DJO Vol. 31, No. 2, October-December 2020
E-ISSN: 2454-2784 P-ISSN: 0972-0200 1 Delhi Journal of Ophthalmology
DJO Vol. 31, No. 2, October-December 2020
E-ISSN: 2454-2784 P-ISSN: 0972-0200 2 www.djo.org.in
DJO Vol. 31, No. 2, October-December 2020
Delhi Journal of Ophthalmology DJO
Official Journal of Delhi Ophthalmological Society Editorial Board Volume 31 Number 2 October- December, 2020
Editor-in-Chief
Vinod Kumar
R.P. Centre, AIIMS, New Delhi
Associate Editor
Devesh Kumawat
Assistant Editors
Pranita Sahay, Sonali Gupta, Pallavi Singh
Abhidnya Surve Abhishek Dagar Section Editors Amit Mehtani Annu Joon
Arvind Kumar Morya Ashwini Behera Bhuvan Chanana Chirakshi Dhull
Daraius Shroff Hanspal Binder Amit Khosla Jitender Bhalla Mainak Bhattacharyya
Manpreet Kaur MD Singh Bhupesh Singh N Lomi Neha Goel
Noopur Gupta Pallavi Sugandhi Ikeda lal Prafulla Maharana Priyanka Ramesh
Puneet Jain Rachna Meel Monika Kapoor Rajat Jain Ritesh Narula
Ritika Mukhija Ritika Sachdev Pradeep Kumar Rushad Shroff Saumya Yadav
Saurabh Kamal Seema Das Rahul Mayor Shorya Azad Smriti Nagpal
Sumit Monga Suneeta Dubey Rohan Chawla Swati Phuljhele Taru Dewan
V Krishna Vikas Menon Shikha Gupta
Suraj Senjam
Vivek Gupta
International Editors
Antonio Carlos centelhas Arun Nrayanswami Haroon Tayyab Hidetaka Matsumoto
Jai Shankar Luke Nicholson
Jay Chabblani Kamal Sahni
Ajay Aurora Arun Sangal Emeritus Editors Dinesh Talwar Kamlesh
M. Vanathi Mahipal S. Sachdev Rajpal Rohit Saxena
Ruchi Goel V. P. Gupta Bhavna Chawla
Rajesh Sinha
AK Grover Anju Rastogi Advisory Board B Ghosh Cyrus Shroff
GK Das Hemant Trehan JL Goyal Jolly Rohatgi
JS Tityal JS Tityal Atul kumar Lalit Verma Mahipal Sachdev
MS Bajaj Namrata Sharma JC Das Noshir Shroff Om prakash
Parijat Chandra PK Pandey Kirti Singh Pradeep Sharma Pradeep Venkatesh
Praveen Vashisht R Sihota Neelam Pushkar Ritu Arora Sarita Beri
SK Khokhar Subhash Dadeya PK Sahu Tanuj Dada Tushar Agarwal
Umang Mathur Upreet Dhaliwal Radhika Tandon
Sushil Kumar
Virender Sangwan
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DJO Vol. 31, No. 2, October-December 2020
Contents
Editorial
Making Of An Ophthalmic Surgeon �����������������������������������������������������������������������������������������������������������������������������6
Vinod Kumar
Guest Editorial
E-Learning in Times of COVID-19 Crisis ������������������������������������������������������������������������������������������������������������������������ .7
Devesh Kumawat
Challenges In Optical Coherence Tomography Interpretation For Diagnosing Glaucoma In Myopic Eyes................9
Kirti Singh
Review Article
“Covid – 19 Revisited” With Ocular Manifestations ������������������������������������������������������������������������������������������������ 18
Raunaq Poonia, Anju Kochar
Seeing World From The Eyes of Low Vision Subject................................................................................................ 23
Punita Kumari Sodhi
Original Article
High Myopia: A Hospital-Based Study of The Clinical Profile and Visual Impairment...........................................30
Rejitha Chinnu Varghese, Uma Kulkarni
Prosection of the Goat’s Eye as a Teaching-Learning Method for the Undergraduate Medical Students During
Clinical Postings in a Medical College in South India: A Study of Reflections .......................................................36
Aditi Vidha, Uma Kulkarni
Pterygium Excision With Suture- Free, Glue- Free Limbal Conjunctival Autograft By Cut And Paste Method
– A Prospective Interventional Hospital Based Study .............................................................................................41
Arathi Choudhary, Dyamenahali S. Hamsa, Menashinkai P. Jayashree, Halmuthur V. Raksha, Divya Ramanna
Reliability of OCT Assisted RNFL Thickness In Diagnosing Glaucoma In High Myopia .........................................47
Neha Yadav, Aanshu Sahai, Raj Kumar Sharma, Mohd. Abid Shamshad, Salani Gupta, Yamni Singhal
Bandage Contact Lens: a boon for corneal ulcer cases ........................................................................................... 51
Rashmi Kewaliya Joshi, Surbhi Kanawa, Anju Kochar
Effect of Quantum of Energy used During Nd:YAG Laser Posterior Capsulotomy on Magnitude of IOP Rise....56
Neha Verma, Ashish Ahuja
Role Of Social Media As A Catalyser For Ocular Injury:A Case Study Of Calcuim Carbide Gun Use In India........62
Namrata Kabra, Smriti Gupta
Comparison of Angiography Performance of Low-cost portable Fundus camera with standard FFA camera
– a Validation Study................................................................................................................................................... 65
Deependra Vikram Singh, Gaurav Mathur, Rishi Bhardwaj, Ajay Sharma
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DJO Vol. 31, No. 2, October-December 2020
Case Report
Visual Loss following Daily Dose Regimen of Anti Tubercular Treatment............................................................. 71
Silni Chandra, Ranjini K. Christie, Sarah Mathew
Late Opacification of (PCIOL) Posterior Chamber Intraocular Lens ...................................................................... 75
Mohmad Uzair, Amit Mehtani, Deepak Varma, Jatinder S. Bhalla
Metastasis of Squamous Cell Carcinoma of Conjunctiva in Anterior Chamber: A rare Case Report .................. 78
Jayati Pandey, Perwez Khan, Alok Ranjan
A Case Report of Coincidental Finding of Kayser-Fleischer Ring in a Patient Seeking Treatment for Trauma...80
Senny Chapagain
Ocular Manifestation As Earliest Presentation Of Non-Hodgkin’s Lymphoma, Mimicking Multiple Chalazia: A
Rare Case Report....................................................................................................................................................... 82
Pallabi Ray Chaudhuri, Uttam Biswas, Soumya Ray, Koushik bose, Avik Dey Sarkar, Asim Kumar Dey
Cryotherapy in Giant Papillary Conjunctivitis with Shield’s Ulcer ..........................................................................85
Divya Deepthi Syamala, Malleswari Medikonda
Torpedo Maculopathy with Satellite Lesion.............................................................................................................90
Sonia Singh, N.S.Muralidhar, Hemanth Murthy
Euphorbia Plant Induced Toxic Keratopathy............................................................................................................93
Atul Kumar Singh, Ashish Pandey, Anjali Maheshwari
Photo Essay
Retained corneal glass foreign body: look for it or miss it!! ..................................................................................95
Rinky Agarwal, Rahul Kumar Bafna, Vatika Jain, Namrata Sharma
Gluing the Glued Patch: A Glue in Time Saves it all .................................................................................................97
Rinky Agarwal, Anubha Rathi, Chetan, Namrata Sharma
Granular Corneal Dystrophy Type II .........................................................................................................................99
Siddharth Madan
Association of Goldenhar with Duane’s Retraction Syndrome..............................................................................103
Shagun Korla, Savleen kaur, Jaspreet Sukhija
P G Snippt
Deviant Behaviour in Third nerve Palsy....................................................................................................................105
Savleen Kaur, Shagun Korla, Jaspreet Sukhija
Complete Fleischer’s Ring........................................................................................................................................107
Kshama Popat
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DJO Vol. 31, No. 2, October-December 2020
Radiological Features of Thyroid Eye Disease (TED) ...............................................................................................108
Ayushi Agarwal, Samreen Khanam, Akash Raut, Ruchi Goel
Letter to Editor
What example are we setting for younger generation during COVID-19 pandemic an emotional connect??....111
Rinky Agarwal, Nitin Gupta, Chanchal Gupta, Namrata Sharma
Comment on “Patterns of Ocular Trauma Presenting to the Tertiary Eye Care Centre in the Islands of
Andaman and Nicobar” ............................................................................................................................................113
Bharat Gurnani, Kirandeep Kaur
Response to “Patterns of Ocular Trauma Presenting to the Tertiary Eye Care Centre in the Islands of
Andaman and Nicobar” ............................................................................................................................................114
Sujit Das
Cover Image
Late Opacification of PCIOL
Mohmad Uzair, Amit Mehtani, Deepak Varma, Jitender S. Bhalla
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DJO Vol. 31, No. 2, October-December 2020
DOS Executive Members 2019-2021
DOS Office Bearers
Dr. Subhash Dadeya Dr. Pawan Goyal Dr. Namrata Sharma Dr. Hardeep Singh
President Vice President Secretary Joint Secretary
Dr. Jatinder S Bhalla Dr. Vinod Kumar Dr. Manav Deep Singh
Treasurer Editor Library Officer
Executive Members
Dr. Dewang Angmo Dr. Jatinder Bali Dr. Shantanu Gupta Dr. C. P. Khandelwal
Dr. Rahul Mayor Dr. Vipul Nayar Dr. Rajendra Prasad Dr. Kirti Singh
DOS Representative to AIOS Ex-Officio Members
Prof. J.S. Titiyal Prof. M. Vanathi Dr. S.K. Khokhar Dr. Subhash C. Dadeya Dr. Arun Baweja
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DJO Vol. 31, No. 2, October-December 2020
Editorial
From the Editor’s Desk
Making Of An Ophthalmic Surgeon
Ophthalmology has evolved immensely over the last century like all other sciences. Striving for better outcomes with earliest
rehabilitation and aided by huge leaps in biotechnology and improvement in techniques, ophthalmic surgery has also become
super specialised. Out of these ophthalmic super-specialities, cataract and refractive surgery and vitreoretinal surgery have
grown enormously in last two decades. While this has been beneficial for the patients and society as a whole, the road to
become a surgeon has become much longer and challenging. Specially in our country, where the number of postgraduation
seats is much less than the MBBS seats, not all medicine graduates are able to get in to the postgraduation courses. Non-
uniform infrastructure, teaching faculty, curriculum and clinical exposure further add to the woes of medical postgraduate
students specially in surgical disciplines.
Due to this, after completing three years of postgraduation, all the fresh pass out students are not proficient even in
basic ophthalmic surgeries like phacoemulsification (or small incision cataract surgery), dacryocystorhinostomy and lid
procedures. In fact many students do not even get the chance of exposure to various super specialities in the ophthalmology.
This has created the need for further clinical exposure that may be in the form of senior residency, lectureship and fellowships.
The exposure even during this period tends to be variable and may be associated with poor renumerations. Performing
independent ophthalmic surgeries requires a mountain of exposure and self-confidence. A surgeon is never complete unless
he can anticipate complications and manage them without further damage. Another skill of a successful surgeon is to
recognise cases which are not to be operated. All these make the journey of becoming a surgeon a daunting and time
consuming task.
Recently, the Central Council of Indian Medicine issued a gazette notification allowing postgraduate (PG) ayurvedic
practitioners to receive formal training for several general surgery ENT, ophthalmology and dental procedures. The decision
followed the amendment to the Indian Medicine Central Council Regulations 2016, to allow PG students of Ayurveda to
practise general surgery. The various ocular procedures taught to them would include, ocular blocks, cataract surgery, lid
surgeries (including benign tumors and ptosis surgery), horizontal squint surgery, traumatic repairs, lacrimal sac surgery
and trabeculectomy. These students will simultaneously learn various ENT and dental procedures as well.
The surgical training is poorly regulated even in mainstream allopathy. Allowing doctors of Indian medicine to perform
specialised surgeries will add to the already existing problems and is likely to demoralise allopathic surgeons . Further this
may carry medicolegal implications in the event of a complication which is an integral part of any surgery. While it may
be good to increase the numbers of doctors (in view of poor doctor patient ratio in our country), policymakers must not
compromise on the quality of future surgeons.
Vinod Kumar DOI: http://dx.doi.org/10.7869/djo.582
(MS DNB MNAMS FRCS)
Editor, Delhi Journal of Ophthalmology
Associate Professor, Vitreo-retina Services
Dr. Rajendra Prasad Centre for Ophthalmic Sciences,
All India Institute of Medical Sciences (AIIMS), New Delhi
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DJO Vol. 31, No. 2, October-December 2020
Guest Editorial
Devesh Kumawat
E-Learning in Times of COVID-19 Crisis
The novel Coronavirus-19 (COVID-19) pandemic has adversely affected healthcare, society, and the economy. With no
definitive drug therapy, the governments worldwide have taken preventive measures such as social distancing to curb the
spread of COVID-19. There has been widespread closure of the schools, colleges, and universities since World Health
Organization declared the situation as a pandemic in March 2020.1
Medical education has faced the brunt, especially as the teaching hospitals have been converted to COVID-care hospitals,
healthcare professionals are involved in COVID-care rather than their specialization, academic gatherings have been
restricted, and the clinical teachings in hospitals have been curtailed.2-3
With COVID-19 likely to stay for uncertain amounts of time and its negative effect on learning opportunities, the education
systems have rapidly come up with online-learning as an alternative to in-person teaching.4-5
‘Online learning’ or ‘e-learning’ or ‘web-based learning’ may be defined as “learning in synchronous or asynchronous
environments using different devices with internet access.”6-7 The students/ learners may be present anywhere and still
participate in learning and interact with the teachers/ instructors. Synchronous learning involves live classes, lectures,
and webinars. These have the advantage of real-time interaction between students and teachers and instant feedback.
Asynchronous learning is not live and includes recorded classes or lectures. The students may attend the classes/ lectures
as per their choice of time. However, interpersonal interaction and instant feedback are not possible with asynchronous
learning. For e-learning to be of most benefit, there are certain prerequisites. These include a reasonable number of eligible
students, good internet connection, access on multiple devices (mobile phones, i-pads, or laptops), the opportunity for learner-
instructor interaction, and the option of recording the session for watching later. E-learning has increased exponentially in
the current pandemic, and it is no longer merely an option. The pandemic has forced the education systems to switch from
in-person age-old mode to modern technology-based teaching mode. The greatest benefit of the online mode of pedagogy is
that many learners and instructors may attend at any time and from any-place across the world. The education systems have
to adapt to this change and do so in a short span of time and maintain the quality of education. Lucrative solutions include
video-conferencing software’s such as Zoom, Skype, Microsoft Team, Google Meet, etc. and online course platforms such as
Thinkific, Teachable, Udemy, WizIQ, etc.
Online learning has its own difficulties and problems.8-9 Technical difficulties may involve internet connectivity, installation
of software, login, download, and audio and video telecast. Organizational problems may include a poor design of the
class/lecture, all-theoretical or mediocre content, and lack of interaction between students and teachers. There may also be
present learner-associated barriers such as poor motivation, lack of perceived benefit, concerns about the content validity,
time constraints due to COVID duty, and inadequate access to technology or the internet. The students may face a dilemma
from innumerous options of online learning platforms available. The balance between study, work, family, and social life
may be disturbed with over-occupation in online learning. Increased digital-screen time also adversely affects the ocular
surface, refractive state of the eye, sleep pattern, attention span, mental and physical health.10
Since e-learning has become a necessity in the current scenario, we need to look for possible solutions to fix the difficulties
and problems with e-learning. Technical problems can be dealt with using technology based on internet connectivity and
digital skills of students and teachers, temporarily mobilizing the tools/devices for e-learning to those with poor access,
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DJO Vol. 31, No. 2, October-December 2020
and by keeping pre-recorded sessions. The online classes/ courses need to be made interesting and interactive. The quality
of the courses should be improved continuously. The duration of the sessions needs to be defined and regulated as per the
abilities of the students. The teachers/ instructors should make an effort to strategically interact with students throughout the
session to keep them alert and attentive. Social media platforms such as Twitter, Facebook, etc. may extend the interaction
beyond the session. Feedback from the learners and teachers may help educators in making the sessions more effective. The
screen time needs to be regulated as per age-appropriate recommendations with frequent breaks, short sessions, maintaining
proper distance from the digital screen, preferring larger screens rather than mobile phones, and following other screen
etiquettes such as room lighting, screen brightness, and contrast.
The Covid-19 pandemic has changed the way how we receive and impart education. Online learning methods facilitate
teaching activities, but there is a need to weigh the pros and cons of technology. Educators must focus on collaborative and
case-based learning approaches to make e-learning experience better both for learners and teachers.
References
1. World Health Organization. Statement on the second meeting of the International Health Regulations (2005) Emergency Committee regarding
the outbreak of novel coronavirus (2019-nCoV). Available at: https://www.who.int/news-room/detail/30-01-2020-statement-on-the-second-
meeting-of-the-international-health-regulations-(2005)-emergency-committee-regarding-the-outbreak-of-novel-coronavirus-(2019-ncov).
2. Ferrel MN, Ryan JJ. The Impact of COVID-19 on Medical Education. Cureus. 2020;12(3):e7492. Published 2020 Mar 31. doi:10.7759/cureus.7492
3. Rose S. Medical Student Education in the Time of COVID-19. JAMA. 2020 Jun 2;323(21):2131-2132. doi: 10.1001/jama.2020.5227. PMID:
32232420.
4. Bottanelli F, Cadot B, Campelo F, Curran S, Davidson PM, Dey G, Raote I, Straube A, Swaffer MP. Science during lockdown - from virtual
seminars to sustainable online communities. J Cell Sci. 2020 Aug 14;133(15):jcs249607. doi: 10.1242/jcs.249607. PMID: 32801132; PMCID:
PMC7438008.
5. Nahai F, Kenkel JM. Accelerating Education During COVID-19 Through Virtual Learning. Aesthet Surg J. 2020 Aug 14;40(9):1040-1041. doi:
10.1093/asj/sjaa123. PMID: 32453817; PMCID: PMC7314220.
6. Singh, V., Thurman, A. How many ways can we define online learning? A systematic literature review of definitions of online learning (1988-
2018). American Journal of Distance Education. 2019;33(4): 289–306.
7. Dhawan S. Online Learning: A Panacea in the Time of COVID-19 Crisis. Journal of Educational Technology Systems. 2020;49(1):5-22.
doi:10.1177/0047239520934018
8. Assareh A, Hosseini Bidokht M. Barriers to e-teaching and e-learning. Procedia Comput Sci. 2011 Jan 1;3:791–5.
9. O’Doherty D, Dromey M, Lougheed J, Hannigan A, Last J, McGrath D. Barriers and solutions to online learning in medical education – an
integrative review. BMC Med Educ. 2018 Jun 7;18(1):130.
10. Wong CW, Tsai A, Jonas JB, et al. Digital Screen Time During COVID-19 Pandemic: Risk for a Further Myopia Boom? [published online ahead
of print, 2020 Jul 29]. Am J Ophthalmol. 2020;S0002-9394(20)30392-5. doi:10.1016/j.ajo.2020.07.034
Devesh Kumawat
MD (AIIMS, Delhi), FRCS (Glasgow), FAICO-Retina FICO-Uvea
Assistant Professor, Department of Ophthalmology
AIIMS-Rishikesh, Uttarakhand, India
DOI: http://dx.doi.org/10.7869/djo.583
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DJO Vol. 31, No. 2, October-December 2020
Guest Editorial
Kirti Singh
Challenges In Optical Coherence Tomography Interpretation For
Diagnosing Glaucoma In Myopic Eyes
Optical coherence tomography has witnessed a rapidly evolving technology since its debut by David Huang in 1991, to its
present finesse. The non- invasive nature of this imaging tool coupled with speed, reliability and test re-test reproducibility in
analyzing structural damage has made it the cornerstone imaging device for glaucoma. Intricate and precise segmentation
algorithms delineating structure have further enhanced disease understanding and paradigm of glaucoma management
.Increasing prevalence of myopia worldwide with 80- 90% young adults of Asia being affected, one fifth of them with high
myopia, is generating a population who would be screened for glaucoma at some time of their life.1,2 Since the segmentation
algorithms, so critical for glaucoma diagnosis, are tailored for normal retinal anatomy, variations from this normal in form
of high refractive errors raises pertinent concerns regarding accuracy and reliability of OCT in these cases. This concern
is underscored by evidence that myopes are 2-3 times at risk for developing glaucoma despite correcting for axial length
and intraocular pressure. As this myopia cohort of young adults age, their proportion as glaucoma suspects would rise
exponentially over coming decades. Understanding relevant optics and anatomical variations affecting interpretation of
OCT in myopia, is thus essential to prevent mistaken diagnosis of red (false positive) or green (false negative) disease.
Optical coherence tomography uses optical interferometry to measure time delay of reflected light in near infra-red visible
spectrum (810 - 1056 nm) and is therefore affected by refractive status and media opacities. Standard scanning protocols
used for glaucoma diagnosis are - Circum-papillary Retinal nerve fibre layer quadrant scan (cp RNFL), Optic nerve head
scan (ONH), Macular scan (macular ganglion cell complex, mGCC), Glaucoma progression analysis, with some new
machines incorporating disc damage likelihood scale (DDLS) nomograms.
Segmentation software algorithms (layer seeking algorithms) to detect glaucoma have been tailored based on anatomy of
retinal nerve fibre at disc and macula. Axons of ganglion cells (Retinal nerve fibres) arch in the macular area to converge
on superior and inferior poles of disc. The circum-papillary Retinal nerve fibre layer scan (cpRNFL) protocol identifies and
plots RNFL thickness starting from temporal to nasal quadrant in each eye following the Temporal, Superior, Nasal, Inferior
and Temporal (TSNIT) sequence. This is depicted as the double hump pattern in the TSNIT plot (Figure 1). Macular cube
Figure 1: The Optic disc cp RNFL 1b. Macular cube (macular ganglion cell complex ) scanning protocol for glaucoma diagnosis
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protocol scans a 6 X 6 mm2 area, measuring Retinal nerve fibre layer (axons) + Ganglion cell body + Inner plexiform layer
IPL (dendrites), collectively called ganglion cell complex (mGCC). The central area, the foveola, which is devoid of ganglion
cells is masked in the macula scan. (Figure 1). Probability levels for RNFL thickness are then displayed on four colour scale
with red depicting thickness below thinnest 1 % percentile, yellow for measures within thinnest 1-5% of normative database,
green for within 95% percentile and white for values beyond 95% percentile. This colour coding is arrived from population
derived normative database involving adult patients over 18 year age and few races.
Myopic challenge in OCT interpretation
Axial myopia results in stretching of globe and thinning of retina. This thinning manifests as thinned retinal nerve fibre
layer.3,4 Current machines do not incorporate normative data from eyes with high refractive error in their internal database,
therefore scans of myopic eyes with such thinned out RNFL, are interpreted as pathological (red disease). Most machines
have only data from patients with emmetropia or low myopia incorporated.
Red Disease
This is the sobriquet given to false positive errors in interpreting OCT test, with the non - glaucomatous patient being
erroneously labelled as glaucoma. Causes of red disease in myopia can be due to: from poor centration of measurement
circle on optic disc due to poor fixation by patient, lack of normative database for high refractive errors, altered distribution
angle of RNFL with temporal crowding of nerve fibres, magnification factor in axial myopia, split and shifted RNFL peaks to
disc size/ shape variations and lamina cribrosa biomechanics. The following text details these variations in myopic fundus
in conjunction with screening protocol used, for ease of understanding their impact on interpreting scans.
1. Disc Size/ Shape Variations
The disc parameters studied Optic nerve head protocol are vertical cup disc ratio, rim area and mean RNFL thickness.
Segmentation algorithms inbuilt in OCT software are designed for optic disc sizes and shapes within the Gaussian curve
of emmetropic or low myopic populations with disc area between 1.3 - 2.5 mm2. Discs larger or smaller than this, make
interpretation beyond scope of normative database, with erroneous labelling of pathological disease. For such discs,
common in myopia, the measurement circle placement need to be checked and manually placed, prior to interpretation.
Disc margin on OCT is identified, as termination of Bruch’s membrane opening (BMO) and neuro-retinal rim is
measured as the shortest perpendicular from that point to internal limiting membrane, called Minimum rim width
(MRW).5 Tilted or dysplastic disc, often associated with myopia, would pose difficulties in identification of Bruch’s
Membrane Opening BMO, the OCT landmark for disc margin identification, with subsequent erroneous rim measurement.
(Figure 2) Myopic discs larger than 3.46 mm, would be erroneously labelled as damaged, since more distal dispersed
peripapillary RNFL would get imaged. However there is a caveat to this, as evidence exists that circumpapillary
Figure 2: OCT optic disc cube. The red line marks the internal limiting membrane and yellow the Retinal nerve fibre layer. The pink dot is the Bruch’s membrane
opening (BMO) which identifies the optic disc
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RNFL thickness is positively correlated with optic disc size, with smaller discs having less and larger discs having
more nerve fibres.6 This is in contravention to accepted anatomy of nerve fibres being constant in all sized discs.
2. Circumpapillary RNFL Thinning
Retinal nerve fibres are both actually and artifactually thinner in myopia. Let us understand this. Axial myopia results in
scleral stretching with ganglion cell axons spreading out to cover the wider globe area, therefore resulting in actual diffuse
thinning of RNFL. This reduction in RNFL thickness with increasing axial length, is reported to be in the range of 2.2 -3.7
microns /mm. or 1.30 µm for every 1 diopter sphere increase in negative SE.7 Indian subcontinent data has verified thinned
RNFL at 78.7 + 5.7 µ in high myopia, compared with 83.8 + 3.4 µ in moderate myopia and 91.3 + 2.99 in emmetropic eyes.8,9
3. Magnification Factor while scanning ONH
Increasing axial length, results in expanding circumference of cpRNFL measuring circle from 3.46 mm, due to magnification
factor, especially for myopia greater than - 4 D.10 A myopic eye would result in increase of 3.46 mm scan circle, to 4.0mm
for a 28 mm axial length myopia.11 A longer myopic eye, generating an expanded measurement circle, measures RNFL at
distance further from optic disc (Figure 3). Since nerve fibres fan out distal to optic disc, it would make nerve fibres appear
more dispersed and artefactually less in number. To counteract this Littmann’s magnification factor correction needs to be
applied for longer eyes. Some authors do not however ascribe to use of this magnification factor citing occurrence of larger
discs in myopia, which in any case have diluted the effect of circle expansion.8
4. Retinal nerve fibre layer distribution Pattern / Temporal Displacement Of RNFL Peaks
Volume-rendering MRI reveal globe shape in emmetropic eyes to be consistently spherical, with myopic eyes having
symmetrical or asymmetrical anteroposterior elongation and posterior protrusions. With increasing myopia this
asymmetrical anteroposterior elongation makes superotemporal (ST) and inferotemporal (IT) RNFL bundles converge
Figure 3: Magnification of measuring circle in OCT commensurate with increasing axial length
Figure 4: Temporal displacement of RNFL peaks, resulting in thickening of RNFL in temporal quadrants, apparent thinning in superior & inferior quadrants in
Right eye. Reproduced from Akman A, Bayer A, Nouri-Mahadavi K. In Optical Coherence tomography in glaucoma pg 201
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temporally due to retina being dragged temporal to disc. The condition called as “Temporal displacement or convergence,
reduces distribution angle bounded by ST and IT bundles and displaces RNFL peaks temporally, resulting in erroneous
interpretation of thickened temporal RNFL and thinned nasal RNFL.7 (Figure 4) This temporal crowding in myopic eyes,
could either be a result of an anatomical variation or image artefact due to increased vertical curvature of retina.12 The RNFL
distribution angle has been shown to be negatively associated with axial length, with a 3.4 decrease for every 1-mm increase
in axial length, and positively associated with spherical error, with a 2.7 increase for every 1.0 D increase in spherical error.7
This negative association between area of abnormal RNFL measurement and RNFL distribution angle persists even after
adjustment of axial length and spherical error. This finding implies, that even if normative database including high myopia is
incorporated in machine software, RNFL thickness analysis would be erroneous in eyes with a small RNFL distribution angle.
Figure 5: Split nerve fibre bundle in left eye superior pole. The split is still within the 95% perecentile, it is falls short of manifesting as red diseases
5. RNFL split / segmentation
Split or segmented RNFL are anatomical variants of the RNFL bundles entering poles of disc. This variation initially
identified as an artifact by the earlier GDx machine, is often seen in high myopes with peripapillary atrophy (PPA). In this
condition retinal nerve fibres converging on superior and inferior poles of disc do not enter as complete bundles, but instead
split in two. The space between two bundles masquerades as a local RNFL defect (Figure 5).
6. Peri-papillary atrophy (PPA)
The presence of peripapillary atrophy with alpha and beta zones, has long been considered soft sign of glaucomatous disc
damage and often known as halo glaucomatosus. Three zones namely alpha, beta and gamma have been identified in PPA.
Alpha zone α is due to hyper or hypopigmentation (usually former) of RPE at edge of PPA along with slight thinning of
choroidal tissues. Beta zone β, present between α zone and disc margin, is visible as a white grey scleral crescent with loss of
RPE, marked atrophy of photoreceptor layer and choriocapillaries. It is characterized by visibility of large choroidal vessels
and sclera. Refined imaging by OCT advances, has identified two subtype of β PPA namely beta zone PPA and gamma zone
PPA in some myopic eyes. Gamma zone γ, previously called as myopic temporal crescent, is white coloured area interspersed
between beta zone and optic disc border. Gamma zone differs from beta zone in lacking a Bruch’s membrane. Since OCT
algorithms identify disc margin as Bruch’s membrane termination /opening, the presence of gamma zone γ would spuriously
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DJO Vol. 31, No. 2, October-December 2020
Figure 6: a & 6 b Peripheral pigmented part of peripapillary atrophy (infero-temporal to disc) demarcated in pink is α zone
Figure 6: 6c, 6d & 6e Peripapillary atrophy , whitish grey zone with RPE loss, retinal and choriocapillary atrophy demarcated in green is ß zone and that in blue
could be γ zone ( which is essentially an OCT finding)
Figure 7: Examples of Peripapillary atrophy 7a. RNFL calculation circle incorporates the PPA and therefore depicts less RNFL measure.7b Tilted disc with inferior
PPA, the RCNFL calculation circle falls short of PPA and therefore depicts less RNFL measure. In addition the oval disc margin is not completely covered by Disc
circle
enlarge disc area in image interpretation. (Figure 6)
Peri-papillary atrophy is often present in myopic retina and results in discrimination errors to differentiate glaucomatous
damage in myopic disc from a non-diseased myopic optic nerve head. Presence of PPA in addition, makes placement of OD
circle with subsequent measurement of disc and RNFL parameters difficult. The scanning circle diameter for measuring
optic disc in OCT machines is 3.46 -3.5 mm, which may fail to traverse extent of the PPA. Presence of large PPA extending
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DJO Vol. 31, No. 2, October-December 2020
Figure 8: Large peripapillary atrophy with posterior staphyloma. The cp RNFL print out gives erroneous results due to inability of measurement circle to stretch
beyond the large PPA area.
Figure 9: Internal limiting membrane traction, resulting in artefactual increase in RNFL peak, Green disease
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DJO Vol. 31, No. 2, October-December 2020
beyond scanning circle diameter, would result in RNFL measured from beta zone outward, resulting in erroneously low
measures (red disease). (Figure 7 and 8)New versions of Spectralis have options of 4.1 and 4.7 mm circles, to bypass the of
area peripapillary atrophy.13
Larger β zone has been identified as a significant marker of glaucomatous damage. A recent report released from DIGS
(Diagnostic Innovations of glaucoma study) states that the odds of having glaucoma get doubled for each 0.2 mm2 larger
β PPA area, after controlling for age, central corneal thickness and axial length.14 On the other hand larger γ zone is due
to scleral stretching with myopic changes and is more often associated with healthy myopic, non-glaucomatous eyes.15,16
Advances in measurement of ß and γ zone have resulted in development of SALSA algorithms (San - Diego Automated
Segmentation Algorithms), which measures areas of ß PPA with intact Bruch’s membrane, as surrogate indicators of
glaucomatous damage
Figure 10: 10a Macular cube protocol measures etinal nerve fibre layer & ganglion cells and inner plexiform layer 10b. Ganglion cell complex OU print out
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DJO Vol. 31, No. 2, October-December 2020
Green disease
Myopic eyes suspected of glaucoma sometimes would be erroneously labelled as normal. This is seen in situations of
epiretinal membrane, vitreoretinal tractions, Weiss ring or Internal limiting membrane (ILM) traction over optic nerve
head, both causing artefactual increase in RNFL measurement (green disease).17 (Figure 9) However, once total posterior
vitreous detachment occurs, the membrane would obscure light reflectance and that could cause a localized red disease.
In Peri-papillary retinoschisis conditions, a transient increase in RNFL thickness is noted, again a cause of green disease.
Macular cube: Macular Ganglion cell complex (mGCC)
Ganglion cell death is the hallmark of glaucomatous damage and macula has the unique position of containing 50% of ocular
retinal ganglion cells. Due to the above defined confounders while measuring RNFL and optic disc parameters in the myopic
suspect eye, macular GCC measurement has been explored as a more robust option to discriminate glaucoma patients from
non-glaucoma subjects. Macular ganglion cell complex (mGCC) protocol measures ganglion cell, their dendrites (inner
plexiform layer) and their axons (retinal nerve fibre layer). Some machines exclude RNFL and measure ganglion cell with
inner plexiform layer (GC IPL). (Figure 10) A 6 by 6 mm2 area centered on macula is scanned , of which central elliptical
region of 1.2 x 1.0mm, represents foveola (which lacks ganglion cells) being masked. (Figure 11)18 Being less affected by
anatomical vagaries in myopic eyes, macular scan has been established to have higher diagnostic power than cpRNFL
parameters in detecting glaucoma in these patients.19,20,21 However some studies have disputed this with both macular and
optic disc protocols having equivalent diagnostic efficacy in myopic eyes.22 Literature is equivocal on macular thickness
in myopic eyes, with some authors reporting thicker macula23 with others documenting no change.24 In both situations a
myopic normative database for ganglion cell internal plexiform layer (GCIPL) would improve glaucoma detection rate in
myopic eyes.25 In myopic eyes with macular thining/hole, posterior staphyloma and Foster Fuchs however, the macular cube
scanning protocol should not be attempted. (Figure 11)
The commonest challenge faced in discriminating glaucoma in myopic eyes, remains lack of myopic normative data.
Diagnostic Innovations in Glaucoma Study (DIGS 1995) and African Descent And Glaucoma Evaluation Study (ADAGES
2002) are longitudinal cohort studies designed to study participants with or without myopia and rectify this gap in imaging
technology. Structural, functional and vascular testing by Spectral OCT, in Caucasian and African population, seeks to
generate a reference database of healthy myopic and glaucomatous myopic eyes.26
Recent advances in OCT use extended depth imaging and adaptive optics have been used to study lamina cribrosa structure.27
In myopic eyes, documenting changes in peripapillary sclera and lamina cribrosa dimensions may help in diagnosing
glaucoma early.
Figure 11: 11a. Pathological myopia with large annular crescent and Foster Fuchs spot
11b Macular ganglion cell analysis protocol of same case, does not give any meaningful interpretation
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DJO Vol. 31, No. 2, October-December 2020
Conclusion
Optical coherence tomography has become the imaging device of choice in diagnosing glaucoma. Its use in high to moderate
myopia is limited by various anatomical alterations in myopic eye affecting scan acquisition and interpretation.28 Knowledge
of this challenging aspect of OCT is essential for the ophthalmologist keeping in mind the exponential increase in myopia
globally. This would reduce the erroneous labelling of non-diseased myopic as glaucoma and also missing the pathology in
myopic eyes.
References
1. Pei-Chang W, Hsiu-Mei H, Hun-Ju Y, Po-Chiung F, Chueh-Tan C Epidemiology of Myopia. Asia-Pacific Journal of Ophthalmology 2016, 5 (6):
386-93
2. Morgan IG, Ohno Matsui K and Saw SM: Myopia. Lancet 2012, 379: 1739 48
3. Schuman JS. Effect of refractive errors on RNFL thickness measures. JAMA Ophthalmol. 2016, 134(9): 1040.
4. Joel S. Schuman JS, Pedut-Kloizman T, Pakter H, Wang N, Guedes V, Huang L et al. Optical Coherence Tomography and Histologic
Measurements of Nerve Fiber Layer Thickness in Normal and Glaucomatous Monkey Eyes. Invest Ophthalmol Vis Sci. 2007;48: 3645–54
5. Akman A. Role of Optical coherence tomography in glaucoma. In Optical coherence tomography in glaucoma. Eds. Akman A, Bayer A, Nouri
Mahdavi. Springer international Publishing AF-GM Cham Switzerland, 2018, pg 20
6. Schweitzer KD, Ehmann D and Garcia R: Nerve fibre layer changes in highly myopic eyes by optical coherence tomography. Can J Ophthalmol
2009. 44: e13 e16,
7. Leung, C KS, Yu M, Weinreb RN, Mak HK, Lai G, Ye C and Lam DSC Retinal Nerve Fiber Layer Imaging with Spectral-Domain Optical
Coherence Tomography: Interpreting the RNFL Maps in Healthy Myopic Eyes. Invest Ophthalmol Vis Sci. 2012; 53:7194–7200
8. Singh D, Mishra SK, Agarwal E , Sharma R , Bhartiya S, Dada T. Assessment of Retinal Nerve Fiber Layer Changes by Cirrus High-definition
Optical Coherence Tomography in Myopia. J Curr Glaucoma Pract 2017;11 (2):52-57
9. Sihota R, Sony P, Gupta V, Dada T and Singh R Diagnostic Capability of Optical Coherence Tomography in Evaluating the Degree of
Glaucomatous Retinal Nerve Fiber Damage. Invest Ophthalmol Vis Sci. 2006; 47:2006–2010
10. Bae SH, Kang SH, Feng CS, Park J, Jeong JH, Yi K. Influence of myopia on size of optic nerve head and retinal nerve fiber layer thickness
measured by spectral domain optical coherence tomography. Korean J Ophthalmol. 2016; 30: 335–43.
11. Savini G, Barboni P, Parisi V, Carbonelli M. The influence of axial length on retinal nerve fibre layer thickness and optic-disc size measurements
by spectral-domain OCT. Br J Ophthalmol. 2012; 96:57–61
12. Zha Y, Zhuang J, Lin D , Feng W , Zheng H and Cai J . Evaluation of myopia on retinal nerve fiber layer thickness measured by Spectralis
optical coherence tomography. Exp & Therapeutic Med 2017, 14: 2716-2720
13. Akman A. Role of Optical coherence tomography in glaucoma. In Optical coherence tomography in glaucoma. Eds. Akman A, Bayer A, Nouri
Mahdavi. Springer international Publishing AF-GM Cham Switzerland, 2018, pg 206
14. Manalastas PIC, Belghith A, Weinreb RN, Jonas J, Suh MH, Yarmohammadi A, Medeiros FA, Girkin CA, Liebmann, JM and Zangwill LM.
Automated Beta Zone Parapapillary Area Measurement to Differentiate Between Healthy and Glaucoma Eyes. Am J Ophthalmol. 2018; 191:
140–148.
15. Jonas JB, Jonas SB, Jonas RA, Holbach L, Dai Y, Sun X, Panda-Jonas S. Parapapillary atrophy: histological gamma zone and delta zone. PLoS
One. 2012;7(10):e47237.
16. Dai Y, Jonas JB, Huang H, Wang M, Sun X. Microstructure of parapapillary atrophy: beta zone and gamma zone. Invest Ophthalmol Vis Sci.
2013; 54:2013–8.
17. Akman A. Role of Optical coherence tomography in glaucoma. In Optical coherence tomography in glaucoma. Eds. Akman A, Bayer A, Nouri
Mahdavi. Springer international Publishing AF-GM Cham Switzerland, 2018, pg 140
18. Dharwadkar S and Nayak BK. Optical coherence tomography in glaucoma -I. Journal of clinical ophthalmology and Research 2017, 5 (1): 51-63
19. Wang WW, Wang HZ , Liu JR , Zhang XF , Li M, Huo YJ , and Yang XG Diagnostic ability of ganglion cell complex thickness to detect
glaucoma in high myopia eyes by Fourier domain optical coherence tomography. Am J Ophthalmol 2018; 11(5): 791–796.
20. Zhang Y, Wen W, Sun X. Comparison of Several Parameters in Two Optical Coherence Tomography Systems for Detecting Glaucomatous
Defects in High Myopia. Invest Ophthalmol Vis Sci. 2016 Sep 1; 57(11):4910-4915.
21. Shoji T, Nagaoka Y, Sato H, Chihara E. Impact of high myopia on the performance of SD-OCT parameters to detect glaucoma. Graefes Arch
Clin Exp Ophthalmol. 2012; 250 (12):1843-9
22. Akashi A, Kanamori A, Nakamura M, Fujihara M, Yamada Y, Negi A. The ability of macular parameters and circumpapillary retinal nerve
fiber layer by three SD-OCT instruments to diagnose highly myopic glaucoma. Invest Ophthalmol Vis Sci.2013, 5; 54(9):6025-32.
23. Choi SW, MD, Lee SJ. Thickness Changes in the Fovea and Peripapillary Retinal Nerve Fiber Layer Depend on the Degree of Myopia. Korean
Journal of Ophthalmology 2006, 20(4):215-219
24. Lim MCC, Hoh ST, Foster PJ, LimTH, Chew SJ, Seah SKL, Aung T Use of optical coherence tomography to assess variations in macular retinal
thickness in myopia. Invest Ophthalmol Vis Sci 2005; 46(3):974-8.
25. Seol BR, Kim DM, Park KH, Jeoung JW. Assessment of optical coherence tomography color probability codes in myopic glaucoma eyes after
applying myopic normative database. Am J Ophthalmol. 2017; 183:147–55
26. Diagnostic Innovations in Glaucoma Study (DIGS). Grantome grantome.com › grant › NIH › R01-EY027510-03
27. Kostanyan T, Wollstein G and Schuman JS. New developments in optical coherence tomography, Curr Opinion Ophthalmol 2015, 26(2) Invest
Ophthalmol Vis Sci 2005;46 (3):974-8
28. Nouri-Mahdavi K, Weiss RE. Detection of Glaucoma Deterioration in The Macular Region with Optical Coherence Tomography: Challenges
and Solutions. Am J Ophthalmol. 2020 Sep 17:S0002-9394(20)30520-1
Kirti Singh
MD, DNB, FRCS, FAIMER
Dir Professor, Glaucoma Services,
Guru Nanak Eye Centre, Maulana
Azad Medical College, New Delhi DOI: http://dx.doi.org/10.7869/djo.584
E-ISSN: 2454-2784 P-ISSN: 0972-0200 17 Delhi Journal of Ophthalmology
DJO Vol. 31, No. 2, October-December 2020
Review Article
“Covid – 19 Revisited”With Ocular Manifestations
Raunaq Poonia, Anju Kochar
Department of Ophthalmology, Sardar Patel Medical College & Associate Group of Hospitals, Bikaner, Rajasthan, India.
Abstract In December 2019, a novel corona virus (CoV) pandemic, caused by the severe acute respiratory syndrome corona
virus – 2 (SARS-CoV-2) emerged from China. This virus causes the corona virus disease 2019 (COVID-19). The ocular
implications of human CoV infections have not been widely studied. There are few reports on the association
of severe acute respiratory syndrome corona virus 2 (SARS-CoV-2) with ocular abnormalities. Understanding
ocular manifestations of patients with COVID-19 by ophthalmologists and others may facilitate the diagnosis
and prevention of transmission of the disease. The review article will also highlight CoVs and their associated
ocular infections. We hope that this article will serve as further research into the ocular implications of human
CoV infections. As the current pandemic continues, a better understanding of the virus will emerge, hopefully
with more emphasis on research into the relationship between human CoVs and the eye. This understanding
will not only help us to guide infection control measures but can also provide insights on the feasibility of using
ocular tissue or even tears as a medium of diagnosis. Meanwhile, ophthalmologists and other health-care workers
should continue to work on the side of caution and continue to prevent the possible transmission of CoVs through
ocular tissue.
Delhi J Ophthalmol 2020;31;18-22; Doi http://dx.doi.org/10.7869/djo.585
Keywords: Coronavirus Disease; Ocular Manifestation; Severe Acute Respiratory Syndrome
Introduction of Wuhan, China. This new pandemic has spread across the
globe rapidly, affecting 11,598,155 people in 215 countries or
Since December 2019, coronavirus disease 2019 (COVID-19) territories or areas as of the 6th of July 2020. On the 30th
has been reported among patients in China. Currently, the of January, the World Health Organization (WHO) has
disease is quickly spreading worldwide. The pathogen of declared a public health emergency of international concern
COVID-19 is a novel coronavirus (severe acute respiratory (PHEIC).8,9 A set of recommendations for personal protective
syndrome coronavirus 2 [SARS-CoV-2]), identified as a equipment (PPE) based on the experience of MERS-CoV and
member of the coronaviridae family. Another coronavirus, SARS-CoV have been released.10 This set of recommendation
named SARS-CoV-1, was responsible for severe acute includes wearing goggles or face shield for protection against
respiratory syndrome. Compared with SARS-CoV-1, SARS- ocular transmission of the CoV. Interestingly, the evidence
CoV-2 has a similar binding receptor and similar pathologic of ocular transmission has not been well studied. However,
features.1,2 Although there is no direct evidence that SARS- CoV ocular infection has been well established in various
CoV-1 replication results in conjunctivitis and other ocular animals. In some cases, such as CoVs which affect the murine
diseases, reports have emphasized the eye as a potential site and feline orders, they can cause sight-threatening ocular
for virus transmission.3 complications. Such evidence suggests that CoVs can shed
and even infect ocular issues. More research has to be done
Similarly, SARS-CoV-2 transmission through the eye has to understand the ocular manifestation of human CoVs. This
been suspected. Nevertheless, there are no reports in the review article will first introduce the structure of the CoV
medical literature at this time, to our knowledge, that and the various hosts that they have been discovered in. The
identifies a direct relationship between SARS-CoV-2 and article will then highlight the currently available evidence
the eye. Researchers have not reported ocular abnormalities for CoV infection of ocular tissue in humans. Finally, it will
nor have they stated in the medical literature if there was attempt to bridge the knowledge gap by featuring known
conjunctivitis or viral presence detected in the tears of ocular infections by various CoVs in animals such as mice
patients with COVID-19. The objective of this study was (murines) and cats (felines). We hope that this article will
to evaluate ocular involvement systematically in patients serve as a starting platform for research into human CoV
highly suspected of having or confirmed to have COVID-19. infections and its ocular implications.
Coronaviruses (CoVs) are viruses that have been known to Etiology
affect birds and mammals.4 CoVs rose to public prominence
after the outbreak of the Severe Acute Respiratory Syndrome CoVs are positive-stranded RNA viruses with a crown-like
Coronavirus (SARS-CoV) in 2003.5 The SARS-CoV outbreak appearanceunderanelectronmicroscope(coronamistheLatin
was reported to have infected more than 8000 people and term for crown) due to the presence of spike glycoproteins
resulted in 774 deaths globally.6 Since then, the Middle on the envelope. The subfamily Orthocoronavirinae of
Eastern Respiratory Syndrome Coronavirus (MERS-CoV) the Coronaviridae family (order Nidovirales) classifies
has also been in the public spotlight.7 In December 2019, a into four genera of CoVs: Alphacoronavirus (alphaCoV),
new CoV pandemic, caused by the Severe Acute Respiratory Betacoronavirus (betaCoV), Deltacoronavirus (deltaCoV),
Syndrome Coronavirus – 2 (SARS-CoV-2) started in the city and Gammacoronavirus (gammaCoV). Furthermore, the
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DJO Vol. 31, No. 2, October-December 2020
betaCoV genus divides into five sub-genera or lineages.11 respiratory droplets from coughing and sneezing. Aerosol
Genomic characterization has shown that probably bats and transmission is also possible in case of protracted exposure to
rodents are the gene sources of alphaCoVs and betaCoVs. elevated aerosol concentrations in closed spaces. Analysis of
On the contrary, avian species seem to represent the gene data related to the spread of SARS-CoV-2 in China seems to
sources of deltaCoVs and gammaCoVs. indicate that close contact between individuals is necessary.
The spread, in fact, is primarily limited to family members,
Members of this large family of viruses can cause respiratory, healthcare professionals, and other close contacts.
enteric, hepatic, and neurological diseases in different animal
species, including camels, cattle, cats, and bats. To date, Based on data from the first cases in Wuhan and investigations
seven human CoVs (HCoVs) capable of infecting humans conducted by the China CDC and local CDCs, the incubation
have been identified. In general, estimates suggest that 2% time could be generally within 3 to 7 days and up to 2 weeks
of the populations are healthy carriers of a CoV and that as the longest time from infection to symptoms was 12.5
these viruses are responsible for about 5% to 10% of acute days (95% CI, 9.2 to 18).14 This data also showed that this
respiratory infections.12 novel epidemic doubled about every seven days, whereas
the basic reproduction number (R0 - R naught) is 2.2. In other
This, SARS-CoV-2 belongs to the betaCoVs category. It has words, on average, each patient transmits the infection to an
round or elliptic and often pleomorphic form, and a diameter additional 2.2 individuals. Of note, estimations of the R0 of
of approximately 60–140 nm. Like other CoVs, it is sensitive the SARS-CoV epidemic in 2002-2003 were approximately
to ultraviolet rays and heat. Furthermore, these viruses 3.15
can be effectively inactivated by lipid solvents including
ether (75%), ethanol, chlorine-containing disinfectant, It must be emphasized that this information is the result
peroxyacetic acid and chloroform except for chlorhexidine. of the first reports. Thus, further studies are needed to
understand the mechanisms of transmission, the incubation
Epidemiology times and the clinical course, and the duration of infectivity.
Data provided by the WHO Health Emergency Dashboard Pathogenesis
(July 6, 11.00 pm CET) reported 11,598,155 confirmed cases
worldwide since the beginning of the epidemic. 58,735 (1%) The virus enters the body through mucous membranes like
cases have been fatal.13 oral cavity, nasal mucosa, conjunctiva and replicates inside
the host cells. Patients infected with COVID-19 showed
In USA, 2,985,897 cases confirmed clinically and in the higher leukocyte numbers, abnormal respiratory findings
laboratory, and 132,610 deaths are reported. In addition and increased level of plasma pro-inflammatory cytokines.
to USA, there are 8,612,258 confirmed cases in 214 other The main pathogenesis of COVID-19 infection as a
countries or territories or areas. The countries with most respiratory system targeting virus was severe pneumonia,
cases are Brazil (1,604,585) and India (704,607). The most combined with the incidence of ground-glass opacities,
up-to-date source for the epidemiology of this emerging and acute cardiac injury. Significantly high blood levels
pandemic can be found at the following sources: of cytokines and chemokines were noted in patients with
COVID-19 infection. Cytokines exert their effects in tissues
• The WHO Novel Coronavirus (COVID-19) Situation locally or circulate in the blood and lymph. Cytokine storms
Board occur in viral infections when large amount of cytokines
are produced. This can worsen a patient’s condition and
• The Johns Hopkins Center for Systems Science cause multi-organ failure, which is frequently fatal. Cardinal
and Engineering site for Coronavirus Global Cases features of a cytokine storm include unremitting fever,
COVID-19, which uses openly public sources to track the cytopenia, massive increases in ferritin, high erythrocyte
spread of the epidemic. sedimentation rate (ESR) and Adult Respiratory Distress
Syndrome (ARDS).During infection from SARS-CoV-2,
Transmission which causes COVID-19, this cytokine storm is associated
with increased levels of interleukins IL-2, IL-7 and other
Because the first cases of the COVID-19 disease were linked cytokines. Thrombocytopenia is also a marker of a fatal
to direct exposure to the Huanan Seafood Wholesale Market outcome.Cytokine storms can be severe in young patients
of Wuhan, the animal-to-human transmission was presumed who have more efficient immune systems and responses
as the main mechanism. Nevertheless, subsequent cases were than older patients.
not associated with this exposure mechanism. Therefore,
it was concluded that the virus could also be transmitted Differential Diagnosis
from human-to-human, and symptomatic people are the
most frequent source of COVID-19 spread. Moreover, there The symptoms of the early stages of the disease are
are suggestions that individuals who remain asymptomatic nonspecific. Differential diagnosis should include the
could transmit the virus. This data suggests that the use of possibility of a wide range of infectious and non-infectious
isolation is the best way to contain this epidemic. (e.g., vasculitis, dermatomyositis) common respiratory
disorders.
As with other respiratory pathogens, including influenza
and rhinovirus, the transmission is believed to occur through
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DJO Vol. 31, No. 2, October-December 2020
• Adenovirus The potential of infection through ocular secretions is
• Influenza currently unknown, and it remains unclear how SARS-
• Human metapneumovirus (HmPV) CoV-2 accumulates in ocular secretions. Possible theories
• Parainfluenza include direct inoculation of the ocular tissues from
• Respiratory syncytial virus (RSV) respiratory droplets or aerosolized viral particles, migration
• Rhinovirus (common cold) from the nasopharynx via the nasolacrimal duct, or even
hematogenous spread through the lacrimal gland.22
For suspected cases, rapid antigen detection, and other
investigations should be adopted for evaluating common In a study done on 30 COVID positive patients in Zhejiang23
respiratory pathogens and non-infectious conditions. one patient was noted to have conjunctival involvement and
conjunctival swabs taken early in the course of the disease
Human Coronaviruses and The Evidence for Ocular were positive for SARSCoV2 by RT-PCR. Wu P et al. from
Manifestation Guangzhou24 reported conjunctival congestion in 12 out of
38 patients, with conjunctival swabs of 2 patients showing
There are seven types of CoVs known to infect humans: positivity for SARSCoV2 by RT-PCR. This study showed
229E (alphacoronavirus), NL63 (alphacoronavirus), OC43 conjunctival involvement in more severely ill patients with
(betacoronavirus), HKU1 (betacoronavirus), MERS-CoV COVID-19, unlike the previous study 23 which showed
(betacoronavirus),SARS-CoV (betacoronavirus), and the involvement in non-severe COVID-19 patients.
most recent SARS-CoV-2. It is widely agreed that these
CoVs cause respiratory tract infections and patients can While the above two studies raised possibility of transmission
present with a large spectrum of clinical manifestations. of virus through the tears of these patients, another study
229E, NL63,OC43, and HKU1 have been known to cause done on serial tear samples of 17 patients in Singapore,25
mainly self-limiting upper respiratory tract infections which could not demonstrate RT-PCR positivity of tear samples at
present with symptoms such as running nose, sore throat, any time point, though one patient had conjunctival redness
fever, and cough.16 However, in immunocompromised during the course of the illness.
states or underlying cardiopulmonary disease, they can
cause pneumonia or bronchitis.17 On the other spectrum, the Treatment / Management
SARS-CoV,MERS-CoV, and SARS-CoV-2 have been known
to cause life-threatening respiratory failure.18 There is no specific antiviral treatment recommended
for COVID-19, and no vaccine is currently available. The
Ocular manifestations of COVID-19 are overall rare in the treatment is symptomatic, and oxygen therapy represents
published literature. Only 9 (0.8%) out of 1,099 patients from the major treatment intervention for patients with severe
552 hospitals across 30 provinces in China were reported to infection. Mechanical ventilation may be necessary in cases
have "conjunctival congestion."19 of respiratory failure refractory to oxygen therapy, whereas
hemodynamic support is essential for managing septic
A recent case series reported ocular symptoms in 12 (31.6%) of shock.
38 hospitalized patients with COVID- 19 in Hubei province, Treatment to combat cytokine storms requires support
China. These 12 of 38 patients had conjunctival hyperemia including management of the ARDS. As during previous
(3 patients), chemosis (7 patients), epiphora (7 patients), or pandemics (Severe Acute Respiratory Syndrome and
increased secretions (7 patients). Of note is that one patient Middle East Respiratory Syndrome), corticosteroids are not
who had epiphora presented with epiphora as the first routinely recommended and might exacerbate COVID-19-
symptom of COVID-19. Of those with ocular manifestations, associated lung injury. However, in hyperinflammation,
2 (16.7%) patients had positive results of SARS-CoV-2 on immunosuppression is likely to be beneficial. Tocilizumab
reverse-transcriptase polymerase chain reaction (RT-PCR) (IL-6 receptor blockade, licensed for cytokine release
by a conjunctival swab as well as by nasopharyngeal swabs. syndrome), has been approved in patients with COVID-19
Only one patient in this study presented with conjunctivitis pneumonia and elevated IL-6 in China. Role of plasma
as the first symptom.20 The authors noted that patients with therapy as the new emerging treatment modality has shown
ocular symptoms had higher white blood cell and neutrophil promising results.
counts, C-reactive protein, and higher levels of procalcitonin
and lactate dehydrogenase compared to patients without Treatment Of Conjunctivitis during Covid-19
ocular abnormalities. Pandemic
Out of 30 hospitalized patients with COVID-19 tested by
Xia et al., one patient had conjunctivitis and was also the As with other viral infections, ocular manifestations of
sole patient in the study to test positive for SARS-CoV-2 in COVID-19 are presumed to be self-limited and can be
ocular secretions by a conjunctival swab. This patient did not managed with symptomatic care.
have a severe fever or respiratory symptoms at the time of As of March 18, 2020, the American Academy of
testing.21 There have been no reports of COVID- 19 patients Ophthalmology has urged all ophthalmologists to provide
experiencing blurred vision, subconjunctival hemorrhage, only urgent or emergent care to reduce the risk of SARS-
eyelid ecchymoses, conjunctival scarring, keratitis, or CoV-2 transmission and to conserve disposable medical
pseudomembrane formation. supplies. In the absence of significant eye pain, decreased
vision, or light sensitivity, many patients can be managed
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DJO Vol. 31, No. 2, October-December 2020
remotely with a trial of frequent preservative-free artificial for the prevention and control of infections.
tears, cold compresses, and lubricating ophthalmic ointment. • Individuals who are immunocompromised should
A short course of topical antibiotics can be added to prevent
or treat bacterial superinfection based on the patient's avoid public gatherings.
symptoms and risk factors (e.g. contact lens wear).26 For
analgesia, non-steroidal anti-inflammatory drugs (NSAIDs) The most important strategy for the population is to
such as Ibuprofen are better avoided as they have been frequently wash their hands and use portable hand sanitizer
shown to worsen the systemic effects of COVID infection, and avoid contact with their face and mouth after interacting
oral Paracetamol may be added instead. with a possibly contaminated environment.
Although preliminary studies suggest that the risk of viral Healthcare workers caring for infected individuals should
transmission through ocular secretions is low, large-scale utilize contact and airborne precautions to include PPE such
research has not yet been done, and new data is emerging as N95 or FFP3 masks, eye protection, gowns, and gloves to
daily. Healthcare providers are, therefore, still urged to prevent transmission of the pathogen.
wear proper protection of the eyes, nose, and mouth when
examining patients (see below). It has been suggested that Conclusion
ocular transmission of the COVID-19 virus may occur.27
Eye care providers and technicians may be more susceptible As CoVs can cause ocular infection across different animals,
to infection due to the nature and proximity of the ophthalmic the possibility of SARS CoV-2 having ocular implications
examination.28 Eye care providers are encouraged to use slit cannot be ignored. Given the anecdotal nature of evidence
lamp breath shields and should counsel patients to speak regarding SARS CoV- 2 transmission through ocular tissue,
as little as possible when sitting at the slit lamp to reduce more research has to be done to confirm its ability to infect
the risk of virus transmission. Disinfection and sterilization ocular tissue and its pathogenic mechanisms. As the current
practices should be employed for shared clinic equipment pandemic continues, a better understanding of the virus
such as tonometers, trial frames, pinhole occluders, B-scan will emerge, hopefully with more emphasis on research
probes, and contact lenses for laser procedures.29 into the relationship between human CoVs and the eye. This
understanding will not only help us to guide infection control
Sterilization of Equipment measures but can also provide insights on the feasibility of
• The slit-lamp shields are disinfected with 70% ethyl using ocular tissue or even tears as a medium of diagnosis.
Meanwhile, ophthalmologists and other health-care workers
alcohol after each patient. 70% ethyl alcohol has been should continue to work on the side of caution and continue
shown to reduce coronavirus infectivity.30 to prevent the possible transmission of CoVs through ocular
• Slitlamps, B-scan probes, and any other tools are tissue.
similarly cleaned with 70% ethyl alcohol.
• Goldman tonometers are sterilized with a 10% diluted References
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coronavirus-(ncov)-infection-is-suspected-20200125. 2020. move in indoor environments--revisiting the Wells evaporation-
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13. Marco Cascella; Michael Rajnik; Arturo Cuomo; Scott C. 31 (2) :18-22.
Dulebohn; Raffaela Di Napoli. Features, Evaluation and
Treatment Coronavirus (COVID-19). In: StatPearls [Internet]. Acknowledgments: Nil
Treasure Island (FL): StatPearls Publishing; 2020 Jan–2020 Apr 6. Conflict of interest: Nil
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1207. [PMC free article] [PubMed]
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16. CormanVM, Muth D, Niemeyer D, Drosten C. Hosts and sources Professor and Head
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Papadopoulos A. A rare case of human coronavirus 229E Associate Group of Hospitals,
associated with acute respiratory distress syndrome in a healthy Bikaner, Rajasthan, India.
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in tears and conjunctival secretions of patients with SARS-CoV-2
infection. J Med Virol 2020 Jun;92(6):589-594.
22. 5.Seah I, Agrawal R. Can the Coronavirus Disease 2019
(COVID-19) Affect the Eyes? A Review of Coronaviruses and
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23. Xia J, Tong J, Liu M, Shen Y, Guo D. Evaluation of coronavirus
in tears and conjunctival secretions of patients with SARS‑CoV‑2
infection. J Med Virol 2020. doi: 10.1002/jmv. 25725.
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of ocular findings of patients with coronavirus disease 2019
(COVID‑19) in Hubei Province, China. JAMA Ophthalmol 2020.
doi: 10.1001/jamaophthalmol. 2020.1291.
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of tears in coronavirus disease 2019 (COVID‑19) patients.
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in the ophthalmology practice. Eye (Lond) 2020 Jul;34(7):1155-
E-ISSN: 2454-2784 P-ISSN: 0972-0200 22 www.djo.org.in
DJO Vol. 31, No. 2, October-December 2020
Review Article
Seeing World From The Eyes of Low Vision Subject
Punita Kumari Sodhi
Professor in Ophthalmology Guru Nanak Eye Centre and Maulana Azad Medical College, New Delhi, India.
Abstract Low vision is a moderate to severe form of visual impairment wherein best corrected visual acuity varies from less than
6/18 to 3/60 in better eye. A low vision subject is potentially able to use his residual vision for execution of tasks of his
interest. Low vision may be due to retinal diseases, glaucoma and corneal affections. The visual and allied stimulus
carrying neurons including photoreceptors and retinal ganglion cells get affected, resultantly the low vision subject has
various forms of visual disabilities including diminution of vision, reduced contrast sensitivity, altered colour perception,
defective depth perception, deficient form vision and glare. Therefore, affected subject sees the world differently from a
normal one. The article describes how different aspects of vision are defeated due to low vision. Various rehabilitation
measures including magnification, modified reading text material, increased lighting, visual stimulation and coloured
lenses have been utilized in a pursuit to improve entire seeing experience of a low vision subject. However more
extensive and detailed studies are required in order to assess the usefulness of these low vision aids in improving
different aspects of visual functions.
Delhi J Ophthalmol 2020;31;23-29; Doi http://dx.doi.org/10.7869/djo.586
Keywords: Low vision; Low vision aid; Magnification; Stereopsis; Colour vision
Introduction been modified in line with definition given under the World
Health Organization i.e. Blindness is defined as presenting
According to the WHO Working Definition of Low Vision distance BCVA less than 3/60 (20/400) in the better eye or
(1992), a person with low vision (LV) has an impairment limitation of field of vision to be less than 100 from centre of
of visual functioning even after treatment and/or standard fixation, while earlier blind category under NPCB included
refractive correction, and has best corrected visual acuity VA <6/60 to 3/60 also.4
(BCVA) of less than 6/18 to 3/60 in better eye, or a visual
field of less than 100 from the point of fixation, but who uses, Causes Of Low Vision
or is potentially able to use, vision for the planning and/
or execution of a task. In other words, LV is a “moderate The LV can be due to retinal diseases, corneal diseases or
to severe form of visual impairment.”1 In the world, there glaucoma. Few studies have been conducted to compare the
are about 36 million blind people with 217 million people incidence of LV from these diseases. In a study conducted in
Turkish population, it was found that among those aged 18-
Table: 1 showing category of visual impairment based on 50 years, retinal dystrophies (37%), congenital eye anomalies
Best Corrected Visual Acuity (BCVA) of better eye ; Adapted (14%) and myopic degenerations (13%) were the most
from International Statistical Classification of Diseases and common causes for LV. For those aged above 50 years, age-
Related Health Problems, tenth revision, Geneva, World Health related macular degeneration (ARMD) (21%) was the leading
cause. Diabetic retinopathy (17%), corneal opacities (14%),
Organisation, 1982 cataract (12%) and glaucoma (9%) were also important.5
In another study by Ackuaku-Dogbe et al, glaucoma (22.35%),
Category Corrected WHO Working Indian retinitis pigmentosa (RP) (8.94%), ARMD (7.95%), non-
VA- better definition Definition glaucomatous optic atrophy (10.26%) were leading causes of
0 Normal LV in subjects attending teaching hospital at Ghana.6
1 eye Low vision Normal
2 Low vision Pathogenesis
6/6 – 6/18 Normal Low vision
3 Blind The retinal diseases causing LV include retinopathy of
4 <6/18 – 6/60 Visual Low vision prematurity (ROP), albinism, heredo-macular degeneration,
5 impairment Low vision Blind pathological myopia and myopic retinopathy, RP, co-
Blind existing optic atrophy (Primary or secondary), ARMD,
<6/60 – 3/60 Severe Total Total diabetic retinopathy and chorio-retinitis.
visual Blindness Blindness In ROP, the cell invasion of vitreous gel causes contractile
force from cicatricial tissue leading to retinal detachment
impairment (Separation of neurosensory retina i.e. rods and cone from
RPE) and subsequent degeneration of photoreceptors. In
<3/60 – 1/60 Blind albinism, misrouting of the nerve fibers and abnormal
foveal development occurs due to deficient melanin, while
<1/60 - PL Blind appropriate melanin has been included among several
factors present during embryogenesis, which guide
No PL Blind
having severe to moderate visual impairment for distance
(i.e. LV) and 8.8 million blind with 47.7 millions having LV
in India.2,3
In India, the National Programme for Control of Blindness
(NPCB) has been re-designated as National Programme
for Control of Blindness and Visual Impairment (NPCB &
VI). Further, under NPCB & VI, definition of blindness has
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DJO Vol. 31, No. 2, October-December 2020
the development of retinal and vascular structures and appropriate light stimulus from reaching the photoreceptors
the routing of ganglion cells in the retina to the lateral preventing initiation of an ocular/visual stimulus.
geniculate nucleus and on to the occipital cortex. This results
in reduced visual acuity. Other pigments, such as lutein Figure 1: showing glare experienced by low vision subject
and xanthophyll are not affected in albinism.7 In heredo-
macular degenerations, there is malfunction of the ATP- Clinical Presentation
binding cassette transporter (ABCA4) protein of the visual
phototransduction cycle leading to improper shuttling of The LV subjects have glare (Figure 1) and this is more
vitamin A throughout the retina.8 In pathological myopia, the prominently seen in diseases like aniridia, ARMD and
axial elongation of the eye results in stretching of the ocular albinism. There is escapism from light and subject’s face
layers and progressive thinning of the retina and resultant may have a downward tilt. He may need sunglasses, visors
cone-rod dysfunction.9 In RP, there is a progressive bilateral or hats outdoors as well as indoor.
degeneration of the rod and cone photoreceptors that leads The diminution of vision is the prime presenting clinical
to night blindness and progressive visual field defects. The feature. The LV subject has difficulty in seeing distant and
optic atrophy is accompanied with loss of ganglion cells and near objects. Hence he/she may go very close to the object
axon degeneration in the retinogeniculate pathway (lateral in order to see it. Prescription of proper refractive correction
geniculate body) leading to visual dysfunction.10 for both near and distance is required. Additionally,
In ARMD, there is an oxidative damage to retinal pigment magnifiers which are worn on glasses or hand held or in
epithelium (RPE) cells, complement deposition in the form of electronic devices which enlarge target of interest
RPE-Bruch's membrane-choriocapillaris complex, loss and or enlarge the reading text are required. Goldstein et al
later total disappearance of rods and cones at fovea and found that though VA is the strongest predictor of visual
parafovea, vascular leakage from choroidal new vessels and ability (P< .001) and reading ability (P < .001), it additionally
subsequent reparative response resulting into disciform scars has a significant independent effect on the other functional
formation.11,12 The diabetic retinopathy involves systemic domains including mobility, visual motor function, and
microangiopathy, retinal plasma exudation and punctate visual information processing.17 Thus subjects having
haemorrhages, maculopathy due to cystoid oedema, closure diminished vision have difficulty not only in reading but it
of capillaries leading to cotton-wool spots and intra-retinal also reflects through reduction of their movement in their
microvascular anomalies, rod and cone photoreceptor outer surroundings and carrying out daily activities like cooking
segment degeneration and retinal ganglion cell (RGC) food, washing clothes and cleaning their houses.
loss.13,14 The chorio-retinitis involves retinal and choroidal
inflammation, vasculitis and photoreceptor destruction. The LV subjects experience loss of colour vision and have an
altered colour perception (Figure 2), thus they have difficulty
Development Of Clinical Presentation in identifying food cooked, clothes to be worn, ripe fruits
which are fit for consumption, etc. Jolly et al found that CVD
In retinal diseases, the development of clinical presentation deteriorates more and more as degeneration/disease keep
is due to affection of photoreceptors, bipolar cells and retinal progressing to encroach upon the fovea.18
ganglion cells. While cones confer chromatic vision, rods
confer achromatic vision. Though both rods and cones are As these patients experience a reduction in depth perception
required for visual perception, cones are more closely linked (Figure 3) and in recognising edges of objects, they have
to functions of VA, colour vision and contrast sensitivity as difficulty in performing daily activities like driving and
cone-mediated vision can detect a contrast (either spatial or reading; and children may find difficulty in learning for
temporal) as small as 0.5%, whereas rod-mediated vision example through shapes of objects. The patients lose the
needs a minimum contrast of 5% to be detected. Stereopsis
appears to be processed in the visual cortex by fusing and
processing images with disparity, but good VA is required for
visual message “necessarily” to be sent to the cortex, which
happens to take place when photoreceptors are healthy and
functioning well. The glare is due to reduced amount of
xanthophyll pigments including lutein and zeaxanthin, for
example in ARMD, which otherwise filter some harmful blue
light. This was found by Stringham and Hammond, who
measured these pigments with Maxwellian-View Optical
system and found reduced macular pigment optical density.
The xanthophyll pigments also act as antioxidants to tackle
free radicals and eradicate reactive oxygen species which
can damage photoreceptors of macula.15,16 In glaucoma, LV
results from damage to the retinal ganglion cells which are
the final visual message sending neuron via optic nerve to
the visual cortex, while other layers of retina are minimally
affected. The corneal diseases cause LV by interrupting
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DJO Vol. 31, No. 2, October-December 2020
Figure 2: Showing altered colour perception in low vision subject Figure 4: Showing central field defect in a low vision subject
Figure 3: Showing reduced depth perception in a low vision subject Figure 5: Showing reduced contrast sensitivity in a low vision subject
ability to distinguish a relative physical distance between in order to use parafoveal/paramacular region for reading
objects. Even monocular cues become ineffective thus it and use the same eccentric viewing to see distant objects.
becomes difficult to appreciate the relative location of objects Patients with only central diseases however preserve
using healthier eye (in situation when the other eye has an peripheral fusion. Since peripheral fusion is as potent as
extremely poor vision). As stereopsis is directly related to central fusion, peripheral stereopsis may be present in LV
simultaneous perception from both eyes and good vision in cases, which is evidenced by the excellent spatial orientation
both eyes, hence it is the level of VA in the poorer eye which and mobility skills noticed in many of such patients.
defines the achievable level of stereopsis. Fine stereopsis is The LV subjects with wide impact of the disease process
possible only in those who have good VA as well as good however may experience loss of both central and peripheral
macular function in the poorer seeing eye also. However, vision. For example, the concurrent peripheral field defects
only gross stereopsis is possible in those subjects who have also occur in RP, lasered diabetic retinopathy and glaucoma.
a loss of macular function.19 The studies have shown that The subject resorts to eccentric viewing, head turn/tilt,
binocular dysfunctions are prevalent in LV patients although tentative gait, maintenance of close proximity to walls or
stereopsis is present in about two thirds of tested subjects.20,21 handrails and reliance on tactile information by holding
onto individuals.
The subjects who have central field defects (Figure 4) for The LV subjects have a reduced contrast sensitivity (Figure
example in heredo-macular degeneration, optic atrophy, 5). Resultantly, they have difficulty in driving, watching
ARMD and toxoplasma scar, turn their head while reading television and even reading text.
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DJO Vol. 31, No. 2, October-December 2020
The form vision, which is recognition of visual elements damage to the optic nerve and retinal ganglion cells. It shrinks
of objects, specifically those to do with shapes/patterns/ overall area seen and causes defects in side (peripheral)
previously identified important characteristics, is also vision resulting into tunnel vision whereby central vision is
disturbed in LV subject (Figure 6). This results from structural preserved while peripheral vision is lost. In retinal diseases
changes in retina involving displacement of both external however, peripheral vision is generally preserved till later
retinal layers with improper light signal transduction and stages as central vision gets affected earlier from macular
internal layers distortion from sub retinal neovascular involvement. Tunnel vision of glaucoma is described as
membrane (SRNM). The disturbance in form vision may looking at the world through a straw or a pinhole and LV
present as metamorphopsia.22 subject may not be able to see what is directly below, above
The patients with LV do not show a close relationship or around him on the sides. People with glaucoma can often
between threshold visual angle for isolated capital letters still see small details, but they lose the ability to see the entire
and for continuous text. As printed material presents a more picture. There is also difficulty with night vision, reduced
complex and difficult task than do acuity letters, therefore ability to adapt from light to dark and from dark to light
(for example coming out of a movie theatre at daytime),
Figure 6: showing reduced form vision in a low vision subject increased sensitivity to light (glare) and decreased ability to
see contrast.
conventional tests of acuity are of little use in predicting
magnification that the patient needs to read a continuous Corneal Diseases
text with reasonable speed and accuracy. There is often a
poor agreement between reading acuity and distance letter The clinical presentation of low vision in corneal diseases
acuity and the discrepancies between these become more has been infrequently described. Corneal opacity from
pronounced when there is a disturbance of macular function congenital, nutritional, traumatic, infectious, degenerative,
as in macular degeneration and amblyopia. So, assessing and hereditary conditions can cause LV. A corneal opacity
reading speed with use of objective tests like MN read test can also result from poor quality cataract surgery and
is required.23 pterygium. In a Corneal Opacity Rural Epidemiological
(CORE) study by Vashist et al, the VR-QoL (vision-related
Other presentation of LV may include nystagmus from quality of life) was assessed through Indian Vision Function
Questionnaire (IND-VFQ-33) in 435 adult participants (aged
poor vision and oculo-digital sign/eye poking sign (Leber’s ≥18 years) having corneal opacity across three domains of
congenital amaurosis) from difficulty experienced in seeing. vision function i.e. vision-specific mobility, psychosocial
impact and visual symptoms and it was found that these
Loss of vision in one eye or both can have a profound effect subjects had significantly higher score and hence poorer
VR-QoL than equal number of 435 healthy controls having
on binocular visual functions. In most cases with LV, the VA of 6/6 in both eyes (p<0.0001). Additionally, the scores
were inversely related with the level of visual impairment
fine balance of binocularity reached in the past is broken in patients with corneal disease. Patients with unilateral
corneal disease also had poorer VR-QoL scores as compared
and emerging symptoms may disable many activities of with healthy controls (p<0.0001). The authors concluded that
VR-QoL is impaired in patients with corneal disease, more
daily living (ADL) as a result of binocular dysfunction.24 The so in patients with corneal blindness.
subject may have difficulty in daily living, soiled clothing
Clinical Examination
and missing buttons. The overall appearance is a fatigued
The traditional charts (e.g. Snellen’s Chart) used in clinical
appearance which is indicative of ocular or systemic practice are not standardized; they have an irregular
progression of letter sizes and a variable number of characters
disorder. Glaucoma per line. Measurement accuracy may further suffer from
hidden errors that cannot be captured by any recording
The LV due to glaucoma has somewhat different clinical device- such as inconsistent and non-standardized protocol
presentation than LV from retinal diseases. Glaucoma causes including viewing distance, inaccurate projector adjustment
and contrast loss from room illumination. Today, the ETDRS
chart and ETDRS protocol, established by the National Eye
institute in the US, are considered to represent the de facto
gold standard for VA measurements. The International
Council of Ophthalmology, Visual Standard, Aspects
and Ranges of Vision loss (April 2002) is a good reference
document.25 The Early Treatment Diabetic Retinopathy Study
(ETDRS) distance and near are standard tests for examining
LV subjects. The distance BCVA is tested on self-illuminated
ETDRS acuity charts under uniform room illumination at
4 m. The ETDRS acuity log score which patient can read
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DJO Vol. 31, No. 2, October-December 2020
completely is noted. Therefore, the difference between two The stereopsis is assessed by use of Titmus fly test. The
routine clinical measurements should not be considered polaroid vectograph is held at 40 cm ahead. The subject
significant, unless it exceeds 1 line on an ETDRS chart.26 had to wear crossed polaroid filters (1 pair of standard 3D
viewers) to present slightly different aspects of the same
The use of conventional acuity, especially the distance value object to two eyes. The patient is passed thorough all three
has, however, been criticized for not being ideal to calculate aspects of test that is –touching wings of housefly, seeing 9
near VA and for reading power calculation. There is often a sets of four circles and seeing three rows of five animals. The
poor agreement between reading acuity and distance letter results for stereopsis test score is read from answer key and
acuity and these discrepancies become most pronounced recorded.
when there is disturbance of macular function as in macular
degeneration and amblyopia. Thus the subjects’ near vision The LV subjects having glaucoma have presentation similar
is tested using ETDRS N charts having text printed in to LV subjects with retinal diseases except for central vision
high contrast, at reading distance of 40 cm, using optimal preservation, more prominent impaired dark adaptation
illumination with recommended glass prescription. Same and defective night vision in glaucoma. These subjects
reading material having same contrast, illumination, letter present with diminished light sensitivity and they often pick
spacing and font style is used in all subjects. The VA values up trouble when lighting is dim (e.g. cinema halls, dimly lit
measured at reduced near viewing distance from ETDRS restaurants). Poor lighting makes seeing difficult. They have
near vision charts are used for predicting optical powers and difficulty in distinguishing different shades of the same color
visual performance of LV patients. i.e. contrast sensitivity is reduced. They also have glare and
have trouble seeing in bright sunlight and at bright stores
The colour vision assessment may be done by most and extreme changes in lighting makes it hard for people
commonly available Ishihara’s tests but since the LV subjects with vision loss from glaucoma to see clearly.
suffer from undefined colour vision defect (CVD) thus
Farnsworth D15/100- hue test is the most recommended Rehabilitation
one. In these tests, coloured discs are arranged in apparently
correct order according to gradation of hue by LV subject The functional loss in LV is irreversible and there is a great
in an ambient illumination, and variation from normal need for low-vision rehabilitation. Most patients with LV
pattern (diagram on booklet) provides information for type are elderly and have functional limitations from other
of CVD. Scoring is accomplished by reading the color chip/ health problems that could add to the restraints caused by
disc numbers on the reverse side and the sequence selected their visual impairments. Unattended low vision has far-
by the patient is recorded on a copy of the score sheet, for reaching consequences: developmental effects in children,
example 1,15,2,3,14,13,12,11,10,9,8,7,6,5,4. A patient with and functional, mental, socio-economic and quality of life
a CVD arranges the color discs in a different order than a implications for all those affected across the life spectrum.
person with normal CV. Subsequently, the diagramming is People with LV have residual vision with some light
done and a circular results diagram is considered “pass” and perception. Low vision aid (LVA) is a device that aims to
an interlacing pattern is contemplated “fail/colour vision make the most of the remaining vision. The individual’s
defective”. The “interlacing pattern diagrams” are matched visual and environmental requirements are to be determined
with standard diagrams on booklet depicting protanopia/ to find which types of orientation and mobility programs
deuteranopia/tritanopia and the corresponding diagnosis or and devices are most effective
else “an undefined CVD” is inferred. Farnsworth Munsel D
15 test is relatively quick and easy to administer. Magnification is the most widely used rehabilitation for LV
subjects. The magnification devices stimulate more number
The Amsler’s grid [original grid (with white lines on black of photoreceptors thus ensuring that signal necessarily
background)] is used to examine central 200 of visual field i.e. goes to the brain for recognition of reading material or
area of retina providing fine details, at 1/3 m with opposite an object. Near magnification devices include hand held
eye closed. The patient fixates on central spot with reading magnifiers (both illuminated and non-illuminated), stand
glasses “on” and reports blurry areas, scotoma, distorted magnifier, pocket magnifier, spectacle magnifier, etc. Distant
lines or other defects of grid pattern. The test is done in each magnification devices include telescopes and See TV glasses.
eye separately. With the help of closed circuit television, LV patients with
The contrast sensitivity (CS) was tested on Pelli Robson reduced CS are able to enhance their residual vision to read
Charts (86 × 63 cm chart). It consists of 16 triplets of 4.9 cm scripts and notes by the manipulation of contrast, brightness,
(2.8° at 1 m) letters and assesses contrast sensitivity CS at a reverse polarity and magnification which are skills they
spatial frequency of about 0.50 to 1 cycle/degree. Within each acquire during their training in the use of the devices. The
triplet, the letters have the same contrast, and the contrast in use of high contrast materials and reading text becomes
each successive triplet decreases by a factor of 0.15 log units. helpful. The visual stimulation in young children through
The subjects read the chart at 3m and the result is recorded computer-based visual stimulation (VS) program combining
from “readings” given on the chart according to the last checkerboard pattern reversal (passive stimulation) with
triplet which patient can see. The score ranges from 0.25 oddball stimuli (attentional modulation) may be helpful.
(least score) to 2.00 (best score). To improve CS, LV subject needs letters to be made bold
through use of bold chalks on chalkboard. If white board
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DJO Vol. 31, No. 2, October-December 2020
is used, bold black markers are recommended over other the image smaller to increase LV subject’s field of view (so
colors. Reading text written with felt-tipped pens on paper that he can see more at one time). Minimization puts the
and/or use of bold letters on tinted paper is of help. The peripheral images into the remaining central field of vision
corrective lenses with a yellow filter, preferably that which and provides more information in a smaller area by reducing
does not allow infrared rays to pass through, improves or shrinking the intended target and fitting this into the
ability to discern contrast. The eye glasses with custom wave remaining visual field enabling LV subject to see. Reverse
front lenses to reduce higher order aberration can also be telescopes (like holding binoculars backward) and high
utilized. minus lenses minimize what one sees and help LV subject to
see more within his reduced field of view.
The glare can be reduced by using higher contrast settings
when working with computers or electronic devices. There People with glaucoma have a hard time adjusting their eyes
are also special modes, screens and hoods to help reduce to changes in lighting. Walking into a dark room or out of
glare. Other simple ways include covering surfaces that dark room into a bright area can temporarily stun the eyes
reflect light, closing curtains and changing sitting position so that they see less. This can be especially dangerous when
so that less excess light is reflected from computer screen. walking or driving in areas that are light and dark (bridges,
tunnels, shady areas). It can make it harder for LV subjects
As there is no device to enhance stereopsis, the only to see signs, steps, curves or changes in terrain. If one has
suggested corrective measures is to improve VA with use glaucoma, he should take a few extra moments when there
of corrective lenses (to improve vision of affected eye or to is a drastic change in light to let his eyes adjust.
block bad image), LASIK, eye rolling exercises, or resting the
dominant/better eye. Modern low vision rehabilitation (LVR), which took hold
Sectoral prisms can increase field of view allowing one to see in the last few decades, has been propelled to new heights
more at once. by relentless advances in basic and clinical sciences. Today
we can provide significant and meaningful help to visually
Low lights causes “dim” vision and having too little light impaired patients in most situations. It could be as simple as a
reduces the ability of LV subject to see. Thus somewhat hand magnifier or as intricate as a retinal prosthesis. Devices
more than normal lights and utilising task lighting like desk and re-training of skills have been added to complement
and reading lamps and goose-neck lamps can help. When diagnosis and rehabilitation.27
outside on cloudy and overcast days, LV subject can use
amber or yellow lens glasses to help him see better. Conclusions
Glare, caused by bright lights (sun or fluorescent lighting) is Low vision rehabilitation (LVR) is today a recognized
the excess light that comes into eyes from above or the sides discipline in Ophthalmology, expanding and improving
of the visualised target. This extra light makes it harder to the quality of life of numerous visually impaired patients. It
see and can be reduced by wearing hats outdoors or glasses was not so about a century ago when charity work aimed at
with special lenses. Using sunglasses with tinted lenses (or helping blind children was all that LVR was. With advances
contrast-enhancing filters generally yellow filter) can help in science, medicine and public health policy, help for the
reduce the effects of glare. A few different coloured lenses blind expanded its reach to all who were visually impaired.27
including brown, yellow or amber can be tried to find the But LVR can only be achieved successfully provided we
ones that work best. But it is important to know that not all know how different aspects of vision change/deteriorate
sunglasses are helpful. Lenses that are too dark can make it for a LV subject and what aspect is the most vital one to be
harder to see by dimming the light from front while letting improved upon. More studies on visual perception of LV
in excess light from above and on the sides. Thus wrap- patient in varied fields of visual functions and randomized
around glasses that block light coming in from above and controlled trials with intervention comparisons and outcome
the sides are the best for reducing glare e.g. in LV subjects measures are needed to form stronger conclusions for the
with glaucoma. most effective low-vision rehabilitation interventions for
individuals with LV.21
For people with glaucoma-related vision loss, bigger does
not necessarily mean better. People with tunnel vision often References
have trouble with high levels of magnification because of
their lack of side vision and decreased field of view i.e. the 1. World Health Organization. International statistical classification
amount of field one can see at a time. This type of vision of diseases, injuries and causes of death, tenth revision. Geneva,
loss does not benefit from magnifier devices that enlarge or 1993.
make things bigger. Typically as magnification increases, the
field of view decreases and the instability of the image (i.e. 2. Bourne RA, Flaxman SR, Braithwaite T, Cicinelli MV, Das A,
its shakiness) also increases. Thus too much magnification Jonas JB, et al. Magnitude, temporal trends and projections
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there is a need for minimization (minification), or making Lancet. 2017;5(9): 888-897. DOI: https://doi.org/10.1016/S2214-
109X(17)30293-0.
3. The International Agency for the Prevention of Blindness. Vision
Atlas. Global Blindness and Visual Impairment Data 2015–
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Health and Family Welfare, Revision in Definition of Blindness, Epub 2016 Feb 25.
18th July, 2017. 21. Hooper P, Jutai JW, Strong G, Russell-Minda E. Age-related
macular degeneration and low-vision rehabilitation: a systematic
5. Koc F, Erden V, Sefi-Yurdakul N. Causes of low vision and review. Can J Ophthalmol. 2008 Apr;43(2):180-7. Doi: 10.3129/
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7. Pereira DFL, Araujo el, Patuzzo FVD. Profile of albinism with 24. Markowitz SN. State-of-the-art: low vision rehabilitation. Can J
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of optical and/or electronic resources. Rev. bras.oftalmol. 25. Visual Standard, Aspects and Ranges of Vision loss. Report
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8. Tsybovsky Y, Molday RS, Palczewski K. The ATP-binding 26. Oduntan AO. A practical logMAR near reference table
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9. Wang P, Xiao X, Huang L, Guo X, Zhang Q. Cone-rod
dysfunction is a sign of early-onset high myopia. Optom Vis Sci. Cite This Article as: Punita Kumari Sodhi Seeing World From The
2013 Nov;90(11):1327-30. Eyes of Low Vision Subject Delhi J Ophthalmolgy 2020 ; 31 (2) :23- 29.
10. Kjer P, Jensen OA, Klinken L. Histopathology of eye, optic nerve Acknowledgments: Nil
and brain in a case of dominant optic atrophy. Acta Ophthalmol
(Copenh). 1983 Apr;61(2):300-12. Conflict of interest: None declared
11. Green WR. Histopathology of age-related macular degeneration. Source of Funding: None
Mol Vis. 1999 Nov 3;5:27.
Date of Submission: 29 April 2020
12. Zarbin MA, Casaroli-Marano RP, Rosenfeld PJ. Age-related Date of Acceptance: 13 June 2020
macular degeneration: clinical findings, histopathology and
imaging techniques. Address for correspondence
13. J Clay Bavinger et al. The Effects of Diabetic Retinopathy. IOVS. Punita Kumari Sodhi MBBS,MS, DNB
2016; 57 (1):208-17.
Professor in Ophthalmology
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N, Ring M, Bolz M et al. [Morphological retinal characteristics Maulana Azad Medical College,
of patients with low vision due to diabetic macular edema]. New Delhi, India
Ophthalmologe. 2018 Jul 26. Email [email protected]
15. Provis JM et al. Clinical and Experimental Optometry.
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Low Vision Research Network Study Group. Visual ability of
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10.1001/jamaophthalmol.2014.1747.
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Population-based assessment of vision-related quality of life in
corneal disease: results from the CORE study. Br J Ophthalmol.
Quick Response Code
E-ISSN: 2454-2784 P-ISSN: 0972-0200 29 Delhi Journal of Ophthalmology
DJO Vol. 31, No. 2, October-December 2020
Original Article
High Myopia: A Hospital-Based Study of The Clinical
Profile and Visual Impairment
Rejitha Chinnu Varghese, Uma Kulkarni
Department of Opthalmology, Yenepoya Medical College, Mangalore, India.
Introduction: High axial myopia is an increasingly common refractive error leading to retinal degeneration and visual impairment.
Objective: To study the clinical profile and visual impairment in high myopia presenting to a teaching hospital.
Material and methods: This study was a descriptive observational study of high myopia and included unilateral, and bilateral
cases of all age groups. The study was conducted after ethical clearance and a written informed consent. Clinical history, best
corrected visual acuity, ocular fundus findings, axial length and refraction were determined. The results were analyzed using
descriptive statistics, and chi square test.
Results: The mean age in high myopia was 36.28 ± 15.46 years and was significantly higher in males than females (p=0.006828).
There was no significant difference in the age and gender distribution of unilateral (10.66%) and bilateral high myopia (89.33%).
76.05% of the eyes had SE between 6-12 D of which, 9 eyes were corrected to <6D of myopia following cataract surgery. The mean
SE was -9.57 ± 4.4D; the mean axial length was 27.39 ± 1.62 mm and the distribution of SE and axial length in males and females
Abstract was statistically comparable The most common fundus finding was temporal or annular crescent (73.94%) followed by tessellated
fundus (41.54%). Severe visual impairment was seen in 14.78% and blindness was seen in 14.08% of the eyes and the distribution
did not increase with increasing age (p=0.1350), but were significantly more in males than females (p=0.0110) and in eyes with
myopic maculopathy than those without (p <0.00001). The most common cause of blindness was myopic maculopathy (25.35%)
comprising chorioretinal atrophy at the macula (12.69%), posterior staphyloma (11.79%) and choroidal neovascular membrane
(6.33%) and was significantly more in eyes with longer axial lengths (p <0.00001). Other causes of visual impairment included
posterior sub-capsular cataract (19.01%), glaucomatous cupping (11.7%), optic disc pallor (2.8%), retinitis pigmentosa (1.4%).
Lattice and other peripheral retinal degenerations were seen in 15.48% cases.
Conclusion: High myopia causes significant visual impairment affecting 28.87% of the eyes. The most common cause being
myopic maculopathy. The visual impairment tends to be more with longer axial lengths, higher SE, and in males more than
females.
Delhi J Ophthalmol 2020;31;30-35; Doi http://dx.doi.org/10.7869/djo.587
Keywords: High Myopia, Blindness, Visual Impairment, Myopic Maculopathy, Posterior Staphyloma
Introduction macular degeneration, posterior staphyloma and myopic
glaucomatous optic neuropathy.8
Myopia is a common cause of visual impairment. The Etiology of myopia is multifactorial. It has been linked
worldwide prevalence of myopia threatens to double by the to 39 genetic loci in a Genome-wide association study.9
year 2050 from the current 22.9%.1 Myopia is considered an Genetically predisposed children tend to have early
epidemic in the Asian countries owing to the significantly onset and faster progression of myopia.10 Environmental
high prevalence.2 factors like continuous reading, close television viewing,
High myopia is associated with an elongated eye and its use of fluorescent light have been found to be significant
definition varies in different studies. Whereas, high myopia associations.11 Myopia is also known to be linked to
is defined as axial length more than 26.5 mm or when the nutritional factors like vitamin D.12
myopia is more than 8D, the joint report of the WHO on “the Myopia influences quality of life. Myopia is associated with
impact of myopia and high myopia” defines high myopia as poor quality of sleep, depression and great loss of potential
spherical equivalent where the amount of myopia is more productivity due to visual impairment.13,14,15 Although
than 5D.3,4 optical correction in the form of spectacles or contact lenses
High myopia is associated with progressive retinal and refractive surgeries provide optimal visual correction
degeneration and visual impairment. Degenerative myopia and medical measures like low dose Atropine are predicted
accounts for nearly one third of low vision cases in an to reduce the progression of myopia, they do not modify
Asian study.5 Myopic retinopathy refers to a spectrum of or reverse the degenerative changes and complications of
changes ranging from tessellated fundus, diffuse or patchy pathological myopia.16
chorioretinal atrophy and macular atrophy based on the In view of the high and increasing prevalence of high myopia
International META-PM classification.6 It affects 0.2% of in Asia, its multifactorial etiologies, irreversible progressive
the general population in Central India and is associated degenerations, complications, visual impairment and health
with longer axial lengths and lower best corrected visual burden, this study was designed to understand the clinical
acuity.7 Vision threatening complications of myopia profile and visual impairment in high myopia presenting to
include choroidal neovascularization, traction myopathy,
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DJO Vol. 31, No. 2, October-December 2020
the teaching hospital in South India. This is essential in order keratometry reading (average of vertical and horizontal),
to plan strategies to minimize the health burden among ophthalmoscopy for myopic retinopathy and peripheral
myopic population. retinal degenerations. Myopic retinopathy was defined as
The objectives were to study the clinical profile and visual the presence of staphyloma, lacquer cracks, Fuchs' spot or
impairment in eyes with high myopia presenting to a
teaching hospital in south India. chorioretinal atrophy at the posterior pole.
Material And Methods Results
A cross-sectional observational study of high myopia 1. Demographics: 75 participants were enrolled (39 males and
conducted in the Ophthalmology out-patient department of 36 females with a ratio of 1.08:1). There was no statistically
the teaching hospital in a coastal town of south India over a significant difference in the distribution of high myopia
period of one year from March 2015-16 after getting approval in the different age groups (χ2 = 5.7331; p= 0.056894). The
from the Institutional Ethics Committee. The Indian Council mean age was 36.28±15.46 years and the males (40.98±16.986
of Medical Research’s ethical guidelines and the Declaration years) were older than the females (31.44±12.961 years)
of Helsinki were followed. Participants were included after with a statistically significant difference (t-value= -2.78428;
taking written informed consent. p=0.006828).
High myopia was defined as myopia more than 6D Spherical 67 (89.33%) cases were bilateral and 8 (10.66%) were
Equivalent and/or an axial length of more than 26 mm. unilateral. There was no significant difference in bilateral
Inclusion criteria included unilateral or bilateral high myopia and unilateral cases gender-wise (χ2 =1.898, p=0.168) and
with media clear enough for detailed fundus examination. age-wise (χ2 = 3.468, p= 0.176). The distribution of high
Exclusion criteria were grade 3 or more nuclear cataracts myopia is given in table 1.
likely to induce index myopia and average keratometric Parental myopia was reported in 10 (13.33%) (one parent:
value >46 D likely to cause curvature myopia. The sample 7 and both patents: 3) and did not differ among unilateral
size was calculated to be 75 with a 5% prevalence of high (12.5%) and bilateral cases (13.43%). Most wore spectacle
myopia in this hospital, a confidence interval of 95% and correction, only 6 (8%) wore contact lenses.
allowable error of 5%.
The following data was collected: Clinical history 2. High myopia: The highest power of high myopia among
with reference to myopia, best corrected visual acuity was -24D in males and -20.75 in females, with the mean
(BCVA), the spherical equivalent (SE), axial length (AXL), myopia of -9.507 D ± 4.40 (Males: -10.25 D ± 5.3; Females -8.9
D ± 3.5). The gender-wise distribution of high myopia into
Table 1: Age and gender-wise distribution of cases of high myopia
Age Males Females Grand total
(years) Uni Lateral Bi Lateral Bi Lateral
Total Unilateral Total
<20 0 2 20 77 9
21-40 32
> 40 1 14 15 1 16 17 34
Total 75
5 17 22 1 11 12
6 33 39 2 (5.36%) 34 (94.44%) 36
15.39%) (84.61%)
Table 2: Distribution of visual impairment and high myopia
SE<6D Males Normal (6/6 Mild VI Moderate VI No. of eyes No of eyes Sub-Total Total
(corrected) Females to < 6/12) (6/12 to (<6/18 to 6/60) with severe VI with blindness
Males (<6/60 to 3/60) 6 9 (6.33%)
SE 6 to 2 6/18) 2 (<3/60) 3 108
<12D Females 2 1 0 2 51
Males 4 0 19 0 0 (76.05%)
SE 12 to Females 9 6 57 12 (8.45%)
<18D Males 0 5 13 (9.15%)
Females 7 2 7
SE 18D or 13 0 4 10 142
more 3 1 3
19 10 19 2 4
Total 0 0 1 0 1
1 1 1 21 (14.78%) 20 (14.08%)
0 2 2
1 1 0
29 (20.42%) 27 (19.01%) 45 (31.69%)
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DJO Vol. 31, No. 2, October-December 2020
sub-groups is shown in table 2 and showed no statistically retinitis pigmentosa and reattached retinal detachment. The
significant difference (χ2= 4.0199, p= 0.2593). The average peripheral retinal changes included lattice degeneration,
axial length was 27.39 ± 1.62 mm, ranging from 26 mm to pavingstone degeneration, white without pressure and
32.29 mm. There was no statistically significant difference in retinal break.
the average axial length among males (27.7 ± 1.48 mm) and The distribution of these lesions in different degrees of
females (27.05 ± 0.89 mm) [χ2= 5.76, p= 0.056]. high myopia and visual impairment are presented in tables
3 and 4, respectively. Most of the lesions in the posterior
3. Visual impairment: Visual impairment and blindness as segment were more common in higher degrees of myopia
defined by ICD classification was more in males than in but the difference in the distribution of each lesion cannot be
females and this difference was statistically significant (χ2= statistically established.
11.1335, p=0.0110).17 The mean age in the sub-groups with
normal vision, mild, moderate and severe visual impairment 5. Causes of visual impairment: In eyes with blindness,
and blindness were 32.31, 36.40, 34.24, 40.42 and 42.1 years myopic maculopathy was the most plausible etiology of
respectively, indicating that visual impairment increased which chorioretinal atrophy affecting the macula was the
with increasing age but the difference was not statistically most common, followed by posterior staphyloma and
significant (p=0.135084). The distribution of visual choroidal neovascular membrane/scar. Myopic maculopathy
impairment and high axial myopia is detailed in (Table 2.) was seen in 25.35% of the eyes and was found to affect the
The 9 cases of high myopia which had SE < 6D included 8 males more than the females with a statistically significant
pseudophakic eyes and 1 aphakic eye and were included difference (χ2= 11.38; p=0.000739). Myopic Maculopathy
on the basis of axial length being more than 26 mm. 103 was also found to be significantly associated with the longer
eyes (72.53%) had clear lens, 3 (2.1%) had grade 1-2 nuclear axial lengths (χ2= 40.6466; P= <0.00001). Visual impairment
sclerosis and 27 (19.01%) had posterior subcapsular cataract. was also significantly more in myopic maculopathy than in
eyes with no myopic maculopathy (χ2= 39.41; p= <0.00001).
4. Posterior segment lesions: The common disc-related In 19% of the eyes, posterior subcapsular cataract was
changes were peripapillary crescent, glaucomatous present and could be the attributable for visual impairment.
cupping, disc pallor, titled disc and peripapillary atrophy. This was followed by glaucoma, and one case each of
The macular changes included macular atrophy, posterior retinitis pigmentosa and operated rhegmatogenous retinal
staphyloma and choroidal neovascular membrane or detachment.
scar. Diffuse changes included tessellation of the fundus,
Table 3: Distribution of posterior segment findings with degrees of high myopia
Corrected myopia 6 to <12 D 12 to <18 D 18 and More Total number of eyes
(PCIOL/ Aphakia) (n=108) (n=12) (n=13) with the lesion (n=142)
(n=9)
Disc related changes
Temporal or annular crescent 6 (66.66) 79 (73.14) 8 (66.67) 12 (92.3) 105 (73.94)
Glaucomatous cupping 1 (11.11) 2 (15.38) 11 (7.74)
Tilted disc 1 (11.11) 6 (5.55) 2 (16.66) 2 (15.38) 5 (3.52)
Optic disc pallor 4 (2.81)
Peri-papillary atrophy 0 2 (2.3) 0 0 4 (2.81)
1 (11.11) 0
Chorioretinal atrophy- 3 (2.77) 1 (8.3) 18 (12.69)
macula 1 (11.11) 8 (61.53)
2 (2.3) 1 (8.3) 17 (11.79)
Posterior staphyloma 2 (22.22) 6 (46.14) 9 (6.33)
CNVM/ Fuchs spot 1 (11.11) Macular changes 2 (15.38)
11 (7.74)
Lattice degeneration 2 (22.22) 6 (5.55) 3 (25) 2 (15.38) 9 (6.33)
Other peripheral retinal 1 (11.11) 3 (23.07)
7 (6.4) 2 (16.66) 59 (41.54)
degenerations 5 (55.55) 7 (53.84) 2 (1.40)
0 5 (4.6) 1 (8.3) 0 1 (0.7)
Tessellated fundus 0 0
Retinitis pigmentosa Peripheral retinal changes
Treated case of retinal
detachment (Buckle) 6 (5.55) 1 (8.3)
4 (3.7) 1 (8.3)
Diffuse changes 6 (50)
41 (37.96) 1 (8.3)
1 (8.3)
1 (1.6)
0
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DJO Vol. 31, No. 2, October-December 2020
Discussion factors. The mean age of high axial myopia in our study was
36.28 years with men being significantly older than women.
The cross-sectional observational study on 142 eyes of 75 The age distribution of high myopia varies broadly in
cases of high myopia showed no significant difference in different studies from 21 to 41 years.25 This being a hospital
the gender-wise distribution. Literature shows varying (hyphen) based study in south India, the results are expected
distribution of high myopia among males and females. to differ from other geographical areas and from population-
Some studies show no significant difference; some show a based studies.
higher prevalence in females; whereas a study in Central The mean axial length was 27.39 mm similar to other studies
India found a higher prevalence of high myopia in males.18,19, ranging between 26 to 29.4 mm with no significant difference
20,21,22 Majority being bilateral in our study, the proportion of in the mean axial lengths among males and females.26,27 Longer
unilateral cases was only 10.6% and was less compared to axial lengths and higher refractive errors were associated
other studies (22.6% in adults to 50% in a study on children).23, with more lesions in the posterior segment lesions and more
24 These differences could be because of different ethnic visual impairment although not statistically established. In
populations studied since myopia is known to be linked to this study, the common posterior segment changes seen in
several gene loci and is also influenced by environmental
Table 4: Distribution of clinical findings with categories of visual impairment
Normal (6/6 to Mild VI (6/12 Moderate VI (<6/18 No. of eyes with No of eyes with Total number of eyes
to 6/60) severe VI (<6/60 to blindness (<3/60) with the lesion
< 6/12) to 6/18)
3/60)
Visually less significant findings
Temporal 18 (17.14) 22 (20.95) 36 (34.28) 15 (14.28) 14 (13.33) 105 (73.94)
or annular
9 (15.25) 11 (18.64) 18 (30.5) 12 (20.33) 9 (15.25) 59 (41.54)
crescent 4 (36.36) 0 0 2 (18.18) 5 (45.45) 11 (7.74)
1 (11.11) 4 (44.44) 9 (6.33)
Tessellated 0 1 (11.11) 3 (33.33)
fundus 1 (25) 4 (2.81)
0 0 1 (25) 2 (50)
Lattice
degeneration
Peripheral
retinal
degenerations
Peri-papillary
atrophy
Visually significant findings
Posterior 0 4 (14.81) 9 (33.33) 7 (27.92) 7 (25.92) 27 (19.01)
sub-capsular
1 (5.55) 3 (16.66) 0 1 (5.55) 13 (72.22) 18 (12.69)
cataract
0 2 (11.76) 3 (17.64) 4 (23.52) 8 (47) 17 (11.79)
Chorioretinal 0 2 (18.18) 2 (36.36) 3 (27.27) 4 (36.36) 11 (7.74)
atrophy- 2 (22.22) 3 (33.33) 4 (44.44) 9 (6.33)
macula 1 (20) 0 0 5 (3.52)
0 0 4 (80) 0 0 (0) 4 (2.81)
Posterior 0 0 2 (50) 2 (50) 2 (1.40)
staphyloma 0 0 0 2 (100) 1 (0.7)
0 0 0 1 (100)
Glaucomatous 29 (20.42%) 0 0
cupping 27 (19.01%)
45 (31.69%) 21 (14.78%) 20 (14.08%) 142
CNVM/ Fuchs
spot
Tilted disc
Optic disc
pallor
Retinitis
pigmentosa
Treated case
of retinal
detachment
(Buckle)
Total
E-ISSN: 2454-2784 P-ISSN: 0972-0200 33 Delhi Journal of Ophthalmology
DJO Vol. 31, No. 2, October-December 2020
high myopia were identical to the classical descriptions of References
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of pathological myopia among patients in a large tertiary care
center in Egypt. New Front Ophthalmol. 2018;4(5):1-4. Cite This Article as: Rejitha Chinnu Varghese, Uma Kulkarni
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of Pathologic Myopia in Chinese Patients. Journal of Profile and Visual Impairment Delhi J Ophthalmol 2020 ; 31 (2)
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25. Lam DS, Fan DS, Chan WM, Tam BS, Kwok AK, Leung AT, Acknowledgments: Nil
Parsons H. Prevalence and characteristics of peripheral retinal Conflict of interest: None declared
degeneration in Chinese adults with high myopia: a cross- Source of Funding: None
sectional prevalence survey. Optometry and vision science. 2005 Date of Submission: 27 Jan 2020
Apr 1;82(4):235-8 Date of Acceptance: 20 May 2020
26. Ohsugi H, Ikuno Y, Shoujou T, Oshima K, Ohsugi E, Tabuchi
H. Axial length changes in highly myopic eyes and influence Address for correspondence
of myopic macular complications in Japanese adults. PloS one. Uma Kulkarni
2017 Jul 7;12(7):e0180851.
27. Saka N, Ohno-Matsui K, Shimada N, Sueyoshi SI, Nagaoka N, Professor, Ophthalmology
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pathologic myopia. American journal of ophthalmology. 2010 Mailing id: “Lakshmi Keshava, 4th
Oct 1;150(4):562-8. cross, Shivabagh, Mangalore India.
28. Choudhury F, Meuer SM, Klein R, Wang D, Torres M, Jiang Email: [email protected],
X, McKean-Cowdin R, Varma R, Azen SP, Hsu C, Dinh D. [email protected]
Prevalence and characteristics of myopic degeneration in an
adult Chinese American population: the Chinese American eye Quick Response Code
study. American journal of ophthalmology. 2018 Mar 1;187:34-
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demographics of high myopia and an update of its associated
pathological changes. Ophthalmic and Physiological Optics.
2015 Sep;35(5):465-75
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Matsui K, Tan MM, Yang A, Zhao P. Myopic maculopathy and
optic disc changes in highly myopic young Asian eyes and
impact on visual acuity. American journal of ophthalmology.
2016 Apr 1;164:69-79.
31. Ohno-Matsui K, Yoshida T, Futagami S, Yasuzumi K, Shimada
N, Kojima A, Tokoro T, Mochizuki M. Patchy atrophy and
lacquer cracks predispose to the development of choroidal
neovascularisation in pathological myopia. British Journal of
Ophthalmology. 2003 May 1;87(5):570-3.
32. Fang Y, Yokoi T, Nagaoka N, Shinohara K, Onishi Y, Ishida T,
Yoshida T, Xu X, Jonas JB, Ohno-Matsui K. Progression of myopic
maculopathy during 18-year follow-up. Ophthalmology. 2018
Jun 1;125(6):863-77
33. Shih YF, Ho TC, Hsiao CK, Lin LL. Visual outcomes for high
myopic patients with or without myopic maculopathy: a 10 year
follow up study. British Journal of Ophthalmology. 2006 May
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34. Yoshida T, Ohno-Matsui K, Yasuzumi K, Kojima A, Shimada
N, Futagami S, Tokoro T, Mochizuki M. Myopic choroidal
neovascularization: a 10-year follow-up. Ophthalmology. 2003
Jul 1;110(7):1297-305.
35. Chen SJ, Cheng CY, Li AF, Peng KL, Chou P, Chiou SH, Hsu WM.
Prevalence and associated risk factors of myopic maculopathy
in elderly Chinese: The Shihpai eye study. Investigative
ophthalmology & visual science. 2012 Jul 1;53(8):4868-73.
E-ISSN: 2454-2784 P-ISSN: 0972-0200 35 Delhi Journal of Ophthalmology
DJO Vol. 31, No. 2, October-December 2020
Original Article
Prosection of the Goat’s Eye as a Teaching-Learning Method for
the Undergraduate Medical Students During Clinical Postings in
a Medical College in South India: A Study of Reflections
Aditi Vidha, Uma Kulkarni
Department of Opthalmology Yenepoya Medical College, Mangalore, India.
Background: Understanding the complex anatomy of the eyeball is challenging for a medical undergraduate student. We
evaluated the effectiveness of prosection (demonstrated dissection) of enucleated goat’s eye as a teaching-learning method
and explored the reflections of the undergraduate medical students.
Methods: After ethical approval and informed consent, the study was conducted on 71 undergraduate students during their
clinical postings in ophthalmology. The students were randomized into two arms. Arm A was taught anatomy of the eye using
PowerPoint presentation and arm B using prosection. Pre and post-test questionnaires were provided to compare knowledge
scores. Students were asked to write their reflections about prosection.
Results: Mean pre and post Day 0 and Day 7 knowledge scores in both arms were identical and did not differ statistically
Abstract (p=0.530, 0.97, 0.92) indicating that both the interventions were - quantitatively speaking - equally effective. Students’
reflections on prosection were analyzed qualitatively. Students enjoyed the novelty of the teaching method, appreciated the
unraveling of the complicated ocular anatomical arrangements, understood the eye three-dimensionally, saw the otherwise
invisible structures of the eye, appreciated the transparent structures and discerned the complexity and interrelatedness of
structures. Students reported enhanced learning through touching, feeling and seeing. They indicated that the learning was self-
directed, collaborative, and promoted situated-learning through participation. Students opined that prosection supplemented
by PowerPoint presentation should be included in the undergraduate ophthalmology curriculum.
Conclusion: Prosection, when aided by a systematic commentary and interaction, stimulates multi-modal learning to understand
ocular anatomy and should be included in the curriculum to create an interest in the subject of ophthalmology among medical
undergraduate students.
Delhi J Ophthalmol 2020;31;36-40; Doi http://dx.doi.org/10.7869/djo.588
Keywords: Prosection, Dissection, Goat’s Eye, Situated Learning, Reflection
Introduction postings. The objective was to evaluate the effectiveness of
prosection of goat’s eye for understanding ocular anatomy
Understanding the 24-mm miniature and complex eyeball and to explore the undergraduate students’ reflections on
relies on accurate transformation of two-dimensional the innovative teaching method.
diagrams into three-dimensional imagery. For an
ophthalmology teacher, as well as the undergraduate medical Methodology
student, this necessitates out-of-box teaching-learning to
simplify the ‘hard-to-remember and easy-to-forget’ abstruse The study was conducted after approval from the Institutional
anatomy and facilitate its comprehension. Ethics Committee, and after taking written informed consent.
Traditional chalk-and-talk teaching is effective; and the It was a prospective study on 71 undergraduate medical
contemporary PowerPoint presentations can embed colorful students during their first ophthalmology clinical posting
illustrations and aid in recall.1,2 Nevertheless, undergraduate (6th term; 3rd year) between June and August 2019. Pre
students often find ophthalmology complicated and difficult (Day 0) and post-intervention (Day 0 and Day 7) knowledge
to correlate clinically. Applied anatomy is found to be better in ocular anatomy was assessed in both the arms with a
understood through cadaveric dissection among physicians- validated, pre-tested, objective-type, single-best-response,
in-training.3 However, in the embalmed cadaver, the eye is structured questionnaire, consisting of 30 recall items, on
shriveled and collapsed; rendering dissection impractical topics as per curriculum and were scored for correct answers.
and leaving students deprived of this learning opportunity. The students were randomized using envelope method into
Moreover, in the first year of the curriculum, under time- two arms: A (PowerPoint presentation with pictures and
constraints to teach the other anatomical body parts (such text) and B (prosection - demonstrated dissection of goat’s
as superior and inferior extremities, thorax, abdomen, head, eye) ‘(Figures 1 -6)’.
face, neck and brain) the “less important” structures like the Each intervention lasted 40-50 minutes and was carried out
ear and the eye are often neglected. on small groups of 12-15 students and included the following
Perceiving a need to bridge this gap, we explored prosection topics: gross anatomy, the coats, segments and chambers of
(demonstrated dissection) of enucleated goat’s eye as a the eye, lens and zonules, extraocular muscles and optic
teaching-learning method, during the ophthalmology clinical nerve attachments.
The teaching was structured, and the facilitation interactive,
E-ISSN: 2454-2784 P-ISSN: 0972-0200 36 www.djo.org.in
DJO Vol. 31, No. 2, October-December 2020
Figures 1 and 2:
Demonstration of gross
anatomy
Figures 3 and 4:
Approaching the anterior
chamber
Figures 5 and 6:
Extraction of the lens
E-ISSN: 2454-2784 P-ISSN: 0972-0200 37 Delhi Journal of Ophthalmology
DJO Vol. 31, No. 2, October-December 2020
with time for clarification of doubts. In addition, in arm Qualitative part: The students’ reflections were analysed,
B, students were allowed to touch and handle the tissues coded, grouped under themes and subthemes as follows and
through gloved hands. The presentations were prepared some of the narratives are verbatim quoted thereafter:
and presented by the first author (AV) and validated and 1. Novelty of the teaching method: Students expressed
supervised by the second author (UK).
We chose goat’s eye because of its similarity to the human that prosection was interesting and that routine
eye, easy availability from abattoirs, without compromising lectures and PowerPoint presentations were sometimes
animal rights and ethics. Also, there are no cultural and mundane and monotonous. Some of the words/ sub-
ethical issues like those associated with the use of pig’s themes were “interesting” (29 students), “enhanced
eye, which has even more similarity with the human eye. learning” (20), “useful” (10) and “reinforced learning”
One student requested to be shifted to arm A owing to the (8). With prosection, ophthalmology appeared exciting
discomfort anticipated during dissection. After D0 post-test, and interesting, and learning was fun and focused. As
but before D7, students in arm A, after hearing about the a novel experiential-learning technique, prosection
“fun-learning” in arm B, requested that they be shown the created interest and stirred emotions.
prosection. We acceded - in the larger interest of the students’ i. “First I wasn’t interested, but as the dissection started it
enthusiasm. We asked students to write their reflections became interesting” (B15)
about goat’s eye dissection as a teaching-learning method. ii. Usually the ppt and textbook reading feels boring and I
We have reported the narrative experience of the authors would end up sleeping. But dissection was interesting.
too. We present our findings in two parts: a quantitative It was a wonderful experience. (B12)
part based on the questionnaire scores and a qualitative part 2. Elucidation of a complicated topic: Prosection (with
based on the reflective narrations. visual and kinesthetic learning elements) influenced
the perspective of the students’ understanding of ocular
Discussion anatomy. Words used to indicate better understanding
included “see” (25), “understand” (21), “learn” (15),
Quantitative part: There were 35 students in Arm A and 36 in “clarify” (13), “layers” (7), “remember” (3) among
Arm B. The pre-intervention scores and the post-intervention others.
scores on Day 0 and Day 7 are shown in the table below. The a. Understanding the eye three-dimensionally: Students
reported that the two-dimensional cross-section of
Table 1: Pre and post-test scores for prosection of goat’s eye versus the eye failed to give a clear understanding of its
PowerPoint presentation three-dimensional structure, whereas the prosection
experience did. One student confessed that after
Mean scores Pre- Post- Post- dissection, she understood that the zonules were
and range intervention intervention intervention present all around the lens - 360 degrees and not just
above and below.
Day 0 Day 7 “It was a really amazing experience. I was amazed
about what all structures can be found inside the eye.
Arm A 4.7±3.36 17.11±4.19 14.5±4.2 From my childhood I have been drawing pictures of
(range 1 to 12) (range 5 to 23) (range 3 to the eye and I had many questions in my mind. I could
finally clear it perfectly and I am satisfied.” (B9)
22) b. Seeing the otherwise invisible structures of the eye:
Prosection had the advantage of exploring the otherwise
Arm B 5.25±3.77 17.08±5.71 14.6±5 invisible parts of the eye with instruments: inserting
(range 0 to 12) (range 6 to 25) (range 6 to the tip of the forcep between structures to demonstrate
the anterior chamber, its angle, posterior chamber
24) and scleral sulcus; retracting the iris to demonstrate
the zonules and ciliary processes; peeling off the lens
p= 0.530 p= 0.97 p= 0.92 capsule to feel the texture of the nucleus and cortex,
removing the vitreous to visualise retina; peeling of
scores were compared using t test and a p value of <0.05 was retina to uncover the choroid and the optic nerve head
considered statistically significant (Table 1). and so on.
“I have always been confused about the chambers. It
There was no statistically significant difference in the finally made sense. Also now that I have a picture in my
knowledge scores or gain in knowledge scores in the two mind, I understand the pigmented and non-pigmented
arms, indicating that both methods were equally effective structures better” (B8)
in imparting knowledge of ocular anatomy. Studies have i. “Till now I had only “imagined” the interior of eye
demonstrated that cadaveric dissection positively influences whenever I read any topic related to eye. This was a
learning and students retain information longer when good experience that helped me find how much of my
taught anatomy using dissection.1,4 Although PowerPoint imagination was right and how much was wrong”. (A6)
presentation has the advantage of impactful imagery, students c. Understanding transparent structures: Students
are familiar with it and novelty is lacking. Prosection has the appreciated the transparent structures and described
advantage of being novel, allows visualizing and feeling of
the actual eyeball. However, the excitement may have led
to distraction and inattentiveness. The lack of statistical
significance could be because we tested only recall and not
the higher domains of knowledge such as interpretation
and synthesis. In terms of quantitative analysis there was no
statistically significant difference between the two teaching
methods.
E-ISSN: 2454-2784 P-ISSN: 0972-0200 38 www.djo.org.in
DJO Vol. 31, No. 2, October-December 2020
them in their own words. The cornea looked like skill set that enhances the students’ learning in the higher
a contact lens, aqueous like clear ‘water’, the lens
appeared like a ‘marble’ and the vitreous, a ‘pulpish’ domains of analysis, synthesis and evaluation, promotes
clear gel. Through constant questioning, the students
correlated transparency with avascularity, clear image competency-based learning and helps shape the overall
formation and visualization of fundus. The students
wondrously realized that it was the clear cornea that professional development of the student.
was transplanted during eye donation.
d. Understanding the complexity and interrelatedness of Students better understood the complex three-dimensional
structures: The systematic, sequential dissection, layer
by layer unraveled the complex structure of the eye and structure, the transparent tissues, the otherwise invisible
their interrelatedness.
“As ma’am was taking out each layer of the eye, we structures of the eye and their relatedness to each other. This
students were getting more excited as this was our 1st
experience.” (A2) is supported by other studies where students agreed that
“I had doubts regarding chambers and segments (of the
eye). All were cleared during this class.” (B27) dissection helped them understand the three-dimensional
3. Learning through ‘touch’: Along with visualization,
touch helped learning. Students used words like “feel” perspective of structures better.9,10 In our study, prosection
(23), “touch” (6), “texture” (3) in descriptions of the
cornea (soft and thin), lens (globular, moulding nature), led to reinforced learning and increased applicability,as also
vitreous (gel-like, wobbly) and optic nerve (cord-like).
“There is always a difference between what we study observed by Kivell et al (2009) and Pawlina and Lachman (2004)
just by reading books and dissecting, seeing the
structure and touching it. The second method is always who state that dissection provides students an opportunity
more effective than PowerPoint classes.” (A20)
4. Inclusion of prosection as a regular teaching method: to reinforce and validate previous learning through self-
Many opined that prosection should be included as a
regular method in the first MBBS curriculum along with observations and understand three-dimensional structures
cadaveric dissection, and reinforced during clinical
postings. Some students felt a lost opportunity during with a better perspective.11 Balcombe has argued “there is
anatomy classes. Some indicated that each student
should be given an opportunity to dissect goat’s eye. no better way to understand the structure and function of
“Eyeball dissection should be introduced to all MBBS
students in second year as it helps in revising what we an organism than by directly examining the organism”.12
studied in first year as well as make ophthalmology a
more exciting and interesting subject”. (B6) Chan & Ganguly (2008), through a questionnaire-based
5. Facilitators’ perspective: We observed that the learning
was active, enhanced and exploratory through asking study found that small-group teaching through dissection
doubts, observing and feeling tissues with undistracted
attention. Students asked for the structures to be shown improved students’ performance.13 Seeing all the structures
again. Questions included, which part of the eye is
transplanted during eye donation, whether whole eye the way they are in real and not just images, definitely
is removed during eye donation, difference between
enucleation and evisceration, how avascular tissues helped our students in giving a different perspective to what
survive, how cataracts can cause blurred vision, etc.
indicating that the learning was active, reinforced and they had learnt, with a better touch of reality.
self-directed. The enhanced maturity of students during
clinical postings enabled them to process and apply this In our study the facilitator (AV) reported that students
fresh knowledge to the various clinical conditions they
had encountered, indicating that their involvement in were seen thinking aloud and repeatedly asking the same
learning was ‘mindful’.
We found that the teaching of ocular anatomy to students questions. In other words, our students were reflecting-
through prosection of the goat’s eye created an active
‘situated’ learning atmosphere, promoted collaborative in-action, and this was driving their learning. Students
and peer-learning and encouraged reflection-in-action, all
of which are very strong components of learning-by-doing opined that prosection should be integrated in the teaching
or experiential learning.5,6,7 Learning by doing encourages
students to think critically.8 Critical thinking is an important curriculum of the undergraduates in the first year and
reinforced during clinical postings as it increased their
understanding and clinical applicability. Kivell et al (2009)
have similarly recommended dissection of porcine eye, in
the early period of the clinical clerkship. A study by Ramsey-
Stewart (2010) reported that after a 7-week dissection course
on anatomy, a significant increase in clinical anatomical
knowledge was demonstrated among the students and all
students graded the course as helpful and suggested it to be
a part of the curriculum.14
Granger (2004) argues that the importance of dissection
doesn’t merely provide academic merits, but is also
invaluable for psychosocial development of medical
students.15 The same was observed in our study, wherein the
teachers noticed mindful learning of students and enabled
them to think beyond ocular anatomy. There is a need to
diversify teaching style to cater to the learning styles of each
distinctive student.16 Prosection, according to our study,
when aided by a systematic commentary and interaction,
stimulates visual, aural and kinesthetic learners and
may therefore be considered a superior teaching method
satisfying most of the criteria in the VARK model of Neil
Fleming.17 Conclusion
To conclude, prosection of goat’s eye was an effective
teaching-learning tool for undergraduate medical students
and was comparable to PowerPoint teaching in terms of
gain in knowledge scores. In addition, prosection showed
distinct advantages. It allowed an enhanced, systematic
and sequential learning of the complicated, miniature
E-ISSN: 2454-2784 P-ISSN: 0972-0200 39 Delhi Journal of Ophthalmology
DJO Vol. 31, No. 2, October-December 2020
anatomy of the eye. It proved to be a superior teaching 9. Azer S, Eizenberg N. Do we need dissection in an integrated
method suiting different learners (kinesthetic and visual). problem-based learning medical course? Perceptions of first-
Prosection promoted collaboration among peer-groups and second-year students. Surg Radiol Anat. 2007;29:173–80.
and encouraged social development of learning. It was
well-received as an innovative teaching method, instilling 10. Kivell TL, Doyle SK, Madden RH, Mitchell TL, Sims EL. An
interest, attentiveness and involvement among students and interactive method for teaching anatomy of the human eye
teachers. We recommend that proection be considered as a for medical students in ophthalmology clinical rotations.
regular teaching method in conjunction with the traditional Anatomical sciences education. 2009 Jul;2(4):173-8.
classroom teaching methods.
Generally, for a teacher, the essence of teaching is often 11. Pawlina W, Lachman N. Dissection in learning and teaching
lost in the efforts of making an impressive PowerPoint gross anatomy: rebuttal to McLachlan. The Anatomical Record
presentation and for the student, the essence of learning is Part B: The New Anatomist: An Official Publication of the
lost in attendance, grades and percentages. Prosection is that American Association of Anatomists. 2004 Nov;281(1):9-11.
teaching-learning method which can be cherished both by
the teacher and the learner. 12. Balcombe J. (2000). The use of animals in higher education.
Problems, alternatives, and recommendations.Washington, DC:
Limitations Humane Society Press.
It would have been best if each student would have done 13. Chan LK, Ganguly PK. Evaluation of small‐group teaching
the dissection by herself. We used the prosection method to in human gross anatomy in a Caribbean medical school.
explore the worthiness of introducing this innovative method Anatomical sciences education. 2008 Jan;1(1):19-22
in the clinical posting. If we go by the well-described quote
by Confucius, "I read and I forget, I see and I remember, I do 14. Ramsey-Stewart G, Burgess AW, Hill DA. Back to the future:
and I understand” (Kendall, 1991, as cited by Franta, 1994),18 teaching anatomy by whole-body dissection. Med J Aust.
dissection rather than prosection of the goat’s eye may offer 2010;192:668–71.
enhanced benefits to the undergraduate medical students.
The other limitation in our study was that D7 responses 15. Granger NA. Dissection laboratory is vital to medical gross
were probably contaminated due to early crossover in the anatomy education. The Anatomical Record Part B: The New
study design, driven by students’ desire to undergo the Anatomist: An Official Publication of the American Association
prosection experience. Nevertheless, the feedback provided of Anatomists. 2004 Nov;281(1):6-8.
by the students, retrospectively justified our actions.
16. Fleming ND. I′m different; not dumb. Modes of presentation
Disclaimer (VARK) in the tertiary classroom. In: Zelmer A, editor. Research
and Development in Higher Education, Proceedings of the
No animals were harm 1995 Annual Conference of the Higher Education and Research
Development Society of Australasia (HERDSA). Vol. 18. Higher
ed specifically for the purpose of this study. The dissection Education Research and Development;1995. p. 308-13.
was carried out with safety precautions-wearing gloves and 17. Fleming N. VARK: A guide to learning styles. Available from:
http://www.vark-learn.com/english/index.asp.]
using sterilized set of instruments exclusively earmarked
18. Franta P. Service-learning: A new priority for career centers.
for this purpose. Afterward, the dissected eyes and tissues Journal of Career Development. 1994;21(2):131.
were disposed as per biomedical waste disposal policy of the Cite This Article as: Aditi Vidha, Uma Kulkarni Prosection
of the Goat’s Eye as a Teaching-Learning Method for the
hospital. No learner or facilitator reported any injury during Undergraduate Medical Students During Clinical Postings in a
Medical College in South India: A Study of Reflections. Delhi J
the study. References Ophthalmol 2020 ; 31 (2) :36- 40.
1. Ankolekar VH, Souza AD, Souza AS, Hosapatna M. Effectiveness Acknowledgments: Nil
of PowerPoint Presentations in Teaching Anatomy: A Students’
Perspective. Advanced Science Letters. 2017 Mar 1;23(3):1977-9. Conflict of interest: None declared
2. Craig RJ, Amernic JH. PowerPoint presentation technology and Source of Funding: None
the dynamics of teaching. Innovative Higher Education. 2006
Oct 1;31(3):147-60. Date of Submission: 29 Dec 2019
Date of Acceptance: 19 May 2020
3. Shyamal A, Bokariya P, Kothari R, Vajir SJ, Hiware SD, Batra P.
IS Dissection Better Than Prosection For Learning Anatomy?. Address for correspondence
International Journal of Scientific Research. 2019 Jul 1;8(6).
Uma Kulkarni
4. Schrock JR. Defending dissection. The American Biology
Teacher. 1992; 54: 454 Professor, Ophthalmology
5. Yardley S, Teunissen PW, Dornan T. Experiential learning: Yenepoya Medical College, Mangalore
AMEE guide No. 63. Medical teacher. 2012 Feb 1;34(2):e102-15. Mailing id: “Lakshmi Keshava, 4th cross,
Shivabagh, Mangalore , India.
6. Sandars J. The use of reflection in medical education: AMEE Email: [email protected],
Guide No. 44. Medical teacher. 2009 Jan 1;31(8):685-95.
Quick Response Code
7. Kolb DA. Experiential learning: Experience as a source of
learning. 2nd Ed. 2015.
8. Wass R, Harland T, Mercer A. Scaffolding critical thinking in the
zone of proximal development. Higher Education Research &
Development. 2011; 30(3): 317-328.
E-ISSN: 2454-2784 P-ISSN: 0972-0200 40 www.djo.org.in
DJO Vol. 31, No. 2, October-December 2020
Original Article
Pterygium Excision With Suture- Free, Glue- Free Limbal
Conjunctival Autograft By Cut And Paste Method – A
Prospective Interventional Hospital Based Study
Arathi Choudhary, Dyamenahali S. Hamsa, Menashinkai P. Jayashree, Halmuthur V. Raksha, Divya Ramanna
Department of ophthalmology, S. Nijalingappa Medical college and Research centre and HSK hospital ,Navanagar , Bagalkot, India.
Abstract Aim: To evaluate and analyze the surgical outcome of limbal conjunctival autograft by cut and paste method after
pterygium excision.
Materials and Methods: Prospective, interventional, hospital based study. 65 eyes of 65 patients with primary
pterygium were graded, and excision with free limbal conjunctival autograft (LCAG) was performed by the single
surgeon allowing natural autologous coagulum of the recipient bed to act as a bio adhesive. The outcomes were
assessed in terms of operative time, postoperative pain, any recurrence, and complication(s) at post operative day 1
and at each follow-up visit at day 7, 30,120 and 180 .
Results: There were 34 males (52.3%) and 31 females (47.7%). The mean age of all the patients was 43.48 ± 12.128
years, ranging between 23 to 76 years. Cosmetic blemish was the chief indication of surgery (48 eyes, 73.8%).
Mean graft size was 14.4mm2. No recurrence occurred. Graft related complications occurred in 5 eyes (7.6%); graft
displacement in 3 eyes , cystic degeneration in 1 eye and sub-conjunctival haemorrhage in 1 eye . The average
surgical time was 16.91 ± 2.972 minutes. Post operative pain was less which was graded on Visual analogue scale.
Conclusion: The- surgical technique of using a suture-free and glue-free conjunctivo-limbal autograft is safe and
cost-effective method, with less operative time and post operative pain, without adding possible potential hazard
of the surgical adjunct.
Delhi J Ophthalmol 2020;31;41-46; Doi http://dx.doi.org/10.7869/djo.589
Keywords: Pterygium, Autograft, Complications, Recurrence
Introduction of recurrent and advanced pterygium.Sutures or glue is
used to affix the conjunctival autograft after excision of the
A pterygium is a fibro-vascular, wing-shaped encroachment pterygium. Recently, a new technique of using patient’s
of the conjunctiva on to the cornea. The prevalence rates own blood present at the graft bed to fix the graft has been
ranges from 0.7–31% among different populations and also introduced. Sutures and glue being foreign materials are
influenced by age, race, and exposure to solar radiations.1 associated with complications such as infection, granuloma
formation, chronic inflammation, hypersensitivity reactions
Ultraviolet light-induced damage to the limbal stem cell or recurrence.9 This technique is also cost effective when
barrier with subsequent conjunctivalisation of the cornea compared to the techniques using sutures or glue.
is the currently accepted aetiology of this condition.
Indication of surgery include visual impairment, cosmetic In this study, we aim to find out the surgical outcome of this
disfigurement, motility restriction, recurrent inflammation new technique of a sutureless and glue free graft and the
and interference with contact lens wear.2 recurrence and complications associated with it.
The results of pterygium surgery are often compromised Materials and Methods
by postoperative recurrence, which is the leading cause of
surgical failure in a significant number of cases. This prospective study comprised sixty five eyes of sixty
five patients undergoing pterygium surgery at our tertiary
The reported recurrence rates vary widely, from 5% for care hospital. Subjects included in the study were from 23
pterygium excision with conjunctival auto grafting to 89% to 76 years of age having primary pterygium involving any
for simple excision.5 Risk factors for the recurrence are eye. Necessary approval from Institutional Medical Ethics
geographic location, age, gender, morphology and grade of Committee was obtained beforehand. The study adhered to
pterygium, and the type of surgical technique.6-7 Most of the the tenets of Declaration of Helsinki.
recurrence takes place within first 6 months postoperatively,
and it has been attributed to the upregulation of the Sample size has been calculated from the reference article
inflammatory process.8 titled ‘Pterygium excision with suture-free, glue-free
conjunctival autograft (SFGF-CAG): Experience of a tertiary
In 1985, Kenyon et al5 proposed that a conjunctival care hospital of the Northern India ‘ by Dasgupta et al.10 In
autograft of the bare sclera could be used in treatment the above stated study, cases with primary pterygium were
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DJO Vol. 31, No. 2, October-December 2020
60 % i.e P= 60% and by taking 12 % absolute precision at 95 % Figure 1: Grade II nasal pterygium
confidence level, sample size was calculated as 65 by using
OpenEpi , Version 2 software. Figure 2: Dissection of the neck of the pterygium with the help of Lims forceps
and conjunctival scissors.
Eyes with any pathology which would hamper wound healing
such as active infection or inflammation, symblepharon, past Figure 3: Peeling of the head of the pterygium from the cornea using Lims
ocular surgery within last 6 months, trauma, and systemic forceps .
diseases such as collagen vascular disease, pregnancy,
and bleeding disorders were excluded. Written informed
consent was taken from each patient. Preoperative ocular
examination included refraction and assessment of best
corrected visual acuity, slit lamp biomicroscopy, baseline
intraocular pressure (IOP) measurement by Goldmann
applanation tonometer and fundus examination . Patients
who were on oral nonsteroidal anti- inflammatory
drug(NSAID) and/or anticoagulant, discontinued these
medications 1 week before surgery.
Grading of the pterygium was done as Grade I - pterygium
head up to the limbus, Grade II- head between the limbus
and a point midway between limbus and pupillary margin
(Figure 1 ), Grade III- head between a point midway between
limbus and pupillary margin and pupillary margin and
Grade IV- crossing pupillary margin. All the surgeries were
done under a microscope by the same single surgeon using
the same technique.
Statistical analysis was done using SPSS software version
20 . Categorical variables were described through absolute
(n) and relative frequencies (%) and continuous variables
through mean ± standard deviation.
Procedure
The eye was anesthetized with topical proparacaine 0.5%,
one drop every 10 mintues interval, repeated twice. Taking
all aseptic precautions peribulbar block [ 2% xylocaine with
adrenaline (1:100,000) ] was given . Eyelid was separated by a
speculum . The neck of the pterygium then lifted up with the
help of Lims forceps and dissected using conjunctival scissors
(Figure 2). The head of the pterygium gently peeled from
the cornea using Lims forceps , keeping the same constant
tractional force throughout (Figure 3). Gentle dissection was
then carried out in between the conjunctiva and the sclera
with the help of an angled or curved Vannas scissors (World
Precision Instruments, Inc., FL, USA), to resect at least 4–5
mm of pterygium mass that included both the superior and
inferior border (Figure 4). Residual pterygium tissue on the
cornea was scraped with the help of crescent blade (Figure 5).
Cautery was not used throughout the surgery . Tamponade
with cotton tipped applicator was done whenever required to
check excess bleeding . The size of the bare sclera defect was
then measured with Castroviejo calipers (World Precision
Instruments, Inc.,Fl, USA). Approximately 0.5 ml xylocaine
2% was used to balloon up an superotemporal or superior
conjunctival flap (Figure 6). Conjunctival scissor was used
to make a fine film of 0.5 mm oversized, free conjunctival
graft, carefully avoiding inclusion of tenon, or making
buttonhole within it (Figure 7). The graft was then laid over
the bare sclera ensuring same limbus to limbus orientation
(Figure 8). The surgeon waited for 10 min for haemostasis
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DJO Vol. 31, No. 2, October-December 2020
Figure 4: Dissection of the conjunctiva and the sclera and resection of Figure 7: Harvesting of conjunctival autograft
pterygium mass
Figure 5: Scraping of residual pterygium tissue on the cornea with crescent Figure 8: Laying of autograft on bare sclera .
blade .
Figure 6: Ballooning of superior conjunctival flap with 0.5ml xylocaine . Figure 9: Waiting for haemostasis to occur.
E-ISSN: 2454-2784 P-ISSN: 0972-0200 43 Delhi Journal of Ophthalmology
DJO Vol. 31, No. 2, October-December 2020
Figure 10: Pterygium excision with limbal conjunctival autograft with good Results
haemostasis and graft insitu.
A total of 65 eyes of 65 patients underwent suture less and
to occur ( Figure 9) In cases, where the surgeon appreciated glue free autologous conjunctivolimbal auto graft after
the lack of adequate amount of bleed at the recipient site, pterygium excision. The mean age of all patients was 43.48 ±
episcleral blood vessel was intentionally punctured to create 12.128 years, ranging between 23 to 76 years.
bleeding. At the end of surgery it was ensured that graft was There were 34 males (52.33%) and 31 females (47.7%). All
insitu with good haemostasis (Figure 10). The eye was then patients had primary nasal pterygium . Grade II pterygium
patched for 24 hours. was found to be the most common grade (62 eyes, 95.4%),
followed by Grade III (3eyes; 4.6%). No patient had Grade I,
Any intraoperative complication, as well as the operative Grade IV, bilateral, temporal, or double headed pterygium .
time, was documented. Next day, the eye was assessed for Laterality was almost equal (Right eye – 32 eyes ; 49.2 % , Left
symptom, post operative pain by visual analog scale, graft eye- 33 eyes; 50.8% ) with no statistical significance.
adherence, or any complication(s) under slit lamp.
Most common indication of surgery was cosmetic blemish
Postoperatively, patient was put on topical Moxifloxacin (48 eyes, 73.8%), followed by recurrent inflammation (15
0.5% with Ketorolac tromethamine 0.5% eye drop four times eyes, 23.1%) and diminution of vision (2 eyes , 3.1 % ) Mean
daily with Carboxymethyl cellulose 1% eye drop six times operative time was 16.91 ± 2.972 min, ranging between 14–
daily for 1 week followed by Fluoromethalone 0.1 % with 25 min. Mean graft size was 14.4 mm2 while in majority of
Tobramycin 0.3 % 4 times daily tapered over next 2 weeks patients ( 28 eyes ; 43.1%) the size was 18mm2 . Majority of
and Carboxymethyl cellulose 1% eye drop four times daily patients ( 63; 96.9%) did not have any improvement in visual
for 6 weeks. acuity post operatively while two patients(3.1 %) had one
Thereafter, an attempted follow- up of cumulative 6 months line improvement at 1 month follow up.
(at postoperative day 1, 7, 30, 120, and 180) was done for
every patient. At each postoperative visit, thorough slit lamp Follow- up of 6 months observed in 100% patients.
examination and tonometry were done, and any recurrence, Postoperatively, no recurrence was seen.
complication(s), or any complaint were recorded.
Partially displaced graft of 0.5 to 1 mm (hence, graft related
The primary outcome measure was the recurrence and the complication)was noticed in three patients (4.6%) at the first
secondary measures were complication(s), surgical time and postoperative day, post operative 1 week and post operative
post operative pain. 1 month. No intervention was done for the displacement
We defined (1) “Recurrence” as the reappearance of of the graft. Cystic degeneration was seen in one patient at
fibrovascular growth at the site of previous pterygium post operative 1 week which got resolved on treatment with
excision extending beyond the limbus onto the clear cornea. increased dose of steroids. Sub graft haemorrhage was seen in
(2)“Complication” as any adverse event related to (a) the one patient at post operative day 1 and post operative 1 week
surgery in the intra and post operative period, (b) the graft which got resolved spontaneously with routine treatment at
itself, or (c) the drugs prescribed. (3) “ Post operative pain post operative 1 month. No other complication(s) related to
“analysed by visual analog scale. the graft, surgery, or drugs were evident until the end of our
Visual analog scale is a simple scale, consists of a 10 cm line study.
anchored at one end by a label ‘‘no pain’’ and at the other
end by ‘‘worst possible pain.’’ The patient marks on the line Post-operative pain on day 1 after surgery was consistently
how severe the pain is at the moment. rated as less than or equal to 3 out of 10 on a visual analogue
scale. Pain did not increase after the first post-operative day.
Results and observations have been summarized in
(Table 1).
Table 1 : Summary of results and observations
Variable Total (%)
Total no of eyes 65
Male 34(52.33)
Female 31(47.7)
Age, range (years) 23-76
Age, mean±SD (years) 43.48±12.128
Location Nasal
Primary pterygium 65
Grade I Zero(0)
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DJO Vol. 31, No. 2, October-December 2020
Discussion granuloma as comparable with other quoted studies.
The modern concern of avoiding recurrences and Mitra reported, “The main disadvantage of suture-free,
complications while offering rapid recovery safely with glue-free CAG is the risk of graft loss in the immediate
minimal discomfort has encouraged surgeons to revise the postoperative period, but once the graft stays in place for the
conventional surgical methods for pterygium despite very first 24–48 hours, it is going to stick around.”
favourable outcomes.
de Wit et al. in their similar study postulated that there is an
A recently reported meta analysis by Kaufman et al. even tension across the whole graft interface and no direct
indicated the superiority of conjunctival autograft (CAG ) tension on the free graft edges as with sutures, thus reduced
and LCAG over amniotic membrane graft (AMG ), as well as the stimulus for subconjunctival scar tissue formation and
the associated risk of vision threatening complications with hence there is reduced chance of graft retraction .
mitomycin C (MMC).11
Nonetheless, CAG, AMG, or LCAG requires either suture, Average operative time in our study was 16.91 ± 2.972 min
fibrin glue, or autologous blood as an additional surgical (standard deviation), which was comparable with other
adjunct to secure the graft in place.9 studies as well, and definitely lesser than the suturing
technique and possibly the extra time taken to prepare fibrin
The presence of sutures may lead to prolonged wound glue
healing and fibrosis. 12, 13Subsequent complications such as Our study has several limitations. It was non-randomised
pyogenic granuloma formation are easily treated; others and consisted of a small study population and a relatively
such as symblepharon formation, forniceal contracture, short follow-up period of 6 months.
ocular motility restriction, diplopia, scleral necrosis and However, the mean time for appearance of any complication,
infection are much more difficult to manage and may be including recurrence as reported by one study which
sight threatening.14,15 compared the four commonly used surgical techniques
for pterygium surgery was 4 months.26 Koranyi et al. also
Commercial fibrin glue, although has the advantage of reported that there were recurrences in their patients within
avoiding suture related complication(s), is not easily 2–3 months of surgery.
available everywhere, is costly and carry the risk of
transmission of prions and parvovirus B19. Anaphylaxis and Conclusion
even death has been reported from its use, where bovine
protein aprotinin is the allergen to be believed. 16 Whereas, Superotemporal or superior conjunctivolimbal auto graft
in house preparation of autologous blood is expensive,
requires sophisticated laboratory backup, and at least 24 is an effective technique in the surgical management of
hours of processing and the resultant product has a variable
concentration of clotting components (thrombin, fibrinogen). pterygium. The inclusion of limbal tissue in the conjunctival
Although scanty data exist, recent reports on suture-free, auto graft following pterygium excision is essential to ensure
glue -free CAG by different Indian authors, such as Kurian
et al.,17 Singh et al.,18 Choudhury et al.,19Kulthe et al.20 Sharma low recurrence rate.
et al.,21 and Mitra,22 are very encouraging and comparable
with our present study. Whereas, studies conducted in the The surgical technique of using a suture-free and glue-
United Kingdom by de Wit et al. and Shaw et al.23 amazingly
showed no complication or recurrence at all. free conjunctivolimbal autograft is safe and cost-effective
We have observed some amount of graft dehiscence from the method, reduces complications related to the use of foreign
host conjunctiva (up to 1 mm) is common because of graft
shrinkage or ocular movement. This is well tolerated and materials and reduces surgical time when compared to the
does not need to be surgically addressed as long as the graft
is secure in its place, and it heals up well. technique using sutures and fibrin glue.
One case had cyst, which showed only pterygium tissue Autoblood used for graft fixation is having excellent outcome
in histopathology report and another case had sub graft
haemorrhage .These are risk factors for development of with less operative time and post operative pain, without
recurrence of pterygium and hence were followed closely.
The inclusion of tenon in the graft, graft edema, or subgraft adding possible potential hazard of the surgical
hemorrhage has been linked with recurrence by several
authors.24 adjunct. References
None other patient in our study showed any graft related
complication(s) such as excess graft edema, graft loss or 1. Dushku N, Reid TW. Immunohistochemical evidence that
necrosis, infection, dellen formation, symblepharon and human pterygia originate from an invasion of vimentin–
expressing altered limbal epithelial basal cells. Curr Eye
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2. Sebban A, Hirst LW, Kynaston B, Bain C. Pterygium recurrence
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3. Singh G, Wilson MR, Foster CS. Long term follow up studyof
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4. Frucht-Pery J, Ilsar M, Hewmo I. Single dose of mitomycin
–C for prevention of recurrent pterygium: Preliminary report.
Cornea 1994;13:411–3.
5. Kenyon KR, Wagoner MD, Hettinger ME. Conjunctival
autograft transplantation for advanced and recurrent
pterygium. Ophthalmology 1985;92:1461–70.
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6 . Tan DT, Chee SP, Dear KB, Lim AS. Effect of pterygium 21. Sharma A, Raj H, Gupta A, Raina AV. Sutureless and glue- free
morphology on pterygium recurrence in a controlled trial versus sutures for limbal conjunctival autografting in primary
comparing conjunctival autografting with bare sclera excision. pterygium surgery: A prospective comparative study. J Clin
DiagnRes 2015;9:NC06‑9.
Arch Ophthalmol 1997;115:1235-40.
7. Huerva V, March A, Martinez Alonso M, Muniesa MJ, Sanchez 22. Mitra S. Autoblood as Tissue Adhesive for Conjunctival
Autograft Fixation in Pterygium Surgery. Poster Presented
C. Pterygium surgery by means of conjunctival autograft: Long at the Annual Meeting of the American Academy of
term follow-up. Arq Bras Oftalmol 2012;75:251-5. Ophthalmology; October 22 and 23, 2011, Orlando, Fl; 2011.
8. Hall RC, Logan AJ, Wells AP. Comparison of fibrin glue with
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autografts. Clin Experiment Ophthalmol 2009;37:584-9 for Pterygium Surgery. Eye Net Magazine. Cornea. American
9. de Wit D, Athanasiadis I, Sharma A, Moore J. Sutureless and Academy of Ophthalmology 2012.
glue-free conjunctival autograft in pterygium surgery: A
caseseries. Eye (Lond) 2010;24:1474-7. 24. Fernandes M, Sangwan VS, Bansal AK, Gangopadhyay
10. Dasgupta S, Vats V, Mittal SK. Pterygium excision with N,Sridhar MS, Garg P, et al. Outcome of pterygium surgery:
suture-free, glue-free conjunctival autograft (SFGF-CAG): Analysis over 14 years. Eye (Lond) 2005;19:1182-90
Experience of a tertiary care hospital of the Northern India. J
Clin Ophthalmol Res 2016;4:143-8. 25 . Anbari AA. Autologous cryoprecipitate for attaching
11. Kaufman SC, Jacobs DS, Lee WB, Deng SX, Rosenblatt MI, conjunctival autografts after pterygium excision. Middle East
Shtein RM. Options and adjuvants in surgery for pterygium:A Afr J Ophthalmol 2013;20:239-43.
report by the American Academy of Ophthalmology.
Ophthalmology 2013;120:201-8. 26. Alpay A, Ugurbas SH, Erdogan B. Comparing techniques for
12. Koranyi G, Seregard S, Kopp ED. Cut and paste: a no suture, pterygium surgery. Clin Ophthalmol 2009;3:69-74.
small incision approach to pterygium surgery.Br J Ophthalmol
2004; 88: 911–914. Cite This Article as: Arathi Choudhary, Dyamenahali S.
13. Pterygium excision with conjunctival autografting: an effective Hamsa, Menashinkai P. Jayashree, Halmuthur V. Raksha, Divya
and safe technique. Br J Ophthalmol 1993; 77:698–701. Ramanna. Pterygium Excision With Suture-Free, Glue-Free Limbal
14. Solomon A, Pires RT, Tseng SC. Amniotic membrane Conjunctival Autograft By Cut And Paste Method - A Prospective
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after conjunctival autograft. Cornea 1993; 12:181–183. Acknowledgments: Nil
16. Oswald AM, Joly LM, Gury C, Disdet M, Leduc V, Kanny G.
Fatal intraoperative anaphylaxis related to aprotinin after local Conflict of interest: None declared
application of fibrin glue. Anesthesiology 2003;99:762-3.
17. Kurian A, Reghunadhan I, Nair KG. Autologous blood versus Source of Funding: None
fibrin glue for conjunctival autograft adherence in sutureless
pterygium surgery: A randomised controlled trial. Br J Date of Submission: 29th April 2020
Ophthalmol2015;99:464-70. Date of Acceptance: 14th May 2020
18. Singh PK, Singh S, Vyas C, Singh M. Conjunctival autografting
without fibrin glue or sutures for pterygium surgery. Address for correspondence
Cornea2013;32:104-7.
19. Choudhury S, Dutta J, Mukhopadhyay S, Basu R, Bera S, Savale Dyamenahali S. Hamsa, MBBS (MS)
S,et al. Comparison of autologous in situ blood coagulum
versus sutures for conjunctival autografting after pterygium Department of ophthalmology
excision. IntOphthalmol 2014;34:41-8. S. Nijalingappa Medical college and
20. Kulthe SB, Bhosale AP, Patil PU, Pandve HT. Is the Surgical Research centre and HSK hospital
Technique of a Sutureless and glue- free conjunctivolimbal Navanagar, Bagalkot, India.
auto graft after pterygium excision complications free? Med J Email id : [email protected]
DY Patil Univ 2015;8:308-12
Quick Response Code
E-ISSN: 2454-2784 P-ISSN: 0972-0200 46 www.djo.org.in
DJO Vol. 31, No. 2, October-December 2020
Original Article
Reliability of OCT Assisted RNFL Thickness In Diagnosing
Glaucoma In High Myopia
Neha Yadav, Aanshu Sahai, Raj Kumar Sharma, Mohd. Abid Shamshad, Salani Gupta, Yamni Singhal
Sahai hospital and research centre, Bhabha Marg, Moti Dungri, Jaipur, Rajasthan, India.
Abstract Aim : To assess RNFL Thickness in high myopes and evaluating its reliability in diagnosing glaucoma.
Material And Methods: This is a cross-sectional study to compare retinal nerve fibre layer thickness (RNFL) in 112
eyes of 56 subjects presenting to our centre from May 2017 to March 2018. They were divided in two groups based
on their refractive status (emmetropes and high myopes >-6D). Baseline ocular examination and Fourier domain
optical coherence tomography was done and average and quadrant wise RNFL thickness was measured. Both the
groups were compared based on their RNFL thickness. Data was analyzed using unpaired t- test, chi-square test/
Fisher exact test wherever applicable. P-value ˂0.05 was taken as significant.
Results: Mean RNFL thickness was 85.40±15.45µ in myopes and99.34±10.26µ in emmetropes. It was significantly
less (Mean difference 13.94; 95% CI -18.93 to -8.94) in myopes compared to emmetropes. Quadrant wise analysis
showed significant thinning in myopes in comparison to emmetropes except in temporal quadrant.
Conclusion: Though OCT is a valuable tool for diagnosing pre-perimetric glaucomatous changes but we have to
be very cautious in cases of myopia. There is definite thinning of RNFL in high myopes but we must correlate with
the clinical findings. Though the specific pattern of glaucomatous changes can provide clue to differentiate myopic
thinning from true glaucomatous thinning which is more generalized butwe should not rely only on OCT with the
current normative data.
Delhi J Ophthalmol 2020;31;47-50; Doi http://dx.doi.org/10.7869/djo.590
Keywords: High Myopia, OCT, RNFL Thickness, Glaucoma
Introduction tomography (Optovue, Inc.; Fremont, California, USA).
Three circular scans were obtained at the peripapillary
Degenerative myopia (>-6D) is accompanied by posterior retina at a default radius of 3.45 mm from the centre of the
segment changes like scleral thinning, posterior staphyloma, optic disc, and the measurements were averaged to provide
Fuchs spot, chorioretinal atrophy, large tilted optic discs, average and quadrant wise peripapillary RNFL thickness
lacquer cracks, myopic crescent, and localized retinal nerve (superior, inferior, temporal and nasal).
fibre layer (RNFL) defects.1,2 RNFL thinning occurs because
of mechanical stretching and retinal degeneration.3-8 Myopes Inclusion Criteria: individuals with age >18 yrs and <76 yrs,
have 2-3 times higher risk of developing primary open angle emmetropes, Myopes >- 6D and good quality OCT scans.
glaucoma than emmetropes.9-10 OCT assisted RNFL thickness The good quality OCT scans fulfill the following criteria: the
is widely used for diagnosing pre-perimetric glaucoma. This fundus image must be clear enough to see the optic disc and
study evaluates the effect of high myopia on RNFL thickness scan circle or spokes, signal strength > 6 and color saturation
and its reliability in diagnosing glaucoma. must be even and dense across the entire scan.
Materials and Methods Exclusion Criteria: was patients showing any evidence of
glaucoma (either on optic disc evaluation or visual field
This is a hospital based comparative cross-sectional study. analysis on two separate occasions), lenticular myopia,
After obtaining clearance from institutional ethical committee, amblyopia, ocular trauma, previous retinal laser treatment,
112 eyes of 56 subjects were recruited from consenting post refractive surgery, any intraocular surgery, neurological
individuals paying visit to our outpatient department from disease and systemic illness like diabetes mellitus,
May 2017 to April 2018. Visual acuity was assessed using hypertension and thyroid disorders. Based on refractive
Snellen chart. Autorefraction was done after full pupillary error subjects were divided into two groups – Group 1 –
dilatation with 0.8% tropicamide and 5% phenylepherine myopes (> - 6D) and group 2 – emmetropes (< ±0.5 DS).
using Accuref-K 9001 (Shinnipon) autorefractometer.
Intraocular pressure was measured by averaging three Statistical analysis: Continuous variables were summarized
readings taken with the Goldman applanation tonometer. as mean and standard deviation and were analyzed using
Visual field analysis (30-2) was done by Humphrey’s field unpaired t- test. Normal/categorical variable were expressed
analyzer (model- 740i). Axial length measured was by as proportions and were analyzed by chi-square test/Fisher
amplitude scan (MD – 1000 A, Ultrasonic Biometer Medaco). exact test, P-value <0.05 was taken as significant.
Dilated fundus examination was performed with +90D lens
along with indirect ophthalmoscopy and scleral indentation.
RNFL thickness was measured using Optical coherence
E-ISSN: 2454-2784 P-ISSN: 0972-0200 47 Delhi Journal of Ophthalmology
DJO Vol. 31, No. 2, October-December 2020
Table 1: Age distribution in the two groups
Age Group Group 1 Group 2 Total (N=56)
(years) (N=30) (N=26)
No. (%) No. (%) No. (%)
<35 23 (76.66) 18 (69.23) 41 (73.2)
>35 7 (23.33) 8 (30.76) 15 (26.8)
Total 30 (100.0) 26 (100.0) 56 (100.0)
Min. Age – 18-67 19-60
Max. Age
Mean Age 26.86 32.53
Table 2: Sex distribution in both the groups
Sex Group 1 Group 2(N=26)
(N=30)
Male
Female No. % No. % Figure 1: Mean retinal nerve fibre thickness in the two groups in different
Total 34.61 quadrants.
19 63.33 9 65.38
100.0 of disease. For diagnosing pre-perimetric glaucoma, out of a
11 36.66 17 variety of techniques such as scanning laser polarimetry and
confocal scanning laser ophthalmoscopy, optical coherence
30 100.0 26 tomography (OCT) has emerged to the forefront of ocular
imaging because of the wide variety of information it can
Table 3: Quadrant wise and average RNFL thickness provide like high resolution and the complex 3-dimensional
(3D) data.11-13 But it has been reported that high myopia is
Group 1 Group 2 Mean change in P value also associated with significant RNFL loss in some cases.14-16
(N=60) (N = 52 ) RNFL 95% CI Therefore it is important to collect RNFL thickness data of
emmetropes and high myopes to distinguish glaucomatous
Superior Mean Mean -18.54 0.0001 changes found on OCT.
(SD) (SD)
(-25.55 to -11.53) Our study compares the RNFL thickness on OCT in healthy
101.75 120.29 emmetropes and otherwise healthy high myopes (normal,
(21.99) (13.85) non-glaucomatous). The mean RNFL thickness overall was
99.34 ± 10.26µ in emmetropes, 85.40 ±15.45µ in myopes.
Nasal 70.70 80.08 -9.38 0.013 High myopes have stastically significant thinner RNFL as
(23.69) (13.57) (-16.76 to 1.99) compared to emmetropes.
Inferior 98.05 119.77 -21.72 0.0001 Yi Zha et al17 compared RNFL thickness in emmetropes,
(19.37) (15.08) (-28.3 to -15.14) low myopia (<-3D), median myopia (-3D to -6D) and high
myopia (>-6D) and found that it was significantly thin in high
Temporal 71.10 77.21 -6.11 0.051 myopes. They concluded that, as the negative spherical error
(18.77) (12.94) (-12.24 to 0.019) increases, decrease in RNFL thickness occurs.Our study is
comparable to their study in terms of mean RNFL thickness
Average 85.40 99.34 -13.94 0.0001 values and comparison results between these groups.
(15.45) (10.26) (-18.93 to -8.94)
Also in a study by Kelley D schmeitzer et al18 the average
Results RNFL thickness in emmetropes and high myopes were
observed to be 108.8µ and 80.0µ respectively (p= 0.001). Their
A total number of 112 eyes of 56 patients were included results were almost the same as ours. There was a negative
in this study. Age and sex distribution of these subjects is correlation of -0.712 with p<0.001 between axial length and
shown in table 1and 2. There was no statistical difference RNFL thickness. They proposed that increased axial length
between these groups in terms of age. (Chi-square =0.105 is the reason behind RNFL thinning in high myopes. We also
with 1 degree of freedom; p = 0.746) and sex distribution. found a negative correlation of -0.140 between axial length
(Chi-square =3.518 with 1 degree of freedom; P = 0.061) and RNFL thickness, so it can be proposed that increase in
( Table 3 )and figure 1shows the mean RNFL thickness in all axial length may be the reason behind RNFL thinning.
the quadrants as well as the average value in both the groups. Similar study was done in Indian population by Kamath et
There was a significant difference in mean RNFL thickness al19 and D Singh et al.20 They also found significant RNFL
between both the groups in average as well as quadrant wise thinning in high myopia group.
except for temporal quadrant.
Discussion
Primary open angle glaucoma is 2-3 times more common
in high myopes, so if we are able to diagnose it in pre-
perimetric stage it will be very helpful to decrease the burden
E-ISSN: 2454-2784 P-ISSN: 0972-0200 48 www.djo.org.in
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