March-April, 2022 Vol, 28 No. 2

Subspecialty - Glaucoma

Figure 7 : Virtual Reality Googles: With these, no matter where the greater patient-centric engagement in visual field assessment,
patient looks, the stimulus can be shown relative to fixation at that which can improve adherence and positive outcomes and also
moment. Gyroscopes can account for head movement, and the immersive might decrease the burden of increased testing on optometrists
environment can improve user engagement. and ophthalmologist.[23]
Flicker Perimetry
The ability to detect a periodic intermittent flashing stimulus that
is superimposed on a uniform background forms the basis of
flicker perimetry. Flicker perimetry is believed to primarily assess
the Magnocellular visual pathway. There are three types of flicker
perimetry tests that have been developed: (1) determination of
the highest rate of flicker that can be detected at high contrast
(critical flicker fusion, CFF perimetry), (2) evaluation of the
amplitude of contrast needed to detect a flickering stimulus of
fixed flicker rate (temporal modulation perimetry, TMP), and
(3) detection of a flickering stimulus that is superimposed on a
luminance increment above the background (luminance pedestal
flicker).[24] Flicker perimetry can be performed with
commercially available perimeters like Octopus and Medmont.
Each of the flicker perimetry procedures has been shown to
be sensitive for detecting early visual field losses in glaucoma
and retinal diseases.[25-27] One advantage of flicker perimetry
method is that is relatively unaffected by media opacities.[28] In
a comparison study of CFF and TMP, it was reported that TMP
was able to detect glaucomatous visual field loss more frequently
and distinguish glaucoma patients from normal better than CFF
perimetry.[29]

Figure 8 : performing Virtual reality based perimetry. Figure 9 : nGoogle- portable brain-computer interface for objective
assessment of visual function loss.
nGoogle (Figure 9)
Portable brain computer interface that detects visual function Motion Perimetry (Figure 10)
through recorded electrical responses directly from visual cortex Motion detection perimetry is a method that measures a subject’s
i.e Electroretinogram (ERG) and Electrooculogram (EOG) ability to detect a coherent shift in position of dots in a circular
(eliminates the subjective aspect of clicking to indicate when a area (stimulus) against a background of non-moving dots. The
visual stimulus is seen).[22] test background is composed of 10,000 randomly positioned
Robot assistants for visual field testing white dots with 3.26% of pixels illumination. The stimuli are
State of the art human robots are used to give the instructions to of 17 sizes with a diameter step factor of 100.1 (1.259). A 2-1
the patients who are performing perimetry. They may provide staircase procedure is used to estimate the threshold. The test
progresses until the smallest circle size is seen at each test point.

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Subspecialty - Glaucoma

Stimulus presentation is randomized among the preselected test Figure 11 : High Pass Resolution Perimetry stimuli
loci. For clinical testing, 44 locations are tested; these are similar
to the 24-2 Humphrey perimetry test points except the absence
of the top and bottom rows and the two most eccentric points
along the nasal horizontal.
Motion sensitivity is a primitive visual function that is resistant
to changes in many different stimulus conditions (contrast,
size, background illumination, blur, etc). Motion detection is
primarily a property of the Magnocellular pathway which is
believed to be affected early in glaucoma. Many studies have
reported that motion perimetry is able to detect early visual
field deficits in glaucoma and other ocular and neurologic
disorders.[30-31]

Figure 12 : High Pass Resolution Perimetry

Figure 10 : Stimuli in motion detection perimetry. A magnified view of the Rarebit Perimetry (RBP)
target shows that 50% of the dots are moving in random directions (open RBP works on the premise that sensitivity of visual field
circles) and 50% are moving coherently (solid circles). X is the fixation examination to detect early damage improves with the use
target. of test stimuli that are small relative to receptive fields of the
neural elements and that variability decreases by avoiding
High-Pass Resolution (HPR) or Ring Perimetry (Figure 11) thresholding.[37] By using very small stimuli (rarebits or
The intent of HPR perimetry is to achieve detection and microdots), this procedure presents 0,1, or 2 suprathreshold
resolution (identification) of stimuli simultaneously. The stimuli dots at various local visual field regions and requests the patient
used in HPR perimetry are light and dark concentric rings similar to indicate the number of dots that they were able to detect.
to a bull’s eye configuration in which the low spatial frequency RBP uses 24 rectangular test areas in the central 30o field and
components have been reduced to augment the appreciation probes for the presence of vision within each area (Figure 13). By
of the light and dark edges (high spatial frequencies). The evaluating a number of combinations of dots in small localized
dimensions and luminances are carefully determined to make regions, it determines visual performance (detection or “hit”
the target blend into the background if unresolved (vanishing rate) in these areas. Nearly all rarebits are seen with a normal
optotypes). 14 different sizes are used, varying by 0.1 of a retina (close to 100% “hit rate”), while disorders of the visual
logarithmic unit (1 decibel, dB). The largest ring nearly fills a system result in losses from missing or dysfunctional receptive
full quadrant.[32,33] HPR perimetry tests 50 locations inside fields which appear as gaps in the receptive field matrix. The
the 30° central visual field. The locations are distributed in a spatial density of gaps causes a proportionate reduction in hit
pattern reminiscent of normal isopters. Results are plotted as rates. For example, a 10% loss of receptive fields is theoretically
threshold target sizes, showing precisely what the patient could reported to produce a 10% reduction in rarebit hit rate, to
see in each location (Figure 12). Multiple studies have shown 90%.[37] Rarebit perimetry has been used to evaluate glaucoma
the effectiveness of HPR perimetry in detecting glaucomatous and many other retinal and neuro-ophthalmologic disorders
visual field loss and also determining glaucomatous visual field and has been reported to be able to detect early defects.[38-40]
progression earlier than conventional SAP.[34-36]

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Subspecialty - Glaucoma

Figure 13 : Rarebit perimetry

Flicker-Defined-Form (FDF) or Edge Perimetry algorithm for baseline examinations uses a 4-2-2 staircase
approach as well as neighbouring test target information
The FDF stimulus consists of rapidly reversing black and white and a quick termination methodology to reduce test time
dots that modulate in counter-phase at a temporal frequency (Figure 15). ASTA Follow-Up further reduces the test time
of 15 Hz until the subject perceives an illusionary contour during follow-up examinations. Results of previous tests are
(edge) at the border of the random dot areas. The phase reversal used as a starting point for each location of the field. Test time
frequency is varied to determine the minimum contrast needed reductions resulting in a 3 minute test are typically achieved
for detection of the edge, which appears to the subject as a gray while maintaining the same sensitivity. ASTA Fast is a short
patch against the mean luminance background (Figure 14). test protocol advised for patients expected to be “within normal
The Heidelberg edge perimeter (HEP) is a monitor-based limits” or those who have previously shown unusual levels of
perimeter which uses the FDF stimulus to test the central and fatigue. Starting values are based on age-matched normal values.
peripheral vision. It offers a full set of standard tests for the FDF perimetry primarily stimulates the Magnocellular
central 10°, 24° and 30° visual field as well as an extension to the pathway,[41] and it has been reported that abnormalities on FDF
periphery up to 60° (100 points). were frequently present in eyes with glaucomatous structural
The HEP uses the Adaptive Staircase Thresholding Algorithm changes but normal SAP.[42]
(ASTA) for visual sensitivity estimation. The ASTA Standard

Figure 14 : Flicker defined form stimulus 53
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Subspecialty - Glaucoma

Figure 15 : Single field printout of Hiedelberg Edge Perimetry the retina. A 633 nm Helium- neon laser was used to present red
stimuli at known retinal locations. At the end of the investigation,
Fundus Perimetry or Microperimetry the positions of the retinal landmark are superimposed in each
The most recent automated fundus perimetry device frame, and a map of seeing and non-seeing retina is created.
introduced commercially is the Compass (Centervue, Strengths of the SLO-101 included its bright target, high quality
Padova, Italy). retinal image, and the ability to customize many aspects of the
It assess retinal sensitivity to light stimulation while directly target if a suitably skilled computer programmer was available.
examining the fundus. Microperimetry combines fundus However, this instrument was noisy, difficult to use and was
imaging using an infrared fundus camera, retinal sensitivity limited to red stimuli. Furthermore, skilled programmers
mapping and fixation analysis in one exam. However, the term and technicians were required to perform any non-standard
microperimetry is slightly misleading: the size of the target is perimetry and to maintain the instrument. This technique was
the same as in conventional perimetry, and the extent of the time-consuming and required considerable training. Therefore,
visual field measured can be similar in size to a conventional this machine is no longer commercially available.
perimeter. Light stimulus is targeted directly on specific points Nidek mp1 Microperimeters: The MP-1 microperimeter uses
on the retina. An eye tracker is used so that perimetry data an infrared camera to create a retinal image, and stimuli are
is independent of eye movements and exactly related to the presented on an LCD screen within the instrument. This allows
stimulated area. The sensitivities measured by fundus perimetry full color stimuli to be presented. Retinal tracking is performed
are therefore supposed to have better spatial localization.[43] automatically, although the investigator still needs to identify a
Early Microperimeters: The first commercially available device suitable retinal area to track (with high- contrast retinal features
in the literature was the SLO-101 (Rodenstock GmbH, Munich, such as blood vessels or pigment). A conventional fundus camera
Germany). This instrument used a 780 nm infrared laser that is used to take a full color image at the end of the assessment, and
scans across the retina to produce a monochromatic image of the visual field map is super- imposed onto the retinal image.
Although the MP-1 has some advantages over the SLO-101,
in particular being easier to use, there are several limitations.
The infrared camera does not create as clear an image as the
scanning laser based systems, and pupil dilation is required in
many cases to create clear images. The stimulus is relatively dim:
maximum target luminance is approximately 130cd/m2. This
compares unfavorably with the scanning laser ophthalmoscope
(at least 200 cd/m2) and the Humphrey perimeter (3,183cd/m2).
Furthermore, the dynamic range of the screen is only 2 log units,
meaning that the dimmest stimulus which can be presented is
only 1% of the intensity of the brightest target. This limited range
means that people with good vision reach a ceiling (where all of
the targets can be seen at the dimmest intensity), and those with
retinal disease may reach a floor (where none of the targets are
seen even at maximum brightness).
The OCT-SLO: It combines a spectral optical coherence
tomographer (OCT) with a scanning laser ophthalmoscope-
based microperimeter. The maximum stimulus intensity of the
OCT-SLO is approximately the same as the MP-1 at 137cd/m2.
The dynamic range of stimulus presentation is also 2 log units.
The nominal intensities of the OCT-SLO perimetry stimuli are
0 to 20 dB, which is roughly equivalent to 14 to 34 dB on the
Humphrey Field Analyzer. The primary advantage is its multiple
imaging modalities. Direct structure/function comparisons can
be made by imaging the retina underlying each microperimetry
point. The OCT also allows function to be correlated to retinal
thickness and the presence of edema, subretinal fluid or drusen,
and to be directly related to the integrity of the photoreceptor
layer.

The MAIA (Macular Integrity Assessment) Microperimeters:
Compass (Centervue, padova, Italy). This microperimeter uses a
scanning ophthalmoscope combined with an automatic perim-

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Subspecialty - Glaucoma

eter that provides confocal images of the retina, as well as mea- limited opportunities available for performing visual field
surements of retinal threshold sensitivity, under non-mydriatic screening, either for assessment of large populations or
conditions. It has strategies similar to the 24-2 and 10-2 pro- for rapid home or office testing prior to being seen by an
grams of SAP, although a Zippy Estimation of Sequential Thresh- eye care specialist. The technological improvements that
olds (ZEST) procedure has recently been added. Compass uses a have been made for tablets and smartphones now makes
Goldmann size III stimulus size with duration of 200 ms. Back- it possible to consider quantitative testing of individuals
ground luminance and maximum luminance are similar to that who do not have access to traditional health care, persons
of SAP with a dynamic range of 0-50 dB. It also has a normative at risk of developing diseases affecting vision, and personal
database and provides total and pattern deviation plots similar monitoring of vision status.
to that of SAP. In addition to the color image of the optic disc, 2. Improved Structure-Function Relationships – Current
the device also provides a glaucoma severity classification based methods for mapping functional characteristics to struc-
on the Brusini Glaucoma Staging System 2 (Figure 16).[44] tural locations have several limitations, including individual
The main application of microperimetry has been to assess the variations in morphologic features of visual mechanisms,
retinal sensitivity in patients suffering from macular disease. It variability in measurement procedures, differences in re-
offers a fast, easy to perform and reliable method in evaluation gions analyzed by structural and functional assessments,
of visual fields which can be used in the diagnosis of early and other features. By applying new, validated statistical
glaucomatous changes and to monitor progression in glaucoma. and mathematical models to structural and functional mea-
Studies comparing SAP with MP have reported better ability of sures, a better understanding of the pathologic changes pro-
MP to detect visual field defects compared to SAP.[45-46] duced by glaucoma and other diseases on the visual system
can be better understood. Such techniques will also have to
Figure 16 : Microperimetry be simple, easy to comprehend outcomes to be useful and
effective in a busy clinical environment.
Future Advances in Perimetry 3. Dynamic Functional Test Procedures – Currently, visual field
Although there are many possibilities, several topics are assessment techniques provide static one-time information
particularly noteworthy: of the functional performance of the visual system.
1. Visual Field Screening – At the present time, there are Techniques that provide dynamic ongoing functional
information can be helpful in providing information related
to the varying status of dysfunctional visual mechanisms,
and the metabolic performance of the visual pathways.
4. Use of artificial intelligence in perimetry to compare the
results of patient’s perimetry with the database fed in the
system on the basis of deep learning.
It is challenging both for the patients to perform test reliably
and for clinicians to differentiate true progressive changes
from noise. Although, the newer strategies have the potential
to make visual field testing more efficient, reliable and
accessible for glaucoma patients. However, further studies
are required to evaluate if all the recent advances in perimetry
can replace the older standard perimetry techniques along
with addressing these real world challenges.

References

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5. Ichhpujani P, Thakur S, Sahi RK, Kumar S. Validating tablet perimetry SE. Objective assessment of activity limitation in glaucoma with
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ajo.2018.03.009. 24. Johnson CA, Wall M, Thompson HS. A history of perimetry and
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KR, Vingrys AJ.Six-month longitudinal comparison of a portable 26. Nomoto H, Matsumoto C, Takada S, et al. Detectability of
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11. Chang R, Alto P, Calif. The evolution of portable visual field testing. 27. Gin TJ, Luu CD, Guymer RH. Central retinal function as measured
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14. Goldberg I, Clement CI, Chiang TH, et al. Assessing quality of life in
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15. Haymes SA, Leblanc RP, Nicolela MT, et al. Risk of falls and 31. Wall M, Montgomery EB. Using motion perimetry to detect visual
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1995;45:1169-75.
16. Burton R, Smith ND, Crabb DP. Eye movements and reading in
glaucoma: observations on patients with advanced visual field loss. 32. Frisen L. High-pass resolution perimetry. A clinical review. Doc
Graefes Arch Clin Exp Ophthalmol 2014;252(10):1621–1630. DOI: Ophthalmol 1993;83:1-25.
10.1007/s00417-014-2752-x.
33. Frisen L, Nikolajeff F. Properties of high-pass resolution perimetry
17. Skalicky S, Goldberg I. Depression and quality of life in patients with targets. Acta Ophthalmol (Copenh) 1993;71:320-6.
glaucoma: a cross-sectional analysis using the geriatric depression
scale-15, assessment of function related to vision, and the glaucoma 34. Birt CM, Shin DH, McCarty B, et al. Comparison between high-pass
quality of life-15. J Glaucoma 2008;17(7):546–551. DOI: 10.1097/ resolution perimetry and differential light sensitivity perimetry in
IJG.0b013e318163bdd1. patients with glaucoma. J Glaucoma 1998;7:111-6.

18. Mabuchi F, Yoshimura K, Kashiwagi K, et al. High prevalence 35. Chauhan BC, House PH, McCormick TA, LeBlanc RP. Comparison
of anxiety and depression in patients with primary open-angle of conventional and high-pass resolution perimetry in a prospective
glaucoma. J Glaucoma 2008;17(7):552–557. DOI: 10.1097/ study of patients with glaucoma and healthy controls. Arch
IJG.0b013e31816299d4. Ophthalmol 1999;117:24-33.

19. Skalicky SE, Kong GY. Novel Means of Clinical Visual Function 36. Martin LM, Lindblom B, Gedda UK. Concordance between results
Testing among Glaucoma Patients, Including Virtual Reality. J Curr of optic disc tomography and high-pass resolution perimetry in
Glaucoma Pract. 2019 Sep-Dec;13(3):83-87. glaucoma. J Glaucoma 2000;9:28-33.

20. Goh RLZ, Kong YXG, McAlinden C, Liu J, Crowston JG, Skalicky 37. Frisen L. New, sensitive window on abnormal spatial vision: rarebit
probing. Vision Res 2002;42:1931-9.

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38. Brusini P, Salvetat ML, Parisi L, Zeppieri M. Probing glaucoma visual 45. Lima VC, Prata TS, De Moraes CG, et al. A comparison between
damage by rarebit perimetry. Br J Ophthalmol 2005;89:180-4. microperimetry and standard achromatic perimetry of the central
visual field in eyes with glaucomatous paracentral visual-field defects.
39. Celebisoy N, Ozturk T, Kose T. Rarebit perimetry in the evaluation Br J Ophthalmol 2010;94:64-7.
of visual field defects in idiopathic intracranial hypertension. Eur J
Ophthalmol 2010;20:756-62. 46. Orzalesi N, Miglior S, Lonati C, Rosetti L. Microperimetry of localized
retinal nerve fiber layer defects. Vision Res 1998;38:763-71.
40. Steven Houston SK, Weber ED, Koga SF, Newman SA. Rarebit
perimetry for bedside testing: comparison with standard automated Corresponding Author:
perimetry. J Neuroophthalmol 2010;30:243-7.
Dr. Kanika Jain, MBBS, MS, DNB
41. Mulak M, Szumny D, Sieja-Bujewska A, Kubrak M. Heidelberg edge Senior Resident, Department of Ophthalmology,
perimeter employment in glaucoma diagnosis--preliminary report. Deen Dayal Upadhyay Hospital, Hari Nagar, New Delhi.
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42. Horn FK, Kremers J, Mardin CY, et al. Flicker-defined form
perimetry in glaucoma patients. Graefes Arch Clin Exp Ophthalmol
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43. Rohrschneider K, Bultmann S, Springer C. Use of fundus perimetry
(microperimetry) to quantify macular sensitivity. Prog Retin Eye Res
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44. Brusini P, Filacorda S. Enhanced Glaucoma Staging System (GSS
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2006;15:40-6.

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Subspecialty - Pediatric Ophthalmology

Newer perspectives and recent advances in
Amblyopia

Khongbantabam Sushna[1], MBBS, Noornika Khuraijam[2], MS, DNB, Chongtham Sarda Devi[2], DNB
1. 1st year DNB Ophthalmology Trainee, Shija Eye Care Foundation.
2. Consultant Ophthalmologist, Shija Eye Care Foundation.

Abstract: Amblyopia is one of the most common causes of monocular visual impairment in children. Traditional
therapy options have been limited to penalisation of the non-amblyopic eye with either patching or pharmaceutical
agents. While majority of the children show improvement with this method, not all respond to traditional therapies.
With renewed knowledge from various studies by the Paediatric Eye Disease Investigator Group (PEDIG), there
has been recent updates in our understanding of amblyopia. With technological advances in screening, better
understanding of the biological causes of amblyopia and newer treatment modalities, favourable outcome for children
affected by this common eye condition is anticipated.

Introduction without amblyopia.[7] After FDA clearance, RBS is now
Amblyopia is a condition with decreased visual function caused available in the device known as the blinq® vision scanner.
by abnormal binocular interaction or form visual deprivation, Objective Acuity Vision Screener
not explained by any disorder of the eye or visual pathway. The The Objective Acuity Vision Screener is used to record vision in
prevalence is approximately 1-5%.[1,2] The success of treatment children using vanishing optotypes to induce optokinetic nys-
depends largely on early intervention. Recent advances in un- tagmus (OKN).[8] The limitations of a traditional OKN test have
derstanding the disease mechanism, screening and treatment of been overcome in this method. Steady head position was met by
amblyopia promises better outcomes in the near future. facial recognition software that subtract motions of the head, al-
Screening lowing stabilization of the eyes. A software which automatically
Early screening can help detect amblyopia early when treatment detects the presence of OKN is also incorporated via an internal
will be most effective. Repeated early screening results in camera in an iPad.[8] The vanishing optotypes used here highly
decreased prevalence, better outcome and lesser residual correlates with the ETDRS vision chart in adults.[9] Clinical trials
amblyopia.[3] are evaluating the sensitivity and specificity of this approach in
Visual Acuity Charts screening vision.
For amblyopia screening, visual acuity charts is the gold stan- Device for Integral Visual Examination (DIVE)
dard. But less than half of children below 4 years can accurately It is a device that uses eye tracking and artificial intelligence for
complete a visual acuity test.[4,5] A more objective approach is by visual screening. The system is composed of a 12 inch screen and
addressing the risk factors of amblyopia (refractive errors and a smartphone. It uses high resolution images to display different
strabismus), with automated devices. But this can lead to high stimuli. DIVE automatically examines childrens’ eyes for OKN
number of false positives as the prevalence of risk factors is 21% with great accuracy. A fast, accurate and objective exploration of
which is higher than that of amblyopia itself.[6] vision, even for non-collaborative patients, can be made.[10]
Retinal Birefringence Scanning (RBS) Treatment

RBS detects the central fixation of the eye. It is based on Optical Correction
the principle that birefringent materials have a refractive Refractive error correction is the initial step in treating amblyo-
index that depends on the polarization and propagation pia. It can resolve amblyopia in one-third of previously untreat-
direction of light. The birefringence of the eye is from the ed children.[11]
Henle fibres present in the fovea. A laser scan of both ret- Patching
inas is done with a hand-held device to determine foveal Patching is initiated for children who do not improve with eye-
fixation. In the presence of faulty or unsteady fixation due glasses.[12] The amblyopia treatment study (ATS) found that 6
to amblyopia there will be little or no birefringence in the hours of daily patching shows similar improvement to full time
returning light. Binocular RBS is 97% sensitive in detect- occlusion.[13] In moderate amblyopia, 2 hours of daily patch-
ing amblyopia and 90% specific in identifying children ing was found similar to 6 hours of daily patching.[12] Patching

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Subspecialty - Pediatric Ophthalmology

should be considered for previously untreated older children ing. To facilitate its application, the Eye Patch Assistant made
and teenagers. up of biocompatible silicone was designed. It can adhere to a
Pharmacological Penalisation regular size adhesive patch.[21]
Treatment that produces cycloplegia of the non-amblyopic eye Liquid Crystal Glasses
is considered for children with low compliance, presence of la- Intermittent occlusion (IO) therapy with Liquid crystal glass-
tent nystagmus, or for maintenance therapy. Atropine 1% on two es that covers the fellow eye is being done. It changes between
consecutive days per week for 4 months was as effective as once opaque and transparent states every 30 seconds. Treatment via
daily atropine for 4 months in moderate amblyopia.[14] Improve- IO-therapy glasses for 4 hours/day was as effective as 2 hours
ment of 4.5 lines from twice weekly dosing has been reported for patching in moderate amblyopia.[22]
severe amblyopia.[15] Occlupad
Levodopa-Carbidopa The polarizing film layer from the liquid crystal display screen
Increased dopamine levels may improve vision in amblyopia of an iPad is removed and an exactly matched polarizing filter
and retinal dopamine is known to be decreased in deprivation is applied in front of the amblyopic eye. The fellow eye is given
amblyopia.[16] In a PEDIG study, where daily levodopa and car- a neutral density filter to match the luminance but, without a
bidopa were given with 2 hours of daily patching, no significant polarizing filter, it is only able to see the white backlight of the
improvement in vision was seen.[17] But in another study, with display. Therefore, images are selectively seen by the amblyopic
the levodopa dosage three times higher than the PEDIG study, eye even though the child views the tablet with both eyes.[23]
statistically significant improvement was seen.[18] Binocular Treatment
­Citicoline Recently there has been a major shift in our understanding of
It confers cholinergic and neuroprotective properties. Citicoline amblyopia where the older “monocular disorder” view has
has been theorised to protect the integrity of cell membranes, evolved to a “Binocular Disorder” view. This is because many
preventing nerve cell damage. Initial studies demonstrated im- children do not achieve normal vision even after long-term
provement in vision with citicoline that was not sustained fol- patching, and even then, upto half usually regress. Further, nor-
lowing its cessation.[19] More research into the use of citicoline mal binocularity or stereoacuity is rarely restored. This may be
is required. because the eyes are not encouraged to work together during
R­ efractive Surgery treatment. Psychophysical data in amblyopes suggest a structur-
Refractive surgery has shown benefits for children who are non- ally intact binocular visual system that is rendered functionally
responsive to standard treatment. Some methods are clear lens monocular in amblyopia due to active suppression. This sup-
extraction, photorefractive keratectomy (PRK) and phakic in- pression can be reduced by rebalancing the signal between the
traocular lens. PEDIG is currently planning ATS 19 to compare two eyes, allowing binocular interaction.[24]
PRK versus nonsurgical treatment in children who have failed Dichoptic Training
conventional treatment. In this, binocular amblyopia treatment is done by using dichop-
Vision Therapy tic games and movies presented on tablets, computer screens or
These are nonsurgical programmes of visual activities for im- virtual reality headsets. High-contrast images are presented to
proving visual acuity and binocularity. It includes vergence ac- the amblyopic eye and low-contrast images to the fellow eye.[25]
tivities, accommodation activities, eye-hand coordination exer- An example is the “Dig Rush” game, which uses red-green ana-
cises etc. glyphic glasses to allow dichoptic presentation.
Bangerter Filters Perceptual Learning
Bangerter occlusion foils are translucent plastic filters that ad- It utilises the fact that performance on sensory tasks can be im-
here to a spectacle lens with only water. They block light and proved through repeated and extensive practice. During percep-
reduce vision in a graded fashion. Although the Bangerter group tual learning, amblyopic patients are exposed to the same stim-
improved slightly less than the patching group, the Bangerter fil- uli repeatedly and receive feedback. It may be faster and more
ters were associated with a lower treatment burden with better efficient than patching. Combining occlusion with perceptual
compliance and are recommended as an option for moderate learning may reduce the duration of patching.[26] The limitations
amblyopia.[20] though, are specificity and boredom.
Theramon®
One of the biggest hindrances to amblyopia therapy has been Sensitive period for the treatment of Amblyopia
patient compliance. The Theramon® is an electronic system con-
sisting of sensors, readers and software. It is used to monitor The earlier notion was that amblyopia cannot be treated be-
compliance by integrating the temperature-sensitive microsen- yond a certain age, after the critical period for visual develop-
sor into the eye patches to provide a reliable wear time record- ment, where the neural system was still plastic. Recent studies
suggest that there may be some residual plasticity that extends
into adulthood.[27] Studies show that treatment may be effective

www.dosonline.org/dos-times 59
DOS Times - Volume 28, Number 2, March-April 2022

Subspecialty - Pediatric Ophthalmology

in older (13 to 17 years) children who have not been previously
treated.[28]
Other Drugs
Selective serotonin reuptake inhibitors (SSRI) treatment has
shown enhanced visual acuity when combined with two weeks
of occlusion therapy.[29]
Another study using Donepezil, a cholinesterase inhibitor that
is used in Alzheimer’s disease, is being done to boost cholinergic
signalling, and recover vision in amblyopia.[30]

Figure 4 : Dig Rush

Figure 1 : Retinal Birefringence Scanning.

Figure 2 : Bangerter filter Figure 5 : Red-green anaglyphic glasses.

Figure 3 : OccluPad Conclusion
Our understanding of Amblyopia has improved in the last few
DOS Times - Volume 28, Number 2, March-April 2022 decades. Though patching/penalisation of the amblyopic eye
still remains the main mode of therapy, newer binocular advanc-
es such as dichoptic training and perceptual learning along with
medical adjuvants are highly promising. Screening in younger
children using novel screening methods may help in early de-
tection and prompt treatment. A large selection of treatment
options available can increase compliance. The age of initiating
therapy has recently shifted to cover a wider range renewing
hopes and better treatment outcomes.

60
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Subspecialty - Pediatric Ophthalmology

References 18. Sofi IA, Gupta SK, Bharti A, et al. Efficiency of the occlusion therapy
with and without levodopa-carbidopa in amblyopic children-A ter-
1. Ganekal S, Jhanji V, Liang Y, Dorairaj S. Prevalence and etiology of tiary care centre experience. Int J Health Sci 2016;10:249-57.
amblyopia in Southern India:results from screening of school children
aged 5-15 years. Ophthalmic Epidemiol. 2013 Aug;20(4):228-31. 19. Pawar PV, Mumbare SS, Patil MS, et al. Effectiveness of the addi-
tion of citicoline to patching in the treatment of amblyopia around
2. Oscar A, Chernikova S, Haykin V, et al. Amblyopia screening in Bul- visual maturity: a randomized controlled trial. Indian J Ophthalmol
garia. J Pediatr Ophthalmol Strabismus.2014 Sep-Oct;51(5):284-8. 2014;62:124-9.

3. Wiliiams C, Northstone K, Howard M, Sparrow JM, ALSPAC Study 20. Pediatric Eye Disease Investigator Group. A randomized trial com-
Team. Screening for amblyopia in preschool children: results of a pop- paring Bangerter filters and patching for the treatment of moderate
ulation-based, randomised controlled trial. Ophthalmic Epidemiol. amblyopia in children. Ophthalmology. 2010;117:998-1004e6.
2001;8:279-95.
21. Wang J, Xu H, De La Cruz B, et al. Improved monitoring of adherence
4. Wasserman RC, Croft CA, Brotherton SE. Preschool vision screening with patching treatment using a microsensor and eye patch assistant.
in pediatric practice: a study from the Pediatric Reasearch in Office J AAPOS. 2020;24(96):e1-7.
Settings (PROS) Network. Pediatrics. 1992;89:834-8.
22. Wang J, Neely DE, Galli J, et al. A pilot randomized clinical trial of
5. Kemper AR, Wallace DK, Patel N, Crews JE. Preschool vision testing intermittent occlusion therapy liquid crystal glasses versus tradition-
by health providers in the United States: findings from the 2006-2007 al patching treatment of moderate unilateral amblyopia. J AAPOS.
Medical Expenditure Panel Survey. J AAPOS. 2011;15:480-3. 2016;20:326-31.

6. Arnold RW. Amblyopia risk factor prevalence. J Pediatr Ophthalmol 23. Handa T, Ishikawa H, Shoji N, et al. Modified iPad for treatment of
Strab. 2013;50:213-7. amblyopia: a preliminary study. J AAPOS. 2015;19:552-4.

7. Jost RM, Stager D Jr, Dao L, Katz S, McDonald R, Birch EE. High 24. Birch EE. Amblyopia and binocular vision. Prog Retin Eye Res.
specificity of the pediatric vision scanner in a private pediatric prima- 2013;33:67-84.
ry care setting. J AAPOS. 2015;19:521-5.
25. Kelly KR, Jost RM, Dao L, Beauchamp CL, Leffler JN, Birch EE. Bin-
8. Sangi M, Thompson B, Turuwhenua J. An optokinetic nystagmus de- ocular iPad game vs patching for treatment of amblyopia in children:
tection method for use with young children. IEEE J Transl Eng Health a randomized clinical trial. JAMA Ophthalmol. 2016;134:1402-8.
Med. 2015;3:1600110.
26. Kvarnstrom G, Jakobsson P, Lennerstrand G. Visual screen-
9. Harris PA, Garner T, Sangi M, Guo P, Turuwhenua J, Thompson B. ing of Swedish children: an ophthalmological evaluation. Acta
Visual acuity assessment in adults using optokinetic nystagmus. Invest Ophthalmol Scand. 2001 Jun;79(3):240-4.doi: 10.1034/j.1600-
Ophthalmol Vis Sci. 2019;60:5907. 0420.2001.790306.x.PMID: 11401631.

10. Pueyo V, Perez-Roche T, Prieto E, et al. Development of a system 27. Hensch TK, Quinlan EM. Critical periods in amblyopia. Vis Neuros-
based on artificial intelligence to identify visual problems in children: ci. 2018 Jan;35:E014.
study protocol of the TrackAI project. BMJ Open. 2020;10:e033139.
doi:10.1136/bmjopen-2019-033139. 28. Pediatric Eye Disease Investigator Group (2005). Randomized Trial
of Treatment of Amblyopia in Children Aged 7 to 17 years. American
11. Pediatric Eye Disease Investigator Group. Treatment of anisometropic Journal of Ophthalmology, 143, 1634-1642.
amblyopia in children with refractive correction. Ophthalmology.
2006;113:895-903. 29. Thompson B, Lagas AK, Stinear CM, Byblow WD, Russell BR, Kydd
RR, et al. The use of selective serotonin reuptake inhibitors to treat
12. Repka MX, Beck RW, Holmes JM, Birch EE, Chandler DL, Cotter SA. amblyopia in adulthood. Invest Ophthalmol Vis Sci 2014;55:801.
et al. A randomized trial of patching regimens for treatment of mod-
erate amblyopia in children. Arch Ophthalmol 2003;121:603-11. 30. Stryker MP, Loewel S. Amblyopia: New molecular/pharmacological
and environmental approaches . Vis Neurosci 2018;35:E018.
13. Pediatric Eye Disease Investigator Group. A randomized trial of atro-
pine regimens for treatment of moderate amblyopia in children. Oph- Corresponding Author:
thalmology 2004;111:2076-85.
Dr. Khongbantabam Sushna, MBBS
14. Repka MX, Cotter SA, Beck RW, Kraker RT, Birch EE, Everett DF, et 1st year DNB Ophthalmology Trainee, Shija Eye Care Foundation.
al. Pediatric Eye Disease Investigator Group. A randomized trial of
atropine regimens for treatment of moderate amblyopia in children.
Ophthalmology 2004;111:2076-85.

15. Repka MX, Kraker RT, Beck RW, Birch E, Cotter SA, Holmes JM, et al.
Treatment of severe amblyopia with weekend atropine: Results from 2
randomized clinical trials. J AAPOS 2009;13:258-63.

16. Iuvone PM, Tigges M, Fernandes A, Tigges J. Dopamine synthesis and
metabolism in rhesus monkey retina: development, aging, and the ef-
fects of monocular visual deprivation. Vis Neurosci. 1989;2(5):465-
71.

17. Repka MX, Kraker RT, Dean TW, et al. Pediatric Eye Disease Investi-
gator Group. A randomized trial of levodopa as treatment for residual
amblyopia in older children. Ophthalmology 2015;122:874-81

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DOS Times - Volume 28, Number 2, March-April 2022

Surgical Techniques

Intraoperative OCT Guided Bleb Sparing
Epithelial Exchange for Avascular Thin
Cystic Blebs

Dewang Angmo, MD, Jyoti Shakrawal, MD, Ramanjit Sihota, MD
Glaucoma Service, Dr. Rajendra Prasad Centre for Ophthalmic Sciences, AIIMS, New Delhi, India.

Abstract: Intraoperative-optical coherence tomography (iOCT), as a non-invasive tool is evolving and being used
in various glaucoma surgeries like trabeculectomy, goniosynechialysis, AGV implantation, bleb needling etc. With
the advent of newer technology, i.e., real time anterior segment optical coherence tomography integrated with
operating microscope (iOCT), we propose a simple & safe technique of bleb revision with greater precision, under
direct visualisation of bleb anatomy and tissue depth, allowing better localization, easy manoeuvring with lesser
complications. Bleb revision was done using intraoperative real time OCT incorporated in OPMI LUMERA 700
microscope. Live surgical and OCT view were seen on a common screen. iOCT guided bleb sparing epithelial
exchange is a more precise technique for bleb repair with lesser complications, reduced surgical time and better
outcomes.

Introduction epithelial peeling without causing any inadvertent damage to the
underlying functional bleb structure.
Long term results of trabeculectomy have improved over time Methods
with modifications in surgical technique,[1] use of antifibroblastic
agents like mitomycin-C (MMC) and advent of releasable Bleb revision was done using intraoperative real time OCT
sutures. However, the use of MMC and 5-fluorouracil in (iOCT) RESCAN 700 (Carl Zeiss Meditec, Germany) fused
trabeculectomy has increased the susceptibility of thin avascular with OPMI LUMERA 700 microscope (Carl Zeiss Meditec,
bleb later.[2] These blebs are more prone for vision threatening Germany). The Calisto eye displays the live surgical and OCT
complications like hypotonous maculopathy, blebitis and view on the common screen together.
endophthalmitis, especially in pediatric age groups. Ehlers et Case 1: A 58-year-old male with primary open angle glaucoma
al stated that the use of microscope-mounted intra-operative presented with a past history of right eye (RE) trabeculectomy
Optical Coherence Tomography can modify the surgical 7 years back. On examination, RE vision was 6/9 on snellen vi-
decisions of both anterior and posterior segment surgeries.[3,4] sual acuity chart and IOP was 8 mmHg. Slit lamp examination
Various surgical or nonincisional methods using cyanoacrylate showed a thin avascular bleb with bleb sweating visible on fluo-
glue or autologous blood injections for bleb revision have been rescein staining. (Figure 1a and b) Bleb anterior segment optical
described.[5–7] Our technique of Bleb sparing epithelial exchange coherence tomography (ASOCT) showed an overhanging and
(BSEX) is well established and safe.[8,9] elevated bleb. (Figure 1c) RE iOCT guided bleb revision was
In this technique, bleb epithelium is stained with trypan blue performed.
dye followed by epithelial peeling of the thin avascular bleb Case 2: A 36-year-old female with both eyes juvenile open an-
(detailed technique described later). Thereafter, conjunctival gle glaucoma presented with left eye (LE) IOP of 4 mmHg. She
advancement (healthy conjunctiva posterior to the avascular had history of both eyes trabeculectomy done 1 year ago. On
bleb is bluntly dissected) is done, which preserves the functional slit lamp examination, a thin avascular bleb with a bleb leak was
bleb without excising it. This creates a more physiological and present. She also complaint of vision drop in the LE with a vision
functional bleb and thereby less need of glaucoma medications of 1/60, with evidence of hypotonic maculopathy visible in fun-
postoperatively.[8] However, the trypan blue dye used for staining dus. She underwent LE iOCT guided bleb revision.
the epithelium, stains it lightly, which causes difficulty in Surgical technique
visualizing the epithelium and thereby dissection especially for
amateur surgeons. This may either lead to incomplete epithelium After anesthetizing the eye with peribulbar block (0.5%
removal or damage to underlying bleb structure. Multiple bupivacaine+2% lignocaine), a wire speculum was inserted.
segment peeling is required in many cases to avoid inadvertent A curved Vanna’s scissor was used to cut the conjunctiva
damage toto the underlying bleb structure.[8] Therefore, we along the lateral and the posterior margins of the avascular
used iOCT in addition to trypan blue dye to ensure complete bleb. Hemostasis was achieved using bipolar cautery and

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Surgical Techniques

the surrounding normal conjunctiva was separated from cut off. Thereafter, the adjacent conjunctiva was advanced and
underlying Tenon’s with a blunt-tipped Westcott’s scissor, until hitched to the limbus with 6-0 vicryl vertical mattress sutures.
its free margin could be advanced easily to the limbus. Care A water-tight closure of the conjunctival flap was achieved by
was taken to prevent buttonholing of the conjunctiva. Trypan continuous 8-0 vicryl sutures at the lateral edges and dog ears,
blue dye (0.06%) was applied to stain the epithelium over the if present, and two 10-0 nylon horizontal mattress sutures
bleb. The anterior edge of the bleb epithelium was identified, across the limbal extent. In vivo, preoperative and postoperative
and only the stained epithelium was gradually peeled off the assessment of the bleb was done on iOCT. (Figure 3a and b)
surface backward and horizontally under direct visualization of Postoperatively, topical antibiotic-steroid combination eyedrops
the tissue depth on iOCT. This prevented damage to underlying and ointment were prescribed for 4 weeks. Both patients were
functional bleb structure. (Figure 2) As the raised epithelial sheet reviewed at day 1, 1 week, 1 month and 3 month after surgery.
reached the more fibrosed posterior margin of the bleb, it was

Figure 1 : (a) Clinical photograph of the bleb showing a thin, avascular Figure 3 : (a) Pre operative clinical photograph showing a thin and
and multicyctic bleb. (b) Clinical photograph of the bleb showing bleb avascular bleb. The corresponding live iOCT imaging horizontal scan
sweating and a small leakage (black arrow) on fluorescein staining. (c) (blue horizontal line) and vertical scan (pink vertical line) of the bleb area
ASOCT image of the bleb showing a large bleb height, a thin epithelium, shows large bleb height, a thin epithelium, and multiple hyporeflective
and multiple hyporeflective spaces within the bleb tissue. spaces in the bleb. (b) Post operative clinical photograph showing a bleb
covered by adjacent healthy conjunctiva. The corresponding live iOCT
imaging horizontal scan (blue horizontal line) and vertical scan (pink
vertical line) of the bleb area shows reduced bleb height, a thick epithelium,
and few hyporeflective spaces within the bleb tissue.

Figure 2 : Intra operative clinical photograph showing the lightly stained Results
bleb epithelium with trypan blue dye, being peeled off. The corresponding The first case after bleb revision showed a RE diffuse and vas-
live iOCT imaging horizontal scan (blue horizontal line) and vertical scan cular bleb with an IOP of 14 mmHg on postoperative day 1. RE
(pink vertical line) of the bleb area shows an easily visible thin hyper- vision was maintained at preoperative levels at 3 months fol-
reflective epithelium. low-up. Bleb sweating was absent. A moderately elevated, diffuse
functional bleb was noted after 3 months of bleb revision with
RE IOP of 12 mmHg. The ASOCT of the filtering blebs postop-
eratively showed a decrease in the bleb height, a thicker epithe-

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DOS Times - Volume 28, Number 2, March-April 2022

Surgical Techniques

lium, and smaller hyporeflective spaces within the bleb tissue. 6/24 on Snellen visual acuity chart with resolution of hypotonic
(Figure 4a and b) The second patient also showed a functional maculopathy.
bleb at 4 months postoperatively. The vision in LE improved to

Figure 4 : (a) Clinical photograph showing a moderately elevated and vascular, diffuse functional bleb after 3 months of bleb revision. (b) ASOCT image
of the bleb after bleb revision shows decrease in the bleb height, a thicker epithelium, and less hyporeflective spaces within the bleb tissue.

Discussion technique for bleb repair with lesser complications, reduced
surgical time and better outcomes.
Introduction of OCT into clinical practice has made a revo- References
lutionary change in diagnosis, management, and monitoring
of nearly all ocular diseases. Similarly, OCT integrated with 1. Khaw PT, Chiang M, Shah P, Sii F, et al. Enhanced Trabeculectomy
operating microscope (iOCT) has bought a paradigm shift in – The Moorfields Safer Surgery System. In: Developments in ophthal-
ophthalmic surgery. The feasibility of iOCT was first described mology 2012;50:1–28.
by Ehlers et al,[4] and since then, its use in ophthalmology has
evolved. iOCT has been used for bleb needling of encysted bleb, 2. Singh K, Mehta K, Shaikh NM, Tsai JC, et al. Trabeculectomy with
an important guide during crucial steps of lamellar keratoplasty, intraoperative MMC versus 5-fluorouracil. Prospective randomized
as well as during stromal dissection in ocular surface squamous clinical trial. Ophthalmology 2000;107:2305–9.
neoplasia.[10,11]
During surgical maneuvering, the iOCT with heads up display 3. Kumar RS, Jariwala MU, V SA, Venugopal JP, et al. A pilot study on
(HUD) allows rapid visualization of the area of interest and pro- feasibility and effectiveness of intraoperative spectral-domain optical
vides the surgeon with information regarding instrument‑tissue coherence tomography in glaucoma procedures. Transl Vis Sci Technol
interactions. Because of its finer resolution, OCT is able to pres- 2015;4:2.
ent detailed view of the bleb wall, and an accurate assessment of
the location and extent of the bleb structure. 4. Ehlers JP, Dupps WJ, Kaiser PK, Goshe J, et al. The Prospective
The epithelium can be precisely identified and dissected under intraoperative and perioperative ophthalmic imaging with optical
direct visualization without causing any inadvertent damage to coherence tomography (PIONEER) Study: 2-year results. Am J
the underlying bleb structure. This permits better maneuvering, Ophthalmol 2014;158:999–1007.
better dissection of the anterior and posterior bleb wall under
visualization and thereby reducing the risk of complications. 5. Pazos M, Dyrda A, Antón A. Bleb revision for resolution of hypotony
Moreover, iOCT may also be useful in visualizing any underlying maculopathy following primary trabeculectomy. Am J Ophthalmol
scleral defect too. 2015;159:410.
iOCT ensures complete epithelial peeling of the deceased
epithelium, which is important to prevent post-operative rise 6. Lin AP, Chung JE, Zhang KS, Chang MM, et al. Outcomes of surgical
in IOP.[8,12] It also reduces direct trauma to the underlying bleb bleb revision for late-onset bleb leaks after trabeculectomy. J Glaucoma
structure and it can also be used as an excellent teaching tool for 2013;22:21–5.
trainees.
The high cost and difficulty in repeated focusing, to keep the 7. Burnstein AL, WuDunn D, Knotts SL, Catoira Y, et al. Conjunctival
area of interest under view are the major hurdle to begin with, advancement versus nonincisional treatment for late-onset glaucoma
which improves over time with every surgery. In summary, filtering bleb leaks. Ophthalmology 2002;109:71–5.
iOCT guided bleb sparing epithelial exchange is a more precise
8. Sihota R, Angmo D, Sen S, Gupta V, et al. The long-term outcome of
primary “Bleb-sparing, Epithelial Exchange” in dysfunctional filtering
blebs. J Glaucoma 2016;25:571–8.

9. Dada T, Midha N, Shah P, Sidhu T, et al. Innovations in glaucoma
surgery from Dr. Rajendra prasad centre for ophthalmic sciences.
Indian J Ophthalmol 2017;65:103–8.

10. Dada T, Angmo D, Midha N, Sidhu T. Intraoperative optical
coherence tomography guided bleb needling. J Ophthalmic Vis Res
2016;11:452–4.

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Surgical Techniques

11. Titiyal JS, Kaur M, Falera R. Intraoperative optical coherence Corresponding Author:
tomography in anterior segment surgeries. Indian J Ophthalmol
2017;65:116–21.

12. Sihota R, Dada T, Gupta D, et al. Conjunctival dysfunction and
MMC induced hypotony. J Glaucoma 2000;9:392–7.

Dr. Dewang Angmo, MD
Associate Professor, Glaucoma research facility & clinical services
Dr. Rajendra Prasad Centre for Ophthalmic Sciences, AIIMS, New Delhi.

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DOS Times - Volume 28, Number 2, March-April 2022

Photo Essay

Carancular Dermoid Cyst

Divya Ramraika, DOMS, DNB
Senior Resident, Department of Ophthalmology, Hindu Rao Hospital, New Delhi

Abstract: Carancular dermoid cyst is a rare kind of dermoid cyst. The diagnosis of carancular dermoid cyst can be
made clinically by focal, circumscribed lesion in the carancule but it is confirmed histologically by excision biopsy.

Dermoid cysts are congenital, benign neoplasms of the orbit that References
are most commonly located superotemporally near the fronto-
zygomatic suture followed by superonasal location.[1] Carancu- 1. Shields J, Shields C (2004) Orbital Cysts of Childhood-Classification,
lar dermoid cysts are rare kind of dermoid cyst. One of the most Clinical Features and Management. Surv Ophthalmol 49:281-299.
common leisons in orbit in children is dermoid cyst.[1,2] The his-
tory given by the patient is that a slowly progressive, non-tender 2. Cavazza S, Laffi GL, Lodi L, Gasparrini E, Tassinari G (2011) Orbital
mass mostly yellow in colour usually bilateral but can also be Dermoid Cyst of Childhood: Clinical Pathologic Findings, Classifica-
unilateral.[1,2] The diagnosis of carancular dermoid cyst can be tion and Management. Int Ophthalmol 31:93-97
made clinically by focal, circumscribed lesion in the carancule
but it is confirmed histologically by excision biopsy. Any kind of Corresponding Author of the Article:
imaging is not required for the diagnosis of carancular dermoid
cyst. Complete surgical excision is the treatment of choice for
the carancular dermoid cyst.

Figure 1 : a) External photographs of the 13 year old girl showing yellow- Dr. Divya Ramraika, DOMS, DNB
ish well circumscribed lesion in the carancule in the right eye shown by Senior Resident, Department of Ophthalmology,
arrow. Left eye does not show any growth. b) External photograph of right Hindu Rao Hospital, New Delhi
eye showing carancular dermoid cyst shown by arrow.

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PG Corner

Clinical Signs of Corneal Ulcer

Akshi Sharma[1], MBBS, Sarah Khan[1], MS, Devesh Kumawat[1], MD, Siddhi Goel[2], MD, Pranita Sahay[3], MD
1. Department of Ophthalmology, Lady Hardinge Medical College, New Delhi.
2. Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi.
3. Department of Ophthalmology, University College of Medical Sciences & GTB Hospital, New Delhi.

Abstract: A corneal ulcer (keratitis) is characterised by corneal epithelial defect with underlying stromal inflammation
usually due to invasion by bacteria, fungi, viruses, or protozoa; however, it can also be sterile. It is a serious condition
that must be treated promptly to avoid long-term visual problems.

Introduction b) Indistinct: Active ulcer
c) Distinct: Resolving ulcer
Corneal ulcers constitute a major cause of corneal blindness in d) Overhanging edge: Mooren ulcer
the developing countries, leading to serious complications.
Its severity is based on three factors: pathogenic severity of 5. Surrounding area:
causative organism, the underlying condition of the cornea, and a) Satellite lesion: Fungal
individuals immunity status.[1] b) Immune ring: Fungal, HSV, Acanthamoeba
The ocular defence mechanisms against infection are blinking, c) Ground glass oedematous: Pseudomonas
tight junctions present in the corneal epithelial cells, and
chemicals in the pre-corneal tear film such as lactoferrin, 6. Hypopyon:
lysozyme, antimicrobial peptides, antibodies, and bacteriocins a) Mobile: Bacterial
which control bacterial growth.[2] b) Fixed: Fungal
The predisposing factors for corneal ulcer include - ocular trau-
ma, contact lens use (overnight or extended wearing of lenses), 7. Others
ocular surgery (corneal surgery), chronic ocular surface disease, a) Black/brown pigmentation: Fungal
topical steroid use, diabetes mellitus and immunocompromised b) Radial keratoneuritis: Acanthamoeba
states.[3] A breach in the anatomical barrier reduces the effective- c) Ground glass oedema of surrounding cornea: Pseudomonas
ness of host defences against pathogens leading to ocular infec- Examination of ulcer
tion, inflammation, and eventual visual loss.[4]
Clinical Signs • Location of ulcer
• Shape of ulcer
1. Discharge: • Appearance of margin
a) Watery: Viral, Fungal • Size of epithelial defect
b) Mucopurulent: Gonococcus, Pseudomonas • Size and depth of infiltrate
c) Greenish-yellow colour: Pseudomonas • Surrounding cornea
d) Membranous: Corynebacterium diphtheria • Limbus/scleral involvement
• Anterior chamber reaction
2. Location: • Fundus/USG B scan to note vitreous reaction
a) Central: Staphylococcus, Pseudomonas Infective Corneal Ulcer
b) Peripheral: Atypical mycobacteria, HSV, Staphylococcus
1. Bacterial corneal ulcer:
3. Shape: a) Staphylococcus aureus: sudden onset, rapidly progressing
a) Dendritic/Amoeboid/Geographic: Viral central corneal ulcer. Discrete, small abscess like lesion with
b) Oval: Neurotrophic distinct borders and non-oedematous surrounding cornea
c) Ring: Acanthamoeba/Pseudomonas (Figure 1).
d) Wreath like appearance: Nocardia b) Pneumococcus: usually follow trauma or dacrocystitis. In-
e) Cracked windshield appearance: Nocardia/Atypical Myco filtrate starts at site of injury and then spreads towards centre
bacteria of the cornea, also known as serpiginous ulcer. Severe anterior
chamber reaction is seen. Corneal melting and perforation oc-
4. Margin of Ulcer: curs rapidly.
a) Hyphate or Feathery: Fungal

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DOS Times - Volume 28, Number 2, March-April 2022

PG Corner

Figure 1 : Clinical picture of Staphylococcal keratitis showing a central Figure 3: Clinical picture of Pseudomonas keratitis showing ring ulcer in
a contact lens user.
localized corneal ulcer with normal surrounding cornea.

c) Pseudomonas: Diffuse, rapidly spreading necrotic lesions
are seen. Marked lid oedema and conjunctival chemosis with
greenish yellow mucopurulent discharge is present. Epithelial
greying with ring ulcer can seen. If untreated, they perforate
within 2-3 days. (Figure 2 and 3)
d) Moraxella: occur after trauma in debilitated patients. Slowly
growing, localized, oval ulcer in inferior cornea is seen.
e) Nocardia: Slowly growing ulcer with stromal infiltrates with
a wreath pattern or cracked windshield pattern is seen.
f) Mycobacteria: full thickness, dense infiltrate with folds of
surrounding cornea giving cracked windshield appearance and
satellite lesions are seen.

Figure 4: Clinical picture of a case of fungal keratitis having a dry looking
surface with feathery/hyphate margin (black arrow), satellite lesion (red
arrow) and hypopyon (yellow arrow).

Figure 2 : Clinical picture of Pseudomonas keratitis showing near total 2. Fungal corneal ulcer:
corneal ulcer with perforation and uveal tissue prolapse Insidious onset, slowly progressing corneal ulcers with minimal
lid edema and conjunctival injection. Dry looking ulcer with
feathery margins and thickened epithelium, satellite lesions, en-
dothelial plaque, posterior corneal abscess, immune ring infil-
trate, immobile hypopyon and fibrinous reaction can be seen.[5]
(Figure 4) Black or brown pigmentated corneal ulcer can be seen
in infections with dematecious fungi. (Figure 5)
Common causative species in India are Aspergillus and Fusar-
ium[6]
A pseudo-dendritic pattern is seen in early stages, which is often
misdiagnosed as HSV keratitis.[7] (Figure 6)

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PG Corner

c) Endothelitis: it is due to type IV immune reaction occur-
ring in three patterns: Disciform, diffuse and linear patterns. It
is characterised by corneal oedema, keratic precipitates and mild
anterior chamber reaction. (Figure 9)
Herpes Zoster Ophthalmicus:
The most common findings are pseudo-dendrites and punctate
keratitis. The dendrites are more superficial, blunt ends, lack
corneal stain. Disciform stromal keratitis is also seen.

Figure 5: Clinical picture of a case of fungal keratitis caused by dematia-
ceous fungi showing a corneal plaque with brown coloured pigmentation
and hypopyon.

Figure 7: Clinical picture of a case of HSV keratitis in cobalt blue illumi-
nation showing the classical dendritic ulcer.

Figure 6: Clinical picture of a case of fungal keratitis presenting with Figure 8: Clinical picture of a case of HSV keratitis showing (a) geographic
pseudo-dendrites (black arrow) mimicking viral keratitis. corneal ulcer under diffuse illumination and (b) cobalt blue illumination.

3. Viral keratitis: Figure 9: Clinical picture of a case of viral endothelitis under slit illumi-
Herpes simplex virus (HSV) nation showing (a) stromal corneal oedema and (b) presence of keratic
a) Epithelial keratitis: branching linear lesions with terminal precipitates with corneal oedema in high magnification.
bulbs and swollen epithelial borders known as dendritic ulcer 4. Parasitic infection
is the most common presentation. (Figure 7) They coalesce to a) Acanthamoeba
form geographic ulcer. (Figure 8) They are sometimes found It runs a chronic waxing-waning course. Oedematous, loose ep-
near limbus with accompanying blood vessels, where they are
more symptomatic.
b) Stromal keratitis: Two manifestations are seen:
Necrotizing stromal keratitis: direct viral invasion of stroma is
present which is associated with necrosis, ulceration and dense
infiltration.
Immune stromal keratitis: punctate stromal opacities, immune
ring of Wessley are seen

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DOS Times - Volume 28, Number 2, March-April 2022

PG Corner

ithelium with dense stromal ring infiltrate at mid periphery and 5. Srinivasan M, Mascarenhas J, Prashanth CN. Distinguishing infective
radial keratoneuritis is seen.[5] versus noninfective keratitis. Indian Journal of Ophthalmology. 2008
b) Microsporidiosis May 1;56(3):203.
Superficial punctate keratoconjunctivitis or stromal keratitis is
noted. (Figure 10) 6. Srinivasan M. Fungal keratitis. Curr Opin Ophthalmol. 2004
Aug;15(4):321–7.
Figure 10: Clinical picture of a case of Microsporidial epithelial
keratoconjunctivitis (a) in diffuse illumination showing punctate lesions 7. Agrawal V, Biswas J, Madhavan HN, Mangat G, Reddy MK, Saini JS,
(b) in high magnification showing fluorescein staining of the epithelial et al. Current perspectives in infectious keratitis. Indian J Ophthal-
lesion (c) in slit illumination showing superficial involvement of cornea. mol. 1994 Dec;42(4):171–92.

8. Sridhar MS, Sangwan VS, Bansal AK, Rao GN. Amniotic membrane
transplantation in the management of shield ulcers of vernal kerato-
conjunctivitis. Ophthalmology. 2001 Jul;108(7):1218–22.

9. Cetinkaya A, Akova YA. Pediatric ocular acne rosacea: long-
term treatment with systemic antibiotics. Am J Ophthalmol. 2006
Nov;142(5):816–21.

References Corresponding Author:

1. Robles-Contreras A, Perez-Cano HJ, Babayan-Sosa A, Baca-Lozada Dr. Pranita Sahay, MD, DNB, FICO, FAICO, FICO
O. Bacterial Keratitis Infection: A Battle Between Virulence Factors Assistant Professor, Department of Ophthalmology,
and the Immune Response. University college of Medical Sciences & GTB Hospital, New Delhi.

2. Zhou L, Zhao SZ, Koh SK, Chen L, Vaz C, Tanavde V, et al. In-
depth analysis of the human tear proteome. J Proteomics. 2012 Jul
16;75(13):3877–85.

3. Wong RLM, Gangwani RA, Yu LWH, Lai JSM. New treatments for
bacterial keratitis. J Ophthalmol. 2012;2012:831502.

4. Bolaños-Jiménez R, Navas A, López-Lizárraga EP, de Ribot FM, Peña
A, Graue-Hernández EO, et al. Ocular Surface as Barrier of Innate
Immunity. Open Ophthalmol J. 2015 May 15;9:49–55.

DOS Times - Volume 28, Number 2, March-April 2022 70 www.dosonline.org/dos-times

Basic Ophthalmology

Addressing the Spectacle Lens Related
Problems of a Myope

Devanshi M. Dalal[1], B.Optom, M.Optom, FASCO (LVA), FPOO, Rinal Pandit[2], MBBS, MS, FMRF, FAICO, Dhaivat Shah[3], MBBS, MS,
DNB, FMRF
1. Assistant Professor and Clinical Coordinator in Optometry, Department of Paramedical and Health Sciences, Faculty of Medicine, Parul University,

Vadodara - Gujarat, India.
2. Consulting Glaucoma Specialist, Choithram Netralaya, Dhar Road, Indore - Madhya Pradesh, India.
3. Head of Vitreoretina, Research and Academics Department, Choithram Netralaya, Dhar Road, Indore - Madhya Pradesh, India.

Introduction Spectacle corrections are crucial part for myopia management.
Various problems can arise due to inappropriate selection of size
Placing spectacle lenses in front of a patient’s eyes alters the vi- of lens, weight, minification, basecurve, and frame selection.
sual world. Blurred images become clear and the images will Frame and Lens Size
appear to be at different distances than the original objects.[1] A The Size considerations include avoiding frames with lenses
perfect optical system provides an image that is an exact point- that are very large, since the lens edge gets thicker farther away
by-point replica of the original object. Images may be magnified from the center. Frames with rounded corners should be used,
or minified, and prismatic effects will be present that change the when possible, for this same reason. A frame wider than the
apparent position of objects. Lens aberrations may also alter the wearer’s face at the temple area should also be avoided, since
shape or clarity of images.[1,2] high minus lenses make the side of the wearer’s head look nar-
As minus power increases, lens shapes become planoconcave or rower through the lenses. Excessive decentration should be
even biconcave to correct off-axis aberrations. Edge thickness avoided or the outer lens edge will be much thicker than the in-
is also greatly increased and that is one of the most important ner edge. An alternative is to use a wider bridge and smaller eye
problems to be solved when high-minus lenses are prescribed. size. The nose pads can be brought closer together, if necessary,
Small, round frame shapes and high-index lens materials are rather than decentering too much.[2-3] Comparison of high pow-
useful for this purpose, but other solutions may be necessary for ered Minus lenses in frame and thin spectacle lenses for better
higher powers.[2] cosmesis shown in figure 1 and 2.
In this article we will be discussing the various aspects of specta-
cle lens and frame considerations for myopic patients.

Figure 1 : High powered minus lenses in frame. Figure 2 : Thin spectacle lenses for better cosmesis.
In high myopes, most of the time problems may arise due to
www.dosonline.org/dos-times excessive lens thickness and sliding down of spectacles due to
lens weight.[4] Thickness Can cause peripheral distortion in case

71
DOS Times - Volume 28, Number 2, March-April 2022

Basic Ophthalmology

of high-powered lens. Recommend lens material of higher re- decreases the field of view. It can be managed by minimizing
fractive index. Anti-reflection coating can be applied to reduce edge thickness and reflections. Smaller frame size and edge
the amount of peripheral lens reflections. If the lens thickness is coatings can help to manage further.[1,2]
managed eventually decreases lens weight.[1-4] Base Curve and Lens Bevel
Most of the time for high myopic patient’s cosmetic issues related The actual physical form or shape of a spectacle lens is deter-
to lens edge come up leading to noncompliance.[5] Lens edges are mined by its base curve. As a general definition, the base curve
thicker with low-index CR-39 plastic. Using a lens of a higher is a reference curve (surface power) that is the base or basis from
index material will reduce the edge thickness. High index plastic which all other surface powers are calculated. Base curves are
lenses are chosen over high index glass because of the weight usually chosen so that a lens or a group of lenses will have the
factor. High index plastic lenses are an excellent choice for high best off-axis optical quality. Because of this requirement, most
minus lenses. Polycarbonate lenses offer both a weight and edge lenses will be meniscus in shape. Light reflected from the sur-
thickness advantage. Polycarbonate lenses can be made with a face of a spectacle lens can form a focused image (ghost image)
thinner center thickness because of their high impact resistance. annoying to a patient, or it can affect the cosmetic appearance
This translates into a thinner edge. Even if a polycarbonate lens of the lens. curve, and bevel are additional considerations. The
has the same center thickness as a regular plastic CR-39 lens, larger the bevel, the more reflection rings will be noticeable be-
the edge of the polycarbonate lens will still be thinner than the cause these rings are a reflection of the lens edge. (Figure 4)
CR-39 (Figure 3). This is because the polycarbonate lens has a
higher index of refraction (1.586) than the CR-39 lens (1.498).
In some cases, patients may complain of colored haloes with
new spectacles. This can happen because, Lower the Abbe value,
higher will be the chromatic aberration. Patients can complaint
of scattering of colors. Recommend lens material of higher Abbe
value to avoid problems of colored haloes.[1,2,5]

Figure 4 : Bevel changes in minus lenses.

Figure 3 : Edge thickness in minus lenses. Using a now-standard hidden bevel reduces the problem.
The edge of a high minus lens can be made less noticeable by
Minification rolling the edge. This is especially true for metal or thin plas-
Higher the minus power more complaints related to Minifica- tic frames. Rolling the edge changes it from flat to rounded, as
tion are observed. Specifically, the minification of wearer’s eye shown in giving a nice appearance to the lens when polished and
can be seen by observer giving rise to cosmetic blemish. Mini- often reducing measured edge thickness by as much as 2 mm.
fication of retinal image size is observed to wearer. Fit lens with Polishing the edges will make the lens look better to an observ-
decreased vertex distance. Use of contact lenses is best way to er, but unless an antireflection (AR) coating is used, such pol-
manage minification.[2] ishing will introduce internal reflections, which are disturbing
The Ring of diplopia at periphery due to edge reflections to many wearers. Thus the combination of roll and polish looks
very good. Some recommend using a roll and polish with cau-
tion because of the possibility of wearer dissatisfaction because
of the distortion caused by the rolled area in the periphery of the

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Basic Ophthalmology

lens. An edge does not have to be rolled to be polished.[6] A con- refraction and spectacle prescription is a vital part for giving a
ventionally beveled lens edge can also be polished. With better good quality of life. Owing to the progressive nature, especially
manufacturing techniques, polish edges are much easier to pro- in patients with high myopia, addressing the spectacle lens relat-
duce and are coming to be expected on lenses with visible bevels. ed problems for myopia can increase the compliance of patients
Unless antireflection coated, a front curve reduced below +2.00 for spectacle lens wear and improve the quality of life of Myopes.
D will result in a high reflection of light from the front. Unfor- References
tunately, high minus lenses made with ordinary spherical curves 1. Clifford W Brooks , Irvin M Borish ;System For ophthalmic dispensing
require a fairly flat front curve to give good optics. It is possible
to use an aspheric design to allow for a different front curve and 3rd edition chpt 4 pg 50-51.
to slightly thin the edge of the lens by steepening the lens in the 2. Troy E Fannin, Theodore Grosvenor; Clinical optics, 2nd edition pg
periphery. An aspheric high minus lens may have a better cos-
metic appearance than a conventional, spherically based lens of 346.
the same power. Even though a light tint will reduce internal lens 3. Gupta V , Saxena R , Vashist P et al. Spectacle coverage among urban
reflections, an antireflection (AR) coating does a much better
job. Even lenses with flat front curves will lose their mirror like schoolchildren with refractive error provided subsidized spectacles in
reflective appearances with an AR coating. Antireflection coat- North India. Optom Vis Sci 2019; 96: 301-308.
ings also eliminate the concentric rings, which are frequently 4. Jeewanand Bist, Spectacle non-tolerance in clinical practice - a sys-
seen with high minus lens prescriptions. For wearers with exces- tematic review with meta-analysis, Ophthalmic Physiol Opt2021
sively high minus lenses, a minus lenticular design can be opted. May;41(3):610-622.doi: 10.1111/opo.12796. Epub 2021 Mar 9.
Frame selection considerations to be taken care for myopic sub- 5. Vijayalakshmi Arumugam, Reasons for spectacle reassessment in a
jects are-smaller eye size, Rounded corners. Full frame plastic tertiary eye care centre over a period of six years, Clinical and Ex-
frames-help hide any edge thickness. The bridge with good grip perimental Optometry, Volume 101, 2018 - Issue 2, https://doi.
and temple little tight. Avoid using frames with hard temple org/10.1111/cxo.12619.
cause rubbing and irritation.[1,2,6] 6. Sharma P, Gaur N. How do we tackle a child’s spectacle?. Indian J
Other specifications for accurate dispensing for myopia in- Ophthalmol. 2018;66(5):651–652. doi:10.4103/ijo.IJO_369_18.
clude the Pantoscopic tilt. Pantoscopic tilt is a position of wear 7. Naidoo K, Ravilla D. Delivering refractive error services: primary eye
measurement that affects how the lens is positioned in front care centres and outreach. Community Eye Health. 2007;20(63):42–
of the patient’s visual axis in the primary gaze position. If im- 44.
proper pantoscopic tilt can give rise to unwanted reflections
and it can be managed by Nose pad adjustment for maximum Corresponding Author:
pantoscopic changes. Frame adjustment can sometime help, ef-
fectively-related issues. The Optic center of the lens if does not Dr. Devanshi M. Dalal, B.Optom, M.Optom, FASCO (LVA), FPOO
match the geometrical center of frame Can give rise to unwanted Assistant Professor and clinical coordinator in Optometry,
prisms if not matched with pupillary axis leading to asthenopic Department of Paramedical and Health Sciences, Faculty of Medicine,
symptoms. Pantoscopic change can sometimes align the optic Parul University, Vadodara-Gujarat, India.
center.[6,7]
Thus the role of dispensing optometrist is crucial for manage-
ment of refractive errors and prescribing accurate spectacles.
The frame and lenses if chosen appropriately give rise to mini-
mal discomfort and higher compliance.
Conclusion

Myopia is the most common refractive error seen in clinical
practice. Most of the time, the focus is on the progressive retinal
degeneration and the associated complications only. However,

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DOS Times - Volume 28, Number 2, March-April 2022

Beyond Ophthalmology

Humorous one liners

Jatinder Singh Bhalla[1], MBBS, MS, DNB, MNAMS
Senior Consultant & Academic Incharge, Department of Ophthalmology, DDU Hospital, New Delhi.

1. What did the left eye mutter to the right one? It said, “Between you and me, something smells.”
2. What did the optometrist tell the judge when he was in court? He said, “Iris my case.”
3. What is the similarity between an optometrist and a teacher? They both love testing pupils.
4. What happened when the man could see clearly after a long time? He was very ex-eye-ted to see.
5. What happened when a man accidentally rubbed some ketchup in his eyes? He regretted it in Heinzsight.
6. Why did the phone start wearing glasses? Probably because he lost all his contacts.
7. What was the movie they made on the life story of a man who couldn’t see properly since childhood? It was a myopic.
8. How does it feel to wake up every morning? It’s an eye-opening experience.
9. Why are our eyes undoubtedly the most important part of the body? Probably because they always focus on what matters.
10. Have you heard about the boy who was dating a girl that had lazy eyes? Turns out, she was seeing someone else.
11. How did the wonderful carpenter cut the piece of wood by looking at it? Well, he saw it with his eyes.
12. Did you hear about the cashier that scanned the eyes of one rude customer with his barcode reader? Well, the look on the
customer’s face was priceless.
13. What device do eyes usually use to listen to music? They use eye-pods.
14. Why did the therapist suggest anger management to the eye? Because he told her, “Eyelash out whenever Eye’m mad.”
15. Why do the snipers close one eye whenever they’re aiming their shot? That’s because if they closed both their eyes, they wouldn’t
be able to see.
16. How does the street eyeball greet everyone every time? He says, “Hey brow!”
17. What would you call it if an apple user looked you in the eyes? iContact.
18. I wanted to impress my ophthalmologist so I told her a joke about eyes. She said I have a vitreous humor.
19. Did you hear about the Eye Doctor who changed professions to become a comedian? He made a spectacle of himself
20. My earliest childhood memory is visiting the eye doctor and getting my glasses... Before that, life was a blur...

Corresponding Author:

Dr. Jatinder Singh Bhalla, MBBS, MS, DNB, MNAMS
Senior Consultant & Academic Incharge,
Department of Ophthalmology, DDU Hospital, New Delhi.

DOS Times - Volume 28, Number 2, March-April 2022 74 www.dosonline.org/dos-times

Article Review

Management of Recalcitrant Corneal
Hydrops

Anushka Agarwalla[1], MBBS, Pranita Sahay[2], MD, Prafulla K. Maharana[3], MD

1. Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi.

2. Associate Consultant, Cornea Cataract & Refractive Surgery, Centre for Sight Eye Hospital Safdarjung Enclave, New Delhi.

3. Associate Professor, Cornea, cataract & Refractive Services, Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical
Sciences, New Delhi.

Introduction made in and around the areas of stromal clefts using a 20-gauge
microvitreoretinal (MVR) blade. MVR blade entry was stopped
Acute corneal hydrops is a condition characterized by stromal as soon as the egress of fluid was noted through the venting in-
edema due to seepage of aqueous through a tear in descemet cision. After waiting for 10 min, the air was removed partially
membrane. The patient presents with sudden onset decrease in leaving behind an 8mm of air bubble in the AC. The paracentesis
vision, photophobia, and pain.[1] The various risk factors which wound was thereafter hydrated and subconjunctival antibiotics
are associated with the increased risk of hydrops include earlier administered.
age at onset, eye rubbing, vernal keratoconjunctivitis (VKC), at- A total of five patients were included (3 men, 2 women; age
opy, and Down’s syndrome.[2,3,4] range 10–25 years). Four patients had KC and one patient had
Various treatment modalities have been outlined which include keratoglobus. Postoperatively, the DM was attached on day one
medical management using a cocktail of eyedrops including hy- in four eyes and on day three in one eye (case 3). The delayed
pertonic saline drops, steroids and IOP lowering agents, as well re-attachment in case 3 was possibly related to a very thick cor-
as surgical management of which the most commonly done is nea preoperatively. The corneal oedema resolved in 2 weeks in
intracameral injection of isoexpansile gas such as perflouropro- 2 eyes and 3 weeks in 3 eyes. No postoperative IOP spike was
pane.[5,6,7] observed in any of the cases. None of the cases required a repeat
When a case of corneal hydrops fails to resolve despite the use of air injection.
traditional treatment, it may be termed as persistent or recalci-
trant corneal hydrops. The eyes at risk include eyes with severe II. Microscope-Integrated Optical Coherence Tomography
microtrauma in the form of eye rubbing due to allergy, poor (MIOCT)-Guided Drainage of Acute Corneal Hydrops in
compliance with medications, extensive Descemet tear with flu- Keratoconus[11, 12]
id clefts in stroma, and improper surgical techniques employed Maharana et al have described the real time MIOCT Guided
to treat the case. Stromal Fluid Drainage in cases of recalcitrant Corneal Hy-
Although some newer techniques have been described to treat drops. The authors have described excellent outcomes with this
such a condition such as – intracameral injection of platelet technique.[12]
rich plasma[8], or Descemet Membrane Endothelial Keratoplasty Surgical Technique
Patch[9], the literature is limited at best.
Management The surgery was performed under peribulbar anesthesia. In-
traoperative OCT (OPMI Lumera 700 and RESCAN 700, Carl
I. Corneal stab incision with intracameral air injection for Zeiss, Meditec, Germany) was done using the RESCAN 700
management of patients with acute corneal hydrops.[10] [microscope integrated OCT system with a heads-up display
Vajpayee et al conducted a case series including five patients system, external video display panel and a foot pedal control of
with acute corneal hydrops with large Descemet’s membrane the OCT scanner, based on the Lumera 700 (Carl Zeiss Med-
(DM) detachment and multiple stromal clefts. itec) platform]. Anterior segment imaging was achieved with
Under topical or general anaesthesia, after ensuring proper pu- the help of the standard microscope viewing system that includ-
pillary constriction, the eye was cleaned with povidone iodine. ed a 9 mm × 9 mm volumetric cube scan and raster scans (2
Anterior chamber (AC) paracentesis was performed at 10 o’ line and 5 line) at zero degree orientation. The size of the cube
clock limbus and after expressing out some aqueous humour, the was modified depending upon the need. Small cube size 4mm
AC was filled with air. Subsequently, three to four stab wounds x 4 mm was used initially to screen the entire cornea, by mov-
with 45° angulations in relation to the corneal plane were ing the cube with the foot pedal control, to look for presence
made in the cornea using preoperative anterior segment OCT of stromal fluid pockets. (Figure 1a) An MVR entry was made
(ASOCT) pictures as a guiding tool. The venting incisions were at the limbus and air was injected into the anterior chamber to
prevent further ingress of fluid into the corneal stroma. (Figure

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DOS Times - Volume 28, Number 2, March-April 2022

Article Review

1b-c) Subsequently, two to five venting incisions were made in nea with the help of merocel sponge to aid in aqueous drainage.
the cornea at 10˚-30° angulation to the corneal plane with real (Figure 1e) Merocel sponges worked both by mechanical pres-
time monitoring of the fluid pockets using MiOCT. (Figure 1d) sure as well as capillary action in egress of fluid. This maneuver
The venting incisions were created, using a 20-gauge MVR blade was repeated several times to ensure complete egress of fluid,
avoiding the visual axis as far as possible. In addition, the fluid which was confirmed on MiOCT, while maintaining complete
pockets that were in direct contact with anterior chamber were fill of anterior chamber with air. (Figure 1f) Following this, the
avoided while creating the venting incisions in order to avoid air from anterior chamber was released partially leaving behind
corneal fistula formation. Successful vents into the stromal flu- the anterior chamber 2/3rd filled with air. At the end of the pro-
id pocket were evidenced by egress of fluid as well as real time cedure, topical moxifloxacin 0.5% was put and eye was patched.
monitoring of the MVR knife depth on MiOCT. (Figure 1d) In Postoperatively, topical antibiotic, corticosteroid, cycloplegic,
addition, external pressure was applied over the edematous cor- antiglaucoma and hypertonic saline were prescribed for 4 weeks.

MiOCT guided hydrops drainage was performed in six eyes of Visual Duration of Corneal Height of
five patients. The details of the patients have been described in Acuity Hydrops thickness at detachment
Table-1.
Case Age/Sex Diagnosis Association Eye 30
42
presentation at presenta-
(µm) tion

1 18/F Keratoconus IFC Right 1/60 980 -
Left FCCF
2 21/M Keratoconus None 1650 1200

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Article Review

Case Age/Sex Diagnosis Association Eye Visual Duration of Corneal Height of
Acuity Hydrops thickness at detachment
3 presentation
4 1/60 21 (µm) at presenta-
5 PL 3 tion
6 FCCF
18/M Keratoconus VKC Left FCCF 1600 -
30/M Right
Keratoconus Downs 1880 -
5/M Syndrome Right
5/M Left 21 2200 -
Keratoconus VKC 10 930 -

Keratoconus VKC

Table 1 : Baseline characteristics of all cases of corneal hydrops.
Footnotes: F= Female; M=Male; IFC= irido-fundal coloboma; FCCF= Counting finger close to face; VKC= Vernal Keratoconjunctivitis

All cases had bilateral keratoconus with acute corneal hydrops. procedure was 21± 8.8 days. The median corneal thickness on
One patient had bilateral hydrops, although the two eyes got in- presentation, at the highest point of corneal edema was 1625±
volved at different point of time. The age ranged between 5 to 390 microns.
21 years. The study included four male and one female patient. The median resolution time was 17.5± 8.4 days (range 7 to 28
The primary diagnosis was bilateral keratoconus for all cases. All days). No intra-operative complication was noted in any case.
but one case had some associations such as vernal keratocon- Descemet membrane was attached on day one in five eyes while
junctivitis (n=2), fundal coloboma (n=1) and Downs syndrome one case had a delayed reattachment.
(n=1). The median duration of hydrops before undergoing the

Case Corneal thickness (in microns) IOP Time to Complications Final out- BCVA
No. Pod 1 resolution come

Pod 1 Pod 7 Pod 14 Pod 28 Pod 60

1- 321 321 321 - 14 7 Nil Paracentral HMCF
3x5 mm scar

2 1280 - - 564 422 16 14 Nil Central 4x4 1/60
mm scar

3 - - 913 355 - 16 28 Nil Paracentral 6/60
4x4 mm scar

4 1700 1400 900 599 - 14 21 Nil Corneal scar 1/60
8x8 mm

5 1700 1200 800 542 - 14 21 Increased Corneal 4x5 3/60
symptoms mm scar
and edema at
6 week which
resolved with
medical man-
agement

6- 515 410 - - 12 7 Nil Para central 6/36
corneal scar
3x3 mm

Table 2 : Outcome of all cases following MiOCT guided stromal fluid drainage.
Footnotes: Pod 1- post-op day1; IOP- Intra ocular pressure; BCVA- best corrected visual acuity; HMCF- hand movement close to face

No postoperative rise in IOP occurred in any case. In addition, corneal edema, precipitated by vigorous eye rubbing, at six week
none of the cases required a repeat air injection. One of the case post-op that resolved with medical management.
developed increased photophobia and watering with increased Siebelmann et al conducted a case series of 2 consecutive pa-

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Article Review

tients with acute corneal hydrops due to keratoconus using a compressive sutures with gas injection.
novel technique consisting of the MI-OCT-guided puncture and Although the condition is self-limited and benign , in a few cases
drainage of intrastromal fluid pockets combined with anterior it may lead to non-resolution, with added pain and photophobia
chamber sulfur hexafluoride-fill and pre-descemetic sutures and to the patient for long durations. Extensive Descemet membrane
demonstrated good outcomes.[11] tear with substantial oedema may lead to formation of a corneal
III. Compressive sutures alone in the management of acute fistula, or corneal perforation. Longer duration of hydrops may
hydrops in a keratoconus patient[13] lead to increased corneal scarring and vascularisation which
Subudhi et al put forth a case report taking into account a 17yr may further result in graft rejection in the future .
old boy with post keratoconic hydrops. Under general anaes- The various treatment modalities explored in the past, each have
thesia, following aseptic precautions, pupillary constriction was points for and against them. Conservative management, carries
ensured. Anterior chamber formed with visco surgical device. the least risks but takes the longest time to resolve. Intracameral
Technique of suture introduction is positioning the sharp end isoexpansile gas is the most commonly used intervention, but
of the curved needle perpendicular to the surface of cornea at carries the risk of pupillary block with IOP rise. Decompression
the margin of edematous cornea and clear cornea, next enter- sutures have the risks of suture related complications , and re-
ing directly to anterior chamber taking care not to damage the quire suture removal, which may be difficult without general an-
iris following which exit of the curved needle from the horizon- aesthesia in the younger populations, and Down’s children. Early
tally opposite end of the junction. Similarly, four interrupted penetrating keratoplasty in an inflamed eye carries a higher risk
full-thickness corneal compressive sutures were placed centrally of rejection. Intrastromal fluid drainage leads to early resolution
covering the oedematous part of cornea. but at the hands of an inexperienced surgeon may lead to cor-
Results - On the first postoperative day, there were persistent neal fistulas.
stromal oedema and lot of discomfort owing to inflammation. Intraoperative imaging is the future for the management of
However, from the 7th post-op day, there were signs of resolu- acute corneal hydrops, especially those not resolving after medi-
tion and by 28th post-op day, there was complete resolution of cal management or surgical interventions. MI-OCT helps guide
corneal oedema leaving a nebular scar with sutures. On the 45th the surgeon regarding the depth and location of the intrastromal
post-op day, corneal sutures were removed under strict aseptic fluid clefts. After the drainage of fluid has been ensured, the in-
conditions in the operating room. Slit lamp examination showed jection of air in the anterior chamber provides adequate tam-
peripherally clear cornea with central dense scar and suture ponade as well as saves the eye from complications that come
tracks; there was no evidence of corneal vascularisation. along with isoexpansile gases (iop rise, pupillary block).
References
Figure 2 :
1. Maharana PK, Sharma N, Vajpayee RB. Acute corneal hy-
Figure 3 : drops in keratoconus. Indian J Ophthalmol. 2013;61(8):461-464.
doi:10.4103/0301-4738.116062
Conclusion
Acute corneal hydrops occurs in approximately 2.4-3%[2,3] of 2. Grewal S, Laibson PR, Cohen EJ, Rapuano CJ. Acute hydrops in the
eyes with keratoconus, and without any treatment , resolve spon- corneal ectasias: Associated factors and outcomes Trans Am Ophthal-
taneously over a period of a few months. The various manage- mol Soc. 1999;97:187–203
ment options to shorten the resolution time include patching,
bandage contact lens (BCL) application with topical hypertonic 3. Sharma R, Titiyal JS, Prakash G, Sharma N, Tandon R, Vajpayee
sodium chloride, intracameral injection of air/isoexpansile gas, RB. Clinical profile and risk factors for keratoplasty and develop-
ment of hydrops in north Indian patients with keratoconus Cornea.
2009;28:367–70

4. Stoiber J, Muss W, Ruckhofer J, Grabner G. Acute keratoconus with
perforation in a patient with Down’s syndrome Br J Ophthalmol.
2003;87:120

5. Tuift SJ, Gregory WM, Buckley RJ. Acute corneal hydrops in keratoco-
nus. Ophthalmology. 1994;101:1738–44.

6. Sharma N, Maharana PK, Jhanji V, Vajpayee RB. Management of
acute corneal hydrops in ectatic corneal disorders. Curr Opin Oph-
thalmol. 2012;23:317–23.

7. Basu S, Vaddavalli PK, Ramappa M, Shah S, Murthy SI, Sangwan
VS. Intracameral perfluoropropane gas in the treatment of acute cor-
neal hydrops. Ophthalmology. 2011;118:934–9

8. Alio JL, Toprak I, Rodriguez AE. Treatment of Severe Keratoconus
Hydrops With Intracameral Platelet-Rich Plasma Injection. Cornea.
2019 Dec;38(12):1595-1598. doi: 10.1097/ICO.0000000000002070.
PMID: 31335522.

DOS Times - Volume 28, Number 2, March-April 2022 78 www.dosonline.org/dos-times

Article Review

9. Tu EY. Descemet Membrane Endothelial Keratoplasty Patch for Per- 13. Subudhi P, Khan Z, Subudhi BNR, Sitaram S. To show the efficacy of
sistent Corneal Hydrops. Cornea. 2017 Dec;36(12):1559-1561. doi: compressive sutures alone in the management of acute hydrops in a
10.1097/ICO.0000000000001351. PMID: 28872520. keratoconus patient. BMJ Case Rep. 2017;2017:bcr2016218843. Pub-
lished 2017 May 4. doi:10.1136/bcr-2016-218843
10. Vajpayee RB, Maharana PK, Kaweri L, et al Intrastromal fluid drain-
age with air tamponade: anterior segment optical coherence tomog- Corresponding Author:
raphy guided technique for the management of acute corneal hydrops
British Journal of Ophthalmology 2013;97:834-836. Dr. Anushka Agarwalla, MBBS
Dr. Rajendra Prasad Centre for Ophthalmic Sciences,
11. Siebelmann S, Händel A, Matthaei M, Bachmann B, Cursiefen C. Mi- All India Institute of Medical Sciences, New Delhi.
croscope-Integrated Optical Coherence Tomography-Guided Drain-
age of Acute Corneal Hydrops in Keratoconus Combined With Sutur-
ing and Gas-Aided Reattachment of Descemet Membrane. Cornea.
2019 Aug;38(8):1058-1061. doi: 10.1097/ICO.0000000000001958.
PMID: 31276463.

12. Maharana PK, Shaikh F, Nayak S, Sahay P. Comment on: “Micro-
scope-Integrated Optical Coherence Tomography-Guided Drainage
of Acute Corneal Hydrops in Keratoconus Combined With Sutur-
ing and Gas-Aided Reattachment of Descemet Membrane”. Cornea.
2020 Feb;39(2):e6. doi: 10.1097/ICO.0000000000002165. PMID:
31724983.

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DOS Times - Volume 28, Number 2, March-April 2022

Monthly Meeting

Tackling the posterior capsule in pediatric
cataract surgery for prevention of visual
axis opacification

Shailja Tibrewal, MS, Soveeta Rath, DNB, Sharika Ganjoo, MS, Suma Ganesh, MS, DNB
Department of Pediatric Ophthalmology, Strabismus and Neuro-ophthalmology, Dr. Shroff ’s Charity Eye Hospital, New Delhi.

Pediatric cataract is one of the leading causes of preventable Patient-related factors Surgery-related factors
childhood blindness accounting for 7.4% to 15.3% of the
disease burden if not detected and treated early.[1] Treatment Age Extent of cortical clean up
encompasses removal of the opacified lens and its replacement Type of cataract like post trauma, Material and design of IOL
with intraocular lens (IOL) in most cases. Despite advancements rubella cataract, uveitic cataract Location of the IOL
in the surgical techniques involved in pediatric cataract Associated ocular condition Management of the posterior
management, visual axis opacification (VAO) remains the like PHPV, anterior segment capsule
most complication and the most frequent reason for a second dysgenesis Management of the anterior
intraocular procedure.[2,3] Occurrence of a VAO defeats the vitreous
whole purpose of doing an early cataract surgery and precludes Amount of surgical
any further optical rehabilitation or amblyopia management. manipulation
In senile cataract surgery minor modifications in the surgical
technique and the choice of IOL has been able to reduce the PHPV = persistent hyperplastic primary vitreous, IOL = Intraocular
posterior capsular opacification (PCO) rates.[4] However, in lens
children, the rates of PCO and subsequent Nd:YAG capsulotomy
or surgical membranectomy are much higher, especially when Figure 1 : Different types of visual axis opacification (VAO) after pediatric
the posterior capsule is left intact.[5,6] cataract surgery. a) the Elshnig’s pearls type, b) the fibrous type and c)
Mechanism of VAO combination of both Elshnig’s pearls and fibrous VAO.

Visual axis opacification results from proliferation of the Surgical Prevention of visual axis opacification in children
pre-equatorial lens epithelial cells (LECs), their differentiation The choice of intraocular lens
into mesenchymal cells and migration towards the central por- Hydrophobic acrylic IOLs are preferred over PMMA IOL in
tion of the posterior capsule. The triggers for proliferation of children owing to its better biocompatibility and reduced PCO
the pre-equatorial LECs following the surgical intervention are rates.[11,12] The VAO after implantation of a PMMA IOL occurs
the removal of the lens matter, presence of residual lens matter, rapidly after the surgery and is thicker and of the fibrous type.
alteration of the aqueous microenvironment, breakdown of the While the VAO occurring after the hydrophobic acrylic IOL
blood aqueous barrier and the presence of a foreign body in the implantation are proliferative type. Experimental studies have
form of the IOL.[7-9] These responses are exaggerated in children shown that the acrylic IOLs adhere more to the posterior cap-
owing to the greater density of the mitotically active cells at a sule due to which LECs are unable to migrate to the central part
young age. The LECs then not only migrate towards the central of the visual axis. In an intra-patient comparative study wherein
portion of the posterior capsule but also differentiate to form one eye received acrylic IOL and the other eye of the same pa-
two distinct morphological types of after cataract. The first one tient received PMMA IOL, it was observed that visually signifi-
is differentiation into pearl like bladder cells with granular cyto- cant PCO was seen in 75% of eyes with PMMA IOL as compared
plasm and a pyknotic or absent nuclei, which clinically looks like to 21.5% of eyes with acrylic IOL.[13] This study was conducted in
swollen opacified cells (Elschnig’s pearls, Figure 1a). The second children above 5 years of age and the posterior capsule was left
one is the fibrous type PCO (Figure 1b) comprising of elongated intact. Another factor in IOL design is a sharp optic edge which
fibrobast cells positive to alpha smooth muscle actin. This results creates an acute bend in the posterior capsule which acts as a
from the epithelial mesenchymal transition (EMT) of the LECs
triggered by TGF β.[10] A combination of both types of VAO may
be found in some cases (Figure 1c).
Several preoperative and intraoperative factors may affect the
formation of VAO and are listed in Table 1.

DOS Times - Volume 28, Number 2, March-April 2022 80 www.dosonline.org/dos-times

physical barrier to LEC proliferation.[14] Both these factors make forceps). The procedure is best carried under retroillumination
hydrophobic acrylic IOLs with square edge as the ideal choice mode and high magnification of the operating microscope. The
for the pediatric age group. It is important that the IOL edge is anterior chamber is filled with high viscosity viscoelastic (pref-
covered entirely by the anterior capsulorhexis edge in order to erably sodium hyaluronate) and the posterior capsule should be
prevent the fibrous type PCO especially in the PMMA lenses. concave at all times in order to prevent extension of the rhexis.
Similarly, in-the-bag IOL implantation plays some role in reduc- Initial nick is made just outside the center using a bent 26 G nee-
ing the overall incidence of VAO in children. dle (Figure 3a). The PC may be stained with trypan blue to facil-
itate the visualisation of the PC during PPC.[20] After the nick is
Management of the posterior capsule made small amount of viscoelastic is injected behind the PC to
If the posterior capsule is left intact during pediatric cataract separate the anterior vitreous from it. The edge of PC is grasped
surgery, VAO is a surety especially in very young children. The using the microrhhexis forceps and a centripetal force is applied
highly active LECs in children rapidly migrate towards the to initiate a curvilinear opening (Figure 3b and c). The PC is ex-
central posterior capsule obliterating the visual axis soon after tremely thin (3-4µ) and elastic and the opening is always larger
the cataract removal (Figure 2a). Addition of a central primary than desired. Hence the PC needs to be left and regrasped at the
posterior capsulotomy (PPC) alone reduces the rate of VAO edge making small advancements. The ideal size of a PPC should
to 60%.[15,16] One would assume that removal of the central be 4 to 4.5mm and should be smaller than the anterior curvi-
portion of posterior capsule should eliminate the possibility of linear capsulorhexis (ACC). It should be round, circular, well
VAO. However, in children the LECs proliferate over the intact centered and concentric to the ACC (Figure 3d). A well-made
anterior vitreous face in the absence of the posterior capsule PPC has a sturdy border which is resistant to manipulation and
(Figure 2b). Limited anterior vitrectomy removes this scaffold extension during the rest of the procedure. Care should be taken
and hinders the migration of LECs behind the IOL (Figure 2c). to avoid anterior vitreous face disturbance during the PPC and
Thus, for prevention of VAO, surgical removal of the anterior undue traction on the vitreous. This can be seen as strands of
vitreous along with the PPC has become the procedure of choice vitreous attached to the PC while pulling it, strands in the ante-
in children below six years of age.[17] The other procedures for rior chamber or the rolling of the PPC or ACC borders after the
posterior capsule management and prevention of VAO are procedure is completed. Subtle anterior vitreous disturbances
posterior optic capture and bag-in-the-lens IOL implantation. may be unavoidable but should be borne in mind and identified
at the earliest.

Figure 2 : Mechanism of Visual axis opacification in different surgical Figure 3 : Surgical steps involved in creation of a primary posterior
approaches involving the posterior capsule (PC). a) shows that when capsulotomy (PPC). a) shows the initial nick in the posterior capsule
the PC is left intact the lens epithelial cells (LECs) undergo an epithelial created by a bent cystitome, b) and c) show the curvilinear extension of the
mesenchymal transformation (red arrow) and the myofibroblasts (MFs) flap using a microrhexis forceps, and d) shows the PPC after completion.
migrate towards the central visual axis along the PC. b) shows that when
the PC is removed alone and the anterior vitreous is left intact, the latter Certain alternative techniques to create the posterior capsulot-
acts as a scaffold and promotes migration of MFs. c) shows that when the omy have been described. These include the two-incision push-
anterior vitreous is also removed, the MFs fail to migrate to the central pull capsulotomy, radiofrequency diathermy assisted posterior
visual axis. d) shows the course of the LEC and MFs when posterior optic capsulotomy, pars plicata approach manual PPC and vitrector
capture is performed. The PC and anterior capsule (AC) come close to
each other and fuse over the anterior edge of the optic, limiting the MFs. e)
shows the situation in bag-in-lens IOL implantation, wherein the groove
acts as a strong barrier to the LECs and MFs.

Primary posterior capsulotomy with anterior vitrectomy
The combination of PPC with anterior vitrectomy (AV) has
resulted in reduction of VAO rates to as low as an average of
6%.[17-19] A manual PPC is constructed after aspiration of the lens
matter, using a capsulorrhexis forceps (utratta’s or microrhexis

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DOS Times - Volume 28, Number 2, March-April 2022

assisted capsulotomy. The two-incision push-pull technique was ever, it provides certain advantages like, ease of implantation of
popularised by Nischal K in 2002 and has been shown to give IOL and viscoelastic removal with an intact PC, ability to create
consistent results.[21,22] In this technique, two stab incisions are large sized PPC opening, and minimising chances of any vitre-
made 4 to 5 mm apart in the posterior capsule using an MVR ous prolapse during AV. The location of the scleral ports varies
blade. These incisions act as the outline of the capsulorhexis. with age in very young children as the pars plana is still devel-
The two ends of the proximal stab incision are then pushed, one oping. It should be 2.0 mm posterior to the limbus in children
by one, midway towards the distal stab incision. The ends of younger than 1 year of age, 2.5 mm in 1 to 4 years old, and 3.0
the distal stab incision are similarly pulled one by one towards mm in children beyond 4 years of age. Ahmadieh et al found no
the proximal wound. When the two ends meet on either side, statistically significant difference between the two approaches in
it results in complete CCC. The posterior capsule should be terms of outcomes in a randomized controlled double-masked
considerably elastic to achieve success via this technique, thus clinical trial of 45 eyes.[25] The choice of the approach for AV
making it suitable for pediatric age group, especially children largely depends on the surgeon’s experience and skill.
below 12-13 years of age. This technique has an advantage of The rate of retinal detachment following PPC and AV is low in
a shorter learning curve. Radiofrequency diathermy has been the pediatric population.[28] Male gender, myopia and intellec-
described to create a controlled PPC.[23] However, it reduces the tual disability have been found to be risk factors for retinal de-
tensile strength of the capsule making it susceptible to damage tachment after pediatric cataract surgery and warrant long-term
during further intraocular manipulations. Alternatively, the vit- follow up. Considering the risks, albeit small, involved when the
rectomy cutter can be used to create the PPC opening instead anterior vitreous is disturbed, some authors have suggested to
of the manual technique. This method can be adopted in case avoid AV in children more than 3 years of age.[29] With the ad-
the manual technique seems difficult, or when there is an asym- vent of modern vitrectomy machines, the risk of cystoid macular
metric PC plaque. In such cases the cut rate can be lowered to edema[30] and retinal detachment has further reduced, and most
600-700 depending on the thickness of the plaque. The vitrector pediatric ophthalmologists would perform PPC and AV till 6
assisted PPC can be made before or after the implantation of years of age to avoid VAO and a secondary procedure. Posterior
the IOL. However, it needs to be kept in mind that a PPC made optic capture and bag in the lens are two techniques which may
using a vitrector is not as robust as the manual PPC and can obviate the need for an AV and still prevent VAO. These two
tear off while manipulating for IOL implantation. Hence, it is techniques are described below.
preferred to implant the IOL safely in the bag and then lift it
up from one edge and perform vitrector assisted PPC and AV Optic capture (Optic buttonholing)
beneath it. Both limbal and pars plana approaches for vitrector Intraocular lens optic capture in the posterior capsule remains
assisted PPC have been described in literature with comparable one of the methods to prevent visual axis opacification apart
results.[24,25] Pars plicata approach manual PPC involves creation from conventional primary posterior capsulotomy (PPC) with
of stab wound in the pars plicata to approach the PC from be- anterior vitrectomy. Gimbel and DeBroff[31] initially described
hind and then using a coaxial capsulorhexis forceps a PPC is this method in children using implantation of polymethylmeth-
fashioned in the similar manner as a limbal approach. This tech- acrylate (PMMA) IOL. In this technique, after implantation
nique is surgically demanding and has a steep learning curve of IOL in bag the optic is nudged behind the PCC (Figure 4).
which precludes wider application.[26] This brings the anterior capsule and PC in close apposition to
The anterior vitrectomy is performed using a high-speed auto- each other preventing proliferation of residual cortex (Figure
mated vitrector after the successful completion of the manual 2d). Also, the IOL acts as a barrier preventing LEC migration
PPC. In a vitrector-assisted PPC, the AV can be done with the over the anterior vitreous. Single-piece PMMA IOLs and three-
same cutter by just adjusting the cut rate. Vitrectomy procedure piece acrylic IOLs are commonly used in this procedure.[32-35]
is always performed under high magnification and with clear The three-piece design at its optic-haptic junction permits 360
visibility.[27] Triamcinolone acetonide 0.1 ml (4 mg/0.1 ml) may degrees of capsular fusion and since they are hydrophobic, they
be used to stain the anterior vitreous and facilitate its visualisa- adhere well to the capsules preventing large decentration. The
tion. The goal is to create a crater just beneath the PPC opening, other approaches include placing the haptics of IOL in the cili-
removing only the anterior vitreous and leaving the posterior ary sulcus and capturing the optic through the posterior capsu-
and peripheral vitreous intact. The vitrectomy settings depend lorhexis.[36] This approach is also feasible in cases of incomplete
on the available machine, a high cut rate (900 or above) being anterior capsulorhexis, wherein it decreases the total area of
preferred. The endpoint of anterior vitrectomy is considered optic contact with the iris and reduces the uveal inflammatory
when the PC stops fluttering, there is no rolling of PC or anterior response. The technique of posterior optic capture is challeng-
capsule margins and there is no vitreous strand in the anterior ing as it requires well centred and optimally sized of the PPC
chamber. Anterior vitrectomy can be performed via limbal or opening. Ideally the PPC opening should be 1 to 1.5mm lesser
pars-plana approaches. Most surgeons prefer the limbal route than the optic size. Smaller sized opening may endanger rupture
as it is well versed procedure to anterior segment surgeons and while capturing the optic and larger sizes may fail to capture the
does not require creation of additional scleral ports. The pars optic altogether. Grieshaber et al[37] used posterior vertical cap-
plana approach may require additional surgical expertise. How- sulotomy with optic entrapment, a modified technique wherein

DOS Times - Volume 28, Number 2, March-April 2022 82 www.dosonline.org/dos-times

capsulotomy of anterior and posterior capsule in a vertical di- Bag-in-the lens
rection with length comparable to that of IOL and capture was Proliferation of LECs between the optics and haptic is the major
done following PMMA lens implantation. However, with any cultprit in causing VAO. The Bag in the Lens (BIL) technique
of the described techniques of capture, whether simultaneous virtually eliminates the possibility of LEC proliferation behind
anterior vitrectomy must be done is still controversial. Several the IOL. This technique was described by Tassignon et al in 2002
studies have shown that the rate of VAO is almost zero with op- and encompasses the use of a specially designed lens.[44] This lens
tic capture without vitrectomy.[38,39] Vasavada et al conducted a has a 360-degree groove in the rim of the optic formed by two
prospective randomised controlled study comparing results of flanges as shown in Figure 5. The anterior and posterior capsule
posterior optic capture with and without vitrectomy and showed should be positioned in this groove during the surgery, thereby
that the VAO incidence is much lower when vitrectomy is added entrapping the LECs within the doughnut of the capsular bag
(70% vs 21%).[40] They concluded that in cases with intact vitre- (Figure 2e). The circumferential interhaptic groove tightly en-
ous and posterior optic capture the VAO was due to a primary circles the optic when placed appropriately between the anterior
response of the anterior vitreous face to the IOL optic and not and posterior capsular blades. Such a tight apposition acts as a
due to proliferation of the LECs. barrier and prevents proliferation of LECs. This technique de-
mands a calibrated anterior and posterior capsulorhexis, pref-
erably same size (5mm). A ring calliper is used to outline the
size of the anterior rhexis. The posterior capsulorhexis is then
fashioned along the borders of the anterior CCC. To enable sim-
ilar sized anterior and posterior capsulotomies, the PC should
be kept in closed apposition with the anterior capsule while per-
forming the PPC by judicious use of viscoelastic. The IOL is then
inserted, positioning both the anterior and posterior capsules in
the groove. The haptics are suspended centrally by the bag and
have no direct mechanical contact with the ciliary body or sul-
cus. Anterior vitrectomy can be avoided using the BIL technique
even in children younger than 2 years of age unless a disturbed
vitreolenticular interface is present.[45] It is safe and well tolerated
in the pediatric population with negligible chances of reopaci-
fication.[44,46] IOL power calculation in such cases can be done
using the conventional formulae. Apart from nullifying chances
of VAO, other post operative complications are also minimal.

Figure 4 : Schematic diagram of the optic capture technique when the
intraocular lens optic is nudged behind the posterior capsule opening
while the haptics are in the capsular bag. The green dotted lines and yellow
dotted lines represent the anterior and posterior capsule respectively.

Although optic capture remains a viable option to prevent VAO, Figure 5 : Schematic diagram of the bag-in-lens intraocular lens. The two
chances of increased post operative inflammation and iris syn- flanges with the groove (dotted arrow) can be seen.
echiae have been reported al.[37,41] The other most commonly
noted finding was intraocular lens deposits following capture
surgery in children. The deposits may include pigments, inflam-
matory cells, or lens cortex. Studies by Zhou et al and Vasavada
et al have shown increased deposits on the anterior IOL surface
early after surgery and also after long term follow up.[41,42] How-
ever, more recently Kaur et al compared the rates of intraoper-
ative and postoperative complications between posterior optic
capture without vitrectomy and the standard in-the-bag IOL im-
plantation with PPC and AV in a randomised prospective study
with a sample size of 15 children.[43] They found both surgeries
to be comparable with optic capture being better in terms of LEC
proliferation and inflammatory sequelae.

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DOS Times - Volume 28, Number 2, March-April 2022

Special Situations vantage of this technique is that the plaque can be removed in
totality despite its size. Even if there is a strong adhesion which
PC plaque leads to PC rupture while attempting to peel the plaque, the size
Very often posterior capsular plaques may be encountered of the PC opening is small and often does not compromise IOL
which may warrant a modification in the routine manual PPC implantation in the bag.
and AV. The size and thickness of the plaque often determine the Cataracts associated with persistent fetal vasculature (PFV) are
surgical approach in such cases. In the presence of small cen- often found to have a vascularised PC plaque attached to the stalk
tral plaques, a manual PPC can be created around the opacity, (Figure 8a). In such cases endocautery can be used to cauterise
wherein the plaque is removed along with the PC. In larger or the vessels before attempting PPC to avoid intraocular bleeding
asymmetric plaques vitrectomy assisted PPC may be performed (Figure 8b). Again, depending on the size of the plaque a manual
(Figure 6).[47] The cut rate needs to be reduced in such cases. For PPC may be fashioned around it or a vitrector may be used to re-
extremely thick plaques a microscissor may be required to cut move it. The PC opening in such cases should always be made at
the areas not amenable to removal with vitrector. Alternatively, the edge of the plaque and not at the centre (Figure 8c). The edge
it may be possible to peel the plaque off the posterior capsule of the PC opening should be lifted to inspect the stalk (Figure
(Figure 7).[48] After lifting the plaque edge using a sinskey hook 8d). If vascularised, the stalk should be cauterised before sever-
(Figure 7b), the edge is grasped using the Ikeda microrhexis for- ing it from the plaque (Figure 8e).[49,50] Both limbal and pars-pla-
ceps and gently peeled off using tactile and visual cues (Figure na approaches can be opted for managing the plaques associated
7c). In most cases the posterior capsule is found to be completely with PFV. Fugo blade-assisted plasma ablation and femtosecond
intact (Figure 7d). Once the plaque is peeled, the PC can then laser have also been described to create the posterior capsuloto-
be tackled using any of the above-described methods. The ad- my in cases with florid anterior PHPV.[51,52]

Figure 6 : Vitrector assisted primary posterior capsulotmy in the presence
of an asymmetric plaque. a) showing the vitrector being introduced behind
the intraocular lens, b) showing the extension of the PC opening by the
vitrector and c) showing the clear visual axis at the end of the procedure.

Figure 8 : Posterior capsule (PC) management in a persistent fetal
vasculature (PFV). a) shows the vascularised PC plaque, b) shows the use
of endocautery to cauterize the blood vessels on the PC, c) shows the use
of microscissors to cut the PC around the plaque, d) is showing the PFV
stalk (arrow) attached to the undersurface of the plaque which is visible
after the plaque is lifted, e) shows endocauterisation of the PFV stalk and
f) shows the step of anterior vitrectomy underneath the plaque to ensure
no traction on the vitreous when the plaque is pulled out of the eye.

Figure 7 : Surgical steps of peeling of plaque over posterior capsule. a) Posterior lenticonus
shows the large thick plaque, b) shows the edge of the plaque being lifted Posterior lenticonus/globus is a type of lenticular abnormality
using sinskey hook, c) shows the peeling of the plaque using microrhexis characterised by conical/globular projection of the posterior
forceps and d) shows the intact posterior capsule beneath the plaque after surface of the lens with or without a pre-existing PC defect (Fig-
it is peeled. ure 9). It is usually progressive and presents as sudden onset len-
ticular opacity in a child. In the initial stages where a clear lens
is present, it may be seen as an oil droplet sign on retinoscopy.
When the cataract sets it, it appears as a posteriorly located len-
ticular opacification, but may progress to total cataract rapidly.
Spindle shaped or elliptical pre-existing PC defects may be seen
which may be identified as sharply demarcated margins (Figure
9d). Whitish dots seen[53] attached to the PC or in the anterior
vitreous (Figure 9e) should raise the suspicion of a pre-exist-

DOS Times - Volume 28, Number 2, March-April 2022 84 www.dosonline.org/dos-times

ing PC defect. The characteristic ‘fish tail’ sign when the white ter into the vitreous cavity. In the absence of a PC defect the PC
dots in the vitreous move with the globe can be elicited using is found to be thin and inelastic in the conus region. The PC
a forceps preoperatively.[54] Intraoperative precautions during a in these cases is also extremely susceptible to rupture with the
suspected case of posterior lenticonus include avoiding hydro slightest manipulations. It is prudent to perform pars plana or
procedures and keeping the bottle height and flow rate low. This limbal vitrector assisted PPC in such cases as manual PPC may
is to avoid extension of the PC defect and escape of the lens mat- be difficult.

Figure 9 : Posterior capsule (PC) findings in a posterior lenticonus. a) shows the slit lamp view of the well defined cataract with posterior conical
projection, b) shows the intraoperative appearance of the posterior lenticonus after removal of lens matter and c) shows the intraoperative wrinkling of
the intact posterior capsule in this case. d) shows another patient with posterior lenticonus cataract where the elliptical shape of the opacity and the well
demarcated borders provide a hint to the diagnosis, e) shows the preexisting PC defect seen intraoperatively in the cataract seen in figure d. e) shows a
posterior lenticonus cataract with pre-existing PC defect, escape of lens matter into anterior vitreous and whitish dots in the anterior vitreous.

To summarise, management of the posterior capsule during children with aphakia and pseudophakia after unilateral cataract sur-
pediatric cataract surgery is an essential step in maintaining a gery during the first six months of life. J AAPOS 2001; 5:70–75
clear visual axis. Primary posterior capsulotomy with anterior
vitrectomy is recommended in children below 6-7 years of age, 3. Trivedi RH, Wilson ME Jr, Bartholomew LR, Lal G, Peterseim MM.
beyond which the PC may be left intact. Nd-YAG capsulotomy Opacification of the visual axis after cataract surgery and single acryl-
can be performed in older children if the PCO forms in the post- ic intraocular lens implantation in the first year of life. J AAPOS 2004;
operative period. Additionally uncooperative children, or those 8:156–164.
with intellectual disabilities or nystagmus may require PPC even
at older ages. Techniques of posterior optic capture and bag-in- 4. Raj SM, Vasavada AR, Johar SR, Vasavada VA, Vasavada VA.
lens IOL implantation may be valuable alternatives in a surgeon’s Post-operative capsular opacification: a review. Int J Biomed Sci. 2007
armamentarium. Dec;3(4):237-50.
References
5. Dholakia SA, Vasavada AR, Singh R. Prospective evaluation of
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8. Rakic JM, Galand A, Vrensen GF. Separation of fibres from the cap- M, Dehghan MH, Mashyekhi A, Valaei N, Soheilian M, Sajjadi H.
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18. Jensen AA, Basti S, Greenwald MJ, Mets MB. When may the posterior 34. Vasavada AR, Trivedi RH, Singh R. Necessity of vitrectomy when op-
capsule be preserved in pediatric intraocular lens surgery? Ophthal- tic capture is performed in children older than 5 years. J Cataract
mology. 2002;109(2):324–327. discussion 328. Refract Surg 2001;27(8):1185-1193.

19. Kugelberg M, Zetterström C. Pediatric cataract surgery with or with- 35. Koch DD, Kohnen T. A retrospective comparison of techniques to pre-
out anterior vitrectomy. J Cataract Refract Surg. 2002;28(10):1770– vent secondary cataract formation after posterior chamber intraocu-
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20. Saini JS, Jain AK, Sukhija J, Gupta P, Saroha V. Anterior and posteri-
or capsulorhexis in pediatric cataract surgery with or without trypan 36. Faramarzi A, Javadi MA. Comparison of 2 techniques of intraocu-
blue dye: randomized prospective clinical study. J Cataract Refract lar lens implantation in pediatric cataract surgery. J Cataract Refract
Surg. 2003;29(9):1733–1737. Surg 2009;35(6):1040-1045.

21. Kent DG, Sims JCR, Apple DJ. Pediatric capsulorhexis technique. (let- 37. Grieshaber MC, Pienaar A, Stegmann R. Posterior vertical capsu-
ter) J Cataract Refract Surg 1995; 21:236. lotomy with optic entrapment of the intraocular lens in congenital
cataracts-prevention of capsule opacification. J Cataract Refract Surg
22. Hamada S, Low S, Walters BC, Nischal KK. Five-year experi- 2005;31(5):886-894
ence of the 2-incision push-pull technique for anterior and poste-
rior capsulorrhexis in pediatric cataract surgery. Ophthalmology. 38. Raina UK, Gupta V, Arora R, Mehta DK. Posterior continuous cur-
2006;113(8):1309–1314. vilinear capsulorhexis with and without optic capture of the posterior
chamber intraocular lens in the absence of vitrectomy. J Pediatr Oph-
23. Comer RM, Abdulla N, O’Keefe M. Radiofrequency diathermy cap- thalmol Strabismus 2002; 39:278–287.
sulorhexis of the anterior and posterior capsules in pediatric cataract
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644. sulorhexis with optic capture and intracameral heparin in paediatric
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24. Alexandrakis G, Peterseim MM, Wilson ME. Clinical outcomes of
pars plana capsulotomy with anterior vitrectomy in pediatric cataract 40. Vasavada AR, Trivedi RH, Singh R. Necessity of vitrectomy when op-
surgery. J AAPOS 2002; 6:163–167. tic capture is performed in children older than 5 years. J Cataract
Refract Surg 2001; 27:1185–1193.
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41. Vasavada AR, Trivedi RH. Role of optic capture in congenital cata- 50. Lyu J, Zhao P. Intraocular lens implantation in combination with len-
ract and intraocular lens surgery in children. J Cataract Refract Surg sectomy and vitrectomy for persistent fetal vasculature. Graefes Arch
2000;26(6): 824-831. Clin Exp Ophthalmol. 2020 Dec;258(12):2849-2856. doi: 10.1007/
s00417-020-04880-9. Epub 2020 Aug 11. PMID: 32780257.
42. Zhou HW, Zhou F. A Meta-analysis on the clinical efficacy and safe-
ty of optic capture in pediatric cataract surgery. Int J Ophthalmol 51. Tereshchenko AV, Trifanenkova IG, Vladimirovich VM. Femtosecond
2016;9(4):590-596. laser-assisted anterior and posterior capsulotomies in children with
persistent hyperplastic primary vitreous. J Cataract Refract Surg.
43. Kaur S, Sukhija J, Ram J. Comparison of posterior optic capture of in- 2020 Apr;46(4):497-502. doi: 10.1097/j.jcrs.0000000000000139.
traocular lens without vitrectomy vs endocapsular implantation with PMID: 32271292.
anterior vitrectomy in congenital cataract surgery: A randomized
prospective study. Indian J Ophthalmol. 2020 Jan;68(1):84-88. doi: 52. Sinha R, Bali SJ, Kumar C, Shekhar H, Sharma N, Titiyal JS, Vajpay-
10.4103/ijo.IJO_522_19. PMID: 31856476; PMCID: PMC6951169. ee RB. Results of cataract surgery and plasma ablation posterior cap-
sulotomy in anterior persistent hyperplastic primary vitreous. Middle
44. Tassignon M-JBR, De Groot V, Vrensen GFJM. Bag-in-the lens East Afr J Ophthalmol. 2013 Jul-Sep;20(3):217-20. doi: 10.4103/0974-
implantation of intraocular lenses. J Cataract Refract Surg 2002; 9233.114794. PMID: 24014984; PMCID: PMC3757630.
28:1182–1188.
53. Singh D, Singh R, Singh I. Cataract and IOL. New Delhi, India, Jaypee
45. Looveren JV, Dhubhghaill, SN , Godts D et al. Pediatric bag-in-the- Brothers, 1993; 160–167
lens intraocular lens implantation: Long-term follow-up. J Cataract
Refract Surg 2015; 41:1685–1692. 54. Vasavada AR, Praveen MR, Nath V, Dave K. Diagnosis and manage-
ment of congenital cataract with preexisting posterior capsule defect. J
46. Tassignon M-J, De Veuster I, Godts D, Kosec D, Van den Dooren K, Cataract Refract Surg 2004; 30: 403–408.
Gobin L. Bag-in-the-lens intraocular lens implantation in the pediat-
ric eye. J Cataract Refract Surg 2007; 33:611–617. Corresponding Author of the Article:

47. Praveen MR, Shah SK, Vasavada AR, Vasavada VA, Asnani PK, Dr. Shailja Tibrewal, MS
Anwar I, Trivedi RH. Incidence, management, and postoperative Senior Consultant, Department of Pediatric Ophthalmology,
outcomes in pediatric eyes with coexisting posterior capsule plaque Strabismus and Neuro-ophthalmology, Dr. Shroff’s Charity Eye
and cataract. J Cataract Refract Surg. 2010 Dec;36(12):2094-9. doi: Hospital, New Delhi
10.1016/j.jcrs.2010.07.015. PMID: 21111312.

48. Landa G, Pham K. Manual Removal of Primary Posterior Capsu-
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49. Khurana S, Ram J, Singh R, Gupta PC, Gupta R, Yangzes S, Sukhija
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2021 Jan;259(1):213-221. doi: 10.1007/s00417-020-04883-6. Epub
2020 Aug 17. PMID: 32803327.

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DOS Times - Volume 28, Number 2, March-April 2022

Monthly Meeting

SD - OCT Imaging in high myopia and
glaucoma detection

Dr. NZ Farooqui[1], MS, Dr. JS Bhalla[2], MBBS, MS, DNB, MNAMS, Dr. Kiran Bhanot[3], MS, DNB, Dr. Karuna Dhepe[4], DNB, Dr. Pooja Kothari[5],
DNB, Dr. Mahsa Jameel[6], MS,
1. Senior Consultant, DDU Hospital, New Delhi
2. Senior Consultant & Academic Incharge, Department of Ophthalmology, DDU Hospital, New Delhi
3. Senior Consultant & HOD, IGH, Dwarka, New Delhi
4. Resident, DDU Hospital, New Delhi
5. Resident, DDU Hospital, New Delhi
6. Senior Resident, DDU Hospital, New Delhi

Myopia is a common ocular condition and was expected appearance, peripapillary atrophy, disc tilting, disc torsion and
to affect 2.5 billion population by year 2020 according to extremely large/small disc.
prevalence studies.[1,2] The increased prevalence has reached It may be difficult to make an accurate assessment due to
epidemic proportion in certain regions, with an estimated variable deformation of Optic Disc, peripapillary appearance
38.7% adult myopic Chinese in Singapore, 9.1% being high Nerve Head, posterior fundus changes[10] and thinner RNFL
myopes.[2] The highest prevalence rates of myopia and high measurement[11] due to increased axial length in myopic eyes,
myopia is found in Japanese subjects.[3] Myopia is a known risk causing interpretational difficulties in differentiating from the
factor for developing open-angle glaucoma[4] One meta-analysis early glaucomatous changes.[10]
revealed that the pooled odds ratios were 1.77 and 2.46 for The preferred practice Patterns of American Academy of
low and high myopia, respectively, with a cut off value of -3.0 Ophthalmology though suggests detailed routine for glaucoma,
D.[5] In a large Swedish study by Grødum K et al[6] reported however the recommendations for high myopic eyes and
the association between myopia and POAG in the eyes with glaucoma is lacking.[12]
a normal IOP (normal-tension glaucoma). It is of increasing Normative databases incorporated in the OCT devices is consti-
clinical relevance to diagnose glaucoma in early stages especially tuted mainly from normal eyes and low degrees of myopic eyes.
in myopes.[7] The diagnosis of early glaucoma (pre-perimetric Hence, the deviation maps or classification charts provided by
glaucoma) depends on the evaluation of glaucomatous structural the OCT devices may lead to an interpretation errors in highly
abnormalities alone. myopic eyes.
Spectral-Domain OCT, a non-invasive imaging technique is Peripapillary Atrophy
increasingly being used for early detection of glaucomatous
changes in the pre-perimetric stage, and for monitoring of Figure 2 : A : Showing α zone, β zone ; B : γ zone ; C : SD-OCT Imaging
glaucoma. To detect the early changes in glaucoma, it is necessary Showing α,β,γ zones.
to assess the changes and alterations of RNFL thickness (RNFLT)
and Ganglion layer- Inner Plexiform layer thickness accurately Peripapillary atrophy is differentiated into central β-zone and
(GCIPL)/Ganglion Cell Complex (GCC) thickness and optic a peripheral α-zone. The α-zone is characterized by irregular
nerve head parameters. hypopigmentation and hyperpigmentation of RPE and choroidal
However, high refractive errors[8] and increased axial length[9] in tissue thinning.
myopic eyes can significantly affect RNFL thickness and peak In the central β-zone Bruch’s membrane is intact however there
position. In moderate to high myopic eyes, structural changes is loss of RPE, photoreceptors and choriocapillaries making
are commonly present such as shallow enlarged cupping, pale large choroidal vessels more conspicuous. The β-zone is known
to be associated with glaucoma in myopic eyes.
Figure 1 : OHN characteristics in high Myopia: PPA, Optic Disc Tilt, Pale
appearance, Shallow Enlarged cupping.

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This needs to be differentiated from γ-zone also known as myopic peripapillary atrophy zone, increasing disc tilt and progressive
temporal cresent or conus in high myopic eyes, seen as whitish nasalization and nasal rotation of centreal retinal vessel trunk.
area temporal to disc margin, without RPE and choriocapillaries. If the calculation circle overlaps the PPA (Figure 4), segmenta-
The 3 zones cannot be differentiated by infra red image however tion error can occur being misinterpreted as decreased RNFL
they can be easily differentiate by SD-OCT images. thickness. Increasing the Calculation circle from 3.4 mm to 4.7
As the axial length increases the posterior sclearal expansion in- mm thereby excluding the PPA, may correct the segmentation
volving the ONH leads to (Figure 3) progressive enlargement of error.

Figure 3 : Showing progressive enlargement of PPA, more prominent Disc Tilt and progressive nasalization and nasal rotation of central retinal
vessel trunk.

Figure 4 : Showing segmentation error due to PPA in the Calculation Circle(yellow arrow).

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DOS Times - Volume 28, Number 2, March-April 2022

Optic Nerve Head Changes in High Myopic Eyes Figure 6 : Disc Tilt (A) illustrating Temporal Flatenning & Nasal Elevation
& (B) OCT imaging.
Optic Nerve Head (ONH) changes in high myopic eyes is due
to elongation of the eyeball. As the axial length increases there
is scleral thinning posterior to equator with maximal thinning
in the posterior pole, stretching and thinning the lamina
cribrosa.[13] The degree of the disc tilt and torsion are associated
with higher myopia and longer axial length and correlated with
higher susceptibility to glaucoma.[14,15] Optic Nerve Head Tilt
was found to be more prominent feature in myopia associated
with POAG but not torsion. The study by Park et al concluded
that NTG eyes had a greater ONH torsion compared to POAG
eyes with matched axial length. The direction of the ONH tilt
and torsion was related to the location of the visual field defect
only in NTG eyes.[16] Asymmetric posterior sclera expansion,
in either the superior or the inferior region relative to the optic
disc, may result in superior or inferior disc torsion as myopia
develops. The optic disc changes may originate from changes of
the peripapillary sclera as myopia develops and are important in
the pathogenesis of glaucoma in myopia.[17]
Disc Tilting cannot be measured directly. It is estimated by
the disc ‘ovality’ index, measured as the ratio of the longest to
shortest diameter of the disc. It is classified as Tilted Disc if it is
< 0.7518. (Figure 5)
The disc tilt prevalence in NTG (not POAG) with high myopia
usually is smaller disc with greater proportion (56.5%) and of
higher severity.[19,20]
The axial elongation in myopia results in ONH being pulled in
the temporal direction leading to temporally tilted optic disc
appearance and temporal flattening with elevation of the nasal
disc margin.[21] The course of ONH vessels also changes in tilted
discs. (Figure 6)
The tilting of the disc is usually with reference to vertical axis,
however, disc tilt can occur along horizontal (Figure 7A) or
oblique axes (Figure 7B).

Figure 7 : A : Temporal Tilted Disc, B : Supero-Temporal Tilted Disc.

Temporal Optic Disc Tilt in myopia was associated with thicker
temporal RNFL and temporal shifting of the superior/inferior
peak location and thinning nasally.[22] (Figure 8)

Figure 5 : Measurement of Tilt Ratio. A : Normal Tilt Raio >0.75,
B : Tilted Disc : Ratio <0.75

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Figure 8 : Showing Temporal Displacement of RNFL peaks, and Thickening of RNFL Temporally and thinning nasally.
In myopic tilted discs, RNFL may not be measured if there is
marked peripapillary retinal elevation, exceeding the 2-mm
depth of focus of the OCT device, leading to exclusion of the
(Figure 9A) of the RNFL profile out of the scanning zone in the
circular retinal tomograph.

Figure 9 : A. Apex of Peripapillary RNFL being cut off B. Apex being
included in RNFL profile

Myopic Tilted Optic Disc can make it challenging to determine Figure 10 : Calculation for the Degree of Torsion Degree.
BMO centroid. Thus, confounding the peripapillary RNFL
thickness analysis. Any nasal displacement of the calculation cir- Pathogenesis of Optic Disc Tilt, Disc Torsion & Disc Size
cle causes increase in RNFL thickness temporally and decrease The axial elongation in high myopia is associated with posterior
of RNFL thickness nasally. scleral remodelling. This leads to thinning of sclera, unusually
Optic Disc Torsion is the rotation of the Optic Disc with large/skewed scleral canal shape, peripapillary atrophy, and
reference to saggital axis or along plane parallel to the retina. It thinning of lamina cribrosa.[24] The unequal scleral expansion
is measured as the angle between the axis of the longest diameter during the process of axial elongation, leads to varied posterior
deviating from the reference line. The Reference Line if vertical retinal/ONH changes in high myopic eyes. McBrien NA et al
line perpendicular to horizontal line connecting fovea to centre and Samarawickrama C et al reasoned that when the ONH is
of optic disc. (Figure 10) not included in the posterior sclera expansion, it leads to small
Optic Disc Torsion in NTG was observed in 75.9% myopic eyes myopic disc, temporally located Peripapillary Atrophy (PPA),
compared to 33.9% non-myopic eyes. The direction of the Disc Disc tilt and Disc torsion.
Torsion was a strong predictor of visual field defect location in However, if the ONH is affected during the scleral expansion, it
NTG eyes.[19] may result in large myopic disc, less disc tilt and disc torsion and
Sung MS et al[23] concluded in their study that the disc rotation circumferentially located peripapillary atrophy.[24,25] Previous
has a role in developing RNFL damage and visual field defects studies indicate that the processes of disc tilt and torsion exert
in myopic eyes however, these changes may be static and not mechanical stress on the LC and peripapillary nerve fibers,
progressive in nature.

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DOS Times - Volume 28, Number 2, March-April 2022

which increases their susceptibility or directly leads to nerve Kunliang Qiu et al[26] concluded that in healthy myopic subjects,
fiber damage.[20] 88.4% and 37% of eyes did not comply with the ISNT rule on
RNFL thickness and rim area, respectively and thus have limited
RNFL Measurement Errors commonly occur in High Myopic potential in diagnosing glaucoma in myopic subjects
Eyes because of ONH indices tend to be unreliable in high myope. For detecting
glaucomatous optic neuropathy in high myopic eyes, higher
- Temporal Displacement of retinal Ganglion cell axons and priority should be regarding the assessment of RNFL defects
blood vessels and focal rim thinning and/or notching rather that C:D/NRR
- Torsional Changes in RNFL Topography area. Hence, for evaluating glaucomatous Optic Neuropathy in
- Centration Errors high myopes, definite RNFL defects should correspond to visual
- Variable Focusing effect caused by tilting of the ONH. field defects.
- Magnification issues related to myopic refraction
- Segmentation Errors Affect of Axial Length on Scan Circle Diameter
- Peripapillary Retinoschisis

Figure 11 : Effect of axial length (AL) on the scan circle diameter.

The current OCT devices measure RNFL thickness at a fixed Peripapillay Retinoschisis
angular distance of (appx. 12⁰) (Figure 11). RNFLT may be The retinoschisis in high myopia may cause transient abnormal
affected by magnification in myopia <-4.00 D. The standard elevation of RNFL layer of retina. This is seen as an abnormal
measurement circle in emmetropic eyes is 3.46 mm. Longer thickening of RNFL (Figure 13) on OCT analysis.
axial length in high myopia projects a larger measurement circle
resulting in thinner RNFL. Whereas, in Hyperopic eyes with
shorter axial length has a smaller measurement circle nearer to
the disc resulting in thicker RNFL.[11]
PERIPHERAL RETINAL TILT IN HIGH MYOPES: May
result in thicker RNFL profile because the light passes obliquely
(Figure 12).

Figure 12 : A. OCT image showing measuring Light path taken, with Figure 13 : OCT image showing superonasal peripapillary retinoschisis.
and without peripapillary retinal tilt. RNFL profile shows abnormal elevation of the RNFL.
Note thinning of the RNFL in the temporal-inferior sector.
B. Circular RNFL thickness profile showing thicker RNFL
measurement in peripapillary retinal tilt. Macular Assessment
Macula is less affected by myopic globe elongation. The ganglion
cell layer and inner plexiform layer (GCL-IPL) or ganglion cell

DOS Times - Volume 28, Number 2, March-April 2022 92 www.dosonline.org/dos-times

complex (GCC) can be segmented and measured. 4. Czudowska MA, Ramdas WD, Wolfs RC, et al. Incidence of glau-
The assessment of Ganglion Cell and RNFL parameters in comatous visual field loss: A ten-year follow-up from the Rotterdam
the macular area is a useful technique, complementary to Study. Ophthalmology. 2010;117:1705–1712.
peripapillary assessment for clinically evaluating concomitant
glaucoma and high myopia. 5. Marcus MW, de Vries MM, Junoy Montolio FG, et al. Myopia as a
High Myopic eyes usually have axial length ≤ 28 mm and often risk factor for open-angle glaucoma: a systematic review and me-
have symmetrical layer structure. In non-glaucomatous high ta-analysis. Ophthalmology. 2011;118:1989–1994. e2.
myopia in contrast to the variable appearance of Optic Disc &
PPA, the macular vertical scan remain uniformly symmetrical 6. Grødum K, Heijl A, Bengtsson B (2001) Refractive error and glauco-
(Figure 14). ma. Acta Ophthalmol Scand 79:560–566.
The Macular assessment using GCC parameters on SD-OCT
devices was found to have comparable diagnostic power of 7. Bloom RI, Friedman IB, Chuck RS. Increasing rates of myopia: the long
ONH parameters and peripapillary RNFL measurements for de- view. Curr Opin Ophthalmol. 2010;21:247–248.
tection of glaucoma associated with high myopia.[27,28]
8. Shoji T, Nagaoka Y, Sato H, et al. Impact of high myopia on the perfor-
Figure 14 : Macular Scans: Nerve Fiber Layer(NFL), Ganglion Cell mance of SD-OCT parameters to detect glaucoma.Graefes Arch Clin
Laye(GCL), Inner Plexiform Layer(IPL) and uniformly symmetrical mac- Exp Ophthalmol. 2012;250:1843–1849.
ular scan in contrast to variable appearance of Optic disc & PPA.
9. Yoo YC, Lee CM, Park JH. Changes in peripapillary retinal nerve fi-
High Myopic changes can mimic glaucomatous changes leading ber layer distribution by axial length. Optom Vis Sci.2012;89:4–11.
to interpretational error and clinical judgement. It is essential to
examine the raw images and look for signs of segmentation er- 10. Xu L, Wang Y, Wang S, Wang Y, Jonas JB. High myopia and glaucoma
rors and artifacts, instead of relying on color coding to indicate susceptibility: The Beijing Eye Study. Ophthalmology. 2007;114:216–
abnormality in the OCT printout. 220.
A separate normative RNFL data for high myopic eyes may
avoid the misinterpretation of the changes observed in OCT 11. Kim MJ, Lee EJ, Kim TW. Peripapillary retinal nerve fiber layer thick-
imaging. Seol et al adjusted color probability codes of RNFL ness profile in subjects with myopia measured using the Stratus opti-
thickness and reported an improved diagnostic ability of OCT cal coherence tomography. Br J Ophthalmol. 2010;94:115–120.
for detection of glaucoma.[29]
It would be relevant to monitor the RNFL, ONH parameters 12. Shin JW, Sung KR, Song MK. Ganglion cell-inner plexiform layer and
with OCT overtime. If the changes observed are non-glaucoma- retinal nerve fibre layer changes in glaucoma suspects enable predic-
tous in origin , than there would be no change in normal myopic tion of glaucoma development. Am J Ophthamol 2020:210:26-34.
patient. However, the changes would progress if it is glaucoma.
Before making clinical decision, family history, severity of my- 13. Jonas JB, Gusek GC, Naumann GO. Optic disk morphometry in high
opia, central corneal thickness, corneal hysteresis, IOP, ONH myopia. Graefes Arch Clin Exp Ophthalmol. 1988;226:587–90.
Photographs, Visual fields, and OCT images, ONH (BMO-
MRW), RNFL, and Macular analysis should be considered. 14. Lee JE Sung KR, Park JM et al. Optic disc and peripapillary reti-
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tralia. Arch Ophthalmol 2004;122:495–505. 15. Sung MS, Kand YS, Heo H et al.Characteristics of Optic Disc Rota-
2. Wong TY, Foster PJ, Hee J, et al. Prevalence and risk factors for refrac- tion in Myopic Eyes. Ophthalmology. 2016;123:400-407.
tive errors in adult Chinese in Singapore. Invest Ophthalmol Vis Sci
2000;41:2486 –94. 16. Park H et al. Torsion of the optic nerve head is a prominent feature
3. Sawada A, Tomidokoro A, Araie M et al (2008) Refractive errors of normal-tension glaucoma. Invest Ophthalmol Vis Sci .2014 Nov
in an elderly Japanese population: the Tajimi study. Ophthalmology 25;56(1):156-63.
115:363–370.e3. doi:10.1016/j.ophtha.2007.03. 075.
17. Downs JC, Roberts MD, Burgoyne CF. The mechanical environment of
the optic nerve head in glaucoma. Optom Vis Sci. 2008;85:425–435.

18. How AC et al. Population prevalence of tilted and torted optic discs
among an adult Chinese population in Singapore: the Tanjong Pagar
Study. Arch Ophthalmol 2009 Jul;127(7):894-9.

19. Park HY, Lee K, Park CK.Optic disc torsion direction predicts the lo-
cation of glaucomatous damage in normal-tension glaucoma patients
with myopia. Ophthalmology. 2012;119:1844-1851.

20. Lan YW, Chang SY,Sun FJ, Hsieh JW. Different Disc Characteristics
Associated with High Myopia and the location of glaucomatous dam-
age in primary open angle and normal tension glaucoma. J Glaucoma
2019;28:519–528.

21. Witmer MT, Margo CE, Drucker M. Tilted optic disks. Surv Ophthal-
mol. 2010;55:403–28.

22. Hwang YH, Yoo C, Kim YY, Myopic Optic Disc Tilt and the Character-
istics of Peripapillary Retinal Nerve Fiber Layer Thickness Measured
by Spectral-domain Optical Coherence Tomography. J Glaucoma
2012;21:260–265.

23. Sung MS, Kang YS, Heo H, Park SW Optic Disc Rotation as a Clue for
Predicting Visual Field Progression in Myopic Normal-Tension Glau-
coma. Ophthalmology 2016;123:1484-1493).

www.dosonline.org/dos-times 93
DOS Times - Volume 28, Number 2, March-April 2022

24. McBrien NA, Gentle A. Role of the sclera in the development 29. Seol BR, Kim DM, Park KH, Jeoung JW. Assessment of optical co-
and pathological complications of myopia. Prog Retin Eye Res. herence tomography color probability codes in myopic glaucoma
2003;22:307-338. eyes after applying a myopic normative database. Am J Ophthalmol.
2017;183:147–55.
25. Samarawickrama C, Mitchell P, Tong L et al. Myopia-related optic disc
and retinal changes in adolescent children from Singapore. Ophthal- Corresponding Author of the Article:
mology. 2011;118:2050-2057.
Dr. N.Z. Farooqui, MS
26. Kunliang Qiu,1,2 Geng Wang et al. Application of the ISNT rules Dept. of Ophthalmology, D.D.U. Hospital, New Delhi.
on retinal nerve fibre layer thickness and neuroretinal rim area
in healthy myopic eyes. Acta Ophthalmol 2018 Mar;96(2):161-
167.

27. Zhang C, Tatham AJ, Weinreb RN, Zangwill LM, Yang Z, Zhang JZ,
Medeiros FA. Relationship between ganglion cell layer thickness and
estimated retinal ganglion cell counts in the glaucomatous macula.
Ophthalmology. 2014;121:2371–9.

28. Kim NR, Lee ES, Seong GJ, Kang SY, Kim JH, Hong S, Kim CY. Com-
paring the ganglion cell complex and retinal nerve fibre layer mea-
surements by Fourier domain OCT to detect glaucoma in high myo-
pia. Br J Ophthalmol. 2011;95:1115–21.

DOS Times - Volume 28, Number 2, March-April 2022 94 www.dosonline.org/dos-times

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Ex-Officio Member Address for All Correspondence : Dr. Jatinder Singh Bhalla
Dr. Subhash C. Dadeya Secretary - Delhi Ophthalmological Society
Dr. Namrata Sharma
A-23, 1st Floor, Green Park Main,

New Delhi - 110016

Tel. : +91-011-43018576

Email : [email protected]/[email protected]

Address for Correspondence
Dr. Jatinder Singh Bhalla

Secretary, Delhi Ophthalmological Society

A-23, First Floor, Green Park Main, Aurbindo Marg, New Delhi-110016, India
· Email: [email protected] / [email protected] · Website: www.dosonline.org

DELHI OPHTHALMOLOGICAL SOCIETY

A-23, 1st Floor, Green Park Main, New Delhi - 110016
Email: [email protected] / [email protected] Web: www.dosonline.org

rd

73ANNUAL CONFERENCE

Registration Form

Kindly read the “Note” given below before filling the Amount

Name:___________________________________________________ GST Number: ___________________________ DOS Membership No.:__________________________

*Spouse Name:__________________________________________ *Child-1: ____________________________________*Child-2:_____________________________________

Correspondence Address: ______________________________________________________________________City_________________________________________________

Pin code: _______________ State / Country___________________________Mobile: __________________________ Email: _______________________________________

(for Foreign Delegates) Passport Number: _______________________________________________ Passport Validity______________________________________
(Copy of visa to be sent to DOS Secretariat to complete registration processing)

Registration Tariff *

Registration Fees Components: Please check applicable appropriate category and components as desired

Category Early Bird Till August 30, 2022 Till September Spot
August 10, 2022
20, 2022 Registration

DOS Member – Ophthalmologist (Indian Delegates)

Member Delegate INR 3390 INR 4238 INR 5509 INR 7204
Member’s Spouse / child# INR 2543 INR 3814 INR 4662 INR 6357

Member Resident* INR 2543 INR 3814 INR 4662 INR 6357

Non Member Ophthalmologist (Indian Delegates)

Non Member Delegate INR 5085 INR 5933 INR 6780 INR 8052

Resident INR 4238 INR 5085 INR 5933 INR 7628

Optometrist INR 4238 INR 5085 INR 5933 INR 7628

Non-member’s Spouse/Child*/*# INR 4238 INR 5085 INR 5933 INR 7628

Exhibitor (Indian)

Exhibitor *** INR 3390 INR 4238 INR 5509 INR 7204

Foreign Delegates & Exhibitors

Foreign Delegate/Spouse/ USD 212 USD 225 USD 276 USD 340
Resident (USD)

Past President (DOS & AIOS)/DOS## Complimentary (Registration will be processed only upon receipt NIL
Member Senior Citizen (>70 Years)## of completed form by the DOS Secretariat till 20th September, 2022) NIL
Complimentary (Registration will be processed only upon receipt of
completed form & age proof by the DOS Secretariat till 20th September, 2022)

Please carry your invitation card and registration badge during the Conference Total - 1

Scientific Courses (Optional) Rs. 424/- per Course*

Phaco SICS Intravitreal Injection Ant Vitrectomy Botox Total - 2
OCT in Retina Trab Visual Fields OCT in Glaucoma Perimetry
Corneal Topography Dry Eye Treatment

Note: Please tick the Courses Choosen

Total 1 + 2 = Rs.: _____________________________ *GST18% Rs.: _______________________________ Ground Total Rs.: _______________________________

Total Rupees in words ___________________________________________________________________________________________________________________________________

By Demand Draft/Multicity Cheque No/US$______________________ Dated _____________________________Drawn on Bank ______________________________

__________________________ in favour of “Delhi Ophthalmological Society” payable at New Delhi.

DECLARATION Office use:

I certify that I have read the terms and conditions for registration of the Regn. No: _________________________________________

73rd Annual DOS Conference - 2022 and am willing to accept them. Receipt No : ______________________________________

Signature _______________________________ Date : _____________________________________________

Points to Note:

Ø GST 18% will be extra.
© DOS GST Number 07AAATD2302G1ZD.
© Bank charge applicable on the online transaction for online registration.
© Pre-registration Closes on September 20th, 2022.
© No Requests will be Entertained by the Conference Secretariat beyond the dates Mentioned for Concessions.
© *Letter of Proof of residency (Signed & Sealed) from HOD is required to be submitted to the Conference Secretariat

along with the Registration Form.
© Confirmation of registration will be sent only upon verification.
© **Registration for spouse and children is to be done separately for each person. Ophthalmologists will not be

eligible for registration under spouses category.
© ***Exhibitor manning the exhibition stalls are required to be registered for the conference. Unregistered exhibitor

will not be eligible for delegate kits & Fellowship Dinner.
© Cancellation & Refund: Cancellation is permitted up to September 20th, 2022 only against a written request addressed to

the Organizing Secretary, submitted to the conference secretariat; 50% of the registration fee would be deducted as
processing charges. No cancellation request will be accepted thereafter.
© Photo I-card & Mobile handset of number provided in registration form will be required at the time of collection of
registration kit. Delegate kit for spot Registrants will be subject to availability. Wearing of identity badge is
mandatory at all times.
© Presentation of Registration Badge & Invitation card is mandatory for fellowship dinner entry.
© Lost badge/duplicate badge will be replaced at the registration counter only upon payment of a fee of Rs. 1000/-.
© Registration Kit can be collected by the concerned delegate / faculty only. No third person will be given the
registration kit.
© All company representatives bringing in delegate registrations are required to completely fill in the registration
forms offline before payment processing.
© ## DOS office will not entertain any calls concerning complimentary registration. Completed Registration forms with
required details may please be sent to the DOS office.
© Complimentary Registration for Past Presidents of DOS or AIOS & Seniors Citizens (>70 years) will be entertained till
September 20th, 2022.
© Members should ensure that one correct registration form is filled and submitted to the Secretariat. Submission of multiple
form lead to cancellation of registration.
© No cash payment will be acceptable for registration.
© No Certificate will be issue to Spouse Delegate/Child/Optometrist.

Address for all Correspondence

Dr. Jatinder Singh Bhalla
Secretary

(Delhi Ophthalmological Society)

A-23, 1st Floor, Green Park Main, New Delhi - 110016
P: +91-11-43018576

E: [email protected]
W: www.dosonline.org