DJO April - June vol 32 No 4 07072022

DJO Vol. 32, No. 4, April-June 2022

E-ISSN: 2454-2784  P-ISSN: 0972-0200 1 Delhi Journal of Ophthalmology

DJO Vol. 32, No. 4, April-June 2022

E-ISSN: 2454-2784  P-ISSN: 0972-0200 2 Delhi Journal of Ophthalmology

DJO Vol. 32, No. 4, April-June 2022

Delhi Journal of Ophthalmology DJO

Official Journal of Delhi Ophthalmological Society Editorial Board Volume 32   Number 4   April-June 2022

Editor-in-Chief
Kirti Singh

Associate Editors

Annu Joon Devesh Kumawat Divya Jain Mainak Bhattacharyya

Arshi Singh    Assistant Editors Priya Saraf

Anjali Mehta Charu Khurana Khushboo Chawla Gunjan Budhiraja Himshika Aggarwal
Jatinder Bali Jatinder Bhalla Manisha Agarwal Neha Chawla
Neha Rathie Nisha Chaudhary Section Editors Pooja Bansal Prateek Kumar
Priyadarshi Gupta Priyanka Golhait Rahul Mayor Ritu Aurora
Shipra Sharda Shweta Vishwanath Deepanjali Arya Suma Ganesh Sumit Grover
Siddharth Madan V.Krishna Jigyasa Sahu
Palak Gupta
Prachi Dave
Siddharth Baindur
Vineet Sehgal

International & Emeritus Editor

Arun Naryanswami Bhavna Chawla George L. Spaeth Milind Pande M. Vanathi
Rajesh Sinha Samira Khan
Vinod Kumar Ruchi Goel Sonal Dangda Satish Kotta

A. K. Grover Atul Kumar Advisory Board Deepak Verma Jolly Rohtagi
J.S.Titiyal Mahipal S. Sachdev N.P. Singh Namrata Sharma
Pawan Goyal Pradeep Sharma Bithi Chowdhary Rakesh Bhardwaj Ramanjeet Sihota
Ritu Arora Rajender Khanna M.D. Singh Suneeta Dubey S.C. Dadeya
Praveen Vashisht
Sarita Beri

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DJO Vol. 32, No. 4, April-June 2022

Contents

Editorial
Ocular Optics: Sculpted and Harmonized for Vision ......................................................................................6
Kirti Singh

Guest Editorial
Corneal Cross linkage – An Optical Marvel.......................................................................................................7
Rohit shetty, Bhavya G

Review Article
Perimetry- Recent Advances ..........................................................................................................................15
Vaibhav Khanna, Annu Joon, Shweta Viswanath, Kanika Chhabra

Centurion Syndrome- Rarity Revisited............................................................................................................25
Bijnya Birajita Panda, Jyotsna Sharma

Original Article
ROSE K2 Contact Lens Rehabilitation in Keratoconic Corneas .....................................................................28
Sneha Aggarwal, M Vanathi, Vinay Gupta, Noopur Gupta, Radhika Tandon

Prevalence of Dry Eyes in Postmenopausal Females in Hadoti Region of Rajasthan...................................36
Jaishree Singh, Ashok Kumar Meena,Tarun Gupta, Ekta Garg, Pushkar Dhir, Neeraj Aggarwal

Change In Vessel and Perfusion Densities with Varying Signal Strengths
on Optical Coherence Tomography Angiography.......................................................................................40
Saurabh Verma, Rohan Chawla, Amar Pujari

Descemet membrane detachment after ocular chemical burns:
case series and review of literature ..............................................................................................................44
Sohini Mandal, Hemant Jhajharia, Prafulla Kumar Maharana

Case Reports
Management of Pseudophakic Myopia Using Implantable Phakic
Contact Lens with A ‘Piggy Back’ Technique................................................................................................48
Kanchita Pandey, Devika Joshi, Shrikant Dinkar Joshi

Cornea Verticillata With Toxic Optic Neuropathy: A Case Report.................................................................52
Anurag Kumar Kashyap, Archana Yadav, Deepak Mishra, Tanmay Srivastav,
Kirti Verma, Prashant Bhushan

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Bilateral Herpes Simplex Keratitis Associated with Dengue Fever................................................................56
Ravi Kaur Sandhu, Pawan Prasher
A Unique Case of Conjuctival Choristoma Masquerading As Nasal Pterygium.............................................59
Mukta Sharma, Shruti Anand
Central Retinal Artery Occlusion Secondary To High Altitude Exposure......................................................61
Diviyanshu Nadda, Jyoti Sheoran, Saurabh Sachar, Anurag Narula

Pictorial CME
A Rare Case of Cilia Incarnata Externum........................................................................................................66
Divya Ramraika, Bithi Chowdhury, Anurag Anand

Omnibus Humanus (Masters, Change Makers, Out of Box Thoughts)......................67
Medicine Through A Humanistic Lens
Upreet Dhaliwal
Theme Section (i- optics)
Demystifying Intraocular Lens Power Calculation.........................................................................................69
Nirupama Kasturi, Arup Chakrabarti
Types of intraocular lenses.............................................................................................................................77
Vaibhav Nagpal
Prisms in Ophthalmology................................................................................................................................83
Himshikha Aggarwal
Electrophysiology In Vision ...........................................................................................................................88
Aakanksha Raghuvanshi, Paromita Dutta
A Guide for Diagnostic and Therapeutic Lenses used in Posterior Segment.................................................97
Khushboo Chawla, Shraddha Raj Shrivastava
Slit lamp Examination techniques.................................................................................................................104
Arshi Singh, V Krishna
Assessing Macular Function: Seat For Highest Visual Ability
With Potential Vision Tests...........................................................................................................................109
Priyadarshi Gupta, Yashi Gupta, Ekta Shaw

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Special Features
Competency-Based Medical Education for The Indian Medical Graduate:
Implementation & Assessment in Ophthalmology.......................................................................................112
Kirti Singh, Neha Rathie, Parul Jain
Cover Image
i Optics ...............................................................................................................................................................
(a) Hyperoleon- emulsifed oil in anterior chamber on retroillumination
(b) Rosette cataract seen on focal illumination
(c) Microspherophakia on retroillumination
(d) Rosette cataract on retoillumination
Kirti Singh

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DJO Vol. 32, No. 4, April-June 2022

DOS Executive Members 2021-2022

DOS Office Bearers

Dr. Pawan Goyal Dr. Rajendra Prasad Dr. Jitender Singh Bhalla Dr. Sandhya Makhija
President Vice President Secretary Joint Secretary

Dr.Alkesh Chaudhary Dr. Kirti Singh Dr. Jitender Bali
Treasurer Editor Library Officer

Executive Members

Dr. O. P. Anand Dr. Gagan Bhatia Dr. Vivek Gupta Dr. Vivek Kumar Jain

Dr. Prafulla Maharanaa Dr. Amar Pujari Dr. Bhupesh Singh Dr. Pankaj Varshney

DOS Representative to AIOS Ex-Officio Members

Dr. J.S. Titiyal Dr. M. Vanathi Dr. Subhash ChDarn. dSuDbahdaesyhaC. DadeyaDr. Namrata Sharma

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DJO Vol. 32, No. 4, April-June 2022

Editorial  

From the Editor’s Desk

Ocular Optics: Sculpted and Harmonized for Vision

Optics synonymous with human eye function, is a pure science of geometry and physics. Human eye on the other hand while
following most dictates’ of optics, deviates often for convenience of vision. The asphericity of cornea with its antecedent
aberrations, crystalline lens curvature and photoreceptor alignment to optimize vision, formation of inverted image on fovea
depending on the brain to set it right being some examples.

Human eye has been sculpted for vision par excellence with all structures resonating in harmony. Witness the severe scalpel
of anatomy in removing all extraneous objects from the path of vision like blood vessels, nerves even at the cost of inability
to repair from harm. Admire the physiological refinement of yoking of two eyes, crossing of fibres, the explicit dance of
extraocular muscles and implicit one of intraocular muscles. Marvel the biochemical wizardry of retinal photoreceptor
alterations being transformed to electrical impulses. Human eye is truly an optical wonder where science and evolutionary
refinements harmonize to create the most faithful interpreter and most appropriate representative of the soul.*

Optics has been the foundation stone for all ocular inventions. The journey started from couching to clear the optical pathway
by Sushrut (Sushrut- Samhita) in 5th century BC, contact lens neutralizing cornea by Leonardo da Vinci (Codex of eye),
deciphering of optical laws by Rene Descartes in 16th century to replacement of crystalline lens for optical restoration by
intraocular lens use by Harold Ridley in the 20th century. Building on blocks of optics has led to invention of ophthalmoscope
(von Helmholtz), gonioscope (Trantas, Salzmann & Koeppe), perimeter, tonometer (Hans Goldmann) to name a few. It is
only fitting that the only ophthalmologist to be honoured with the Nobel Prize, Alvar Gullstrand in 1911, for on optics of eye
which ultimately led him to design his masterpiece, the slit lamp.

Optics remains the cornerstone of understanding of human eye, the foundation of ophthalmologist’s education and genesis
behind most inventions. Issac Newton overturned the prevailing dogma of his times claiming sunlight to be “pure white”
by demonstrating its rainbow hues using optics of prisms. (Classic book opticks) In current times, many inventions like
operating microscopes, advances in perimeter, advanced designs in IOL and interventions like corneal crosslinking rely on
optics to both unearth nature’s mysteries and undo her mishaps .To rephrase Claude Debussy, optics maybe the geometry of
light but human eye optics is a tapestry of geometry, physiological adaptations and artistic creativity in vivo.
This issue of Delhi Journal Ophthalmology deals with “i optics” in its theme section from slit lamp to prisms, perimetery to
electrophysiology, bio-microscopy to operating microscopes, IOL designs to cross linking techniques.

Keeping in mind the academic pulse of our ophthalmic fraternity we have included a special feature on Competency
Based Medical Education implementation and assessment including logbook for the benefit of our members involved in
undergraduate teaching.
References

• Opticks: Treatise of Reflexions, Refractions, Inflexions and Colours of Light. Isaac Newton 1704
• Gloor BR Hans Goldmann (1899-1991).Eur J Ophthalmol 2010; 20(1):1-11.
• Kansupada KB & Sassani JW. Sushruta: Father of Indian surgery & Ophthalmology Doc Ophthalmol 1997; 93(1-2):159-67
* Charlotte Bronte. The soul, fortunately, has an interpreter – often an unconscious but still a faithful interpreter – in the eye.

Dr. Kirti Singh DOI : http://dx.doi.org/10.7869/djo.759

MD, DNB, FRCS, FAIMER, DHA

Editor, Delhi Journal of Ophthalmology
Dir Prof & Director GNEC, State Nodal Officer NPCB
Guru Nanak Eye Center, Maulana Azad Medical College
& assoc hosp. Ranjit Singh Marg,

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Guest Editorial

Rohit Shetty, Bhavya G

Corneal Cross linkage – An Optical Marvel

Keratoconus is an inflammatory related progressive ectatic condition of the cornea due to focal biomechanical
decompensation.1,2 This focal biomechanical decompensation leads to progressive stromal thinning and ectasia with
resulting topographic and visual abnormalities. Collagen crosslinking (CXL) is the only safe, effective procedure to halt the
progression of keratoconus and other ectatic disorders. In this review, we discuss the principles and clinical applications of
CXL.

 Patho-mechanisms behind ectatic disorders
The biomechanical stiffness of corneas with keratoconus is shown to be decreased by a factor of 0.7 (70 % lesser strength).
The total content of collagen in ectatic corneas is similar to healthy corneas but the arrangement of collagen fibrils and
lamellae is widely different. The collagen fibrils at the apex of a keratoconus cornea form a wide layer, show no delimitation
of the lamellae and almost absent interlacing among the fibrils. This disorganized arrangement and poor interlacing of the
collagen lamellae reduces the biomechanical strength of the corneas with keratoconus.

Basics of CXL
The word crosslinking means the formation of chemical bonds or bridges between proteins and other large molecules. These
crosslinks increase the tissue strength, stiffness, and resistance to degeneration.
Crosslinking is employed in multiple industries and manufacturing practices. It is utilized to harden materials in polymer
industry, to strengthen filling materials in dentistry and to stabilize tissues in bio-engineering.3 Among many applications in
medical industry, crosslinking is used to polymerize intra-ocular lens materials, and to manufacture vascular graft materials.4

Natural cross-linking of collagen in cornea
Enzymatic cross-linking is a natural post-translational modification of collagen by lysyl oxidase enzyme. Lysyl oxidase
creates covalent cross links between the collagen fibrils through oxidative deamination of the lysine and hydroxylysine
residues.5 Non enzymatic crosslinking occurs through glycation in diabetics as a natural ageing process.6

Cross-linking as a chemical process
CXL is a photochemical reaction similar to photosynthesis where light energy (derived from UV-A) is converted into chemical
bonds. As riboflavin absorbs UV-A light, it excites and transforms into singlet and then triple excited states. In the presence
of oxygen (type-2, aerobic reaction), the excited riboflavin reacts with the triplet oxygen, and generates singlet oxygen
radical. This highly reactive oxygen free radical reacts with the carbonyl groups on the amino-acids in the collagen peptides
and forms crosslinks. In the absence of oxygen, (type-1, anaerobic reaction), the riboflavin free radicals interact with the
collagen peptides and form the crosslinks. The type-1 crosslinking is less efficacious than type-2 crosslinking.

Components of CXL
In the following section, we discuss the three major components of this photochemical reaction – ultraviolet light, riboflavin
and oxygen. The discussion focuses on the mechanisms of involvement of these factors, the proposed modifications in their
application to improve the technique.

Ultra-violet (UV) light
UV light is the source of the energy for the crosslinking process. The absorption peak of riboflavin is at 370 nm, providing
protection to the endothelium and internal ocular structures at this wavelength. In the absence of a photosensitizer, cornea
absorbs 35% of the incident UV A irradiation. In the presence of 0.1% riboflavin, corneal stroma of 400 microns thickness,
absorbs 90% of the UV-A irradiation, thus less than 10% of the UV-A energy reaches the intraocular structures, which is
absorbed by the lens. The resulting endothelial exposure is 0.18mW/cm2, which is lesser than the safety threshold of 0.35
mW/cm2.

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Figure 1: Mechanism of crosslinking reaction

Another important parameter that determines the intra- ocular toxicity of UV-A irradiation is the vergence of the beam.
Divergent beam from shorter distances such as given by UV devices used during cross-linking has lesser energy density and
is less deleterious to ocular structures.

Riboflavin
Riboflavin acts as a photosensitizer in the process of CXL, and increases the stromal absorption of UV- A irradiation. As
mentioned earlier, riboflavin has peak absorption at UV-A wavelength, hence protects the intraocular structures from the
radiation toxicity. Riboflavin is a micronutrient, used as a food coloring agent and is safe in the event of systemic absorption.
Riboflavin has poor permeability through epithelial tight junctions, hence the necessity for epithelial removal during CXL.
To improve the permeability, chemicals like Benzalkonium chloride (BAK),7 Ethylene-diamine-tetraacetic acid (EDTA), were
added to riboflavin solution. Trans-epithelial CXL irrespective of the modifications, was inferior to the standard epithelium-
off CXL in terms of biomechanical efficacy.8,9

Physical and Biomechanical Effects of Collagen Crosslinking
The structural effects of CXL are mentioned in (table1).

Table:1 Physical and Biomechanical Effects of Collagen Crosslinking:

Effects of CXL Reason / Clinical Significance
Increase in stiffness (Young’s modulus) Halts progressive biomechanical weakening in ectatic disorders
Increase in shrinkage temperature Indirect evidence of strength of cross-linking
Increase in resistance to enzymatic digestion Increased resistance to collagenases
Decrease in the swelling pressure Influx of water is prevented due to interfibrillar crosslinks Can be explored in the treatment of Bullous
Keratopathy

Increase in the thickness of collagen fibril Induced crosslinks may have pushed the collagen polypeptide chains apart, thereby increasing the
diameter interpeptide spacing.

Cellular and Extra-cellular effects of CXL:
The effects of cellular and extra-cellular ocular structures are mentioned in the (table 2).

Cellular and Extracellular Effects of CXL on Ocular Structures

Structure Effect Recovery
Epithelium Removal during CXL procedure No damage to limbal cells10 Re-epithelialization within 3 days10

Keratocytes Apoptosis of keratocytes in anterior stroma11,12 Repopulation of the anterior stroma by peripheral activated
Lacunar edema around the apoptotic keratocytes keratocytes by 4-6 weeks

Stromal extracellular Increased density due to collagen compaction by the induced crosslinks Long term sustenance of the induced collagen crosslinks
matrix explains the long-term stability of ectasia.

Nerves Disappearance of sub-basal nerve plexus in the crosslinked stroma Regeneration starts in a week after CXL
Endothelial cells
No significant effect on the density, morphology of endothelial cells13
( Figure 2)

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Figure 2: (a)- Pre-CXL specular microscopy of a cornea – The endothelial density was 2882
(b)- Post CXL specular microscopy of a cornea with thickness 390µ that underwent accelerated CXL with UV irradiation dose calculated by NXT-UVA calculator

– The endothelial density was 2865

Dresden Protocol
Wollensak et al reported the first in vivo use of UV-A irradiation with riboflavin in humans.14The protocol named after the
place of study (Dresden, Germany) involves debridement of central 7 mm of the epithelium, application of 0.1% riboflavin
solution 30 minutes before the procedure and every 5 minutes during the UV-A irradiation at a dose 3mW/cm2 for 30
minutes. The standard CXL has been demonstrated to effectively stabilize keratoconus and improve the topographic and
biomechanical outcomes.15–17

Accelerated Cross-linking (ACXL)
Technique

The Bunsen-Roscoe law of reciprocity states that the photochemical effect is directly proportional to the total dose of the
irradiation(W/cm2) irrespective of the dose and duration of the exposure over certain range.18 The law has been named after
R. Bunsen and H.E. Roscoe for their pioneering work in photochemistry.19 The Dresden protocol involves the irradiation
time of 30 min with 3mW/cm2 dose amounting to a total UV-A energy of 5.4J/cm2. To reduce the irradiation time, multiple
combinations of irradiation dose and time, 9mW/cm2 for 15 min, 10 mW/cm2 for 9 min, 18 mW/cm2 for 5min , 30 mW/
cm2 for 3 min, and 45 mW/cm2 for 2 min have been studied with the total UV-A energy of 5.4J/cm2.20–22 These techniques
of CXL with shorter irradiation time are termed as accelerated CXL (ACXL).23 The accelerated protocols are introduced to
clinical practice due to the observation that the corneal stiffening effect of the higher UV-A fluences over shorter durations
were comparable to the original 3mW/cm2 irradiation. However, it is essential to understand that the Bunsen- Roscoe law
of reciprocity is applicable only till certain irradiation intensities. Any accelerated CXL protocol should strike a balance
between the irradiation intensity, exposure duration, the biomechanical strengthening effect and the safety profile.

ACXL- Outcomes (Figure 3)
A meta-analysis of eleven trials comparing ACXL with SCXL reported that SCXL resulted in greater reduction in steep
keratometry (Kmax) compared to ACXL.24 However, there are reports of ACXL showing equally good topographic outcomes
as SCXL.25,26 The variance between the topography outcomes can be explained by the different exposure times followed by
the authors.20 Improvement in visual acuity is reported to be similar between ACXL and SCXL.24 Among the different ACXL
protocols, lower irradiance and shorter exposure time protocols may result in better visual outcomes.27 The depth and latency
of onset of the demarcation line is shown to be shallow and delayed in eyes treated with ACXL protocols than SCXL protocol.

Figure 3: (a)- Preoperative Sagittal curvature map of an eye with keratoconus, BCVA was 6/12 with the refractive error of +2.25DS/-6.50DC@80⁰
(b) –Sagittal curvature map of the same eye after topography guided trans-epithelial PRK and accelerated crosslinking, BCVA was 6/9 with refractive error of

+0.25DS/-2.75DC@110 ⁰
Note- the magnitude of keratometric flattening (depicted in c) and the relative surface regularization following the procedure

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Cross-linking in thin cornea
Safe and effective cross-linking in eyes with thin corneas faces two challenges. First is the safety threshold of UVA energy at
the endothelium. Wollensak et al, in their original article on collagen cross-linking, reported that in a 500 µ thick cornea with
the 3mW/cm2 irradiance at the surface and 0.1% riboflavin, the UVA energy reduces by 95% and the energy at the endothelial
level is 0.27J/cm2, leaving a twofold margin for toxic irradiance(0.65J/cm2).14 However, the total fluence employed in
classic Dresden protocol, if used in corneas thinner than 400µ (after de-epithelialization), the toxicity threshold of 0.65J/
cm2 could be reached at the endothelial level. Hence, the authors cautioned the use of Dresden protocol in corneas thinner
than 400µ. Second is post collagen cross-linking stromal haze, which is seen more often in eyes with advanced keratoconus,
and thin corneas.28 Since significant proportion of patients with keratoconus have eyes with thinnest pachymetry < 400µ,
modifications in the technique of collagen cross-linking to make it a safer tool in these corneas is necessary. To ensure safety
of cross-linking in thinner corneas, one has to ensure shallow depth of UVA treatment so that the endothelium is not exposed
to the UV-A energy beyond the safe threshold level. To achieve this, one can increase the thickness of the cornea, or place
a layer of biological or synthetic origin above the cornea. Apart from this, the total fluence of the UVA irradiation can be
reduced by reducing the irradiation dose, exposure time or customize the irradiation dose as per the thickness parameters.
The newer techniques are mentioned in the (table 3).
NXT-UVA calculator is a freely available online calculator, that helps customize the UV-A ‘on’ time to the thickness of the
treated cornea.(Figure 4) The UV-A ‘on’ time was calculated based on Lambert- Beer equation. Since, the total irradiation
dose is within the limits of endothelial toxic exposure, there is no risk of endothelial toxicity or decompensation.29,30

Figure 4: NXT -UVA calculator screen. The clinician can enter the thickness of the cornea, the calculator gives the time duration for exposure of UV -A irradiation
for 3mW/cm2 and 9mW/cm2 and for the riboflavin concentration of 0.1% and 0.2%. The clinician can follow the UV-A exposure time based on the UV-A irradiation

dose and riboflavin concentration

Table: 3 Modifications of CXL in corneas thinner than 400µ

Modification of CXL Technique Outcomes Limitations

Hypo-osmolar Riboflavin31 Iso-osmolar 0.1% riboflavin applied every Equal to eyes treated with Iso-osmolar Failure in extremely thin corneas33
Hafezi et al (2009) 3 minutes x 30 minutes followed by hypo- riboflavin32
osmolar riboflavin-
0.1% in riboflavin in 0.9% Sodium chloride
(NaCl) every 20 sec x 5 min/till the pachymetry
becomes 400µ

Contact lens assisted - CXL34 Iso-osmolar 0.1% riboflavin applied every Stable keratoconus with no progression Oxygen permeability of the
Jacob et al 2014 3 minutes x 30 minutes, UV-A barrier free in 80% eyes, Keratometric flattening in contact lens, UV-A absorption by
contact lens (Soflens, B&L) immersed in 40% eyes35 the contact lens and pre-corneal
isoosmolar riboflavin x 30 minutes placed riboflavin film are limiting factors
over the cornea

Customized epithelial Central 8mm of epithelial debridement Stability of keratoconus upto 9 months Unpredictable riboflavin
debridement36 leaving an island of epithelium over inferior follow up36
Kymionis et al 2009 area of steepening and thinning followed by penetration through intact
0.1% riboflavin every 3 minutes for 15 minutes
epithelium over the cone

Stromal Lenticule assisted CXL37 Stromal lenticule (6.2mm diameter) was Stability of keratoconus demonstrated Limited evidence on the efficacy
Sachdev et al 2015 placed over the apex of the cone of the cornea in 3 patients over 6 months37
0.1% riboflavin every 5 minutes for 30
minutes followed by every 1 minute during
UV-A irradiation

Individualized Fluence CXL UV- A irradiation “on” time individualized to Stability demonstrated at 12 months Needs to be validated in large
Hafezi et al
the thickness of the treated cornea following CXL sample size studies

NXT UVA calculator30 A simple calculator to decide the UV-A on
Shetty et al (2020) time in thin corneas

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Laser Based Treatment Protocols in KC
Keratoconus and Ocular Aberrations

Keratoconus (KC), being a progressive ectatic condition with asymmetric corneal steepening, causes corneal surface
(anterior and posterior) irregularities and induces both lower and higher order aberrations (HOA) in many magnitudes
higher than a normal eye.38 The higher order aberrations are shown to be approximately 5.5 times higher in eyes with KC
than in normal eyes.38 Coma like aberrations including vertical coma are the dominant HOA in these eyes.38,39

Surface Normalization and the Visual Effects in KC
Before discussing the laser based treatment approaches in KC, we need to understand the concept of surface normalization.
The laser based ablation in eyes with KC is not aimed at refractive correction rather to regularize the corneal surface, to
create better aspheric profile of the cornea, and to reduce the higher order aberrations. The location of the ectatic cornea
affects the corneal asphericity and the magnitude and pattern of higher order aberrations.

Concept of Topography guided surface normalization
The topography guided surface normalization usually follows a specific ablation profile. The ablation pattern is planned in
such a way that simultaneously flattens the ectatic cone area and an arcuate area of cornea in the periphery away from the
cone usually in the superior nasal location. This peripheral flattening induces steepening adjacent to the cone similar to a
hyperopic treatment. The combination of flattening in cone area and adjacent steepening regularizes the corneal surface
thereby reducing the HOA.40
Let us discuss the planning technique in the two popular laser based platforms employed globally in keratoconus eyes

Parameters
Maximum Ablation depth
Multiple authors have used different permissible upper limits for the stromal ablation in topography guided PRK in ectatic
eyes. The maximal permissible ablation depths by various authors are : Kymionis et al – 50 µ41, kanellopoulos et al – 50 µ42,
Camellin et al – 55µ43, Shetty et al- 40µ40.

WaveLight Allegretto Wave™ Excimer Laser System (Wave Light Laser Technologie AG)
For this platform, the topography examinations are done by the ALLEGRETO WAVE Topolyzer Vario, with the T-CAT
(Topography guided custom ablation treatment) software for treatment. The platform also enables the clinician to choose
the post ablation aspheric profile of the treated cornea.__42

Protocol followed by the authors40
The asphericity of the cornea, location of the cone (centered vs decentered) and the refractive error is taken into account
while planning the topography guided custom ablation in keratoconic eyes.

Eyes with Centered Cone
The ectatic cone area is considered central if more than 50% cone area is with in the central 3mm zone on posterior elevation
map. In these eyes, cornea has more negative asphericity (high negative Q value) and a myopic refractive error due to
central steepening. We target either the reduction of Q by 20-30% or partial refractive correction, where both approaches
would induce central flattening and regularization making the cornea achieve a more physiological aspheric profile. To
achieve this, the authors optimize the Zernike polynomials to achieve the equivalency between the defocus (C4) and the
spherical aberration (C12) by a specific spherical error input in the targeted refraction tab. The choice to partially correct
the refractive error is taken based on the baseline refractive error (<6D ) and thinnest pachymetry (>45µ).

Eyes with Decentered Cone
Eyes with decentered cone, have a less negative Q value but other dominant higher order aberrations, including coma
and trefoil. During the attempted surface regularization and reduction of HOA, the Q value may reduce significantly to a
more negative values. If no refractive correction is attempted, the preoperative Q can be selected as zero. Partial refractive
correction can be targeted without breaching the 40µ stromal ablation thickness rule.
We initially assess the plano treatment ablation profile planned by the software, then apply Zernike polynomial optimization
(to target C4 (Defocus) and C12 (Spherical Aberration) equivalency, and then finally attempt partial refractive correction
based on the baseline refractive error and thinnest pachymetry.

AMARIS (SCHWIND eye- tech- solutions) (Figure 5)
The AMARIS is a flying spot laser platform that performs reversed single step wave-front based customized Trans epithelial
PRK. The ablation profile is planned using ORK-CAM software. The step wise planning of topography guided trans PRK
is mentioned in detail in (figure 5).

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Figure 5: (a)- The scans captured by the topographer prior to export to planning software
(b)- Initially enter zero refractive error

(c) – Assess the ablation depth while treating higher order aberration only applying the zero rule
(d)- Minimize depth of ablation by correcting only significant higher order aberrations, through selecting the “depth minimization” option. With this input, the

software corrects only significant HOA, further reducing the depth of ablation.
(e)- Assess the summary of HOA corrected through the ablation (highlighted in red square)
(f)- Enter partial refractive error to be corrected keeping the depth of ablation lesser than 50µ

Outcomes of CXL (Figure 6)
Demarcation line is a transition zone, between the crosslinked anterior stroma and untreated posterior stroma.44 (Figure 7)
Ultrastructurally , the treated stroma shows keratocyte apoptosis, increased density of the extracellular matrix and collagen
fibre shrinkage. It is still debatable whether the depth of demarcation line is a valid structural marker of efficacy of CXL.

Figure 6: (a and b) – Two post CXL axial curvature maps of an eye that underwent crosslinking 10 years ago
Note- the stability in the keratometry 10 years (b) following crosslinking
Table 4: Outcomes of CXL

Outcome Reason
Topographic Flattening Crosslinking induced compaction of stroma
Demarcation line Visible transition between crosslinked dense anterior stroma and non/ less crosslinked posterior stroma.
Arrest of progression Improved biomechanical strength
Improvement in Visual Acuity Regularization of the corneal surface

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DJO Vol. 32, No. 4, April-June 2022

Figure 7: AS-OCT picture demonstrating the demarcation line

Conclusion
Newer advances in CXL have reduced the procedural duration, improved the patient comfort without significant reduction
in the efficacy outcomes. The techniques of crosslinking in thin corneas have improved the safety profile of crosslinking in
thin and ultra-thin corneas where standard CXL could lead to endothelial complications. Individualized CXL is a newer
modality with the novel approach of modifying the irradiation times and total UV-A energy based on the pachymetry profile.
Topography guided CXL shows superior visual outcomes compared to other forms of CXL.

Future directions in the research on CXL should focus on improving predictable refractive outcomes of the procedure.
Customized crosslinking with/without laser ablation protocols will make CXL a truly therapeutic and refractive procedure.

References

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and UVA. Cornea. 2007 Jun;26(5):600–5.
13. Mazzotta C, Caporossi T, Denaro R, Bovone C, Sparano C, Paradiso A, et al. Morphological and functional correlations in riboflavin UV A
corneal collagen cross-linking for keratoconus. Acta Ophthalmol (Copenh). 2012 May;90(3):259–65.
14. Wollensak G, Spoerl E, Seiler T. Riboflavin/ultraviolet-a–induced collagen crosslinking for the treatment of keratoconus. Am J Ophthalmol.
2003 May;135(5):620–7.
15. Caporossi A, Mazzotta C, Baiocchi S, Caporossi T. Long-term Results of Riboflavin Ultraviolet A Corneal Collagen Cross-linking for
Keratoconus in Italy: The Siena Eye Cross Study. Am J Ophthalmol. 2010 Apr;149(4):585–93.
16. Wittig-Silva C, Chan E, Islam FMA, Wu T, Whiting M, Snibson GR. A Randomized, Controlled Trial of Corneal Collagen Cross-Linking in
Progressive Keratoconus. Ophthalmology. 2014 Apr;121(4):812–21.
17. Shetty R, Nagaraja H, Jayadev C, Pahuja NK, Kurian Kummelil M, Nuijts RMMA. Accelerated Corneal Collagen Cross-Linking in Pediatric
Patients: Two-Year Follow-Up Results. BioMed Res Int. 2014;2014:1–5.
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20. Shetty R, Pahuja NK, Nuijts RMMA, Ajani A, Jayadev C, Sharma C, et al. Current Protocols of Corneal Collagen Cross-Linking: Visual,
Refractive, and Tomographic Outcomes. Am J Ophthalmol. 2015 Aug;160(2):243–9.
21. Schumacher S, Oeftiger L, Mrochen M. Equivalence of Biomechanical Changes Induced by Rapid and Standard Corneal Cross-linking, Using

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Riboflavin and Ultraviolet Radiation. Investig Opthalmology Vis Sci. 2011 Nov 24;52(12):9048.
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keratomileusis. J Cataract Refract Surg. 2012 Aug;38(8):1424–31.
24. Wen D, Li Q, Song B, Tu R, Wang Q, O’Brart DPS, et al. Comparison of Standard Versus Accelerated Corneal Collagen Cross-Linking for

Keratoconus: A Meta-Analysis. Investig Opthalmology Vis Sci. 2018 Aug 1;59(10):3920.
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A radiation, and riboflavin collagen cross linking for progressive keratoconus. Clin Ophthalmol. 2012 Jan;97.
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n;25(9):1081597X-20090813–12.
29. Shetty R. A Next Generation Crosslinking (CXL) Calculator for Titration of Ultraviolet Energy (UVA) in Thin Keratoconic Cornea-NXT UVA

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Cataract Refract Surg. 2009 Apr;35(4):621–4.
32. Wollensak G, Spörl E. Biomechanical efficacy of corneal cross-linking using hypoosmolar riboflavin solution. Eur J Ophthalmol. 2019

Sep;29(5):474–81.
33. Hafezi F. Limitation of Collagen Cross-Linking With Hypoosmolar Riboflavin Solution: Failure in an Extremely Thin Cornea. Cornea. 2011

Aug;30(8):917–9.
34. Jacob S, Kumar DA, Agarwal A, Basu S, Sinha P, Agarwal A. Contact Lens-Assisted Collagen Cross-Linking (CACXL): A New Technique for

Cross-Linking Thin Corneas. J Refract Surg. 2014 Jun;30(6):366–72.
35. Knyazer B, Kormas RM, Chorny A, Lifshitz T, Achiron A, Mimouni M. Corneal Cross-linking in Thin Corneas: 1-Year Results of Accelerated

Contact Lens–Assisted Treatment of Keratoconus. J Refract Surg. 2019 Oct;35(10):642–8.
36. Kymionis GD, Diakonis VF, Coskunseven E, Jankov M, Yoo SH, Pallikaris IG. Customized pachymetric guided epithelial debridement for

corneal collagen cross linking. BMC Ophthalmol. 2009 Dec;9(1):10.
37. Sachdev MS, Gupta D, Sachdev G, Sachdev R. Tailored stromal expansion with a refractive lenticule for crosslinking the ultrathin cornea. J

Cataract Refract Surg. 2015 May;41(5):918–23.
38. Maeda N, Fujikado T, Kuroda T, Mihashi T, Hirohara Y, Nishida K, et al. Wavefront aberrations measured with Hartmann-Shack sensor in

patients with keratoconus. Ophthalmology. 2002 Nov;109(11):1996–2003.
39. Pantanelli S, MacRae S, Jeong TM, Yoon G. Characterizing the Wave Aberration in Eyes with Keratoconus or Penetrating Keratoplasty Using

a High–Dynamic Range Wavefront Sensor. Ophthalmology. 2007 Nov;114(11):2013–21.
40. D′Souza S, Shetty R, Srivastava S, Ashwini R. Topography-guided custom ablation treatment for treatment of keratoconus. Indian J

Ophthalmol. 2013;61(8):445.
41. Kymionis GD, Kontadakis GA, Kounis GA, Portaliou DM, Karavitaki AE, Magarakis M, et al. Simultaneous Topography-Guided PRK

Followed by Corneal Collagen Cross-Linking for Keratoconus. J Refract Surg. 2009 Jan;25(9):1081597X-20090813–09.
42. Kanellopoulos AJ, Binder PS. Management of Corneal Ectasia After LASIK with Combined, Same-Day, Topography-Guided Partial

Transepithelial PRK and Collagen Cross-Linking: The Athens Protocol. J Refract Surg. 2011 May;27(5):323–31.
43. Camellin M, Guidotti JM, Arba Mosquera S. Corneal-Wavefront guided transepithelial photorefractive keratectomy after corneal collagen

cross linking in keratoconus. J Optom. 2017 Jan;10(1):52–62.
44. Spadea L, Tonti E, Vingolo E. Corneal stromal demarcation line after collagen cross-linking in corneal ectatic diseases: a review of the literature.

Clin Ophthalmol. 2016 Sep;Volume 10:1803–10.

Prof. Rohit Shetty

DNB, FRCS, PhD

Department of Cornea and Refractive surgery
Vice Chairman, Narayana Nethralaya,
Bangalore, India

E-ISSN: 2454-2784  P-ISSN: 0972-0200 DOI : http://dx.doi.org/10.7869/djo.760
14 Delhi Journal of Ophthalmology

DJO Vol. 32, No. 4, April-June 2022

Abstract Review Article

Perimetry- Recent Advances

Vaibhav Khanna, Annu Joon, Shweta Viswanath, Kanika Chhabra

Guru Nanak Eye Centre, Maulana Azad Medical College, New Delhi India.

Despite innumerable developments in the field of glaucoma, it is one of the most undiagnosed disease,
causing irreversible blindness. Perimetry is investigation in glaucoma management as it narrates the amount
of functional loss of visual field secondary to the disease. In this review article we will journey through some of
the landmark developments and future prospects in perimetry. This will include the new algorithms and testing
strategies, pre-perimetric tests, novel techniques such as microperimetry, binocular field testing etc which
have not only decreased the testing time but improved reliability of the tests. With the newer advancement
such as Guided Progression Analysis(GPA) and Visual field Index(VFI) the focus of glaucoma management has
now shifted to the rate of visual field loss, leading to timely surgical or medical management of glaucoma.

Delhi J Ophthalmol 2022; 32; 15-24; Doi http://dx.doi.org/10.7869/djo.761
Keywords: Pre-Perimetric Test, Testing Strategies, Testing Patterns, 24-2C

Introduction approximation of surrounding points, thus decreasing the
slope of the boundary around visual field deficits.2 GATE-i/
Visual field is a measurable part of visual function. GATE is similar to Full Threshold staircase and the SITA
Interpretation of visual field is an integral part of evaluation Standard strategy it starts by determining the sensitivity at
of many ophthalmic conditions such as glaucoma, neuro- five predefined seed locations. The threshold is defined as
ophthalmology and retinal pathologies. Standard automated the mean of the dimmest seen stimulus and the brightest not
perimetry (SAP) is the most widely used method to assess seen stimulus. The ASTA Standard algorithm for baseline
visual field deficit in glaucoma.1 Many articles have been examinations uses a 4-2-2 staircase approach as well as
published on perimetry interpretation, but none of them neighbouring test target information and a quick termination
have covered about the recent advances in perimetry. In this methodology to reduce test time. ASTA Fast is a short test
article, we will learn about the recent advances and their protocol advised for patients expected to be “within normal
significance in the current era of modern perimetry. limits” or those who have previously shown unusual levels
of fatigue while ASTA Follow-Up further reduces the test
Algorithms- Evolution time during follow-up examinations. ASTA alogorithms are
used in Heidelberg edge perimetry. CLIP is a fast threshold
Currently in perimetry, adaptive mode of threshold strategy, using stimuli with constantly rising luminance,
estimation is used in which the stimulus luminance varies offered for use with the Oculus Easyfield perimeter. In this
in ascending or descending steps until the threshold algorithm stimulus luminance is continuously increased
is estimated. This process is also known as staircase or in smaller steps(usually 1dB), from an infrathreshold level
bracketing. Early algorithms initiate examination from four according to the patient’s reaction time until it is seen. The
principal stimulus locations called anchor points (Octopus) CLIP algorithm has been found suitable for the examination
or seed points (Humphrey Field Analyser) followed by 4-2- of children above the age of 8 years. SPARK strategy was
1 dB bracketing strategy which crosses the threshold twice. first introduced on Oculus Easyfield perimeter. The SPARK
Second generation algorithms include Dynamic strategy, Quick strategy is good for follow-ups and for screening
wherein the step size increases from 2dB to 10dB in Octopus, examinations, it also offers a separate training strategy to
when the visual field defect increases. FASTPAC algorithm reduce the curve of the learning effects in standard perimetry.
of Humphrey applied 3dB steps either in ascending or SITA standard is analogous to Full Threshold algorithm,
descending fashion,but the threshold is crossed only while SITA fast is analogous to FASTPAC. In 2019 Heijl and
once. Current algorithms used are Swedish Interactive associates introduced a new time saving threshold visual
Thresholding Algorithm(SITA), Zippy Adaptive Threshold field testing strategy called SITA Faster which is intended to
Algorithm(ZATA), Tendency Oriented Perimetry(TOP), replace SITA Fast.3
German Adaptive Thresholding Estimation(GATE-i/
GATE), Adaptive Staircase Thresholding Algorithm (ASTA), Advances In Testing Strategies
Continuous Light Increment Perimetry(CLIP), SPARK
Precision and SPARK Quick. SITA Faster: At least five threshold visual field testing is
required to quantify how quickly the patient is losing visual
ZATA was introduced for Henson 8000 perimeter with field sensitivity and there is a need of much frequent visual
two versions, Standard and Fast. It makes use of retinal field testing in a newly diagnosed glaucoma patient.4 But
sensitivity if available from previous tests to set the starting in actual practice, perimetric testing is considerably lower
intensity for each test location thus saving considerable time. than recommended due to lack of resources.5 In order to
TOP was first introduced in 1996 for Octopus perimeters, achieve higher number of testing, SITA faster strategy was
it uses linear interpolation between test locations. TOP introduced which is 50% faster than SITA standard testing
uses the response of subject at a specified point to estimate and uses the same SITA algorithm and normative data as
the sensitivity at that point and also modify sensitivity

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Figure 1: Comparative testing duration of various SITA strategies high specificity compared with most of the Spectral Domain
OCT(SD-OCT) parameters in differentiating glaucomatous
SITA fast.(Figure 1) optic neuropathy from non-glaucomatous eyes.9 However
SITA Faster starts much closer to the expected threshold in SWAP has high test-retest variability and is highly affected
the principal points and necessitates only 1 reversal at prime by cataract and media opacities, thus it is not solely used for
test points as compared to two staircases in earlier SITA glaucoma management.
tests, also perimetrically blind points are not rechecked.
Due to shorter duration of the test, patients with severe Frequency Doubling Technology (FDT)
glaucoma appreciated SITA Faster the most. The testing time
is also reduced by not using blind spot and false negatives FDT presents an achromatic sinusoidal grating stimulus of
detection in analysis; instead it uses gaze monitoring and low spatial frequency undergoing counterphased flickering
false positives for test quality monitoring. SITA faster also at a high temporal frequency, leading to apparent doubling
has the advantage for GPA analysis and regression analysis of the spatial frequency of the grating, known as frequency
wherein the software allows comparative interpretation of doubling illusion.10 FDT offers many advantages such
the three SITA thresholding strategies because of strong as high sensitivity and specificity for diagnosing early
similarity between their visual field index findings.6 glaucomatous damage11, not greatly affected by refractive
error and cataract.
Pre-Perimetric Tests
FDT stimulus predominaths stimulates magnocellular
As much as 35-50 % ganglion cells can be lost before a visual ganglion cell pathway(My cells) involved in motion and
field defect is detected, thereby emphasing the importance flicker detection (Table 1). FDT has two presentation
of techniques to diagnose early glaucoma.7 A brief of the patterns, C-20 which represents the central 20 degree with
genesis behind such tests is enumerated in Table 1. 17 stimulus locations and N-30 which has two additional
Short wavelength automated perimetry (SWAP) also points in the nasal field. There are screening and threshold
known as blue on yellow perimetry is a specialised technique tests both of which compare individual test results with the
in which a blue type V stimulus is used on a yellow normative database of more than 700 eyes of 450 subjects.12
background of 100 candela per square metre. Introduced in The C-20-1 has got higher specificity, while the N-30-5 has
1993, SWAP is based on the principle that yellow background got higher sensitivity for detecting glaucomatous field
light reduces the responsiveness of red and green cones by damage. The second generation matrix FDT has improved
saturating them, so as to mainly test the blue cones, which spatial resolution of visual field defects and can detect
are primarily affected in early glaucoma patients.8 It helps small localized defects due to smaller target size and
to detect development of glaucoma in ocular hypertension increased number of testing locations. Matrix threshold
(OHT) patients and progression of disease in early stages. tests use Zippy Estimation of Sequential Thresholds(ZEST)
In a study done by VK et al, SWAP was found to have a very algorithm which is based on Bayesian Statistics.13 Matrix
FDT has many advantages over the first generation as it has
Table 1: Types of ganglion cells and their role in pre-perimetric a video eye monitor for patient alignment tracking with an
testing option to pause the test in between, patient display screen
is larger thus preventing any movements to change fixation
Ganglion Midget cells Parasol cells Bistratified cells for seeing nasal points, data storage option and enhanced
Cell statistical analysis for better evaluation and interpretation of
70% 8-10% 6-10% test results (Figure 2).
Distribution
Size Small Large Small High Pass Resolution Perimetry (HRP)
LGN
Prjections Parvocellular Magnocellular Interlaminar HRP assesses the function of “P ganglion cells” which are
layer layer zones of concentrated in the central retina. The stimulus consists
Other Name Parvocellular of a range of ring targets with dark borders and lighter
Function layer centres stimuli(14 sizes) (Figure 3) used at 50 locations,
the sensitivity is verified by varying the size and not the
P cells M cells luminance of the stimulus. The stimulus distribution of the
HRP corresponds with the arrangement of the ganglion
•High resolution •Motion •Short cells, therefore it could be superior to SAP in detection of
wavelength visual field defects.14 The HRP demonstrates less variability
•Colour •Flicker blue stimuli at visual field locations with reduced sensitivity than SAP,
however studies comparing HRP with SAP shows variable
•Flicker results.15,16

Rarebit perimetry (RBP)

This type of perimetry uses stimulus nearer in size to an
individual ganglion cell (rarebits, microdots)17 to identify
abnormal function of any one fixed retinal ganglion cell.

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Figure 2: 24-2 Matrix FDT reliable fields revealing early scotomas in a 33 year old patient

Figure 3: High-pass resolution perimetry (HRP) stimulus consisting of variable Figure 4: Rarebit perimetry with rarebits stimulus (source:www.neuro-o.se)
size, fixed luminance. (Source: www.neuro-o.se)
Flicker defined form (FDF)
(Figure 4) The test uses 0,1 and 2 suprathreshold dots
at 24 rectangular test areas and checks for the patient This test consists of flickering random black and white dots
response. By evaluating a number of combinations of dots on a background of 50 cdm2 of mean luminance, creating an
in small localized regions, it determines visual performance imaginary edge outline due to phase differences between the
(detection or “hit” rate) in these areas. Nearly all rarebits are stimulus and the background (stimulates the magnocellular
seen with a normal retina (close to 100% "hit rate"), while pathway)23 (Figure 6) The Heidelberg edge perimeter (HEP)
disorders of the visual system result in losses from missing
or dysfunctional receptive fields which appear as gaps in Figure 5: Motion Perimetry video display. X represents the fixation target, small
the receptive field matrix. The outcome of the algorithm was dots represent the motion targets.(Source: www.webeye.opth.uiowa.edu)
adversely affected by optical defocus and by cataract.18 RBP
has been used as a screening method to detect central vision
defects such as macular lesions, optic neuropathies and
chiasmal lesions.

Motion Perimetry

Motion detection is largely detected by large ganglion cells
via magnocellular pathway19 and a damage to this pathway
is associated with loss of motion perception.20 Glaucoma
patients who have been tested with full-field motion
stimuli demonstrate deficits in motion perception.21 The test
background consists of randomly arranged white dots on a
grey background, while the motion targets are circle random
dot cinematograms randomly placed in order to reduce the
effect of positional cues.22 (Figure 5) These stimuli are of 17
different sizes with a diameter step factor of 100.1(1.259)
and a 2-1 staircase is used to estimate threshold. The test
evaluates 44 locations and progresses until the smallest
circle is seen at each test point, making it time- consuming.

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DJO Vol. 32, No. 4, April-June 2022

is a monitor-based perimeter that uses the FDF stimulus to a flickering stimulus, superimposed on a base of a steady
test central and peripheral visual fields. It offers a full set of luminance and specifies the temporal frequency required
standard tests for central 10°, 24° and 30° visual field as well to separate the stimulus from the base.28 CFF perimetry
as an extension to the periphery up to 60° (100 points) and determines the highest temporal frequency at which a
uses the Adaptive Staircase Thresholding Algorithm (ASTA) flickering stimulus of constant luminance is originally
for visual sensitivity estimation. There is a considerable perceived as a continuous(non-flickering) stimulus.29 A few
learning effect over three visits for the Edge stimulus, studies have reported flicker perimetry superior to SAP, in
therefore there is a lack of agreement between the HFA and the investigation of glaucomatous field loss.30
FDF.
Microperimetry/ Fundus Perimetry
Pulsar Perimetry
It is a novel functional method which assesses retinal
This technique can evaluate both parvocellular and the sensitivity while directly examining ocular fundus, thus
magnocellular visual pathway.24 It consists of two images correlating the pathology(nerve fibre layer loss, macular
the phase and counterphase image that alternate with pathology etc.) and the corresponding functional loss.31
a frequency of 10 Hz over 500 ms and merge with the The fundus is imaged in real-time and the visual field is
background luminance of 32 cd/m2 at the edges to avoid directly mapped on it, thereby providing a direct structural
stimulating direction-selective ganglion cells. The Pulsar and functional correlation. An eye tracker detects eye
examination method of the Octopus 600 exclusively uses movements during stimulus projection, allowing accurate
the Tendency Oriented Perimetry in which correlation of matching between expected and projected stimulus on the
the threshold values in neighbouring locations is taken into retina. Currently, there are three popular models: NIDEK
account thereby reducing the examination time by nearly 80 MP3, Optos OCT/SLO, MAIA microperimeter(Centervue).
%. The variability was lower for Pulsar, compared to both

Figure 6: Fliker defind from perimetry (Reference: www.oftis-opta.cz)

SAP and FDT.25 Pulsar perimetry seems able to detect more The Compass perimeter(Centervue Padova, Italy) is a
cases of clear progressive glaucomatous damage than either combination of scanning ophthalmoscope and automated
confocal scanning laser ophthalmoscopy or nerve fibre perimeter, providing confocal images of the retina with
polarimetry.26 retinal threshold sensitivity under non-mydriatic conditions.
It has strategies similar to 24-2 and 10-2 programmes of SAP,
Flicker Perimetry along with recent addition of ZEST algorithm. There are
three different testing modes namely Fast test, Expert test
This perimetry stimulates M ganglion cells. It consists of three and Follow up test. The Fast test is done for uncooperative
different techniques: Temporal Modulation perimetry(TMP), patients requiring only 3 minutes per eye. Microperimeter
Luminance Pedestal Flicker perimetry(LPF) and Critical can be used for diagnosis and progression in early glaucoma
Fusion Frequency perimetry(CFF). TMP reveals greater cases, and evaluation of retinal sensitivity in localized areas
defects in early glaucoma at all temporal frequencies and of retinal nerve fibre layer defects (pre-perimteric glaucoma
thus identifies cases of ocular hypertension that are likely analysis)( Figure 7).
to develop glaucoma.27 LPF perimetry is commercially
available in Medmont M600 perimeter and demonstrates

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DJO Vol. 32, No. 4, April-June 2022

Advances in testing patterns 24-2c Pattern Deviation scores in each of the five zones in the
upper hemifield are compared to findings in mirror-imaged
The standard 24-2 algorithm of perimetry is known to miss zones in the inferior visual field and compared to normative
the early macular damage which has been identified on 10-2 significance limits specific to each zone pair (Figure 9).
and OCT parameters.32 The Humphrey 24-2C visual field
test is a modified 24-2 visual field test that incorporates 10 GHT findings are divided into the following categories:
additional test points in the central 10° of vision to aid in
the detection of this missed damage. It was introduced on i. Outside Normal Limits- One zone pair differs by an
the Humphrey platform (HFA3) in 2019. The additional 10 amount found in fewer than 1 % of normal subjects.
points in the center are asymmetric in the two hemifields
and are chosen as per studies indicating the more susceptible ii. Borderline- At least one zone pair differs by an amount
areas for early ganglion cell damage (Figure 8). It is available found in 1% to 3% of normal subjects.
in the SITA faster testing mode by default, which helps keep
iii. General Depression Best test point locations have low
sensitivity to the level seen in fewer than half a percent

Figure 7: Microperimetry print out (Reference: www.oftis-opta.cz)

the testing time comparable to 24-2 despite the addition of of normal subjects.
10 extra points. This novel testing pattern helps to study iv. Abnormally High Sensitivity- Best test points are so
the structure-function concordance in early glaucoma and
suspects. Comparative studies have been done evaluating high as to be at levels seen in fewer than half a percent
its role in glaucoma as well as neuro-ophthalmology.33 24-2c of normal subjects.
testing pattern has been compared with the standard 24-2 v. Within Normal Limits.
and 10-2 patterns. The results of comparative studies so far
have been variable, citing no additional benefit to detection The GHT has been reported to have high sensitivity and
of extra field defect areas, although structural-functional specificity37, with easy interpretation, especially by novice
concordance was not accurate.34 The 24-2C exhibits the users. The method was designed to have an overall specificity
potential to be used as a hybrid between the 24-2 and 10-2 to between 84% to 90% depending on whether the Borderline
better evaluate visual field defects.35 findings are considered Outside Normal Limits or Within
Normal Limits.
Advances in Analytical indices
Glaucoma Hemifield Test (GHT) Visual Field Index (VFI)

GHT is an artificial intelligence-based analysis that provides Introduced by Bengtsson and Heijl in 2008, the Visual Field
plain language classifications of 24-2 and 30-2 test results Index is an improved version of the older mean deriation
(points common to both) and is based upon patterns of (MD) index, that is less affected by cataract than MD,
loss specific to glaucoma (not neurological disorders).36 except in fields having MDs worse than -20dB. As opposed
to MD, VFI is expressed in the percentage of normal age-

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Figure 8: Extra points covered during 24-2c examination in comparison to relying heavily on the quantification and velocity of visual
24-2 examination. field loss over time. Defining a baseline test is important, as it
could be the beginning of glaucoma therapy or a significant
Figure 9: GHT mirror-imaged zones (Source: www.keogt.com) modification in the glaucoma treatment plan. GPA has been
programmed to choose by default the earliest two fields as
corrected visual function, and is intended for use in baseline tests.
assessing glaucoma progression and staging glaucomatous
functional damage on a scale from normal function (100%) GPA can be event based (Glaucoma Change Probability
to perimetric blindness(0%). MD value associated with Maps) and trend based (VFI), both of which are reflected
blind fields depends upon age and testing strategy, while in the standardized GPA reports (Figure 10). The event
VFI in a perimetrically blind field is always 0%, regardless based analysis determines visual field progression to be
of age or strategy and 100% in normal fields. VFI gives either present or absent, based on a predefined change in
more weightage to the central test points as compared to the the parameters, and gives a point wise glaucoma change
peripheral ones to account for the higher density of ganglion probability analysis. The progression analysis shows a
cells found in the central retina.38 numerical plot and a plot using intuitive symbols indicating
progression of the disease. A solid triangle represents a
Guided Progression Analysis (GPA) point changing by an amount that is significant (P<0.05)
and is repeated in three consecutive follow-up exams; half
Over the past decade, a paradigm shift has occurred in filed triangle identifies a point changing by an amount that
glaucoma management from monitoring progressive is significant (P<0.05) and is repeated in two consecutive
perimetric glaucomatous damage on serial field testing to follow-up exams; small open triangle symbol is used when
current focus on the patient’s rate of disease progression, the change was not seen on the previous follow up test. A
significant deterioration in the probability maps at same
three or more points on two subsequent field tests predict a
possible progression, whereas that on three subsequent tests
determine a likely progression. The trend-based analysis is
computed by the visual field index which provides the actual
rate of change of visual field parameters and is based on linear
regression analysis. The ‘p’ value of VFI slope determines
the change of VFI with time and a negative slope represents
disease progression. The VFI Bar histogram graphically
represents the patient’s current VFI value along with a 3-5
year projection of the VFI regression line, considering the
same rate of progression is maintained. Mixed GPA program
now allows intermixing of different strategies such as SITA
Faster, Fast, Standard, 24-2, 30-2, and 24-2C in progression
analysis due to their clinical equivalence.

Advances in Data Integration

Data synchronization and review is now available in recent
models which keeps all perimeters connected through a local
network, thereby decreasing patient waiting time, as fields
may be performed on any one of the connected perimeters,
with constant synchronisation of patient’s fields over all
connected perimeters.

Integrated Glaucoma Workplace has also been introduced
in the advance models of Humphrey perimeters to enable
digital synchronisation and integration of various glaucoma
imaging modalities such as Humphrey visual field perimeter,
OCT-RNFL, Ganglion cell analysis and macular GCC. This
will enable an elaborate structural-functional correlation of
the disease pathology and progression.

Advances in patient alignment and fixation
monitoring

The initial perimeters utilised manual assessment of patient
alignment by an extrenal examiner during the duration of
the test., however this type of assessment was gross and
had a lot of demerits including inter-examiner variability.

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Figure 10: GPA analysis showing signs of progression in the right eye.

In 1974, Heijl-Krakau method was first described in which The corneal view in the machine screen provides useful data
moderately bright stimuli are presented at the expected regarding patient's pupil and lens centration using a green
location of the physiological blind spot of the tested eye star, red star and green plus coding (Figure 11).
and any positive response to the stimuli suggested a loss
of fixation.39 The method though still widely used in many The Gaze tracker is a novel patient alignment monitoring
automated perimeters, has a few shortcomings because the system present in Humphrey perimeters and measures gaze
patient’s blind spot is not always situated in the location direction every time a stimulus is presented. The patient’s
assumed, thus making the fixation loss stimuli a positive alignment is displayed in the form of lines, marks with a
response during the examination. Also, the amount of gaze precision of approximately +/- 2 degrees and is presented
data provided by this method is quite limited, because only at the bottom of the HFA printout. A line with full-scale
a few blind spot check stimuli can be presented during a marking extending upward indicates an off fixation i.e gaze
visual field test. error of 10 degrees, a small downward mark indicates that
the gaze tracker was unable to measure gaze direction, while

Figure 11: Perimeter screen view showing- A: Misalignment; B: Proper alignment

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larger downward mark indicate eyelid interference with the the simulated binocular results and the binocular Esterman
device’s view of the eye such as in blinking or squinting test in classifying glaucomatous patients.
(Figure 12).
Advances in Refractive Error Correction
Figure 12: Gaze tracker indicating off fixation Liquid Trial Lens

The HFA gaze tracker uses image analysis to separately locate Refractive error correction prior to initiating visual field
the centre of the pupil and the reflection of the light-emitting testing is crucial for obtaining optimal test results. One
diode from the corneal surface. The spacing between these diopter of spherical refractive blur in an undilated pupil
two points strongly depends upon gaze direction while will produce approximately one decibel of depression of
being largely independent of the head position. Separate the hill of vision when testing with a Goldmann size III
calculations provide head position information and are used stimulus. This can be avoided by performing perimetry with
to automatically keep the eye aligned at the centre of the trial the patient wearing his refractive correction in the form of
lens. glasses or contact lenses (along with near add in presbyopic
age group) or by manually placing the corrective trial lenses
Binocular Testing Strategy in the perimeter holder. A newly introduced liquid trial lens
Esterman Binocular Field Testing technology has proven to be equally effective, convenient
and time saving technology for refractive correction. It
This binocular field testing method available on the HFA automatically adjusts to the spherical and presbyopic power
utilises size III white stimuli of 10dB intensity to test 120 of the patient by changing the fluid pressure within the lens
points in the central and peripheral visual field and records which changes its shape from concave to convex (Figure13).
the visualisation response at each point. Esterman test can be The power adjustment can be made between +8.0 D to -8.0
used for driver’s license screening and is as effective as HVF D range. It is recommended to use spherical equivalent
in detection of central defects in case of advanced glaucoma.40 corrections for astigmatism upto 2.0 D. The user interface
Binocular testing allows for naturally-occuring binocular contains + and – buttons to change the liquid trial lens power
enhancement wherein either eye compensates for the defects in 0.25 D steps, while the patient is asked whether the target
in the fellow eye, thereby making it more functional and is perceived as blurred or focussed before the procedure.
relevant for the patient. However, it is difficult to judge
whether the defect is absolute or relative, and there is no Advances in Perimetric Unit
way to control fixation stability since the binocular testing Portable Perimeters
conditions eliminate naturally occurring blind spots which
are used for fixation control in other tests. The idea of portable visual field testing was borne in order
to facilitate monitoring of presumed stable or controlled
Crabb et al in 1998 described another new method known glaucoma patients or suspects reducing the overall number of
as Integrated Visual Field (IVF) which simulates a binocular office visits for the patient. Although the portable perimeters
visual field from the data of monocular visual fields of either have a low resolution and are not as accurate as compared
eye.41 The study revealed a substantial agreement between to the in-office gold standard method, aggregating more
data over a longer period of time may be more predictive
than the smaller amount of higher quality data that’s
acquired only during annual or semi-annual office visits.
Portable perimeters can be used in the office setup as well
as for home screening and follow-up. Three most popular

Figure 13: The liquid tial lens changes power with a change in its shape which is due to an increase or decrease in fluid pressure within the lens.

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DJO Vol. 32, No. 4, April-June 2022

portable perimeter designs at present are Moorfields 8. Kanski JJ, Bowling B. Clinical Ophthalmology: A Systematic
Motion Displacement Test(MDT), Melbourne Rapid Fields Approach. 7th ed. Philadelphia: Elsevier/Saunders; 2011. P.3348.
Test and Virtual Reality Peripheral Vision testing. MDT was
one of the early portable visual field test in which 32 white 9. Kalyani VK, Bharucha KM, Goyal N, Deshpande MM.
lines on a gray background was used while fixating in the Comparison of diagnostic ability of standard automated
centre and any wiggling movement was documented by the perimetry, short wavelength automated perimetry, retinal nerve
patient with a button click. However, MDT is no longer in fiber layer thickness analysis and ganglion cell layer thickness
use and not available. Melbourne Rapid Field Test uses a analysis in early detection of glaucoma. Indian J Ophthalmol.
free Ipad software and takes advantage of a moving fixation 2021 May;69:1108-12.
target in order to effectively increase the tablet surface area
to test up to 30 degrees of field. Several published studies 10. Kelly DH. Frequency doubling in visual responses. J Opt Soc
have validated the device as a screening tool similar to a Am. 1966;56:1628-33.
tangent perimeter.42 Virtual Reality peripheral Vision testing
overcomes one of the major limitations of portable devices 11. Cello KE, Nelson-Quigg JM, Johnson CA. Frequency doubling
i.e. inability to control fixation and the screen to eye distance. technology perimetry for detection of glaucomatous visual field
With the virtual reality, no matter where the patient looks, loss. Am J Ophthalmol. 2000 Mar;129:314-22.
the stimuli can be shown relative to fixation at that moment.
Gyroscopes can account for head movement, and immersive 12. Adams CW, Bullimore MA, Wall M, Fingeret M, Johnson CA.
environment can improve user engagement. Various Normal ageing effects for frequency doubling technology
inexpensive, light weight, mobile VR applications and perimetry. Optom Vis Sci. 1999 Aug;76(8):582-7.
software platforms are now available. Tsapakis et al showed
a high correlation between the realibility of VF testing using 13. Turpin A, McKendrick AM, Johnson CA, Vingrys AJ. Properties
a VR testing system and Humphrey test.43 However, further of perimetric threshold estimates from full threshold, ZEST and
long term studies are needed to validate portable perimeters. SITA-like strategies, as determined by computer simulation.
Invest Ophthalmol Vis Sci. 2003 Nov;44(11):4787- 95.
Conclusion
14. Spry PG, Johnson CA, Mansberger SL , Cioffi GA. Psychophysical
Perimetry has come a long way from the era of kinetic investigation of ganglion cell loss in early glaucoma. J Glaucoma.
perimeters consisting of heavy equipments to modern 2005 Feb;14(1):11-9.
automated static perimeters consisting of faster and portable
computers. The future of perimetry is now moving towards 15. Ennis FA, Johnson CA. Are high-pass resolution perimetry
artificial intelligence for automated analysis of visual thresholds sampling limited or optically limited? Optom Vis Sci.
fields for the detection of glaucoma and predicting future 2002 Aug;79(8):506-11.
progression. Another aspect of research and development
is a portable brain-computer interface that detects visual 16. Artes PH, Chauhan BC. Longitudinal changes in the visual
function through recorded electric responses directly from field and optic disc in glaucoma. Prog Retin Eye Res. 2005
the visual cortex thereby eliminating the subjective aspect of May;24(3):333-54.
clicking to indicate when a visual stimulus is seen.44
17. Hackett DA, Anderson AJ. Determining mechanisms of visual
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al. Detection of central visual field defects in early glaucomatous Cite This Article as: Vaibhav Khanna, Annu Joon, Shweta
eyes: Comparison of humphrey and octopus perimetry. PLoS Viswanath, Kanika Chhabra. Perimetry-Recent Advances.
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30. Matsumoto C, Takada S, Okuyama S, Arimura E, Hashimoto S,
Shimomura Y. Automated flicker perimetry in glaucoma using Acknowledgments: Nil.
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between Humphrey Field Analyzer and Micro Perimeter 1 Source of Funding: None
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33417411. Guru Nanak Eye Centre,
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Review Article

Centurion Syndrome- Rarity Revisited

Bijnya Birajita Panda1, Jyotsna Sharma2

1Department of Ophthalmology, All India Institute of Medical Sciences, Bhubaneswar, Odisha, India.
2Department of Ophthalmology, Srirama Chandra Bhanja (S.C.B) Medical college, Cuttack, Odisha, India.

Centurion syndrome is a rare cause of unexplained epiphora which often goes unrecognized due to a lack of awareness

Abstract among ophthalmologists. This entity should be considered in the differential diagnosis of causes of epiphora which can
be managed surgically. This article is a short review of the available literature on etiopathogenesis, clinical features,

diagnosis, and current management of Centurion syndrome.

Delhi J Ophthalmol 2022; 32; 25-27; Doi http://dx.doi.org/10.7869/djo.762

Keywords: Epiphora, Centurion Syndrome, Medial Canthal Repositioning

Introduction 13 case reports in 1993 by Timothy J. Sullivan et al. Based on

Centurion syndrome is a rare idiopathic disorder review of medical records of those 13 patients, they reached
characterised by abnormal anterior insertion of medial to the conclusion that epiphora in them was caused due to
canthal tendon along with a prominent nasal bridge and abnormal anterior insertion of medial canthal tendon which
malposition of the medial part of lid away from the globe causes inferior punctum to displace anteriorly out of lacus
displacing the lacrimal puncta out of lacus lacrimalis, lacrimalis and named the disorder as Centurion Syndrome
resulting in epiphora. It was first described by Sullivan, due to similarity in nasal structure of their patients and the
Welham and Collins in 1993 in an article based on a series description of Roman Centurions. Two theories have been
of thirteen patients with unexplained epiphora in whom a proposed for pathogenesis- one theory as proposed by
peculiar anterior insertion of medial canthal tendon (MCT) Sullivan et al is the abnormal anterior insertion of medial
along with a high nasal bridge was observed. They described canthal tendon, which has been confirmed based on pre
these patients as having ‘Centurion syndrome’ owing to the and postoperative (i.e., after performing medial canthal
nasal structural similarity between their patients to those tendon release) findings of lacrimal scintillography and the
of Roman centurions.1 Few studies have been published other theory is based on a more complex anatomic disparity
regarding the diagnosis and management of this clinical between orbit and its contents.1
entity.2-6 The exact insertion of anterior limb of MCT to
the anterior lacrimal crest could be anterior, normal or It is important to look for medial canthal tendon abnormality
maldeveloped and can be visualized on magnetic resonance in patients presenting with epiphora. This disorder is more
imaging 7 The techniques described in literature for surgical common in males (89.8%). Age at presentation of Centurion
correction are disinsertion/release of anterior limb of medial syndrome cases may vary from 1st decade to 4thdecade of
canthal tendon followed by suturing of the MCT stump life mean age being around 21 years of age. Age of onset
to the anterior lacrimal crest. This can be accompanied by varied in different case reports as Sullivan et al noted it
adjunctive procedures like canthoplasty, retractor plication to be between 3-10 years of age whereas majority of other
and dacryocystorhinostomy. The purpose of this review case reports mentioned epiphora becoming apparent in 2nd

is to summarize the clinical features which clinch to the

diagnosis of this rare condition and further analyse the

various surgical techniques utilized to treat this condition.

Material and Methods

An online search was made using the key words “centurion
syndrome eyelid” on Google scholar, PubMed and Medline.

Results Figure 1: Twenty years young male presenting with epiphora with typical
''beak sign''' diagnosed as Centurion syndrome
A total of 11 articles were retrieved which comprised of 5
case series and 6 case reports. Two articles were excluded decade of life. However, Sullivan et al mentioned that the
considring linguistic barriers of other than English language. symptom aggravated in their patients during puberty [1].
A total of 53 cases were analysed on the basis of clinical The reason being growth of mid facial structures especially
features, clinical tests performed, surgical procedure and frontal process of maxilla and nasal bone during puberty
their outcomes and summarized in (Table 1). which draws medial canthal tendon further forwards.
Epiphora is mostly bilateral, in this review we found that
Discussion 95% of cases whose laterality is mentioned are reported to
be bilateral. Sullivan et al however reported that 15% cases
Various ocular abnormalities may lead to epiphora including may be unilateral. Prominent nasal bridge is an important
hyper lacrimation, eyelid abnormalities, lacrimal outflow factor aiding in diagnosis but its absence doesn’t exclude
obstruction. In this literature review we have described
Centurion Syndrome which is a rare cause of epiphora and
often goes undetected. It was first published as a series of

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Table 1: Detailed analysis of various studies related to centurion syndrome

Name of Type of Total Gender Average age at Typical Clinical tests No. of Surgical procedure Outcome (No
no. of (M/F) presentation clinical supporting patients /persistent
study study patients (years) presentation Centurion who Anterior MCT epiphora
- (Epiphora, syndrome underwent release with
Sullivan Case series 13 At birth-4 cases prominent (Increased tear surgical posterior plication No epiphora
et al 38/40 3-10 years-9 cases nasal bridge, film height, correction of tendon stump (7/8),
(1993) 4/0 deep set eyes, delayed FDDT, (eyes) one required
1/0 20.5 displaced negative primary Bilateral lateral DCR for
Sujatha Retrospective 40 1/0 20-33 lower puncta) Jones dye test, 8(12 eyes) tarsal strip associated
et al case series 10/3 21 hard stop on procedure for outflow
(1999) 33 Present probing, patent 1 concomitant obstruction
12-35 syringing) anterior No epiphora
Ma'luf Case series 4 Present Present 3 displacement of (1/1)
et al Special tests- lateral lid margin
(2003) Present Lacrimal 22 Anterior MCT No epiphora
scintillography- release with (3/3)
Chang Case report 1 Present 10 functional 4(8 eyes) DCR due to
(2006) block associated outflow No epiphora
Present ROPLAS 1(2 eyes) obstruction (22/22)
Huerva Case report 1 positive-3 Disinsertion of
et al Present Hertel’s Exoph- 1 anterior limb of Persistent
(2007) normal in all MCT without epiphora
4 posterior plication (4/4)
Murthy Retrospective 13 Present 5 Disinsertion of No epiphora
et al case series Special tests-none 4 anterior limb of (2/2)
(2009) MCT without
Present posterior plication No epiphora
Anterior MCT
Present release with No epiphora
Special test-none medial lower No epiphora
eyelid retractor
Not mentioned plication Persistent
Anterior MCT epiphora
Present release and (3/4)
posterior plication
of tendon stump
followed by
retractor plication
Anterior MCT
release alone
Anterior MCT
release with
conjunctivoplasty
Anterior MCT
release alone with
punctoplasty

the diagnosis. Beak sign is the inferior angulation of medial reported to be associated in 25.7% of cases in this review
canthus which can be looked for in suspected cases. Other which contributes to the pathogenesis of disease by pulling
causes of epiphora have to be ruled out by excluding history the globe further inwards away from the lid by causing
of discharge, pain over lacrimal sac area, any ocular trauma relative retro displacement of globe. Sullivan et al however
or surgery and by performing tests like ROPLAS, syringing didn’t find enophthalmos in their cases and concluded that
or lacrimal passage irrigation, probing of puncta, Jones it only has a minor role to play in the pathogenesis, if at all
Primary Dye test. Deep set eyes or enophthalmos has been any.

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Tests like Fluorescein dye disappearance test which shows surgical management. Ophthalmic Plastic and Reconstructive
delayed emptying of dye (i.e., persistence of dye beyond Surgery. 1999; 15:243-244.
3 minutes), tear film height which is raised, and lacrimal 3. Murthy R, Honavar SG, Naik M, Menon V, Bhaduri A, Das S.
scintillography which shows functional block at medial Centurion syndrome: clinical presentation and surgical outcome.
canthus with hold up of activity before entry into the sac, are Orbit. 2009;28(5):269-74.
performed to help in finalising the diagnosis. 4. Ma'luf RN, Bashshur ZF, Noureddin BN. Anterior canthal tendon
release for correction of the centurion syndrome. Ophthalmic
Treatment options include disinsertion of anterior limb of Plastic and Reconstructive Surgery. 2003 Nov;19: 446-448.
medial canthal tendon with or without posterior plication 5. Chang JH, O'Donnell BA. Medial canthal tendon release and
of the tendon stump with periosteum of lacrimal fossa just lower eyelid retractor plication for Centurion syndrome. Clin
posterior to anterior lacrimal crest. Decision to do posterior Exp Ophthalmol. 2006; 34:284-5.
plication can be made on table during surgery depending 6. Huerva V, Sánchez MC, Canto LM. Surgical management of
on whether adequate retro displacement of lid to globe Centurion syndrome. Can J Ophthalmol. 2007 Dec;42 :879-80.
has been achieved by anterior MCT release alone or not. 7. Alam MS, Tongbram A, Noronha OV. Magnetic Resonance
Similarly, anterior MCT release can be supplemented with Imaging Features of Medial Canthal Tendon in Centurion
conjunctivoplasty to achieve adequate lid globe apposition Syndrome. Curr Eye Res. 2021 Apr;46(4):592-595. doi:
and align the punctum with lacus lacrimalis. It can also be 10.1080/02713683.2020.1817492. Epub 2020 Sep 7. PMID:
combined with punctoplasty. This surgery has been proven 32857945.
to be effective in almost all cases without enophthalmos
except for one case reported by Huerva et al6 in which status Cite This Article as: Bijnya Birajita Panda, Jyotsna Sharma,
of enophthalmos was not mentioned. However, it has been Centurion Syndrome- Rarity Revisited Delhi J Ophthalmol
reported to be ineffective in patients having enophthalmos 2022; 32 (4): 25 - 27.
as seen in 4 case reports by Ma'luf et al4 where epiphora Acknowledgments: Nil.
persisted after anterior MCT release and in 4 cases mentioned Conflict of interest: None declared
by Murthy et al who also reported 4 of their cases having Source of Funding: None
enophthalmos. Date of Submission: 02 Jun 2021
Date of Acceptance: 04 May 2022
Anterior MCT release along with medial eyelid retractor
plication has been effective in both the cases it was Address for correspondence
performed, one of them having enophthalmos suggesting Bijnya Birajita Panda
it as the preferred surgery for Centurion syndrome cases
with enophthalmos. Bilateral lateral tarsal strip procedure Assistant professor
done in a case having concomitant anterior displacement Department of Ophthalmology
of lateral lid margin by Sullivan showed successful result.1 All India Institute of Medical Sciences,
Post op follow up should be done up to a minimum period Bhubaneswar, Odisha, India.
of 6 months to assess the outcome of surgery subjectively E-mail: [email protected]
by grading epiphora and objectively by Fluorescein dye
disappearance test. Post op lacrimal scintillography can also Quick Response Code
be done and compared with the pre op findings.

Conclusion

Diagnosis of Centurion Syndrome should be kept in mind
while dealing with patients complaining of epiphora.
A typical patient is a male in 2nd to 4th decade of life
complaining of bilateral epiphora which affects his daily
studies or work with the symptom becoming apparent during
puberty having a prominent nasal bridge, deep set eyes,
forward displacement of punctum out of tear lake and loss
of lid globe apposition mostly involving medial side is likely
to have Centurion syndrome. General ophthalmologists
should be aware of this condition, recognizing and referring
them to specialized personnel at appropriate time for
surgical correction.

References

1. Sullivan TJ, Welham RA, Collin JR. Centurion syndrome.
Idiopathic anterior displacement of the medial canthus.
Ophthalmology. 1993. ;100(3):328-333.

2. Sujatha Y, Sathish S, Stewart WB. Centurion syndrome and its

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DJO Vol. 32, No. 4, April-June 2022

Original Article

ROSE K2 Contact Lens Rehabilitation in Keratoconic Corneas

Sneha Aggarwal, M Vanathi, Vinay Gupta, Noopur Gupta, Radhika Tandon

Cornea, Lens & Refractive Surgery Services, Dr. R. P. Centre, AIIMS, New Delhi, India.

Purpose: To evaluate the modifications required in ROSE K2 contact lens (CL) fitting in keratoconic corneas.

Methods: A retrospective study with ROSE K2 CL wear in keratoconic corneas was done. Study data noted stage of
keratoconus, Uncorrected Visual Acuity (UCVA), Best Spectacle Corrected Visual Acuity (BSCVA) and the Best CL Corrected
Visual Acuity (BCLCVA), type of ROSE K2 CL, base curve (BC), overall diameter (OD), edge fit and modifications, Asymmetric
Corneal Technology (ACT) & Toric Periphery (TP) design, lens exchanges, and follow ups. Data was analyzed based on the
fitting guidelines of ROSE K2 CL [BC Kmean of ≤5.99mm (group 1), 6.0mm to 6.99mm (group 2), >7.0 Group 3)] and in
accordance to the keratoconus staging.

Results: 92 eyes of 64 patients of mean age 22.12 ± 5.57years [(range 11 to 36 years) (males 50, females 14)], which had
undergone prior collagen crosslinking, were recruited into the study. Mean logMAR UCVA was 1.01 ± 0.41, mean logMAR
Abstract BCVA with spectacles was 0.52 ± 0.31 and mean logMAR BCVA with ROSE K2 contact lenses was 0.12 ± 0.09. The difference
between the recommended and prescribed CL BC was 0.33 ± 0.34 mm in group 1, 0.19 ± 0.17 mm in group 2 and 0.18 ±
0.16 in group 3. Edge modification was required in 90%, 58.7% and 45.5% in group 1, 2 & 3 respectively. Eyes of advanced
keratoconus required mean change of 0.26 ± 0.24 mm in BC from recommended trial, with a mean difference from K-max
of 1.02 ± 0.44 mm, and change in overall lens diameter by 0.21 ± 0.14 mm.

Conclusion: Advanced corneal ectasias of keratoconus staging IV and with mean K base curve values of < 6 mm require
more fitting modifications from recommended manufacturer’s guidelines in order to achieve an optimal CL fitting. Our
experience provides guidance on the fitting modifications in parameters required for achieving better customization of
ROSE K2 CL in post C3R keratoconic corneas with advanced ectasias.

Delhi J Ophthalmol 2022;32; 28-35; Doi http://dx.doi.org/10.7869/djo.763
Keywords: Keratoconus, Collagen Crosslinking, Rose K2, Contact Lens, Corneal Ectasia, Base Curve, Overall Diameter, Edge Lift

Introduction The ROSE K2 lens applies very small changes to the curves
on both the anterior and posterior surface which help in
Visual rehabilitation in keratoconus patients is optimally focusing the light within the pupil zone to a single point
achieved with multicurve lenses such as ROSE K2 CL as providing better sight with minimum aberrations.11-13 The
compared to spectacles, soft, mono-curve or bi-curve GP expected primary measure outcome was to analyze the
lenses.1 Studies have also reflected the use of ROSE K2 modifications required in fitting parameters of ROSE K2
lenses for the enhancement of binocular resolution and contact lenses in post collagen crosslinked keratoconic
three-dimensional depth perception in keratoconic eyes as corneas to achieve optimal and successful fitting.
compared to spectacles.2 Literature has shown that visual
rehabilitation with RGP or multicurve contact lenses help Materials & Methods
in restoring vision and improving the quality of lives with
better comfort and satisfaction in patients with keratoconus A retrospective observational study of all patients of
eyes. (3-5) The higher magnitude of irregular astigmatism is keratoconus following collagen crosslinking treatment who
optimally corrected with these contact lens systems, thereby were referred to the Low vision services – cornea, of our
avoiding, or postponing the need for surgical intervention.6 centre for contact lens fitting. This study was performed to
CL fitting in post collagen crosslinked (C3R) keratoconic analyze the fitting parameters of ROSE K2 contact lenses
corneas is performed after stabilization of the corneal (CL). Institutional ethics clearance was obtained.
topography for an invariable contact lens fit in the long term.7
Cases records of patients of post C3R treated keratoconic
Lens fitting parameters protocol offered by the manufacturer corneas on ROSE K2 contact lens wear between the period
needs to be modified according to the fitting characteristics of March 2015 – April 2018 and on follow-up for a minimum
and fluorescein pattern observed on a custom basis, in order of three months were included for analysis. All eyes had
to achieve a tailored fit.8 Post C3R corneas were included in undergone CL fitting on documenting stable corneal
order to avoid the probable risk of lens parameter change topography after C3R treatment (Figure 1). Data of those
due to altered corneal topography if the corneal ectasia patients of keratoconus using other contact lens systems,
progresses. (9-10) Unlike the conventional RGP lenses, ROSE or those with other ocular morbidities was excluded. Data
K2 lenses are multicurve, which are designed by utilizing included demographic details (stage of keratoconus, time
computerized digital lathes that compensate the parameters following collagen crosslinking treatment of ROSE K2 CL
such as base curve, diameter, power, center thickness and fitting, laterality, uncorrected visual acuity (UVCA), best
paracentral fitting curves whenever a change is made to the corrected visual acuity (BCVA) with spectacles, BCVA with
central or peripheral parameters of CL.1 The aim for this ROSE K2 CL, refraction details, details of ROSE K2 contact
adjustment is to maintain the optimum posterior lens touch lens fitting parameters, duration of ROSE K2 contact lens
(sagittal height) when a change in edge lift is required. wear, lens exchanges, post wear problems, Scheimpflug

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DJO Vol. 32, No. 4, April-June 2022

Figure 1: Clinical Photograph showing the contact lens fit evaluation
(A) ROSE K2 Lenses with fluorescein staining in post collagen crosslinked keratoconic cornea showing the desired “3-point touch”

(B) Nipple cone design
(C) Toric periphery (TP) incorporation
(D) Asymmetric Corneal Technology (ACT) incorporation
(E) Proper coverage of Rose K2 XL Miniscleral on the sclera without any impingement of vessels
(F) Desired tear vault without any apical touch in ROSE K2 XL Mini Scleral
(G) Figure depicting a conventional RGP lens with good central fit, but flat edge at 6 O’clock leading to edge stand-off and bubbles to trap, no tuck is possible in

a conventional RGP lens
(H)- fluorescein-stained ROSE K2 lens with good feather touch at the steepest point having a good diameter and flat edge at 6O’clock, ACT incorporation

recommendation is desirable in this lens from 0.8 to 1.3 mm depending upon the edge lift.

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corneal topography (for corneal curvature of anterior but approximately the last 1mm of peripheral curve
surface – K1 & K2, K-max, average K, thinnest pachymetry). was toric; resulting in differential pooling. It is variably
The ROSE K2 contact lens fitting parameters included ROSE dependent on lens diameter which shows good edge lift
K2 CL initial trial (base curve, overall diameter, edge fit) and at one meridian and thin pooling of edges at the other
prescribed CL fitting parameters and modifications (BC, meridian indicating steep or tight edges.
lens diameter, edge lift, Asymmetrical Corneal Technology • Incorporating toric periphery eliminated edge toricity
(ACT) and Toric Periphery (TP) designs), lens exchanges, (TP is preferred where the central fit is good, but the
time duration of daily wear, period of follow up, and post peripheral curves are toric where one meridian is
CL fitting problems. steeper than the other resulting in variable pooling
and affecting tear exchange. This modification serves
As per manufacturer’s recommendations, the first trial optimal peripheral configuration when fluorescein
lens was selected and inserted on the patient’s eye. After assessment shows toric edges.
approximately 20 minutes, sodium fluorescein dye was
instilled in the eye for contact lens fitting assessment. Static The available designs include ROSE K2, ROSE K2 Irregular
and dynamic fit of the lens were assessed. The Back Optic Cornea (IC), ROSE K2 Nipple Cone (NC), ROSE K2 Post
Zone Radius (BOZR) was evaluated for apical feather touch, Graft (PG) and ROSE K2 XL (XtraLimbal) Mini Scleral (Table
if attained other CL fitting parameters were evaluated 1). All detailed ROSE K2 lens parameters available in trial
otherwise trial lens was changed. Depending on the central inventory and for dispensing are mentioned in table 1 (a) (b).
staining, the BOZR of the lens was flattened or steepened in All required details of contact lens fitting, and assessment
0.10 mm steps until an apical feather touch was obtained. were entered in to a predesigned proforma for analysis. All
Once the CL achieves feather touch, the overall diameter the parameters that were modified for the optimum ROSE
and edge fitting were assessed to ensure that the lens was K2 CL fit were also recorded and evaluated.
well centered and has a proper lens movement and the lens
facilitates tear exchange. Lens Diameter and Edge lift were Results
empirically modified by observing trial lens and visual
acuity with the trial contact lens was noted and CL was Case records of 92 eyes of 64 patients (mean age 22.12 ± 5.57
prescribed to the patient after over-refraction. years, range 11 to 36 years) having keratoconic corneas who
were fitted with ROSE K2 CL were analyzed. There were
Optimal fit was adjudged with that contact lens which 50 male (mean age 21.52 ± 5.59 years) and 14 female (mean
achieved the following for lens parameters: age 24.11 ± 5.95 years) patients. The mean age of the patients
at the time of collagen crosslinking was 19.46 + 7.42 year
• Optimal Base Curve: An approximate 20 microns (range 11 to 26 years). The time interval between collagen
fluorescein-stained tear film was desired over the crosslinking and CL fitting was 24.08 ± 24.91 months; (range
steepest point on the cornea for a small feather touch. 2 to 110 months) (Figure 2).

• Optimal Diameter: Assessment was done according to Figure 2: The time interval between collagen crosslinking and CL fitting in
lens type, stage of keratoconus, palpebral aperture and the study eyes
lens coverage and centration. The lens should hang off
the top lid and clear of the limbus. Central cones require Table 1(a): Availability of Inventory of ROSE K2 contact lenses
small diameter while decentered and early cones need
larger diameter. CL Type Base Curve Overall Diameter Edge Lift
(mm) (mm)
• Optimal lens centration: Assessment was done on the ROSE K2 (26 lenses) Standard
basis of base curve, diameter and lens edge lift. ROSE K2 IC (18 lenses) 5.10 to 7.60 Variable, 8.50 to 9.20 Standard
6.00 to 8.40 Standard, 11.4 Standard
• Optimal Edge Lift: A fluorescein tear film band of 0.6 to ROSE K2 NC (25 4.60 to 7.40 Variable, 8.10 to 8.90
0.8 mm width facilitating tear exchange at the lens edge Lenses) Standard
was desired for comfortable peripheral edge. 6.00 to 9.00 Standard, 10.4
ROSE K2 PG (22 Standard
• Optimal lens movement: 1 to 2mm of lens movement on Lenses) 6.00 to 8.00 Standard, 14.6
blink was necessitated to facilitate proper tear exchange
(mainly influenced by the edge lift). ROSE K2 XL Mini
Scleral (16 Lenses)
• Asymmetric Corneal Technology (ACT) was advocated
in cases of inferior lens edge standoff with pooling
(approximately from 5 o’ to 8 o’clock) to steepen the
inferior quadrant of the lens. (ACT is incorporated in an
asymmetric cornea; where the inferior corneal quadrant
is significantly steeper than the superior, causing the
standard RGP lens to lift off inferiorly, allowing bubbles
to trap and break-up of tear meniscus. ACT is a CL
design which tucks the inferior quadrant giving a good
and comfortable inferior edge along with 3, 9 and 12
O’clock and better stability).

• Toric Periphery (TP) was recommended where the
central optical zone was spherical having feather touch

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DJO Vol. 32, No. 4, April-June 2022

Table 1(b): Range of available Lens parameters for Dispensing Table 2: Characteristics of the Study eye parameters

CL Type Base Overall Edge Lift Study eye characteristics Mean ± Std Dev (Min to Max)
Curve Diameter
(mm) UCVA 1.01 ± 0.41 (0.16 to 1.8)
(mm)

ROSE K2 4.30 to 8.59 7.90 to 10.40 Standard, standard flat, BSCVA 0.52 ± 0.32 (0.08 to 1.56)
standard steep
BCVA with ROSE K2 CL 0.12 ± 0.09 (0 to 0.54)

ROSE K2 IC 5.70 to 9.30 9.40 to 12.00 Standard, standard Manifest Refractive Spherical -4.2 ± 1.9 (-22 to +16)
Equivalent
flat, standard steep,

double flat, double steep Pachymetry 401 ± 40.2 (267 to 496)

Standard

ROSE K2 4.30 to 7.69 7.60 to 9.00 Standard, standard flat, Kmax 5.61 ± 0.69 (4.55 to 7.23)
NC standard steep
Kmean 6.42 ± 0.63 (4.81 to 7.98)

ROSE K2 PG 5.70 to 9.30 9.40 to 12.00 Standard, standard flat, The characteristics of study eye patients is shown is table
standard steep, double 2, the amount of astigmatism in the study subjects is
flat, double steep represented in Figure 3(a) and history of contact lens use
(type and drop-outs) is shown in Figure 3(b).
ROSE K2 XL 5.70 to 8.40 13.6 to 16.00 13 options in 0.5 steps

Mini Scleral from -3.0 decreased lift The mean follow-up time of our patients was 15.60 + 9.84
months (range 3 to 34 months). The mean logMAR UCVA,
to +3.0 increased lift. BCVA with spectacles and BCVA with ROSE-K2 CL of all
study subjects is depicted in (Table 2). The visual outcomes
Special lens design and parameters for customization are analyzed in accordance to the base curve of the eyes and
stages of keratoconus (Table 4 and Figure 4).
Asymmetric ACT is available from 0.4mm to 1.5mm, in single
Corneal steps,

Technology Standard is 0.8, ACT Grade 1# 0.7, ACT Grade 2# 1
(ACT) and ACT Grade 3# 1.3mm

Toric Toric periphery (range from 0.4 to 1.3mm) creates The mean difference of K-mean and the K-max in the entire
Periphery difference in the meridians, eliminating tighter areas study group was 0.97 + 0.32 mm (range 0.13 to 1.98 mm), 0.99
resulting in better fitting of edges, and standard TP ± 0.37 mm in stage I, 1.02 ± 0.34 mm in stage II, 0.94 ± 0.40
(TP) mm in stage III and 0.89 ± 0.22 mm in stage IV keratoconus
is 0.8mm. eyes. The distribution of K-max, K-mean, the recommended
BC and the prescribed BC in the study eyes is depicted in
(Figure 5).

The mean difference between the manufacturer’s
recommended base curve and final prescribed base curve in
eyes with K-mean < 6mm was 0.33 ± 0.34mm; (range 0.25 to
0.5 mm) (p=<0.001, one-sample t-test), 6 to 6.99 mm was 0.19
± 0.17 mm; (range -0.6 to 0.6 mm) and for and ≥ 7 mm 0.18 ±
0.16 mm (range -0.35 to 0.6 mm) as shown in table 5, figure
6a. The mean difference between the trial fit assessment
and final prescribed overall diameter in eyes with K-mean
< 6.0mm was 0.17 ± 0.11 mm; (range 0 to 0.6 mm), 6.0 to 6.99
mm was 0.19 ± 0.14 mm (range 0 to 0.5 mm) and ≥ 7.0 mm
was 0.16 ± 0.12 mm; (range -0.2 to 0.3 mm), table5, figure

Table 3: Characteristics of the Contact lens parameters in the study eyes

Contact Lens parameters Group 1 Group 2 Group 3
(Mean K< (Mean K 6 to (Mean K ≥ 7.0
Recommended
Prescribed 6.0mm) 6.99 mm) mm)
Mean + SD Mean + SD Mean + SD

(range) (range) (range)

5.94 ± 0.18 6.44 ± 0.38 7.13 ± 0.25
(5.5 to 6.3) (6.0 to 7.0) (6.8 to 7.8)

Base 5.71 ± 0.34 6.47 ± 0.34 7.09 ± 0.25
Curve (5.1 to 6.3) (5.7 to 7.15) 6.6 to 7.5

Overall Trial CL 8.45 ± 0.12 8.88 ± 0.85 9.06 ± 0.84
(8.3 to 8.9) (8.7 to 8.9) (8.9 to 9.1)
Diameter

Prescribed CL 8.82 ± 0.28 8.90 ±0.3 8.84 ± 0.22
Prescribed CL Power 8.5 to 9.1 8.7 to 9.2 (8.7to 9)

Figure 3: Pie charts representing study eye characteristics of eyes reflecting -15.8 ±5.98 -9.45 ± 4.12 -6.73 ± 3.95
(a) Distribution of amount of Astigmatism (0 to -25.5) (7.75 to -17.5) (-1.25 to -15.5)
(b) History of contact lens use.
Prescribed CL Edge Lift 0.73 ± 0.43 0.21 ± 0.46 0.03 ± 0.47
(-0.5 to 1.5) (-1.3 to 1.3) (-1.3 to 1)

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DJO Vol. 32, No. 4, April-June 2022

Figure 5: The distribution of Kmax, Kmean with respect to recommended and
prescribed contact lens in the eyes with base curve < 6.0 mm, 6.0 – 6.99.0

mm, ≥ 7.0 mm.

Table 5: Mean Change in fitting parameters from manufacturer’s
recommendation

In accordance to Base Cure

CL Group 1 Group 2 Group 3
Parameters K Mean (< K Mean (6 K Mean (≥ 7mm)
to 6.99 mm)
6mm)

Figure 4: Mean logMAR UCVA, mean logMAR BCVA with spectacles and Base Curve 0.33 ± 0.34 0.19 ± 0.17 0.18 ± 0.16
contact lenses in accordance to the base curve of the study eyes and in Diameter 0.17 ± 0.11 0.19 ±0.14 0.16 ± 0.12
accordance to the grade of keratoconus (Amsler Krumeich classification)
Edge lift 0.64 ± 0.50 0.35 ± 0.42 0.34 ± 0.42
respectively.
CL In accordance to Keratoconus Staging
Parameters
Table 4: Details of visual acuity correction achieved in the study eyes Base Curve KC Stage 1 KC Stage 2 KC Stage 3 KC Stage 4
Diameter
Keratoconus Mean Spectacle Mean CL BCVA *p value Edge lift 0.17 ± 0.16 0.21 ±0.20 0.23 ± 0.18 0.29 ± 0.24
BCVA (range) 0.16 ±0.12 0.17 ±0.14 0.23 ±0.14 0.19 ±0.13
(range) 0.37 ±0.42 0.37 ± 0.39 0.44 ± 0.40 0.63 ± 0.44

In accordance to Keratoconus grading

Grade I 0.39 ± 0.21 0.08 ± 0.09 p< 0.001 Table 6: Details of study eyes requiring fitting parameters modifications
Grade II (0.08 ± 0.86) (0 to 0.3) p< 0.001
Grade III p< 0.001 Base Curve Diameter Edge lift
Grade IV 0.38 ± 0.17 0.11 ± 0.09 p< 0.001 Changes Changes Changes
(0.08 ± 0.76) (0 to 0.54) eyes (%) eyes (%) eyes (%)

0.55 ± 0.37 0.13 ± 0.06 Group 1 (< 6.0mm) 16 14 15
(0.16± 1.56) (0 to 0.2) (n=17 eyes) (94%) (82%) (83.3%)

0.73 ± 0.37 0.14 ± 0.09 Group 2 (6 to 6.99 mm) 49 48 34
(0.2 ± 1.56) (0 to 0.4) (n = 58 eyes) (84.4%) (83%) (58.7 %)

In accordance to base curve Group 3 (≥ 7.0 mm) 14 9 8
(n = 17 eyes) (82%) (53%) (47%)
< 6 mm 0.79 ± 0.37 0.15 ± 0.09 p< 0.001
(0.2 ± 1.56) (0 to 0.4)
ROSE K2 CL base curve modifications were required in
6 – 6.99 mm 0.45 ± 0.27 0.12 ± 0.08 p< 0.001 19 eyes, in ROSE K2 diameter in 16 eyes and edge lift
(0.08 ± 1.56) (0 to 0.54) modifications in 18 eyes of those keratoconic eyes with
mean K < 6mm; ROSE K2 CL base curve modifications were
> 7 mm 0.40 ± 0.21 1.1± 0.09 p< 0.001 required in 53 eyes, in ROSE K2 diameter in 53 eyes and edge
(0.08 ±0.86) (0 to 0.3) lift modifications in 37 eyes of those keratoconic eyes with
mean K 6- 6.99mm; ROSE K2 CL base curve modifications
*Dunn's Pairwise Comparison were required in 18 eyes, in ROSE K2 diameter in 13 eyes
and edge lift modifications in 10 eyes of those keratoconic
6b. In analysis as per severity of the keratoconus, the mean eyes with mean K ≥ 7.0 mm; (Table 6). ACT and TP were
change from manufacturer’s recommendation in CL fitting prescribed in 20 eyes (one eye in Kmean < 6 mm, 16 eyes
parameters were mentioned in (Table 5). in 6 – 6.99 mm, three eyes >7 mm) and 5 eyes (one eye in
Kmean > 6 mm, three eyes in 6 – 6.99 mm, two eyes > 7 mm)
Overall Modification: Modifications in overall ROSE respectively which ensured a better and comfortable lens fit.
K2 CL fitting parameters as against the manufacturer’s
recommendations were required in 21 eyes with mean K
base curve of < 6mm, 58 eyes with mean K base curve of 6
to 6.99mm and 19 eyes with mean K base curve of ≥ 7 mm.

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lenses were required to achieve an optimal lens fit. Study
also mentioned that eye care practitioners should anticipate
higher optimal lens fit rates when using three-point-touch
(83%) in comparison with apical touch contact lens fittings
.(71%) 14 Another study reflected that two to four diagnostic
trial lenses were required to determine the best fitted base
curve for a desired three-point touch fitting on a keratoconic
eye 2 ). An Indian retrospective study reported that a mean
of 1.73 ± 0.9 (range 1-5) ROSE K trial lenses were required to
lens base curve parameters to achieve desired fit .1

This retrospective study describes the results of our
experience of ROSE K2 CL fitting in post collagen crosslinked
keratoconic corneas. The standard manufacturer’s
recommendations may require modifications in several
cases of advanced keratoconus depending on the severity
or the stage of the corneal ectasia being dealt with. In
several instances, custom modifications need to be adopted
upon observing the static and dynamic fluorescein fitting
characteristics in order to achieve an optimal contact lens fit.
All our patients were referred for CL fitting after a minimum
period of three months of collagen crosslinking treatment
the trend observed in stabilization of collagen crosslinking
treated corneas was immediate worsening between baseline
and 1 month, resolution at approximately 3 months, and
improvement thereafter.15 The relatively varying interval
between the time of collagen crosslinking and contact lens
fitting is due to the late reporting of patients (in accordance
to their convenience for reporting), as most of our patients
were referred and come to our clinics from areas located far
away from our centre. Analysis of our contact lens fitting
experience in 105 post collagen-crosslinked keratoconic
corneas in this study observed that the optimal contact lens
fit concurred well with manufacturer’s recommendations in
eyes with where the mean K values ranged between 6.0 to
6.99 mm (56.25 to 48.12 D) and mean K ≥ 7mm (≥48.21 D).

Figure 6: Box and Whisker’s plots depicting The mean difference between the recommended and final
(a)Mean change in recommended and prescribed base curve of contact lenses prescribed CL base curve in cases of Kmean < 6.00 mm was
found to be statistically significant. In Kmean <6.0mm, 95%
as per their base curve of study eyes required modification in lens base curve, 80%
(b)Mean change in contact lens diameter in final contact lens trial v/s in lens diameter and 90% of eyes required modification in
edge lift as compared to those study eyes in group 2 and 3
prescribed contact lens (Table 7).
diameter The Box and Whiskers plots (figure 4) clearly demonstrate

(c)Mean change in contact lens edge lift in the final contact lens trial v/s Table 7: Details of the number of fitting parameters modifications that were
prescribed contact lens edge lift required in the study eyes

Discussion KC Grade No 1 2 3 4
modification parameter Parameters Parameters Parameters
This study describes clinical evaluation of ROSE K lens fitting eyes (%) modified s modified modified s modified
for the visual rehabilitation of post C3R keratoconic corneas. eyes (%) eyes (%) eyes (%) eyes (%)
The ROSE K2 CL for keratoconus is a proprietary design.
It is a multi-spherical posterior design with aberration 1 3 9 7 3 1
control aspheric optics across the front and back optic zone (n= 23 (13.04%) (39.13%) (30.43%) (13.04%) (4.35%)
diameters. The ROSE K2 contact lens design being effective eyes)
in providing good comfort, better quality of vision with less 2 9 13 12 0
chair time for fitting has been described to have a greater 2 (5.56%) (25%) (36.11%) (33.33%)
acceptability in the management of corneal ectasias.12 As per (n=36 2
the earlier study, first definite apical clearance lens (FDACL) eyes) 1 08 3 (14.29%)
was chosen as a starting point in oval and nipple cones (7.14%) (57.14%) (21.43%)
and the result showed that an average of 2.3 trial ROSE K2 3 1
(n= 14 4 8 14 8 (3.13%)
eyes) (3.13%) (25%) (43.75%) (25%)

4
(n= 32
eyes)

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DJO Vol. 32, No. 4, April-June 2022

that recommended BC and prescribed BC are in alignment require three or more parameters modification in cornea
with each other in group 2 of Kmean 6 - 6.99mm and group with Kmean <6mm, Kmean 6 to 6.99mm, Kmean ≥7mm
3 of Kmean ≥ 7.0mm whereas prescribed BC in group 1 respectively. Corneas with advanced keratoconus with base
of Kmean < 6.0mm shows deviation with preponderance curve < 6.0 mm seem to require more modifications in terms
towards steeper side. of adjustments required for optimal base curve fit, overall
diameter and edge lift fitting.
A greater deviation from the recommended BC is noted
in eyes with advanced ectasia (of Kmean < 6.0mm). The Our experience can serve to guide ophthalmologist and
recommended base curve of contact lens in group 1 was optometrist dealing with contact lens fitting about the
noted to be slightly flatter than the mean K, concurring with optimal modifications which can affect better customization
the manufacturer guidelines i.e., 0.3 mm flatter than the of multicurve contact lens fits achieved based on base
Kmean, but prescribed CL BC is even steeper than mean K, curve parameters. It is imperative for health care personnel
shifting towards K-max Figure 5(a). In eyes with advanced dealing with contact lens fitting to understand the corneal
keratoconus (stage IV), the deviation of K-mean from K-max topography of each cornea that is being dealt with in order
is (0.89 ± 0.22 mm). Analysis of the overall diameter and lens to plan an optimal fitting that would minimize chair time
edge modifications noted that the mean difference between and patient discomfort during the fitting trials. Patients
these fitting parameters of Kmean <6.00mm group corelated with advanced corneal ectasia present with significant low
with study eyes of KC stage IV, Kmean 6 to 6.99mm aligned and distorted vision as vision correction with spectacles
well with study eyes KC stage II and III and Kmean ≥7.00 and conventional rigid gas permeable contact lenses is not
mm was in proportionate to the modification of KC stage 1 as successful. Visual rehabilitation is best achieved in these
depicted in (Figure 5). This highlights that the steeper radii eyes with the use of multicurve and cornea-scleral /scleral
of curvature of advanced keratoconic corneas necessitated contact lens. These patients tend to over wear their contact
modifications in the base curve fitting parameters as lenses for long periods of time during the day due to the
compared to recommended guidelines, leading to more better quality of vision afforded by these and hence get
amount of change in lens diameter and edge lift. dependent on these contact lenses. Comprehension of the
optimal fitting parameter changes required to achieve ideal
As the available steepest base curve option with the trial contact fits will result in enhancing the comfort of contact
lens set of ROSE K2 lens is 5.0 mm, in those corneas where lens wear and alleviate the need for to look for options of
the trial CL was assessed to have less than desirable fit corneo-scleral / scleral lens in these scenarios.
parameters, we proceeded with adopting modifications
in the final prescription, based on the fitting observations References
in our experience. Achieving an optimal base curve fitting
is paramount in being able to fit these irregular corneal 1. Jain AK, Sukhija J, ROSE K2 contact lens for keratoconus, Indian
contours and influences the overall diameter requirements J Ophthalmol 2007; 55: 121-125
and edge lift modifications. ROSE K2 multicurve lenses do
provide a custom fit to mask the irregularities where the 2. Nilagiri VK, Metapally S, Kalaiselvan p, Schor CM, Bharadwaj
modification in one parameter is independent of the other SR. LogMAR and Stereoacuity in Keratoconus Corrected with
and allows a wide range of modifications to facilitate the Spectacles and Rigid Gas-permeable Contact Lenses. Optometry
desired modification in lens diameter and edge lift. and Vision Science 2018; 95: 391-398.

Asymmetric Corneal Technology (ACT) and Toric Periphery 3. S, Jung G, Lee HK. Comparison of Contact Lens Corrected
(TP) incorporations in the final lens fit prescriptions were Quality of Vision and Life of Keratoconus and Myopic Patients.
prescribed in 20 study eyes (1, e in Kmean group <6mm, 16 Korean J Ophthalmol. 2017; 31: 489-496.
in 6 to 6.99mm, 3 in ≥7mm) and 5 study eyes (1 in Kmean
group <6mm, 3 in 6 to 6.99mm, and 1 in ≥7mm) for better and 4. Abou Samra WA, Badawi AE, Kishk H, Abd El Ghafar A, Elwan
stabilized lens fit. Our protocol recommendation that was MM, Abouelkheir HY. Fitting Tips and Visual Rehabilitation of
followed in prescribing ACT incorporation in the final lens Irregular Cornea with a New Design of Corneoscleral Contact
fit prescription is in those cases where an edge stand-off was Lens: Objective and Subjective Evaluation. J Ophthalmol. 2018:
noted with heavy pool at inferior lens quadrant. The amount 3923170. doi: 10.1155/2018/3923170. eCollection 2018.
of ACT prescribed depended directly on the quantity of
edge lift at 6 O’clock. TP incorporation in the final lens fit 5. Smiddy WE1, Hamburg TR, Kracher GP, Stark WJ. Keratoconus.
prescription was in those cases where toric periphery was Contact lens or keratoplasty? Ophthalmology 1988; 95: 487-92.
asymmetrical. This served appropriately for all our patients
with all accepting their final prescribed contact lens well. 6. Mandathara Sudharman P, Rathi V, Dumapati S. Rose K lenses
None of our patients required any CL exchange. for keratoconus: An Indian experience

The number of modifications, i.e., whether only one of the 7. O'Brart DP, Kwong TQ, Patel P, McDonald RJ, O'Brart NA.
three (base curve, overall diameter, edge lift) or more was Long-term follow-up of riboflavin/ultraviolet A (370 nm) corneal
required was also analyzed and it was observed that 3, 15, collagen Crosslinking to halt the progression of keratoconus. Br J
8 eyes required one parameter modification, 11, 21, 10 eyes Ophthalmol. 2013; 97: 433-437.
required two parameters modification and 12, 15, 3 eyes
8. h t t p s : / / c d n . m e n i c o n . n l / u k / p d f s / M L 0 1 4 _ V 4 _ R o s e - K 2 -
Practitioners-Fitting-Guide.pdf

9. Hashemi H, Seyedian MA, Miraftab M, Fotouhi A, Asgari S.
Corneal collagen cross-linking with riboflavin and ultraviolet a
irradiation for keratoconus: long-term results. Ophthalmology.
2013; 120: 1515-1520

10. Asri D, Touboul D, Fournie P, et al. Corneal collagen crosslinking
in progressive keratoconus: multicenter results from the French
National Reference Center for Keratoconus. J Cataract Refract
Surg. 2011; 37: 2137-2143.

11. Gupta R, Sinha R, Singh P, Sharma N, Tandon R, J S Titiyal. ROSE

E-ISSN: 2454-2784  P-ISSN: 0972-0200 34 Delhi Journal of Ophthalmology

DJO Vol. 32, No. 4, April-June 2022

K2 versus Soper Contact Lens in Keratoconus: A Randomized Cite This Article as: Sneha Aggarwal, M Vanathi,
Comparative Trial. Middle East African J Ophthalmol 2014; 21: Vinay Gupta, Noopur Gupta, Radhika Tandon. ROSE K2
50–55. Contact Lens Rehabilitation in Keratoconic Corneas. Delhi
12. Betts AM, Mitchell GL, Zadnik K. Visual performance and Journal of Ophthalmology.2022; Vol 32, No (4): 28-35.
comfort with the ROSE K lens for Keratoconus. Optometry and
Vision Science 2002; 79: 493-501. Acknowledgments: Mr. Ashish, Biostatistics Department for
13. Rico-Del-Viejo L, Garcia-Montero M, Hernández-Verdejo statistical support
JL, García-Lázaro S, Gómez-Sanz FJ, Lorente-Velázquez A.
Nonsurgical Procedures for Keratoconus Management. J Conflict of interest: None
Ophthalmol.2017; 9707650.
14. Romero-Jiménez M1, Santodomingo-Rubido J, González- Source of Funding: None
Méijome JM. An assessment of the optimal lens fit rate in
keratoconus subjects using three-point-touch and apical touch Date of Submission: 02 April 2022
fitting approaches with the ROSE K2 lens, Eye Contact Lens. Date of Acceptance: 09 May 2022
2013; 39: 269-272.
15. Chang CY, Hersh PS. Corneal collagen cross-linking: a review of Address for correspondence
1-year outcomes. Eye Contact Lens. 2014 Nov;40(6):345-52. M Vanathi, MD,

Prof of Ophthalmology,
Cornea, Lens & Refractive Surgery Services,
Dr. R. P. Centre, AIIMS, New Delhi, India.
Email : [email protected]

E-ISSN: 2454-2784  P-ISSN: 0972-0200 35 Quick Response Code
Delhi Journal of Ophthalmology

DJO Vol. 32, No. 4, April-June 2022

Original Article

Prevalence of Dry Eyes in Postmenopausal Females in Hadoti
Region of Rajasthan

Jaishree Singh1, Ashok Kumar Meena1,Tarun Gupta2, Ekta Garg2, Pushkar Dhir2, Neeraj Aggarwal3

Abstract 1Department of Ophthalmology, Government Medical College, Kota, Rajasthan, India.
2Department of Ophthalmology, Dhir Hospital & Eye Institute, Bhiwani, Haryana, India.
3Department of Ophthalmology, Sri Jagdamba Charitable Eye Hospital, Ganganagar, Rajasthan, India.

Introduction: Dry eye syndrome (DES) is one of the most frequently encountered ocular conditions. Although clinical
observation has long been suggested that DES is more common in women, particularly among older women, there are only
few epidemiological studies which are available to describe the magnitude of the problem of DES among post-menopausal
women especially in India.

Materials and Method: A total of 200 post-menopausal females attending the Out Patient Department were included in
the study. All patients were given Ocular Surface Disease Index (OSDI) questionnaire. Diagnosis of dry eye in our study was
made when two of the 3 tests are positive viz. Schirmer-I test (<10mm), Tear Film Break –Up Time (TBUT) (<10sec) and
Ocular surface dye staining with Lissamine green dye (Van Bjisterveld’s score ≥4).

Results: Prevalence of dry eye syndrome was high in this age group i.e. 44% (88/200 post-menopausal women(PMW).
49% (98 Post Menopausal Women) responded with symptoms of dry eye (OSDI score >12). Tear Film Break-Up Time test
sensitivity was 97.6% and specificity was 92.36%. Lissamine Green dye staining was less sensitive but more specific test to
diagnose dry eye syndrome (sensitivity of 33.6% and specificity of 98.91%). Schirmer I test has high sensitivity (91.2 %) and
high specificity (96.36%). The positive predictive value was 91.94% and negative predictive value was 96.01%. All three
tests were reliable in diagnosing dry eye as each had p value < 0.001. Meibomian Gland Dysfunction was present in 10%of
Dry eye positive females.

Conclusion: The high prevalence of dry eye in post-menopausal females is responsible for significant morbidity..

Delhi J Ophthalmol 2022; 32; 36-39; Doi http://dx.doi.org/10.7869/djo764.

Keywords: Dry Eye Disease, Postmenopausal Females, Prevalence, Osdi, Schirmer, TBUT

Introduction 3. Ocular infection within past 3 months like Herpes
zoster and varicella zoster
Dry eye is a multifactorial disease of the tears and ocular
surface that results in symptoms of discomfort and visual 4. Chronic ocular allergy like allergic blepharo-
disturbance. It is accompanied by increased osmolarity of conjunctivitis.
the tear film and inflammation of the ocular surface.1 Dry
eye is a common source of discomfort that can seriously 5. Topical medication such as glaucoma medications,
affect a patient’s quality of life, especially in the elderly vasoconstrictors, corticosteroids, antihistaminic.
population.2, 3 Epidemiological studies have found that
women are more likely to report dry eye symptoms than 6. Systemic diseases like ceased menses due to
men4,5 and is a condition of multifactorial etiology, which, in autoimmune disease, pelvic irradiation, hysterectomy
most cases, is chronic and progressive.6 A key aspect of dry or smoking, Rheumatoid Arthritis, Parkinson’s,
eye that remains a major problem is the lack of association Lupus, Diabetics.
between the symptoms and signs of dry eye7-13 and the poor
test reproducibility of objective tests,14 making it difficult to 7. Systemic medications like antihistaminics, tricyclic
assess disease progression and the impact of treatments antidepressants, diuretics, hormonal replacement
on symptoms. This study is first initiative to determine the therapy and chemotheraphy were excluded from the
prevalence of dry eye in post-menopausal females in Hadoti study.
region of Rajasthan.
Patient evaluation
Material and Method
All patients, after obtaining informed consent, were
A total of 200 post-menopausal females (>50yrs) were examined. Examination included: visual acuity
enrolled in the study from the out -patient department over measurement with correction, external eye examination,
a period of 1 year.' and slit-lamp biomicroscopy. Participants were given the
Ocular Surface Disease Index (OSDI) and were categorized
Exclusion criteria as being symptomatic or asymptomatic of dry eye based on
1. Pre existing ocular surface disease like chemical their response to OSDI. An OSDI score of 0-12 represented
burns, Vernal-Keratoconjuncivtis, Steven Johnson No Dry Eye; an OSDI score of 13-22 was categorized as mild
Syndrome, aniridia, Sjogren syndrome, etc. Dry Eye; an OSDI score of 23-32 moderate dry eye and an
2. Ocular surgery in the past 6months like cataract OSDI score of more than 32 as severe dry eye.15,16
surgery, corneal refractive surgery, prior ptosis
surgery, ectropion/ entropion surgery, blepharoplasty. Diagnosis and confirmation of dry eyes was done by series
of tests performed in standard sequence with difference of
at least 10 min as follows: Schirmer’s test, Tear film breakup

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DJO Vol. 32, No. 4, April-June 2022

time (TBUT), ocular surface dye staining (Lissamine green), eye and13.64% had severe dry eye. The OSDI total score was
assessment of meibomian gland. Diagnosis of dry eye in our significantly different between the two groups (Non Dry Eye
study was made when two of the 3 tests were positive. (NDE) = 8.92+ 7.74 vs. Dry Eye (DE) = 20.86 + 11.31; p<0.001).
(Table 2)
Schirmer- I test
Table 1: Dry eye in relation to residence
A pre-calibrated dry filter paper strip measuring 5 × 40 mm
was placed in each lower fornix at the junction of outer and Residence Dry Eye Dry Eye Total Percentage
middle thirds without touching the cornea, and left for 5 Present Absent
minutes and patient was asked to close eyes. After 5 minutes Urban 158 43.67%
the strips were removed and the amount of wetting in mm Rural 69 89 42 45.23%
was recorded. The result was considered positive if the
amount of wetting of the paper was <10mm. 19 23

Tear break-up time (TBUT) test Table 2: OSDI Score and correlation with dry eye

It was performed by moistening a fluorescein strip with OSDI Score Dry Eye Dry Eye Total No. Of
sterile non- preserved saline and applying it to the inferior Present Absent Patients
tarsal conjunctiva. The tear film was examined using a broad 0-12 102
beam of the slit-lamp microscope with a cobalt blue filter. >12-22 10 92 67
The time lapse between the last blink and the appearance >22-32 51 16 16
of the first randomly distributed dark discontinuity in 15 1 15
the fluorescein stained tear film was TBUT. The result is >32 12 3
considered positive if value was less than 10 seconds.
Figure 1: Bar diagram showing dry eye in relation to age group
Ocular surface dye staining
• Lissamine green staining stains superficially damaged TBUT was found to be positive (<10 seconds) in 143 eyes
cells with a defective mucin layer. A pre-sterilized (35.75%). Among these, 122 eyes were proved to be positive
filter paper strips with 1.5mg Lissamine green per for dry eye based on pre-determined diagnostic criteria. This
strips was placed in lower cul-de-sac of each eye after test was found to have a sensitivity of 97.6% and specificity
adding sterile non-preserved saline. Exposure-zone of 92.36%. The positive predictive value was 85.31% and
punctate or blotchy staining was observed in dry eye. negative predictive value was 98.83%.

Van Bjisterveld’s score was used to analyses the staining A total of 45 eyes (11.25%) showed positive staining. Among
pattern. A score of 4 or more was considered positive for dry these, 42 eyes (93.33%) were positive for dry eye. The test
eye diseases.17 was found to have a sensitivity of 33.6% and specificity of
98.91%. The positive predictive value was 93.33%% and
To determine the condition of the meibomian glands, negative predictive value was 76.62%.
the eyelid margins in both the lower and upper lids was
examined in the slit lamp. Digital pressure was applied on A total of 124 (31%) eyes gave a wetting of less than 10mm
the tarsi to assess the degree of obstruction. The presence on performing the Schirmer I test. Among these, 114 were
of lid margin telangiectasia, collarette and meibomian gland proved to be positive for dry eye based on pre-determined
plugging was recorded and graded diagnostic criteria. The Schirmer I test showed a sensitivity
of 91.2 % and specificity of 96.36%. The positive predictive
Ethics value was 91.94% and negative predictive value was 96.01%.
Schirmer I Test score was < 0-5 in 44 eyes (11%), between 6-9
Clearance was taken from the local ethical committee of in 80 eyes (20%) and ≥ 10 in 276 eyes (69%).
college and procedures were done according to the standards
of the committee.

Result

The age group was between 50 to 85 years, with the mean
age of the patients being 59.23 + 7.39 years. Among the entire
group, 88 patients (125 eyes) were diagnosed to have dry eye
based on the tests, i.e. prevalence of 44%. (Figure 1)

In our study prevalence of dry eye among females from
rural areas were slight higher than urban areas (45.23% and
43.67% respectively). (Table 1)

The ocular surface disease index (OSDI) was administered
to the patients before subjecting them to examination or
tests. Of the entire study group, 49% (98 patients) responded
with symptoms of dry eye (score >12). According to OSDI
score 57.95% had mild dry eye, 17.04% had moderate dry

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DJO Vol. 32, No. 4, April-June 2022

Meibomian Gland Dysfunction (MGD) was found in 18 out standardized instrument to evaluate symptoms, and can
125 dry eyes (14.4%) and 20 out of 275 non dry eyes (7.27%). easily be performed and used to support the diagnosis
Overall prevalence of MGD was 9.5% (38/400 eyes). of dry eye syndrome.

Discussion • Similarly Schiffman et al22 in their study of 139 person
(09 patients of dry eye and 30 normal controls) reported
Dry eye is a distressing problem for both subject and treating OSDI demonstrated both high internal consistency and
ophthalmologist. The actual prevalence of this condition in good to excellent test-retest reliability in a large sample
the community is unknown because patient present late to of patients with dry eye disease and normal controls.
ophthalmologist when the condition is moderate to severe
and the symptom have become intolerable. Even at this In our study Tear Film Break-Up Time test sensitivity
stage, the diagnosis may not be made if the ophthalmologist was 97.6% and specificity was 92.36%. The positive
does not perform the diagnostic tests required to detect dry predictive value was 85.31% and negative predictive
eye. The condition of dry eye is therefore often overlooked value was 98.83%. Chi- square test was applied and
and hence under diagnosed in the population. p value was < 0.001 so the results were statistically
significant and we conclude that TBUT test is a reliable
In our study, out of 200, 88 females were positive for dry test to diagnose dry eye coherent with studies of J.H.
eye based on the tests, i.e. prevalence of 44%. This result was Lee et al 23 on 30 normal subjects and 20 dry eye patients.
similar to result of Mohana Majumdar et al18 who included
293 post-menopausal females and reported prevalence of Ocular surface staining is an important endpoint, reflecting
dry eye to be 43.34% in their study group. ocular surface integrity.24,25 In our study Ocular surface dye
staining score using van Bijsterveld system with Lissamine
• Similar results were reported in Shihpai Eye Study.19 Green dye was less sensitive but more specific test to diagnose
It was a population-based survey of eye diseases in dry eye syndrome (sensitivity of 33.6% and specificity of
98.91%). The results were significant as the p value was
the elderly (> or =65 years). In this population, 33.7% <0.001. As reported by P Hamrah et al26 that Lissamine Green
(459/1361) were symptomatic, defined as reporting 1 or has good inter-observer reliability and is well tolerated for
more dry-eye symptoms often or all of the time. Women the diagnosis of dry eye syndrome.
were more likely to report frequent symptoms of dry
eye (odds ratio, 1.49; 95% confidence interval, 1.19-1.87). In our study, Schirmer I test sensitivity was 91.2 % and
In our study prevalence of dry eye among females specificity was 96.36%, i.e. a high sensitivity and specificity.
from rural areas were slight higher than urban areas The positive predictive value was 91.94% and negative
(45.23% and 43.67% respectively). Though it was not predictive value was 96.01%. The results were statistically
statistically significant (p = 0.85). This in coherence significant as p value was <0.001. This is in coherence with
with the study of Schuamberg et al,4 surveyed 39,876 results of M. Ramesh Chandra et al27 who in their study of 70
US women participating in the Women’s Health Study, patients reported that Schirmer test has a sensitivity of 91.1%
who reported there were no significant differences with and specificity of 93.7%. The positive predictive value of the
respect to region of residence on the probability of test was found to be 91.07% and the negative predictive
having dry eye syndrome. value was 93.7%.

This is in contrast to other studies such as Beijing Eye In our study prevalence of MGD was 14.4% in dry eyes and
Study20 that reported higher prevalence of dry eye 7.27% in non dry eye. There were substantial differences
in urban areas. This difference between the studies in the exact clinical signs used to define MGD across these
can be attributed to difference in cohort selected and studies. So direct comparisons between studies or drawing
geographical location and the criteria selected for overarching conclusions is difficult.
diagnosis of dry eye in the study.
This study provides data about the prevalence of dry eye in
In our study out of 200 PMW, 49% (98 PMW) responded Post menopausal females in the Hadoti region of Rajasthan
with symptoms of dry eye (score >12). Among them which has not been done prior, thus , it signifies the
89.80% (88 females) were diagnosed to have dry importance of dry eye as a major morbidity causing factor.
eye based on the objective test performed, that was
statistically significant (p value <0.001). The OSDI References
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5. Lin PY, Tsai SY, Cheng CY, Liu JH, Chou P, Hsu WM. Prevalence evaluation of Lissamine Green parameters for ocular surface
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F, Javate R, Nepp J, Paulsen F, Rahimi A, Raus P, Shalaby O, Acknowledgments: Nil
Conflict of interest: None declared
Sieg P, Soriano H, Spinelli D, Ugurbas SH, Van Setten G. Source of Funding: None
Date of Submission: 09 May 2019
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HR. The epidemiology of dry eye in Melbourne, Australia.

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Assoc 1986;57:512-7.

14. Nichols KK, Mitchell GL, Zadnik K. The repeatability of clinical

measurements of dry eye. Cornea 2004;23:272-85.

15. Lee AJ, Lee J, Saw SM, Gazzard G, Koh D, Widjaja D, Tan DT.

Prevalence and risk factors associated with dry eye symptoms:

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2002;86:1347-51.

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JJ. Prevalence and associations of dry eye syndrome in an older

population: the Blue Mountains Eye Study. Clin Experiment

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E-ISSN: 2454-2784  P-ISSN: 0972-0200 39 Delhi Journal of Ophthalmology

DJO Vol. 32, No. 4, April-June 2022

Original Article

Change In Vessel and Perfusion Densities with Varying Signal
Strengths on Optical Coherence Tomography Angiography

Saurabh Verma, Rohan Chawla, Amar Pujari

Dr. Rajendra Prasad Centre for Ophthalmic Sciences, AIIMS, New Delhi, India.

Abstract Purpose: To evaluate change in vessel and perfusion densities with varying signal strengths on optical coherence
tomography angiography (OCTA).

Materials and Method: Quadrant wise vessel densities and perfusion densities in superficial capillary plexus were
measured using 3*3 mm OCTA scans. Images were obtained in 26 normal eyes, out of which 10 were finally evaluated to
study the variations in the aforementioned parameters with signal strengths (SS) 8, 9 and 10.

Result: The total vessel and perfusion densities increased significantly from SS 8 to 10 and 9 to 10. The mean vessel
densities along the superior, inferior, temporal and nasal quadrants showed a consistent increase in values with a
progressive increase in the scan strengths. Similarly, the perfusion densities along all four quadrants also showed a
progressive increase in the percentage values with increasing signal strengths.

Conclusion: Even minor variation in signal strength of OCTA, even within the generally accepted scan strengths, affects
the quantitative analysis. Therefore, future studies using OCTA must specify the signal strength of the scans for a head to
head comparison or interval analysis.

Delhi J Ophthalmol 2022; 32; 40-43; Doi http://dx.doi.org/10.7869/djo.765
Keywords: Octa; Signal Strength; Vessel And Perfusion Densities

Introduction AG, Jena) scan of the macula. Multiple scans were done
for each eye to ensure that at least three scans with signal
Following the introduction of optical coherence tomography strengths of at least 8/10, 9/10 or 10/10 were obtained for each
angiography (OCTA), a significant number of studies have eye. All the scans were obtained by a single observer and the
been performed to understand the anatomical changes best scan in each category of individual signal strength was
along the retinal and choroidal microvascular networks.1 It included for the final analysis. After auto segmentation, the
provides insights into capillary densities and the perfusion acquired scans were assessed for the automated quadrantic
densities by analysing the white and dark pixels in a given vessel and perfusion densities along the superficial retinal
area. The white pixels are assumed as areas with perfusion plexus using in built proprietary software. Values were
and the dark areas as non-perfused regions or areas lacking documented along each quadrant with increasing signal
any form of vasculature. However, the brightness or the strengths (SS) for each individual. The data were entered in
quality of the scan improves as the acquisition signal strength an excel sheet, statistical analysis was performed using strata
increases. Signal strength representation depends on the software 12.2, and p values less than 0.05 were considered as
machine used to perform OCTA. OCTA (Ziessangioplex statistically significant.
OCT, Carl Zeiss AG, Jena) used in our study represents the
signal strength with score ranging from 1-10. In routine Results
clinical practice on a scale of 10, scans with more than 7
signal strength are considered as adequate for assessment. 2-4 The average age was 26 years and out of 10 eyes evaluated,
six belonged to female subjects (M: F=2:3). The mean
Materials and Methods vessel densities along the superior, inferior, temporal and
nasal quadrants showed consistent increase in values with
Here in this observation, we assessed the effect of variation progressive increase in the scan strengths (Figure 1, Table
of signal strength from 8 to 10 on OCTA automated vessel 1, graph 1). Similarly, the perfusion densities along all
density and perfusion density values. A total of 26eyes of 15 four quadrants also showed progressive increase in the
healthy ophthalmic residents were evaluated. However, only percentage values with increasing signal strengths (Figure
10 eyes were considered for final assessment after excluding 1, Table 1, graph 2). The total vessel and perfusion densities
images with various artefacts. Under dim room light increased significantly from SS 8 to 10 and 9 to 10 (Table
conditions and without use of any mydriatics, all subjects 1, 2 and Graph 3). On inter strength density comparison,
underwent 3*3 mm OCTA (Ziessangioplex OCT, Carl Zeiss between 8 and 9 SS, the change in the values obtained were

Table 1: Vessel and perfusion density changes (total and quadrantic) with increasing signal strengths (8, 9, 10). (SS= Signal Strength)

SS8 SS9 SS10 SS8 SS9 SS10
20.11±2.73 21.87±1.85 41.34±2.59
Superior 19.56±2.64 20.18±2.15 21.59±1.90 34.3±6.19 38.45±3.19 40.7±2.45
20.55±1.71 21.48±1.74 40.65±2.05
Inferior 19.3±2.37 20.24±2.27 21.81±1.77 35.26±4.17 38.22±3.78 41.05±2.65
81.06±8.06 86.75±6.94 163.74±8.59
Temporal 19.52±2.68 35.96±5.71 38.54±3.22

Nasal 19.73±2.33 34.94±3.09 37.56±3.59

Total 78.11±9.29 140.46±17.78 152.77±12.60

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DJO Vol. 32, No. 4, April-June 2022

Figure 1: (a,b,c) Automated vessel density values along four quadrants with increasing signal strength. (a=8 SS, b=9 SS, c=10 SS) (three images on the left side
of panel); (d,e,f) Automated perfusion density values along four quadrants with increasing signal strength. (d= 8 SS, e=9 SS, f=10 SS) (three images on the right

side of panel).

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DJO Vol. 32, No. 4, April-June 2022

Graph 1: Vessel density changes along the four quadrants with increasing Graph 2: Vessel density changes along the four quadrants with increasing
signal strength. signal strength.

expressions of the perceived pixels within the captured
image.1 Vessel density is defined as the sum of the length
of the vessels in the given map and perfusion density gives
the percentage of the evaluated surface where circulation is
present.

Graph 3: Total vessel and perfusion density changes with increasing signal There are a different set of algorithms devised by the
strength. researchers for the quantification of pixels within a given
image. But till now, there are no universally defined
not statistically significant along any of the quadrants; algorithms for these examinations. Studies have shown
[Table 2] whereas the values between SS 9 and 10, and 8 and variation in macular vessel density with age and retinal
10showed a statistically significant increase in the superior, diseases.[5,6] But their results are effected by signal strength
nasal and inferior quadrants (p<0.05). Likewise, changes in of image which has been used for analysis. Better signal
the perfusion density values were also statistically significant strength results in better image, higher pixel density and
between SS 8 and 10, and between 9 and 10 along all four better auto segmentation. Different manufacturers give
quadrants; and only along the inferior quadrant between the different measurements of signal strength in their machines
SS 8 and 9. Rest of the values, however, did not show any with a scale of 1-10 being one of the most commonly used. In
significant statistical difference (Table 2). routine studies, signal strength of 7/10 or more is considered
as satisfactory for the assessment of vascular changes.1-4 But
Discussion our study shows that even change in the signal strength
by 1 point beyond 8/10 alters the vessel density by 3.5 %
OCTA with its three-dimensional imaging capability maps (min) to 9.9%(max), and perfusion density by 6.69%(min) to
the vessels by observing the movement of the blood cells 14.21%(max) amongst the total values.
against the static retinal tissue background. Therefore, based
on the perceived movements detected by analysing the In certain pathological conditions of the eye with low
decorrelation of the optical coherence tomography signals, vision, the scan qualities are often poor and this can alter
a vascular map is constructed. The vessel areas are depicted the pixel densities significantly. Thus, results of the studies
with white pixels and the non-vessel or non-perfused areas comparing the quantitative data of such poor scans with
as dark pixels. Therefore, the quantification of vascular the data of scans in normal eyes may not be correct as they
parameters such as vessel density, perfusion density, non- would have overlooked the bias/error which can occur by
perfusion areas and the longest vessel length are mere a mere variation of signal strength by 1 point. In a study
by Lim et al, they noted significant changes in vessel and
perfusion densities from signal strengths 7 to 9 but not
between 9 and 10.3 However, in our observation, we noted
statistical significant changes in the values between the
signal strengths of 9 and 10, and between 8 and 10.

Table 2: P value after comparing the signal strengths of 8 (S1, I1, T1, N1), 9 (S2, I2, T2, N2) and 10 (S3, I3, T3, N3). VD= Vessel density, PD=
Perfusion density, S=Superior, I=Inferior, T=Temporal, N= Nasal. VDT= Vessel density total, PDT= Perfusion density total.

S1 vs S2 S2 vs S3 S1 vs S3 11 vs 12 12 vs 13 11 vs 13 T1 vs T2 T2 vs T3 T1 vs T3 N1 vs N2 vs N1 vs
N2 N3 N3

VD 0.311 0.017 0.005 0.260 0.012 0.010 0.175 0.085 0.052 0.267 0.048 0.013
PD 0.06 0.045
0.017 0.026 0.042 0.001 0.094 0.044 0.025 0.090 0.018 0.003

VDT1 vs VDT2 VDT2 vs VDT3 VDT4 vs VDT3 PDT1 vs PDT 2 PDT2 VS PDT3 PDT1 vs PDT3

P Value 0.202 0.021 0.011 0.055 0.026 0.004

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DJO Vol. 32, No. 4, April-June 2022

In our observation, even though we performed scans on Cite This Article as: Saurabh Verma, Rohan Chawla, Amar
twenty-five eyes, acquisition of scans without artefacts and Pujari. Change In Vessel and Perfusion Densities with Varying
with consistently high signal strengths (8, 9, and 10) was Signal Strengths on Optical Coherence Tomography Angiography
challenging. We could acquire 9/10 and 10/10 signal strengths Delhi J Ophthalmol 2022;32; (3) 40- 43.
in our subjects as they were very co-operative and young Acknowledgments: Department of General Medicine
with 20/20 uncorrected visual acuity and very clear media. Conflict of interest: None declared
Though our sample size is small, it definitely highlights the Source of Funding: None
variations in the automated vessel and perfusion density Date of Submission: 30 Mar 2022
values obtained with change in signal strengths. Other Date of Acceptance: 15 May 2022
limitations of this study are that we did not assess the deeper
retinal and choroidal plexuses and it would be difficult to Address for correspondence
extrapolate the results in other protocols such as 6*6 or 9*9 Saurabh Verma, MD
mm scans.
Dr. Rajendra Prasad Centre for
To conclude, from our observations, it is evident that a Ophthalmic Sciences,
minor variation in signal strength, even within the generally AIIMS, New Delhi, India.
accepted scan strengths of OCTA, can affect the quantitative Email: [email protected]
analysis. Therefore, future studies using OCTA must specify
the signal strength of the scans for a head to head comparison
or interval analysis.

Reference

1. de Carlo TE, Romano A, Waheed NK, Duker JS. A review of
optical coherence tomography angiography (OCTA). Int J Retina
Vitr. 2015:2;1.

2. Al-Sheikh M, GhasemiFalavarjani K, Akil H, Sadda SR. Impact
of image quality on OCT angiography based quantitative
measurements. Int J Retina Vitr. 2017;3(1).

3. Lim HB, Kim YW, Kim JM, Jo YJ, Kim JY. The Importance of
Signal Strength in Quantitative Assessment of Retinal Vessel
Density Using Optical Coherence Tomography Angiography.
Sci Rep.2018;8(1).

4. Venugopal JP, Rao HL, Weinreb RN, Dasari S, Riyazuddin
M, Pradhan ZS, et al. Repeatability and comparability of
peripapillary vessel density measurements of high-density and
non-high-density optical coherence tomography angiography
scans in normal and glaucoma eyes. Br J Ophthalmol. 2018:17.

5. Khadamy J, Aghdam K, Falavarjani K. An update on optical
coherence tomography angiography in diabetic retinopathy. J
Ophthalmic Vis Res. 2018;13(4):487.

6. Pujari A, Chawla R, Markan A, Shah P, Kumar S, Hasan N, et
al. Age-related changes in macular vessels and their perfusion
densities on optical coherence tomography angiography. Indian
J Ophthalmol. 2020;68(3):494.

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Delhi Journal of Ophthalmology

DJO Vol. 32, No. 4, April-June 2022

Original Article

Descemet membrane detachment after ocular chemical burns:
case series and review of literature

Sohini Mandal1, Hemant Jhajharia1, Prafulla Kumar Maharana1

Dr. Rajendra Prasad Centre for Ophthalmic Sciences, AIIMS, New Delhi, India.

Background: Descemet’s membrane detachment (DMD) is a rare complication after ocular chemical injury and its
pathogenesis remains unclear. In this study, we reported three cases of DMD with traction demonstrated on Anterior
segment optical coherence tomography (ASOCT).

Abstract Case presentation: Two patients sustained ocular chemical injury with 50% sodium hydroxide and one patient with
hydrochloric acid 10%. ASOCT revealed detached Descemet’s membrane in the inferior quadrant at 40 days, 36 days and
30 days after the injury respectively. Apart from receiving conservative treatment, the first case received intracameral
tamponade with 12% C3F8 gas and the third case underwent amniotic membrane transplantation with symblepharon
ring. However, DMD persisted in all the cases.

Conclusions: The atypical features of DMD on anterior segment optical coherence tomography in our cases suggested
the presence of an inflammatory component caused adhesions and traction to Descemet’s membrane and prevented
reattachment of DMD even with gas tamponade.

Delhi J Ophthalmol 2022; 32; 44-47; Doi http://dx.doi.org/10.7869/djo.766
Keywords: Descemet’s Membrane Detachment, Ocular Alkali Burn, Ocular Acid Burn

Introduction clock hours along with diffuse corneal epithelial and stromal
edema (Figure 1a). The patient was treated with 0.3%
Most of the reports of DMD in chemical injury has been ofloxacin four times a day, 0.1% prednisolone acetate eye
described following alkali injury. Deeper ocular penetration drops four times a day, 1% atropine sulfate eye drops twice
following an acid injury is considered rare in view of the daily and oral 2000 mg vitamin C per day. The epithelial
coagulative necrosis induced by acids. However, this case defect resolved at one week follow up and the best-corrected
highlights that severe form of acid injury can cause damage visual acuity (BCVA) improved to 20/400. Six weeks
to the deeper structures of the eye and a DMD. after the initial injury, DMD was noted in the inferonasal
quadrant on slit-lamp examination (Figure 1b) and the
Descemet’s membrane detachment (DMD) is a known BCVA was 20/ 200. AS-OCT confirmed a localized DMD in
complication of various intraocular surgeries such as the inferior quadrant. The detached Descemet membrane
cataract surgery, trabeculectomy, corneal transplantation, was thick and adherent to the underlying iris tissue. The
iridectomy etc. with incidence rates being reported at 2.5% iris was pulled anteriorly (Figure 1c-f). Confocal scanning
and 0.044–0.5% during extracapsular cataract extraction and microscopy failed to detect the corneal endothelium. On
phacoemulsification, respectively.1-3 DMD is a relatively rare the following day, 0.1 ml of 12% perfluoropropane (C3F8)
untoward event following ocular chemical injury. Several gas was injected into the anterior chamber. However, the
authors have reported DMD in cases of chemical injury detached Descemet’s membrane persisted postoperatively
(mostly alkaline in nature) in around seven cases.4,5 The (Figure 1g and h). The central cornea clarity improved
most common site of DMD is the inferior half of cornea due gradually and the BCVA of the left eye recovered to 20/100
to gravitation of inflammatory cells and fibrinous exudates and 20/50 at two and four months after the initial injury
in the inferior anterior chamber with onset being 3 days
to 4 months. Few proposed mechanisms include massive Case 2
cellular damage at stromal and endothelial level leading to A 28-year-old male presented to our hospital 36 days after
development of an inflammatory retrocorneal membrane ocular chemical injury with 50% sodium hydroxide. The
thereby pulling the DM or retrocorneal membrane might patient irrigated his eyes with tap water immediately after
develop neovascularization that can rupture and fill the pre- the injury and presented an hour later to our hospital. At
descemetic space leading to hemorrhagic DMD. However, in the time of presentation, the BCVA was 20/40 in the right
literature there has been no reports of Pre-descemet’s/ Dua’s eye and 20/200 in the left eye. There was extensive corneal
layer (PDL) detachment in cases of ocular chemical burns. edema along with limbal ischaemia (Figure 2a). Treatment
was commenced in the form of topical levofloxacin 0.5%
Case presentation four times a day, topical atropine 1% gel nocte and oral
vitamin C 2000 mg per day. Five weeks later, slit lamp
Case 1 examination revealed a DMD, which had not been present
A 44-year-old male was referred to our hospital 40 days after during the initial examination. AS-OCT showed a localized
an accidental chemical injury in his left eye with 50% sodium DMD in the inferior quadrant. Similar to the first case,
hydroxide solution. The patient irrigated his left eye with the detached Descemet membrane was thick, adherent
tap water immediately after the injury and was subsequently to the underlying iris tissue and pulled the iris anteriorly
treated at a local clinic. At the time of presentation to our (Figure 2c-f). Topical prednisolone acetate 1% eye drops
hospital, his visual acuity was hand movements in the
left eye and 20/20 in the right eye. Slit-lamp examination
revealed an inferior corneal epithelial defect involving 2

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DJO Vol. 32, No. 4, April-June 2022

Figure 1: (a)- Right eye slit lamp image (diffuse illumination mode) shows 12 clock hours of limbal ischaemia, inferior corneal epithelial defect and diffuse corneal
stromal edema; (b)- on making slit, Descemet membrane detachment (yellow arrow) with pre-descemetic sterile exudate collection of 2mm in the inferior half

of cornea can be noted.

Figure 2: Anterior segment optical coherence tomography shows an anterior hyperreflective band representing the pre-descemet layer (yellow dotted arrow)
and a posterior undulating band (white solid arrow) corresponding to the detached descemet membrane; the maximum height of PDL detachment being 252 μ

and that of DM detachment being 663 μ.

and sodium chloride 5% eye drops were administered eye revealed entropion of upper eyelid and 360-degree scleral
every 2 h; however, the DMD persisted at the end of one thinning. Corneal epithelial defect involving 3 clock hours
week and one month (Figure 2g and h). There was severe inferiorly and 12 clock hours of limbal ischaemia along with
corneal neovascularization (Figure 2b) and the BCVA of diffuse corneal stromal edema was also present (Figure 1a).
left eye dropped to hand movements at one-year follow- Additionally, descemet membrane detachment (DMD) with
up visit. He received penetrating keratoplasty at another pre-descemetic sterile exudate collection of 2mm was noted
institute and the BCVA improved to 20/200 postoperatively. in the inferior half of cornea.(Figure 1b) ASOCT (Visante, Carl
Zeiss Meditec AG) OD confirmed a mixed form of DMD,6 an
Case 3 anterior hyperreflective band of 18 μ thickness representing
A 54-year-old male was referred to our hospital 30 days the PDL (long arrow) and a posterior undulating band
after an accidental chemical injury in his right eye with (short arrow) of same thickness representing the DM; the
toilet cleaner (constituent including 10% hydrochloric maximum height of PDL detachment being 252 μ and that
acid). Patient irrigated his right eye with tap water instantly of DMD being 663 μ. (Figure 2) The patient was treated with
following injury and was later treated at a local eye hospital preservative free 0.5% moxifloxacin four times a day, 2%
the same day. At presentation, visual acuity was hand homatropine eye drops four times daily, preservative free
movements OD and 20/40 OS. Slit-lamp examination of right lubricants 2 hourly and oral 2000 mg vitamin C per day.

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Right eye amniotic membrane transplantation (AMT) with As reported by Najjar et al.5 and Hua et al.4, DMD occurred
symblepharon ring was performed under local anaesthesia. 1–4 months after the initial injury. Najjar et al.5 hypothesized
All the preoperative medications alongwith topical steroid two possible mechanisms: 1) an inflammatory retrocorneal
were continued in the postoperative period. The epithelial membrane with an organizing hyphema that caused
defect resolved at one week follow up and the height of tractional DMD; 2) collection of blood between corneal
exudates gradually decreased with persistence of DMD and stroma and DM due to rupture of neovascularization on the
corneal edema. retrocorneal membrane. Our case also presented with DMD
at 30 days after initial insult, similar to the cases reported by
Differential diagnosis Najjar et al. However, hyphema was not noted in our case.

The Descemet membrane detachment was present in Recently Dua et al. have described three types of DMD.6
the inferior half of cornea with pre-descemetic exudate Type 1 includes cases where the PDL and DM were detached
collection. On careful slit lamp examination, we could not together. In Type 2, only the DM was detached. In mixed
find any corneal infiltrate or any sign that would have form, the PDL and DM both were detached and separated
pointed towards an infective etiology. Besides, literature from each other. Based on this classification our case 3 falls
has several reports on tractional Descemet membrane into mixed type of DMD.6
detachment following ocular alkali burn and our patient’s
clinical picture corroborated with those. In the cases reported by Yuen et al.7 gas bubble was detected
in the pre-descemetic space, thus hypothesizing that
The second diagnostic dilemma was to identify the type hydrogen peroxide produces gas, that pushes the DM away
of detachment as per the classification system recently from the corneal stroma actively. AS-OCT showed that the
proposed by Dua et al.6 Mixed DMD was defined by Dua detached PDL and Descemet’s membrane was thick and
et al. as the anterior taut hyperreflective line like a chord taut and partially adherent to the iris in the inferior half.
of a circle representing the Pre-descemet layer separated Therefore, based on the clinical presentation and AS-OCT
from posterior stroma, and another posterior straight or features, following hypothesis given by Zhang et al.[8] holds
undulating double contour line representing the DM, with good: inflammatory cells and fibrinous exudates incited
the latter also separated from the former. This was also by chemical burn, gravitate down inferiorly in the anterior
corroborating to our case as the posterior undulating hyper- chamber causing iris and Descemet’s membrane adhesions;
reflective membrane was extending to periphery unlike the contraction of the fibrinous adhesion caused DMD.
anterior hyper-reflective line; and was partially adherent to
iris tissue inferiorly. There is lack of knowledge regarding management for DMD
after chemical injury in literature due to small number
Discussion of cases published. In early onset cases of post-chemical
injury DMD resolution has been reported with 20% SF6
Various intraoperative factors such as clear corneal incisions, intracameral injection or spontaneously. The DMD fails to
use of blunt blades, inadvertent insertion of instrument reattach even after intracameral gas tamponade in late onset
between stroma and DM, entry into anterior chamber in cases5 due to traction force of the underlying iris tissue.
a soft globe and improper shelved or oblique incisions
predispose to iatrogenic DMD. DMD following chemical Most of the reports of DMD in chemical injury has been
burn has been described previously by several authors. described following alkali injury. Deeper ocular penetration
Cases of Descemet’s membrane detachment after ocular
chemical injuries in literature and our study are summarised
in Table 1.

Table 1: Summary of cases of Descemet’s membrane detachment after ocular chemical injuries in literature and our study

Article Yuen HK 20047 Zhang B 20128 Najjar DM 200045 Najjar DM 20045 Hua MT 20104 Case report
Age 40 49 45 26
19 54
Gender Male Male Female Male
Chemical Hydrogen peroxide Male Sodium hydroxide Unknown Ammonia Male
Location
inferior Sodium cyanide inferior inferior Inferior Hydrochloric acid 10%
Exam Slit lamp Slit lamp Slit lamp Slit lamp
Initial VA extensive inferior
Hyphema HM 20/80 20/800 HM
Management No UBM Yes Yes Yes Slit lamp, ASOCT
Intracameral 20% Intracameral 18% Intracameral air
SF6 injection 20/800 SF6 injection unknown bubble injection HM

No unknown No

1% prednisolone Amniotic membrane
and 0.5% transplant with

levofloxacin eye symblepharon ring;
drops 0.5% moxifloxacin, 1%
prednisolone acetate,
Outcome reattached reattached unresponsive unknown 2% homatropine eye
drops, preservative free
lubricants, oral 2000 mg

vitamin C

unknown

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DJO Vol. 32, No. 4, April-June 2022

following an acid injury is considered rare in view of the Cite This Article as: Sohini Mandal, Hemant Jhajharia, Prafulla
coagulative necrosis induced by acids. Kumar Maharana. Descemet membrane detachment after ocular
coherence tomography chemical burns: case series and review of literature Delhi J Ophthalmol
2022;32; (4) 44- 47.
References
Acknowledgments: Department of General Medicine
1. Li YH, Shi JM, Fan F, et al. Descemet membrane detachment
after trabeculectomy. Int J Ophthalmol. 2012;5(4):527–9. Conflict of interest: None declared

2. Mulhern M, Barry P, Condon P. A case of Descemet's Source of Funding: None
membrane detachment during phacoemulsification surgery. Br J
Ophthalmol. 1996;80(2):185–6. Date of Submission: 20 May 2022
Date of Acceptance: 22 June 2022
3. Ti SE, Chee SP, Tan DT, et al. Descemet membrane detachment
after phacoemulsification surgery: risk factors and success of air Address for correspondence
bubble tamponade. Cornea. 2013;32(4):454–9. Prafulla Kumar Maharana, MD

4. Hua MT, Betz P. Descemet membrane detachment after alkali Associate Professor of Ophthalmology
ocular surface burn. Bull Soc Belge Ophtalmol. 2010;(316):85-6 Cornea, Cataract and Refractive Surgery Services

5. Najjar DM, Rapuano CJ, Cohen EJ. Descemet membrane Dr. Rajendra Prasad Centre for
detachment with hemorrhage after alkali burn to the cornea. Am Ophthalmic Sciences,
J Ophthalmol. 2004;137(1):185-7 AIIMS, New Delhi, India.
Email: [email protected]
6. Dua HS, Sinha R, D'Souza S, et al. "Descemet Membrane
Detachment": A Novel Concept in Diagnosis and Classification.
Am J Ophthalmol. 2020 Oct;218:84-98.

7. Yuen HK, Yeung BY, Wong TH, et al. Descemet membrane
detachment caused by hydrogen peroxide injury. Cornea.
2004;23(4):409–11.

8. Zhang X, Jhanji V, Chen H. Tractional Descemet's membrane
detachment after ocular alkali burns: case reports and review of
literature. BMC Ophthalmol. 2018 Sep 24;18(1):256.

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DJO Vol. 32, No. 4, April-June 2022

Case Report

Management of Pseudophakic Myopia Using Implantable
Phakic Contact Lens with A ‘Piggy Back’Technique

Kanchita Pandey, Devika Joshi, Shrikant Dinkar Joshi

Department of Ophthalmology, Deenanath Mangeshkar Hospital and Research Center, Erandwane, Pune, Maharashtra, India.

Purpose: We report a case of a pseudophakic myopic patient who received placement of an implantable phakic contact lens
(IPCL) via a ‘piggyback technique’ resulting in improved visual acuity.

Case report: A 35year old male patient with both eyes pseudophakic myopia came with complaints of diminution of vision in the

right eye more than his left eye. After evaluating all available optical and surgical options, he received off-label placement of a

Abstract posterior chamber IPCL with a piggyback technique for the pseudophakic right eye with a manifest refraction of -20.0 Ds. Best-
corrected distance visual acuity improved from 20/60 to 20/30.

Conclusion: Our case demonstrates the successful use of an implantable phakic contact lens (IPCL) in a pseudophakic myopic
patient by a piggyback technique, resulting in improved visual acuity. This off-label use of IPCL offers a good alternative treatment
option for pseudophakic patients with high refractive error.

Delhi J Ophthalmol 2022; 32; 48-51; Doi http://dx.doi.org/10.7869/djo.767

Keywords: Implantable Phakic Contact Lens(Ipcl), Piggyback Technique, Pseudophakic Myopia

Introduction examination, an irregularly shaped pupil with peripheral
iridotomy and multiple posterior synechiae along with
Refractive errors post-cataract surgery conflict with the an IOL in the capsular bag in both eyes was noted (Figure
patient’s expectations of emmetropia especially a large 1). Examination of the posterior segment with 90D lens
refractive error that causes significant visual difficulty. and indirect ophthalmoscopy of both eyes showed disc,
Refractive changes should be anticipated while operating macula, and periphery within the normal limit (Figure 2).
on children with myopic errors even years after primary Intraocular pressures (IOP) by applanation tonometer were
intraocular lens (IOL) implantation either due to A-scan normal in both eyes. Corneal tomography revealed normal
errors, wrong choice of IOL formula in patients with short corneal thickness and architecture bilaterally. Refractive
axial length, human error, mislabeling of an implanted analysis revealed high myopia in the right eye with myopic
IOL, or postoperative myopic shift.1,2,3 In order to correct
residual refractive error post cataract surgery, there are
multiple options available such as glasses, contact lenses,
lens exchange or supplementation surgery4 and corneal
refractive surgery such as PRK or LASIK.5

We present a case of a patient with pseudophakic high
myopia in right eye and pseudophakic myopic astigmatism
in left eye who requested evaluation for available refractive
procedures. With the goal of offering emmetropia,
patient received off-label placement of posterior chamber
implantable phakic contact lens (IPCL) with a piggyback
technique for the right eye.

Case Report

A 35-year-old male patient having high myopia in both eyes
after cataract extraction and posterior chamber intraocular
lens (PCIOL) implantation following congenital cataract
during childhood, presented with a diminution of vision in
the right eye more than the left eye. His other past, personal,
family and medical history was not contributory. Patient did
not give history of intake of any medications, allergies or
addictions.

A comprehensive ophthalmic examination was done. Figure 1: Pre-operative anterior segment image of right eye showing
The corrected visual acuity in right eye was 6/18 (20/60) irregularly shaped pupil with peripheral iridotomy and multiple posterior
on Snellens’s chart and N6 on roman’s test type with
manifest refraction of -20.0DS with addition of +2.5DS synechiae along with an IOL in the capsular bag
and in left eye was 6/9 (20/30) and N6 with refraction of
-9.0DS/ -3.0DC @110 with addition of +2.5DS. On slit-lamp

E-ISSN: 2454-2784  P-ISSN: 0972-0200 48 Delhi Journal of Ophthalmology