nonsurgical
Special investigations based on clinical evaluation (See D/D)
Occlusion: In children prevention of
amblyopia by patching one eye is advised.

The patching may be alternate,

allowing for eye movements and

Congenital Traumatic Vasculopathic Non Vasculopathic prevention of secondary contracture of
the medial rectus in the paretic eye. In

adults patching of either eye is advised to

Almost always resolves If there is a progression of the palsy in 2 weeks prevent diplopia.
spontaneously or no improvement in 3 months MRI is indicated Botulinum toxin (BTX-A): While
Rule out mimics
to exclude non-vasculopathic cause awaiting recovery, Botulinum toxin
injection in the antagonist medial rectus

can be given as a temporizing measure.

Imaging preferably CT scan in acute period following MRI It is usually given after about one
trauma. If SNP is stable no further imaging needed indicated month of the onset. Besides tackling the
problem of diplopia, it is also believed to

In children with acquired 6th nerve palsy Imaging prevent contracture of the medial rectus.
indicated Brain stem glioma commonest neoplasm However, it does not appear to influence
the percentage of patients requiring
Urgent if papilloedema surgery. Transient vertical deviations are
seen in 5-30% and ptosis in 15-30% after
characteristic of DRS confirm the 9. Inflammatory disorders involving BTX-A5.
diagnosis. the globe/orbit: Cause restrictive
myopathy. Prisms: In those patients who have
2. Infantile esotropia with cross Follow up: Many cases show a small residual esotropia, prisms are
fixation. Patching one eye will a useful option either as a temporizing
demonstrate normal abduction. spontaneous recovery, without the need option while awaiting recovery in
patients who need the binocularity
3. Divergence paralysis: Seen in the

elderly usually, though it has also

been reported in young adults Treatment algorithm for Sixth Cranial Nerve palsy
(Figure 9).

4. Fibrosis syndromes: Not very Wait 6 months for recovery *
difficult to differentiate, because they

are usually associated with ptosis

and limitation of other extraocular Full recovery Partial or no
movements. recovery

5. Thyroid eye disease usually presents FDT/AFGT

with inferior and medial rectus
involvement. Blood tests can confirm

diagnosis.

6. Myasthenia gravis can be a mimic. Good LR function and Moderate LR function Poor LR function
Variable ptosis is characteristic. esotropia <20PD
Laboratory tests of Anticholine
esterase antibody and Repetitive

nerve stimulation test can aid

diagnosis.

7. Trauma: History points to diagnosis LR resection +/- Botulinum <40PD esotropia – Unilateral MR Transposition
toxin to ipsilateral MR recession+ LR resection procedures
usually. Seen in medial wall blow out
>40pd esotropia in primary position - Full/partial tendon
fracture with restrictive myopathy. Contralateral MR recession
Imaging of orbit confirms diagnosis. Hummelsheim
8. Spasm of near reflex: Is usually *While awaiting recovery- Ipsilateral MR Botulinum toxin Procedure
associated with miosis of pupil, Prism trial for mild esotropia Jensens
Procedure
diminution of vision and variable SRT with MR
recession
esotropia with pseudo myopia and

nystagmus.

44 DOS Times - July-August 2017 Srinivasan G et al. Sixth Nerve Palsy

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or later as a permanent option when SR + IR transposition with or without 4. Clark RA. http://www.aao.org/
recovery is suboptimal after 6 months. botulinum toxin to MR6. The aim of the pediatric center/strabismus: Sixth
Fresnel prisms can also be tried in those tendon transfer is to reduce the esotropia nerve palsy
with larger deviations. in primary position. Abduction deficit
generally persists even after surgery. 5. Lee J, Harris S, Cohen J, et al. Results
Surgery: Aim of surgery is to of a prospective randomized trial
maximize binocular vision, treat the The split tendon transfers of botulinum toxin therapy in acute
diplopia by improving abduction and (Hummelsheim and Jensens procedure/ unilateral sixth nerve palsy. J Pediatr
comitance and improve the compensatory have the advantage of minimizing the Ophthalmol Strabismus 1994;31:283-
head posture. Surgical options in a lateral risk of anterior segment ischemia. The 6.
rectus palsy are dictated by the amount of Hummelscheim procedure is not a
force that the muscle can generate. preferred choice because of complete 6. Rosenbaum AL. Costenbader lecture.
disinsertion of the vertical recti and The efficacy of rectus muscle
Preoperative assessment: Forced higher risk of anterior segment ischemia. transposition surgery in esotropic
Duction test and Active Force generation Some advocate Superior Rectus (SR) Duane syndrome and VI nerve palsy.
test should be done pre-and intra- transposition with MR recession as an JAAPOS 2004;8:409-419.
operatively to assess the residual lateral equally effective procedure7.
rectus function. 7. Guntan KB. Vertical rectus
References transpositions in sixth nerve palsies.
Based on these tests, surgery is Curr Opin Ophthalmol. 2015; 26:366-
planned. 1. Patel SV, M Srinivas, Leske DA et al. 70.
Incidence, associations and evaluation
1. Horizontal muscle surgery: of sixth nerve palsy using a population 8. Miller RW, Lee AG, Schiffman JS.
LR resection if esotropia is <20PD based method. Ophthalmology 111; A practice pathway for the initial
and LR function is good with no MR 2004. 269-375. diagnostic evaluation of isolated
contracture. sixth cranial nerve paresis. Med Decis
If LR function is moderate (-1 to 2. Galbraith RS. Incidence of neonatal Making 1999:19:42-48.
-2) Unilateral MR recession (maybe sixth nerve palsy in relation to mode of
adjustable) and LR resection +/- delivery. Am J Obstet. 1999 Correspondence to:
contralateral MR recession if >40PD Dr. Geetha Srinivasan,
esotropia in primary position. 3. Chen JW, Abretson J. Causes of ICARE Eye Hospital and Research Centre,
2. Vertical transpositions If LR isolated recurrent isolated sixth NOIDA, India
function is poor (-3 to -4) with or without nerve palsy in older adults: a case
a tight MR, full tendon /partial tendon series and review of literature. Clin
Ophthalmol.2015;9:373-377.

Srinivasan G et al. Sixth Nerve Palsy www. dosonline.org 45

Review Articles

Diagnosis and Management of
Third Nerve Palsy

Birsen Gokyigit MD
HSU Beyoglu Educational and Training Eye Hospital, Istanbul, Turkey.

Cranial nerve third innervates five extra ocular us both in acute and chronic cases. In acute cases, injection is to
muscles ‘medial rectus, inferior rectus, inferior be made to antagonist muscle to induce temporary palsy and/
oblique, superior rectus and levator palpebralis or to prevent secondary fibrosis. In old cases, injection is to be
superior’ and carries parasymphathetic out flow given to antagonist muscle pre-operatively or intra-operatively
to the ciliary ganglion which are responsible for to gain more effectiveness or to release the contracture; or to
pupillary constriction and accommodation. Palsy be performed in post operative stage to help to enlarge the
may either be partial or complete. binocular visual field (Picture 1).
Clinical signs in complete palsy are ptosis, restriction
of ocular movement except for abduction and the pupil may SUPERIOR RECTUS MUSCLE PALSY
be fixed and dilated. Eye is found in exo hypotropia position
with incyclotorsion. In partial palsies; we notice ptosis and Superior rectus palsy can be seen in congenital cases
upgaze restriction in superior division palsy and restriction in or secondary to trauma. In acute cases, we have a defective
downgaze, restricted adduction and pupil dilatation in inferior elevation in abduction with normal elevation in adduction.
division palsy. There can be elevation deficit both in abduction, adduction
Partial paralysis may give different clinical signs according and primary position in chronic cases. Overaction of ipsilateral
to the localization of the lesion or according to the involved inferior rectus and contralateral inferior oblique and
muscle. Even though, the palsy can occur in inferior or superior excyclotorsion is also noted. There is hypotropia with ptosis
branch of the third nerve, sometimes it affects only one muscle. in primary position and absence of Bell phenomenon amongst
Because of this reason partial palsies may mimic many other other findings. There is ocular torticollis as the face is turned
types of strabismus. Aberrant regeneration or oculomotor upward, the chin is elevated the head is inclined toward the
synkinesis, loss of accommodation, loss of near light reflex can sound eye with pseudo ptosis.
occur in old cases.
Common Causes of 3rd nerve palsy are congenital, Differential diagnosis includes: Double Elevator Palsy
vasculopathy, neoplasm and traumatic in children. Important (DEP), mechanical causes like contracture, fibrosis, high
parameters in history include diabetes mellitus (DM), myopia, myositis, endocrine orbitopathy and blow-out fracture;
hypertension, hyperlipidemia, herpes zoster, leukemia and new and structural abnormality in differential diagnosis.
onset headache.
There are several choices for treatment. These are
TREATMENT inferior rectus recession, superior rectus resection, vertical
transposition of horizontal rectus muscles, inferior rectus
Basically, the treatment of nerve palsies involves treating faden operation and nasal transposition of superior oblique5,6.
the primary problem. If the primary pathology is treated,
motility turns to normal very soon1-4. Recent treatment modality is novel inferior rectus recession
which doesn’t cause lower lid retraction operation - introduced
Botulinum toxin injection as a surgical procedure can help in Brazil & USA in 2006 and in literature in 20137,8. During
the operation, we separate ciliary artery with few superficial
muscle fibers and connective tissues from deeper muscle fibers

Figure 1: The sectoral diagrams of novel inferior rectus recession operation. 1- Surface Conjunctiva 2- subconjunctival tissues with adjacent structures
3a-10% surface layer of tendon, 3b. - 90%deeper leyer of tendon, 4a- 10% Surface layer of IR muscle, 4b- 90% deeper layer of IR muscle, 5- Sclera,-
6- Disinserted 90% deep layer.
Gokyigit B. Third Nerve palsy. www. dos-times.org 47

Review Articles

via a tunnel. Then we release deeper
fibers from insertion and recess them up
to ten-twelve mm from their insertion.

The sectoral diagrams show and explain

how to perform the operation (Figure 1).

MEDIAL RECTUS MUSCLE PALSY Picture 1: Complete CN3 palsy in left eye above, 3 months following btx injection below.

There is exotropia with adduction Figure 2: Split lateral rectus, medial rectus area sectoral diagrams. Superior aspect shown
deficit in isolated medial rectus paralysis. on the right, inferior aspect shown on the left.
It is very rare but if suspected needs a 1. Lateral Rectus 2. Superior Rectus, 3. Superior arm of Lateral Rectus, 4. Superior Oblique
very careful examination to determine 5.Medial Rectus, 6. Inferior arm of Lateral Rectus, 7. Inferior Rectus.
the difference from similar diseases like
internuclear ophthalmoplegia, synergistic contralateral superior rectus recession by two goals: 1) weakening of the lateral
divergence, Duane’s syndrome type II and operation to above surgeries13. Inferior rectus and fixation of medial rectus to
supranuclear disorders. oblique plication may be effective in the medial orbital tissues 2) Using the
selective cases. power in lateral rectus to change the
Surgical treatment choices include globe position to more nasal. Good or
medial rectus resection and vertical recti In the presence of partial or weak the healthy eye surgery can be done for
transposition to the medial rectus area. nerve third palsy rules are: to perform enlargement of binocular visual field.
Lateral rectus recession may be added maximum LR recession, strengthening
when needed. Total tenotomy of the MR (i.e. weakening the strong muscle, Myectomy of lateral rectus, or
lateral rectus muscle (LR), resection of the strengthening the weak muscle). If these disinsertion and orbital fixation of lateral
medial rectus muscle (MR) and tenotomy muscle surgery is ineffective; to apply rectus with medial rectus resection; or
of the superior oblique and myectomy transposition procedure. Lastly if there to use titanium t- plate as platform for
of the inferior oblique muscles surgery is ptosis, ptosis surgery in patients after globe alignment operation are the other
are performed for aberrant innervation checking the Bell phenomenon. choices for surgical treatment which
treatment9,10. were published ten-fifteen years ago.
COMPLeTE 3rd nerve PARALYSIS
INFERIOR RECTUS MUSCLE PALSY Inferior nasal transposition of
In complete cranial third palsy, lateral rectus operation is another choice.
In a patient with inferior rectus Similarly splitting the lateral rectus and
palsy, we note down gaze limitation paralyzed eye is in a position of abduction, transposing the arms to medial side of
especially in abduction, incyclotorsion the globe near the vortex veins was tried
and hypertropia. Etiology might be either slight depression, and intorsion. but the results were not good. Lateral
congenital or following trauma. Vascular rectus transposition to the nasal pole of
diseases and myasthenia gravis are the Additionally, there is ptosis of the upper superior rectus muscle or medial rectus
other reasons. nasal orbital wall fixation have limited
lid, small degree of proptosis, dilated effectiveness14.
For surgical treatments choices are
inferior rectus muscle resection alone, and non-reactive pupil and paralysis of We published the technique of
inferior rectus plication, superior rectus medial transposition of Y split lateral
recession, reverse Knapp procedure accommodation in affected eye. Aberrant rectus introduced by me 7 years ago.
and/or inferior oblique muscle anterior In this operation, lateral rectus arms
transposition11,12. regeneration may occur in congenital or are transposed just near medial rectus
insertion. Surgical procedure involves
INFERIOR OBLIQUE MUSCLE PALSY old cases. “Splitting the lateral rectus muscle for all
length posterior from the insertion and
Inferior oblique (IO) muscle Simple recession-resection reattach the superior arm to the medial
paralysis is also seen very rarely and
has to be differentiated from Brown procedure was preferred in the past.
syndrome. In IO palsy, there is negative
force duction with a pattern strabismus. But the results of these operations were
Limited elevation in adduction, marked
superior oblique overaction and positive not successful over time, because of the
head tilt test are their other clinical signs.
Etiologies are similar with the other ineffective medial rectus. Adding superior
muscle palsies.
oblique nasal transposition and long
Surgical plan is created according duration fixation suture has improved the
to amount of hypotropia. If hypotropia
is less than 10 pd in primary position, results.
ipsilateral superior oblique tendon Recent surgical approach is defined
expander operation or superior oblique
split tendon elongation operation is
performed. If hypotropia is over 10 pd
in primary position, we need to add

48 DOS Times - July-August 2017 Gokyigit B. Third Nerve palsy.

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REFERENCES

1. Tanriverdi F et all. Complete surgical resolution

of bilateral total opthalmoplegia without
visual field defect in an acromegalic patient

presented with pituitary apoplexy. Endocr J.

2007;54:681-4.

2. Chen Z et al Pituitary apoplexy presenting

as unilateral third cranial nerve palsy after

coronary artery bypass surgery. Anesth analg

2004;98:46-8.

3. Tiedemann LM et al Iatrogenic inferior

oblique palsy: intentional disinsertion during

transcaruncular approach to orbital fracture

repair. J AAPOS. 2014;18:511-4.

4. Arrico L et al Intracranial aneurysm and

diplopia due to oculomotor nerve palsy:

pre- and post-operative study. Clin Ter.

2014;165:e258-62.

5. Young T. Et al. Anterior transposition of the

superior oblique tendon in the treatment
of oculomotor nerve palsy and its influence

on postoperative hypertropia. J Pediatr

Ophthalmol Strabismus. 2000;37:149-55.

6. Rose LV. Elder JE Management of congenital
elevation deficiency due to congenital third
nerve palsy and monocular elevation deficiency.

Clin Experiment Ophthalmol.2007;35:840-6.

7. Gokyigit B. A novel technique for inferior rectus

recession. Clin Ophthalmol. 2014;21;8:263-9.

8. Gokyigit B. et al. Long-term results of deeper
muscle fibers recession of an inferior rectus

operation. J Pediatr Ophthalmol Strabismus.

2014;51:17-26.

9. Dawson EL., Boyle NJ, Lee JP. Full-tendon nasal

Picture 2: A patient with right eye complete palsy, A. preoperative, B. early postoperative and C. transposition of the vertical rectus muscles: a
following 4 years of operation- late postoperative gaze positions.
retrospective review. Strabismus. 200;15:133-

6.

10. Mohan KJ. et al. Treatment of congenital

adduction palsy with synergistic divergence.

Pediatr Ophthalmol Strabismus. 1998;35:149-

5.

11. Akbari MR, et al. Clinical features and surgical

outcomes of isolated inferior rectus muscle

paralysis. Strabismus. 2014;22:58-63.
12. Awadein A. Clinical findings, orbital imaging,
and intraoperative findings in patients with

isolated inferior rectus muscle paresis or

underaction AAPOS. 201216:345-9.

13. Khawam E, et al. Diagnosis and treatment

of isolated inferior oblique muscle palsy: a

report of seven cases. Binocul Vis Strabismus

Q. 1998;13:45-52.

14. Gokyigit B, et al. Medial transposition of a split

lateral rectus muscle for complete oculomotor

nerve palsy.J AAPOS. 2013;17:402-10.

Picture 3: A patient with left eye complete palsy, preoperative and postoperative gazes. 15. Shah AS, et al. Adjustable nasal transposition of

split lateral rectus muscle for third nerve palsy.

JAMA Ophthalmol. 2014;132:963-9.

16. Sukhija J, Kaur S, Singh U. Nasal lateral rectus

rectus superior pole and inferior arm to as transient complication but it improves transposition combined with medial rectus
the medial rectus inferior pole to the its in a couple of weeks. We had only one case
insertion. Resect or plicate the medial who had similar complaint. His diagnosis surgery for complete oculomotor nerve palsy.
rectus muscle maximally if necessary”. was not choroidal effusion but posterior
During the technique, adjustment is scleritis and it can occur following any J AAPOS. 2014;18:395-6.
applied only on operation table. The reoperation of strabismus.
Figure 2 from original paper, shows post 17. Saxena R, Medial transposition of split lateral
operative inferior and superior aspects. Conclusion rectus augmented with fixation sutures in
One of our young cases preoperative,
early postoperative and following 4 years Complete oculomotor paralysis can cases of complete third nerve palsy. Br J
of operation-late postoperative gaze be corrected surgically. Perfect results
positions photos seen in the Picture 2. can be achieved with proper approach Ophthalmol. 2016;100:585-7.
Picture 3 shows another patient’s pre-and in selected patients at the appropriate
post operative gaze positions. Adjustable time. The excellent result expected from 18. Chaudhuri Z, Demer JL. Magnetic resonance
suture, augmentation suture and the eye surgeon is that the eyes are in
simplified modifications were published a primary position, with the widest imaging of bilateral split lateral rectus
with very successful results following possible binocular viewing area and good
our publication15-17. In later studies MRI cosmetic appearance. Complications transposition to the medial globe. Graefes Arch
findings have also been published18,19. should always be anticipated and must be
followed meticulously. Clin Exp Ophthalmol. 2015;253:1587-90.
The technique has choroidal effusion
19. Sorenson R, Soni A. Central serous

chorioretinopathy following medial

transposition of split lateral rectus muscle for

complete oculomotor nerve palsy. J AAPOS.

2017;21:161-62.

Correspondence to:
Dr. Birsen Gokyigit
Assoc. Prof. of Ophthalmology
HSU Beyoglu Educational and Training Eye
Hospital, Turkey

Gokyigit B. Third Nerve palsy. www. dos-times.org 49

Perspective

Lost Muscle in Strabismus Surgery – How to
Handle the Problem?

Seyhan B. Özkan
Adnan Menderes University Medical School, Department of Ophthalmology, AYDIN, Turkey

Summary: Lost muscle is accepted as one of the most serious complications in strabismus surgery. Prevention is far more
important than the treatment since the majority of these develop due to the problems with the surgical technique. If an
extraocular muscle is lost, it must be searched with respect to the tissues and if it cannot be found transposition surgery may
be considered. Botulinum toxin A is helpful to reduce the contracture of the antagonist muscle where necessary.

Loss of an extraocular muscle (EOM) may occur Empty muscle capsule
related to strabismus surgery, pterygium surgery
and retinal detachment surgery. Orbital surgery, Figure 1: In slipped extraocular muscle the sutures do not include the
endoscopic sinus surgery and trauma are the muscle tendon fibers but only the capsule.
other main causes of this problem. Lost muscle is
most commonly seen during strabismus surgery During recession
and it is a nightmare complication for the surgeon. The term “Long muscle with tendon”
“lost muscle” is something to be questioned as the EOM is still
there in its anatomical location. Most of the time the problem is Following resection
the “lost surgeon” rather than the “lost muscle”. The former is “Short muscle, no tendon”
much more harmful for the patient indicating an inexperienced
surgeon without a good knowledge of the anatomy of the Figure 2: The EOM muscle may be lost during recession where there is
surgical field. In this article, etiology and types of lost muscle, a long tendon and the muscle. If the EOM muscle is lost after resection,
preventive measures, clinical presentation and methods of there is a short muscle with almost no tendon.
management will be evaluated.
Broken (snapped) EOM
Clinical types The break usually occurs at the tendon – muscle junction

The types of lost EOM are evaluated in four groups: and the major etiological factor is excessive pulling of the EOM;
• Slipped EOM within its capsule which is called as “pulled - in - two syndrome” (Figure 3).
• Cut and lost EOM Inadvertently transected EOM
• Broken (snapped) EOM
• Inadvertently transected EOM The most frequently transected EOM are the inferior rectus
and lateral rectus muscles that develop during inferior oblique
Slipped EOM within its capsule surgery. Superior rectus transection may occur during superior
oblique surgery. The main etiological factor for this problem is
The extraocular muscle slips within its capsule1. The blind hooking.
sutures do not include the muscle – tendon fibres but only
the capsule. The recognition of the slipped muscle is at the Ozkan Sb. Lost Muscle.
postoperative stage (Figure 1). It is demonstrated that stretched
scar tissue formation may cause consecutive deviations and
the stretched scar tissue and slipped EOM may be confused in
diagnosis2,3. In stretched scars there is minimal or no limitation
of versions, less separation of the tendons from sclera, and
thicker appearance of the scar segments. Magnetic resonance
imaging (MRI) demonstrates the EOM in distant location to
limbus in slipped EOM, in contrast to stretched scar formation4.

Cut and lost EOM

The muscle is lost during the surgery. If the problem
occurs during recession there is a long muscle with its tendon.
However, if it occurs after resection, there is a short muscle
without tendon. If the latter is the case it is much more difficult
to re-localize the muscle (Figure 2).

50 DOS Times - July-August 2017

Perspective

Figure 3: The ‘pulled-in-two syndrome occurs careful removal of the anterior Tenon’s problem that may occur in lost muscle
at the tendon-muscle junction with excessive capsule, avoiding dissection over the EOM is penetration of the posterior Tenon’s
pulling of the EOM. area without hooking the muscle, avoiding capsule by blind fishing and addition
unnecessary posterior dissection of of the fat adherence syndrome which
Etiology fascial structures and avoiding the use of converts the problem into a much more
serrated instruments for sutures are the complicated one. If it is not possible to
The etiological factors may be major preventive measures to reduce the find the EOM, transposition might be
evaluated in 5 groups: risk of a lost muscle in strabismus surgery. considered. However, it is not an easy
• Poor surgical technique In reoperations, the risk of lost muscle is decision to consider transposition during
• Inexperienced assistance higher because of the adhesions and scar primary surgery if two recti have already
• Poor instrumentation tissue. Especially in previously recessed been operated because of the anterior
• Problems with the suture quality muscles there are some adhesions at the segment ischemia risk.
• Patient with high risk original insertion area and dissection
of those adhesions carry the risk of When a lost muscle is suspected in
Poor surgical technique: Improper inadvertent cutting of the muscle tissue. post operative period, early intervention
suture placement, inadvertent cutting Severing the tissues from the sclera must is essential to increase the chance for
of the sutures, damage to the sutures be done after hooking the muscle and finding the lost muscle. However, in some
with cautery, cutting the muscle before locating the EOM insertion. cases the patient may present at a later
placement of the sutures are the major stage with an excessive inflammatory
faults in surgical techniques that may Clinical Findings reaction. In such cases, it is preferable to
result in lost muscle. wait for six weeks till the inflammation
A large over or under correction with resolves. It is stated that the contracture
Inexperienced assistance: Excessive marked limitation of ductions or marked of the unopposed antagonist can occur
pulling may cause a break of the EOM. incomitance in the field of action of the as early as 2 weeks’ time6,7. We found
Inadvertent suture cutting may also occur operated EOM are the signs that suggest a botulinum toxin A (BTXA) very effective to
because of inexperienced assistance. lost muscle problem. A mild exophthalmos prevent the contracture of the antagonist
or widening of the palpebral fissure may during the waiting period for surgical
Poor instrumentation: Instruments develop in some of the cases. intervention. It also enables the eye to
with rough surface may tear off the stay at primary position during wound
sutures. Slippage of the EOM from the Medial rectus (MR) muscle is healing. It also enables the surrounding
muscle clamp may occur, so the insertion the most commonly lost EOM. Unlike soft tissues to attach to a more anterior
should not be cut before locking the other rectus muscles, MR has no fascial point to the globe representing another
preplaced sutures. attachments with the oblique muscles. additional advantage of BTXA injection
When the MR muscle is lost, it recoils (Figure 4).
Problems with the suture quality: easily posterior to the penetrance of the
The 6/0 coated polyglactin 910 is a good Tenon’s capsule. During search for a lost muscle
suture material for strabismus surgery the globe should not be pulled towards
but it is not perfect. The suture may If a lost muscle is suggested, MRI the opposite direction (Figure 5).
easily tear with repeated touch with may be helpful for locating the muscle. In Retropulsion of the globe increases the
the instruments. Theoretically that risk case of any doubt about the innervation chance for locating the EOM. During
increases with adjustable suture surgery of the posterior fibres, kinematic MRI is the search for a lost muscle, all the
and with hang loose recessions. required to demonstrate the functional clues of fascial structures that may be
capacity of the posterior fibres. Forced attached with the muscle must be used.
Patient with high risk: Sometimes generation test can easily be performed It is a useful strategy to find the oblique
the individual structural changes may in an office setting and saccadic velocity muscles first if the lost muscle is superior,
make a patient prone to a loss of an EOM. measurements give reliable results if inferior or lateral rectus muscles. Their
It is known that in patients with old age available. intermuscular septa may hold the rectus
the EOM are fragile. Previous surgery muscles. Trypan blue dye 0.1% may be
or trauma, chronic progressive external Management helpful to differentiate some tissues and
ophthalmoplegia and patients with it stains fibrotic tissue, muscle sheath and
restrictive strabismus have a higher risk When lost muscle is recognized tendon but not muscle fibers8.
for lost muscle. during surgery, the first rule is not
to fall into panic and to be calm. The One of the most common mistakes
Preventive Measures anaesthesiologist must be warned about is to search for the muscle at the scleral
the problem and the anesthesia must site. However scleral plane may take the
Placement of the full thickness be deepened in order to prevent any surgeon even closer to the optic nerve.
locking bite at the edges of the muscle, contraction of the muscle that may cause When an EOM is lost it moves posteriorly
the muscle to move backwards further. within the Tenon’s capsule at the orbital
The anaesthesiologist must be informed site, so the surgeon must be aware of
not to use atropine as the oculocardiac the correct plane to look for the muscle
reflex may be helpful to differentiate the (Figure 6).
EOM tissue5.
If the problem is a slipped muscle
Using high magnification is very within the capsule the search must
useful to differentiate the tissues. The be done through the muscle capsule
major rule is not to make more harm (Figure 7). The relocation of MR muscle
to the patient. The most devastating

Ozkan SB. Lost Muscle. www. dos-times.org 51

Perspective

Figure 4: The effect of botulinum toxin A (BTXA) in lost muscle. It prevents Figure 5: The globe should not be pulled towards the other side and
the contracture of the antagonist and by keeping the eye in primary retropulsion of the globe helps to reach the lost EOM.
position, it allows the soft tissues to attach at a more anterior location (point
A instead of point B).

considered with their potential risk of
complications.

It is known that a lost and found
muscle may function even years after
surgery. However, these muscles may
have contracture and it may not be
possible to suture them at their original
insertion.

Figure 6: The search for finding the lost EOM Figure 7: In slipped muscle, the search must be CONCLUSIONS
must be done in the correct plane. The search done through the empty capsule.
on the scleral site takes the surgeon towards In conclusion, for a correct
the optic nerve. management and not to be the “lost
surgeon” a good knowledge of the
anatomy is essential. The majority of
lost muscle complications develop
because of the mistakes about the basic
rules of surgery. Blind fishing during
attempts to find an EOM may result with
penetration of posterior Tenon’s capsule
and development of adherence syndrome
which is much worse than a pure lost
muscle. BTXA has a significant role in
management of lost muscle by preventing
the contracture of the antagonist. An
acceptable outcome is possible in most
of the cases either with retrieval of the
lost muscle or muscle transposition
procedures.

Figure 8: The schematic representation of the orbital approaches to reach the lost EOM References

is reported between 10% and 86% in lost transcutaneous medial orbitotomy, 1. Parks MM, Bloom JN. The
muscle and 92% and 100% in cases of trans nasal endoscopic approach, “slipped” muscle. Ophthalmology.
slipped muscles6,7,9,10. transcaruncular incision and anterior 1979;86:1389–1396.
orbitotomy11,12 (Figure 8). These methods
If standard conjunctival approach require experience and their use instead 2. Ludwig IH, Chow AY. Scar remodeling
fails some alternative methods of muscle transposition surgery must be after strabismus surgery. J AAPOS.
are reported. These methods are 2000;4:326–333.

3. Jae Ho Jung, David A. Leske, Jonathan
M. Holmes. Classifying medial rectus
muscle attachment in consecutive
exotropia. J AAPOS. 2016; 20:197–200.

4. Negishi T, Hikoya A, Isoda H, et al.
Magnetic resonance imaging of the
medial rectus muscle of patients
with consecutive exotropia after
medial rectus muscle recession.
Ophthalmology. 2010;117:1876–82.

5. Apt L, Isenberg SJ. The oculocardiac
reflex as a surgical aid in identifying a

52 DOS Times - July-August 2017 Ozkan Sb. Lost Muscle.

slipped or ‘lost’ extraocular muscle. Br J 9. Plager DA, Parks MM. Recognition Perspective
Ophthalmol 1980; 64:362-65. and repair of the “lost” rectus muscle.
Ophthalmology 1990; 97:131-37. rectus muscles with a combined
6. Murray ADN. Slipped and lost muscles ophthalmologic and otolaryngologic
10. Yasar Duranoglu, Hatice Deniz Ilhan, surgical approach. Am J Ophthalmol
and other tales of the unexpected. Meryem Guler Alis. Surgical results 2000; 130:645-52.
of the slipped medial rectus muscle
Journal of AAPOS 1998; 2:133-43. after hang back recession surgery. Int J Correspondence to:
Ophthalmol. 2014; 7:1035–38. Dr. Seyhan B. Özkan,
7. MacEwen CJ, Lee JP, Fells P. Aetiology Adnan Menderes University Medical School,
and management of the ‘detached’ 11. Underdahl JP, Demer JL, Goldberg RL, Department of Ophthalmology, AYDIN, Turkey
rectus Muscle. Br J Ophthalmol 1992; Rosenbaum AL. Orbital wall approach
with preoperative orbital imaging
76: 131-36. for identification and retrieval of lost
or transected extraocular muscles.
8. Shokida F, Aguirre R, Croxatto O. The Journal of AAPOS 2001;5:230-37.

Use of Trypan Blue Dye for Strabismus 12. Lenart TD, Reichman OS, Mcmahon
SJ, Lambert S. Retrieval of lost medial
Reoperations, Surgery Complications,
and Especially for the Identification
and Recovery of a “Slipped” or “Lost”

Extraocular Muscle. Binocular Vision &

Strabology Quarterly 2011;26:1-8.

Ozkan SB. Lost Muscle. www. dos-times.org 53

Perspective

Squint Surgery is not just“Cosmetic”, but
Functional and Restorative Procedure

Sumit Monga MS, FRCS
Centre for Sight Group of Eye Hospitals, Delhi, India

Summary: Times are changing, so are the health care trends. One of the paradigm shifts in healthcare management has been
the facility of medical insurance to the patients for their healthcare needs, reducing their financial burden. However, when
it comes to squint surgery, the insurance claims are often declined, the reason assigned being that squint surgery is purely
cosmetic and hence the costs need not be reimbursed. Needless to say, this deters many patients, especially children, to avail
the benefits of squint surgery. This view is not much different from the general mindset prevalent in society that squint needs
to be tackled mainly for “cosmetic” reasons. This short article attempts to dispel the notion of squint surgery being a cosmetic
procedure alone.

Strabismus, abnormal ocular alignment, is one of the (a) (b)
most common ocular problems in children, affecting
Figure 1: Functional and restorative benefit. (a) This young boy, with
5% of the preschool population and around 4% of infantile esotropia, was often teased in school and was often not invited
adult population1. The ocular misalignment can be to his friend’s birthday parties, as he looked different. (b) Squint surgery
was able to restore his normal appearance. He also developed some
vertical, horizontal, torsional or a combination of the stereovision. An earlier intervention (around 6 months of age) would
have, probably, resulted in greater functional benefit.
three. Strabismus can be treated with conservative
(a) (b)
therapy such as glasses, prisms, patching and/or orthoptic
Figure 2: Restorative benefit. (a) This gentleman, with infantile
exercises, with a majority of the cases eventually requiring esotropia, was dissuaded from squint surgery in childhood, by relatives
and family physician. (b) Alignment restored by squint surgery in
correction with eye muscle surgery. When the patient does not adulthood. But, binocular vision deficit was irreparable.

suffer from diplopia, squint surgery has long been regarded as (a) (b)
a cosmetic procedure. The term ‘cosmetic’ originated in the
early 17th century as a noun denoting the art of beautifying Figure 3: Functional and restorative benefit. (a) Case of decompensated
the body2. The English variant of the term derives from French intermittent exo-tropia with asthenopic symptoms. (b) Restoration of
‘cosme´tique’ or Greek ‘kosmetikos’. Both of these mean “to alignment with resultant increase in binocular coordination, decrease
arrange” or “adorn”. in asthenopic symptoms and increase in binocular field of vision.

The primary goal of strabismus surgery is to improve the

alignment of the visual axis of the eyes. It offers both functional
and restorative benefits (Table 1). In children, untreated
misalignment of eyes impairs visual acuity development and

leads to amblyopia. In other words, the alignment of eyes helps

in visual development and binocular coordination of eyes and
helps to maintain it. The corrective benefit of squint surgery
on the facial appearance of affected individuals is noticeable;

however, the widespread belief that corrective squint surgery

is a purely cosmetic procedure is incorrect. This is because,
first, it seeks to restore the normality disrupted by a disease
process rather than to add glamour. This directly influences
the social and psychological issues directly related to their

condition, which impact all aspects of their lives: education,

social relationships, employment prospects, and self-esteem.

Therefore, a distinction needs to be made between squint

surgery, which restores normal eye alignment (and thus aids

normal functional performance of eyes) and other cosmetic
procedures, available for enhancing one’s look. In the figures
below, different case scenarios are presented to highlight
the functional and restorative benefits of squint surgery
(Figures 1 to 5).

In a study performed by Olitsky et al., patients without

strabismus had their photos digitally altered to create the
appearance of strabismus3. Study subjects were then asked

to judge the photos and rate personality characteristics and

Sumit Monga. Squint Surgery is not just Cosmetic www. dos-times.org 55

Perspective

Table 1: Benefits of Squint Surgery Figure 5: Correction of Abnormal head posture current evidence shows that the effect of
Functional and expansion of field of vision (Functional successful strabismus surgery has long
Re-establish binocular single vision and restorative benefit). A) Case of Duane’s lasting effects both on the functional and
(Eliminate diplopia, if any) syndrome in forced primary gaze position psychological well being of the patients
Promote stereo-acuity (Had left face turn and esotropia in primary and far beyond a cosmetic effect. It would
Improve ocular strain related to gaze on cover test). B) Large abduction therefore be sensible to redefine the so
intermittent deviations deficit preoperatively. C) Post-operative called cosmetic squint surgery as “recon-
Decrease visual confusion primary gaze (Correction of face turn). D) structive/restorative” with the aim being
Improve abnormal head posture Moderate Improvement of abduction (by 2 to restore parallel visual axes, which is
Restore peripheral visual field units, expanding the binocular field) after the “normal” condition.
Restorative transposition strabismus surgery, combined
Restores normal eye alignment with medial rectus recession. References
and facial appearance (positive
psychosocial impact) the non-strabismic face. The effect of 1. Coats DK et al. Reasons for delay of surgical
esotropia was worse than exotropia.” In intervention in adult strabismus. Arch
(a) (b) many other studies, including the study Ophthalmol 2005; 123:497–99.
by Menon V et al, there is overwhelming
Figure 4: Functional and restorative benefit. (a) evidence describing the negative impact 2. Lesley Adkins, Roy A. Adkins, Handbook to
Case of Right eye decompensated congenital of manifest strabismus on patients4,5. life in Ancient Greece, Oxford University.
superior oblique palsy with occasional Press, 1998.
diplopia. (b) After squint surgery, alignment CONCLUSIONS
regained and patient was relieved of double 3. Olitsky, S. E. et al. The negative psychosocial
vision. To conclude, the perception impact of strabismus in adults. J AAPOS,
employment capability of the strabismic that squint surgery, which is usually 1999; 3, 209-211.
and non-strabismic patients. The study regarded as cosmetic and as such may
found, “Overall, the strabismic faces were be less deserving of funding in health 4. Menon, V et al. Study of the psychosocial
judged significantly more negatively, than care systems, needs to be changed. The aspects of strabismus. J Pediatr Ophthalmol
Strabismus, 2002:39, 203-208.

5. Satterfield D et al. Psychosocial aspects of
strabismus study. Arch Ophthalmol 1993;
111: 1100–1105.

Correspondence to:
Dr. Sumit Monga,
Consultant, Pediatric Ophthalmology,
Strabismus and Neuro-Ophthalmology Service,
Centre for Sight Group of Eye Hospitals,
Delhi, NCR, India.

56 DOS Times - July-August 2017 Sumit Monga. Squint Surgery is not just Cosmetic

Perspective

Skew Deviations:
The Brain Throws a Wild Pitch

P.K. Pandey MD, Annu Joon, Divya Kishore, Kartik Rana, Anupam
Guru Nanak Eye Center, New Delhi

Evolutionary underpinnings The VOR pathways travel in the vestibular nerve synapse at the
level of vestibular nuclei in the pons, cross over to the opposite
Light from the sky above and gravity from below are two side at the level of 6th cranial nerve nucleus and ascend in the
physical constants quintessential for any form of life to exist medial longitudinal fasciculus till riMLF. Interstitial nucleus of
on this planet. Balance and verticality are pivotal for survival. Cajal is very vital for vertical VOR pathways. From riMLF they
The two vestibules and the two eyes serve as balance organs ascend to thalamus and to vestibular cortex in the temporal
in lockstep to maintain verticality in the roll plane, lest the lobe, there are many connections to the cerebellum at the level
animal fall and be preyed upon. In lower lateral eyed animals, of vestibular nuclei (Figure 1).
the two-parallel monocular visual systems are fully crossed like
pyramidal tracts, the right side of brain receiving inputs from The three planes and three dimensions of Skew
the left eye and vice versa. There is panoramic vision but no Deviations- There are three planes - roll (occipito-frontal),
binocularity. In lateral eyed animals, a body tilt along long axis pitch (interauricular), and the yaw (vertical) plane. OTR is
generates rotation of both eyes that is vertical, right ward tilt manifested in roll, whereas laterally alternating skew is in the
causes right eye to be lower in space than the left eye resulting pitch and acute acquired comitant esotropia accompanying
in compensatory skew deviation with upward rotation of lower neurological disease in the Yaw plane respectively.
eye and vice versa. The conjugate torsional eye movement
known as ocular counter roll is most prominent in frontal eyed Etiopathogenesis
binocular animals like man. Skew is thus a vestigial remnant
of primitive otolithic righting reflex released under pathologic Lesion anywhere along the otolithic pathways can give rise
conditions. to motility abnormalities. Fellow travellers often help localise
the site, as the site age and activity of the lesion are the sole
What is a skew / Ocular tilt reaction? determinants of the clinical presentation in neurological disease,
etiology of the lesion has a very little role in the presentation.
For balance, bilateral weighted otolithic inputs are The OTR can be ipsiversive or contraversive depending upon
leveraged to modulate extraocular muscles (EOM) and postural location of the lesion, is it before or after crossing of VOR
tonus in the roll plane. Skew originates from imbalance of pathways at the level of vestibular nuclei in the pons. A selective
vestibulo-ocular reflex (VOR) projections from the two utricles lesion of the ASC produces intorsion of contralateral eye and
to the ocular motor neurons. The utriculo-ocular reflex, hypotropia of ipsilateral eye due to underaction of ipsilateral
manifests as vertical divergence, head tilt and conjugate torsion
to the same direction constituting ‘Ocular Tilt Reaction’. Skew is Figure 1: Otolithic pathways
the vertical component which may be most prominent or very
subtle. Ocular tilt reaction can be physiological / pathological, www. dos-times.org 57
tonic / phasic, complete/ incomplete. Any component may
be present or absent in differing proportions giving diverse
presentation to skew deviations, for example, only extorsion
may be present, intorsion may be trace or even absent as we
shall see later.

Vestibulo-ocular / Otolithic Pathways

The otolithic pathways serving tonic ocular tilt reaction
arise mainly in the two utricles and to a much lesser extent in
saccules. The VOR pathways for phasic ocular tilt reaction arise
in the anterior (ASC) and posterior (PSC) semicircular canals
and serve in a push-pull lockstep fashion. The ASC activates
ipsilateral superior rectus (SR) and contralateral inferior
oblique (IO) while inhibiting ipsilateral inferior rectus (IR) and
contralateral superior oblique(SO). The PSC activates ipsilateral
superior oblique and contralateral inferior rectus and inhibits
ipsilateral inferior oblique and contralateral superior rectus.

P.K. Pandey. Skew Deviations