JOURNAL OF
THE COLLEGE OF
OPHTHALMOLOGISTS
OF SRI LANKA
VOLUME 22 No. 1 2016
• THE ROLE OF ANTERIOR SEGMENT OCT IN GLAUCOMA
• LAMELLAR DISSECTION TECHNIQUE IN
DEEP ANTERIOR LAMELLAR
KERATOPLASTY (DALK) • EFFECT OF AXIAL LENGTH ON ACCURACY
OF DIFFERENT TYPES OF BIOMETRY IN PHACOEMULSIFICATION SURGERY
College of Ophthalmologists of Sri Lanka Annual ISSN 2345-9115
Journal of
The College of Ophthalmologists
of Sri Lanka
Editors
Dr. Mangala Gamage, DO, MS, FRCS
Consultant Eye Surgeon
Dr. Binara Amarasinghe, DO, MS, FRCS
Consultant Eye Surgeon
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Journal of the College of Ophthalmologists of Sri Lanka is published annually in two volumes. It is clinically oriented, designed to keep ophthal-mologists up to date. It contains peer reviewed articles, current research, case presentations and clinical challenges.
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Journal Articles 1. Smith JD. Ophthalmology and the medical community.
Surv Ophthalmol 1996; 41: 1-30. 2. Smith JD, Jones TS. Ophthalmology and society. Surv
Ophthalmol 1997; 42: 65-78.
Books 3. Smith JD, Jones TS. Public JQ, et al. Ophthalmology
and the World. Boston. Bayside Press, 1997, pp 1-9.
Chapters 4. Stevens JT. A transcendentalist’s view of optics, in Smith
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JOURNAL OF THE COLLEGE
OF OPHTHALMOLOGISTS
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VOL. 22 2016 NO. 1
CONTENTS
Page
Editorial
Research and access priorities in eye health 1
Presidential address – 2015
Minimizing barriers for ophthalmic teams in achieving our mission
Baminiwatta Damayantha 2
Refraction planning in cataract: Avoid creating an unhappy patient
Robert H Taylor, Roger B Ellingham 11
Dr. P. Sivasubramanium Oration – 2015
Vascular endothelial growth factor (VEGF): Its role in ocular neovascularization
Saliya Pathirana 17
The role of anterior segment OCT in glaucoma
J. K. Dilruwani Aryasingha 37
Lamellar dissection technique in deep anterior lamellar keratoplasty (DALK)
– does it matter in postoperative progression
K. H. Wickramasinghe, S. K. G. S. Kurera, C. J. Kumarage, W. M. C. M. Andradi,
D. H. H. Wariyapola 40
The effect of preservatives on the ocular surface and success of glaucoma
(Continued)
College of Ophthalmologists of Sri Lanka Annual ISSN 2345-9115
Page
filtration surgery
Nuwan Niyadurupola 41
Knowledge, attitudes and practices of pre-intern doctors on the management
of emergency ophthalmological conditions
M. M. Dissanayake, S. Vithoosan, S. A. A. Senevirathne, N. Wickramasekara,
P. H. Dissanayake 45
Effect of axial length on accuracy of different types of biometry in
phacoemulsification surgery
H. P. M. K Gunewardena, N. G. I. R. De Silva, M. T. K. Perera, W. M. C. M. Andradi,
D. H. H. Wariyapola 47
Astigmatic change following suture manipulation after deep
anterior lamellar keratoplasty (DALK)
S. K. G. S. Kurera, K. H. Wickramasinghe, C. J. Kumarage, W. M. C. M. Andradi,
D. H. H. Wariyapola 49
Conjuctival intraepithelial neoplasia – a case study
G. J. N. Widanage, I. K. Devasurendra, B. Amarasinghe, S. Nanayakkara 52
1
Editorial
Research and access priorities in eye health The Journal of the College of Ophthalmologists of Sri Lanka 2016; 22: 1
Patients, clinicians, clinicians-scientists play a valuable role in shaping the future of vision research.
Limited funding demands targeted research initiatives that ultimately affect health policy and
practice to secure progress in improving patients outcome in eye health.
Top priorities for eye research have been identified as part of a national collaborative initiative
in most of the countries.
It has been identified that a series of unanswered questions considered as great importance to patients, carers and eye health professionals.
The aim would be to inform funders, researchers, clinicians, and the public about the key
areas as to where they believe the research money should be spent. For example in cataract
surgery research questions include the potential for improvement in cataract surgery
outcomes and the efficacy and the safety of the method used.
WHO global eye health action plan for 2014 to 2019 targets universal eye health coverage
through the provision of comprehensive eye care services integrated into national health system at all levels.
In the area of health research WHO highlights two principle activities.
1. Biomedical research for the development of more cost effective interventions for major causes of visual impairment.
2. Operational research for overcoming barriers in service provision and uptake and
improvement of public health approaches and strategies.
Guidance for public eye health research from WHO includes eye health research priorities,
information on causes and magnitude of visual impairment, guidance on stakeholder analysis
for the development of national eye health plans, data collection and monitoring.
Provision of effective and accessible eye care services is the key for effectively controlling
visual impairment and blindness.
Joint Editors
2
Presidential Address 2015
Minimizing barriers for ophthalmic teams in achieving our mission
Baminiwatta Damayantha1
The Journal of the College of Ophthalmologists of Sri Lanka 2016; 22: 2-10
This year’s theme was “minimizing barriers for the visually impaired.” At today’s presentation I have chosen to
elaborate on “Minimizing barriers for the ophthalmic teams in a high output setting.”
Global figures include 285 million people are visually impaired. Out of them 39 million are blind and 246 million
having low vision.
Preventable causes account for 80% of the total global visual impairment burden.
About 90% of the world’s visually impaired people are living in the developing countries. This is actually the
challenge in our developing country having one of the fastest aging populations in the region.
65% of visually impaired and 82% blind
people are over 50 years of age, although
this age group comprises only 20% of world
population.
Globally uncorrected refractive errors are
the main cause of visual impairment. The
cataract is the leading cause of blindness.
Glaucoma, childhood blindness and age related macular degeneration are the other diseases gaining prominence
in our setting.
The regional situation in comparison to
other regions of the world we pose a large
number of persons who require services for
visual impairment.
1President, College of Ophthalmologists of Sri Lanka, 2015.
The Journal of the College of Ophthalmologists of Sri Lanka
Minimizing barriers for ophthalmic teams in achieving our mission 3
The millennium development goals are a much talked about amongst public health professionals. It has now been
shown that out of eight, seven Millennium development goals cannot be reached without sight.
It is estimated that 90% of visually im-
paired children in developing countries
are not in school.
Women suffer from the greatest
burden of blindness globally and they
typically have much poorer access to
treatment and care.
One child becomes blind every minute
of every day.
Vol. 22, No. 1, 2016
4
The learning’s from eye health programs
can serve many other global health
partnerships.
This illustrates the important role “sight”
plays in the global arena.
Prevention of blindness and vision loss brings a range of benefits to society. It ranges from bringing benefits to
economy, like increased employment, increased productivity and reduced welfare cost, in health, improved
quality of life, reduced comorbidities and reduced hospitalization. Socially, reduces extreme poverty and hunger, increased independence and increased community participation is
affected by reduced vision.
Multisectoral approaches benefit from
political leadership and accountability In developing countries a successful prevention of
blindness program, must always have strong
political backing. Success worldwide has been
demonstrated when there is coordinated and well
formulated program which includes: i . Informed and committed political leadership ii. National eye health plans iii. National eye health committees iv. Clear, time-linked targets and indicators v. and very importantly, deliberate investment
in an eye health work force.
The Journal of the College of Ophthalmologists of Sri Lanka
Minimizing barriers for ophthalmic teams in achieving our mission 5
It is interesting to note that the
absolute number. of blind people
in the world has not changed over
the period of 20 years. However
the age standardized prevalence
rate has declined as depicted by
the consolidated data from the
global vision data base. This
indicates that preven-table causes
of blindness are being taken care
of successfully throughout the
globe.
In consideration of the large demand in eye care a
global action plan has been developed by IAPB and
clearly defines the targets and goals.
The target now is to reduce preventable blindness by
25%.
To achieve this, it needs collection of data, a well-trained
and adequate work force and equity in eye care.
A major contributor is the National Eye Health programs of the country like V2020.
The situation in our country, indicates
• 1.1% of people over 40 years are blind. Of which 79% are due to cataract.
• This accounts for approximately 60,000 people blind due to cataract.
Based on 2014 data, • There are 45 General Ophthalmic surgeons islandwide. • If each surgeon does 1500 cataract surgeries per year (30/week). • Considering the lack of data in private practice, • Annually approximately 80,000 cataract surgeries would be carried out.
But, Is this enough?
Vol. 22, No. 1, 2016
6
There are many methods of projections to derive the number of cataract surgeries to be done in a country.
Reference to the model developed by Thulsiraj et al.
Working the numbers, currently we have a need to do 156,000 more cataract surgeries in addition to the 80,000
being carried out per year.
This brings us to the daunting tasks of 236,000 per year.
There is a wealth of data on developing countries, and looking at Sub Saharan African countries where ophthalmic
services are still young we find a number of strategies in place where the service provision for cataract has been
improved to 3 per million populations, developing cadres specific for the needs. In Sri Lanka we remain at 2 per million having established services long before. The projected norms for developing countries by WHO is one ophthalmologist per 150,000 people. If these were applied to Sri Lanka we would need 133 General Ophthalmologists.
Considering the other requirements of the country this is more a dream than a reality.
The bottle necks in the system are naturally infrastructure,
workforce and resources. The Journal of the College of Ophthalmologists of Sri Lanka
Minimizing barriers for ophthalmic teams in achieving our mission 7
Resource allocation, infrastructure is definitely in the hands of the administrators. There should be a well
structured plan to increase our outputs as a professional body.
The methods are many and much debated but it should be emphasized that an interim plan must be put in place
to avoid preventable blindness to the masses in our country.
In this scenario as the debate continues I believe it is time to
increase our service delivery by better utilization of our
work force with the cooperation of all the members to meet
the growing needs.
I quote,
“Human potential is the same for all. Your feeling, “I am of no
value”, is wrong. Absolutely wrong. You are deceiving yourself. We all have the power of thought – so what are you lacking? If you have willpower, then you can change anything. It is
usually said that you are your own master.” – Dalai Lama
I firmly believe in this and would like you to follow the thoughts of these great philosophers.
I quote,
“Pay no attention to the faults of others, things done or left undone.
Consider only what by oneself is done or left undone.” – Lord Buddha
Vol. 22, No. 1, 2016
8
Having this in mind, I wish to present my
view of getting the maximum output from
the available human resources by ensuring a
happy and healthy working environment.
It is my view that, if the worker is happy
and contented, the atmosphere will be
invariably healthy.
Always consider a happy person as a
healthy person and a healthy person could
be motivated to travel the extra distance.
The happiest people Do not necessarily have the best of everything. They just make the best of everything they have. In relation to creating a happy and healthy working atmosphere, I would like to present my views on the
following aspects.
1. Attitudes 2. Knowledge 3. Unity 4. Healthy Workforce 5. View points 6. Leader’s attitude 7. Relaxing environment
Attitudes I consider this aspect, a very significant feature in our day-to-day working environment.
A renowned musician Stevie Wonder has said, “Just because a man lacks the use of his eyes, does not mean he lacks
vision”.
Every one of us needs a VISION to be successful in our life endeavours. It is this vision on which our attitudes are
built on.
This attitude if not nurtured in the proper direction affects the team spirit which in turn adversely affects the
output.
Teams with highest spirits and coordination attain success with the least amount of stress. The importance of
emphasizing the team member’s contribution should not be forgotten.
Thus, each member should consider himself an important
link of the team and contribute in the best manner possible
to achieve the team’s goal.
Another aspect which needs to be highlighted is the
attitudes of being conscious of the thought that “this is our
workplace”, if so, one would always be willing to “run the
extra mile”.
The Journal of the College of Ophthalmologists of Sri Lanka
Minimizing barriers for ophthalmic teams in achieving our mission 9
The supreme being Lord Buddha has declared that caring for patients is equal to caring for the Lord Buddha
himself. Thus, with correct attitude one can improve the teams productivity and contribute to this meritorious
deed. Knowledge Knowledge is power. Sufficient knowledge is essential in reaching a goal successfully. When you’re working in a
team, each member should have the competency for the duties and activities to be performed. Also, each team
member should be aware of the duties entitled to him.
I can not emphasize how important communication skills are amongst our professionals. Especially with those
who are blind or having low vision.
It is best to be aware that the ‘PATIENT’ is under severe stress, disorganized, and long waits at the clinic would
increase their non-cooperative actions. A smile would, I am sure, ease the tensions and develop relationships.
Knowledge can come in many forms. Workshops, seminars, experience, observation, listening and dialogues to
name a few. Sharing the knowledge is also an important factor especially with the team.
A knowledgeable leader would always plan the day’s work in advance and complete the assignments prior to
leaving the work site.
In this way knowledge would contribute positively to a happy environment.
Unity
It is my belief that there is no team work without
unity. Workplace friendships make working more
enjoyable and create a great sense of calmness among
workers. In such an atmosphere, workplace-related
misunderstandings are less likely to occur.
One may argue or view that unity sometimes would
be misused by the subordinates developing into a
state of disrespect to the employment grades. However, my contention is that one could maintain teamwork, attitudes and unity at worksite while upholding
discipline among the staff.
In order to enhance unity among co-workers various activities can be organized. For instance, arranging religious
ceremonies, annual fellowships, a fairwell for a staff member, quiz competitions and concerts can be arranged.
I have found organizing outreach camps with the participation of the entire team develops good interpersonal
relationships.
This unity brings about an environment of “Team Spirit” which is vital for any group of persons with common
goals.
Healthy workforce As we have limited human resources, the absence of even a single worker can paralyze the whole system.
Therefore, to have a healthy workforce arranging regular health check-ups for the staff and directing them to
obtain relevant treatment would be beneficial. This facility could also be extended to the families of the staff.
Vol. 22, No. 1, 2016
10
A good team leader should be aware of each members concerns and deal with empathy especially with regard to
health issues. This would enhance productivity in the long run.
Viewpoints Regular management meetings and review sessions are essential to achieve the goals at the working stations. The
participation of officers representing every category should be encouraged for these sessions. Suggestions on
further improvements and overcoming obstacles should be obtained from them. I am reminded of my teachers at
Centre for Sight, Kandy who had mastered the art of productivity having their monthly meetings, where each
representative from a category was encouraged to voice their views and concerns. This not only exposed areas of weakness, it illustrated the role and importance of each category. I believe this held
the key to their success.
Leader’s attitude My view is that a leader leads from the front. His/her role extends far beyond the boundaries of expertise but also
into the roles of managers. My experience is that delegation of activities hold a vital role.
I am again reminded of my teachers who had the juniors appointed and responsible for various parts of the Centre
For Sight. My colleagues will fondly remember their role as in charge of the toilets, in charge of the library etc.
This shows clearly their management skills of our esteemed teachers. Of course, these appointments were of no
avail if not followed up by regular monitoring, which some of us remember so well.
Hence a leader’s role is no easy task and must be truly backed by the correct attitude.
Relaxing environment The human mind can be relaxed by pleasing the senses especially eyes and ears. An atmosphere pleasing to the
eyes can be created by having a clean, organized, environment with appropriately coloured curtains and walls.
Adding a natural element to the environment by using flowers and plants would enhance the relaxation. This
peaceful setting can be further improved by adding soft music in the background. This would in turn boost our
productivity for the desired results. I presume I have covered most of the requisites for creating a happy and healthy working atmosphere. My belief is
that creating such an atmosphere makes the staff want to come to work, want to work their hardest and at the end
of the day feel good about what they have done, in a place which they never want to leave. I hope my suggestions would encourage you in your role as the “Team leader”, “Team member” and “Team
manager” to fulfill the enormous work load ahead of us. I wish you all the very best in your endeavors.
The Journal of the College of Ophthalmologists of Sri Lanka
Refraction planning in cataract: Avoid creating an unhappy patient 11
Refraction planning in cataract: Avoid creating an unhappy patient
Robert H Taylor1, Roger B Ellingham1
The Journal of the College of Ophthalmologists of Sri Lanka 2016; 22: 11-16
Introduction The focus of this paper is the prevention of an unhappy
patient following cataract surgery. Such patients often
have a technically perfect cataract operation but are
unhappy with their result. There may be other reasons
but commonly this is because of the refractive outcome.
Information, which might have prevented such a disaster
is accessible pre operatively. These include taking a
careful history of prior refractive correction, (contact
lenses/glasses/refractive surgery), age, lifestyle and the
characteristics of the pre-operative refraction
(hypermetropia, myopia, astigmatism, anisometropia).
Information from the biometry measurements (axial
lengths and keratometry) should be factored in. Lastly the
patient should be consulted about their preferred
refractive outcome, and the consequences of their choice.
This article is a personal perspective from the authors.
The diagnosis of cataract is not difficult and the decision
whether to operate is not usually complex, although there
are important factors to consider in determining the
risk/benefit ratio for each individual. These become more
important if the pre-operative visual acuity is still quite
good. The general assumption made in this article is that
the biometry is performed correctly, the correct lens is
selected with the correct formula and the error rate is of
the of the order of 30% of cases having 0.5 dioptre error
from aim. This may be greater in patients with high
ammetropia. This article uses a variety of clinical examples loosely
based on fact, but the details are all made up. The tables
are presented in a manner that is consistent, with the
intraocular lens power on the left in dioptres (D) and the
predicted spherical equivalent (SE) on the right.
There may be many alternatives to the solutions given,
which may include toric lenses, multifocal lenses and
top up laser. The solutions given is aimed at making
the reader think about what might be achieved if these
more complex and expensive options are unavailable.
Case 1 An 81 year old male presents with reduced vision. He
drives. He wears glasses only for close work.
Refraction and best corrected acuity: Right +0.25/+0.25x90 6/9 Left +0.25/+0.25x90 6/12 It is agreed to operate on the left eye.
Calculated lens implant choices: Left eye
22.5 -1.20
22.0 -0.81
21.5 -0.45
21.0 -0.11
20.5 -0.25
Refractive planning The question here relates to picking a 21.0 or 21.5
dioptre lens. Let us assume he wishes distance vision
(as he has now) and is happy with reading glasses. In
a third of cases the error in biometry is in the order of
0.5 dioptre sphere. A 21.0 D lens will result in a
spherical equivalent in the range +0.39 to -0.61 in two
thirds of cases. A 21.5 D lens might leave him almost -
1.00 with which he might easily read, at least large
print or in good light. If such a patient is able to understand these risks, this
can be discussed. If his lifestyle avoids reading then
perhaps the 21D lens is the correct decision. Either
would probably be a good result.
Message: in general operate on the eye with the worst
visual acuity first, although be careful about pre-
existing amblyopia, particularly if patients have prior
history of strabismus, anisometropia or high hyper-
metropia (see later). If acuity is equal, it is acceptable
to operate on the eye the patients prefer.
For the otherwise uncomplicated patient aim for about
-0.3 DS. If their historic refraction (prior to cataract)
was hypermetropic, pick slightly more plus, if myopic,
slightly more minus.
1Consultant Ophthalmologist, York Hospital, England.
Vol. 22, No. 1, 2016
12
Case 2 A 61 year old female presents with reduced vision in
the left eye. She rarely wears glasses for near or
distance and has never had contact lenses. She drives.
Refraction and best corrected acuity: Right -0.75/+0.50x180 6/9 Left -1.25/+0.50x180 6/18 A decision is made to operate on the left eye cataract. Calculated lens implant choices:
Assuming there is no particular demand from the
patient to have both eyes the same, then using the
same dioptre lens for each eye is attractive, probably a
20.0 D lens implant in this example. This philosophy
rarely leads to post operative intolerance as the result
reflects the pre operative anisometropia, to which the
patient has often adapted in their current spectacles.
Case 3 A 73 year old man presents with difficulty driving at
night. He has required frequent changes in glasses
over the last 2 years. His first glasses were for reading
when 45 years old. Right
21.0 -0.81
20.5 -0.52
20.0 -0.12
19.5 +0.2
Refractive planning
Left
20.5 -1.20
20.0 -0.81
19.5 -0.45
19.0 -0.14
Current refraction and best corrected acuity: Right -3.00/+0.50x180 6/12 Left -3.00/+0.50x175 6/18
Calculated lens implant choices: Left eye
24.5 -2.0
24.0 -1.9
23.5 -1.58 The pre operative spherical equivalent in the left eye is -1.00 and the right is -0.50 which explains how she manages for some near vision activities without glasses. She also has a small amount of astigmatism, which will increase her depth of focus – which may or may not be reflected in the keratometry (see later). The pre-existing anisometropia is important and should influence the post operative aim. If the aniso-metropia is historic (and not just a consequence of the cataract) it might lead to the decision to preserve this patient’s pre existing anisometropia and aim for -1.00 spherical equivalent in the left eye (and -0.3 in the right). In this scenario, warnings need to be given to ensure she understands that distance vision may appear blurred post operatively. In addition the pre-existing glasses-independence may not be recreated – particularly if the keratometry does not reflect the astigmatism. Patients are often under the impression that they will
be glasses independent after cataract surgery. This
may be the case, but is not guaranteed. The biometry calculation reflects the pre-existing anisometropia with a smaller dioptre lens for emme-tropia in the left eye. It is worth checking the axial lengths are consistent with this as well (the more myopic eye should be longer). Index myopia may create or neutralise a pre existing anisometropia, which might influence your refractive aim.
23.0 -1.23
22.5 -0.81
22.0 -0.52
21.5 -0.12
21.0 +0.23 The history is important, as the first glasses used were for reading, suggesting the myopia is secondary to cataract formation (index myopia). This is a good example where looking at the biometry measurements before the calculations is worth while. Although not displayed, the history would imply index myopic change. The lens implant calculations seem to suggest a normal axial length. This patient dislikes having to wear distance glasses and is usually relieved to find that you can aim for unaided distance focus post-operatively. In this scenario, patients have to be warned that they will need reading glasses. In the experience of the authors such patients rarely read unaided pre-operatively but it is worth checking. If it is agreed to aim for unaided distance focus, the readings again fall between choosing a 22.0 or 21.5 D lens. Some patient will guide you as to which of the two choices is preferred.
The Journal of the College of Ophthalmologists of Sri Lanka
Refraction planning in cataract: Avoid creating an unhappy patient
If both eyes are similar, one option is to operate on the
dominant eye first and aim for nearer zero, leaving the
non dominant eye to be a fraction more myopic, but
this all depends on the exact biometry calculations and
patient preference.
Case 4 A 65 year old librarian presents with difficulty seeing
small print. She has worn glasses since she was a
teenager. She reads unaided. Best corrected acuity: -3.00/+0.50x180 6/12 -
3.00/+0.50x175 6/12
13
to respect this. If patients are undecided, the fall back
position is to leave them myopic enough to read
without glasses, so in this example 20.5 D for -2.10
spherical equivalent. Note it is rarely necessary to
leave them -3.00, particularly if there is a small amount
of corneal astigmatism. If the cataract is unilateral this raises a different problem.
If the patient prefers to aim for emmetropia this might
create a problem post operatively with binocular balance.
There are a number of options, which include correcting
the myopia in the unoperated eye with a contact lense, or
proceeding to cataract extraction in the second eye (or
clear lens extraction). Warning the patient of these
difficulties is essential.
Calculated lens implant choices: Right eye
20.5 -2.10
20.0 -1.83
19.0 -1.55
18.5 -1.28
18.0 -0.83
17.5 -0.51
17.0 -0.32
16.5 +0.15
Case 5 A 66 year old female presents with reduced vision in
both eyes. She gives a history of wearing glasses as a
child but no surgery or patching. Refraction and best corrected acuity
+5.00/+0.50x180 6/18 right
+5.00/+0.50x180 6/12 left
This patient presents a number of potential problems that need careful consideration. The patient has a lot to gain from cataract surgery including eliminating her
undesirable hypermetropia. In theory there is a magnification benefit of hypermetropia that may be beneficial if there is co-existing macular disease. Warning patients of lack of magnification is prudent, even if this is rarely a problem.
Refractive planning It is impossible to predict what sort of post operative refraction this patient might choose. A discussion is required. An obvious option is to aim for a degree of myopia so that the patient will again read without glasses. If this is the aim it may not be necessary to aim for a similar spherical equivalent as usually about -2.00 spherical equivalent is sufficient for comfortable reading. If a patient reads without glasses, then chooses to aim for an emmetropic end result, it is important to have them understand that they are unlikely to read without glasses. Some patients struggle to comprehend this as they have always read easily without glasses in the past.
Patients often have a slight underlying anisometropia,
which may be masked by index changes. This is
another example where it is important to check the
axial lengths and keratometry readings. If there is
aniso-metropia, the lenses chosen should be selected
Enquiry should be made about amblyopia (sometimes
termed lazy eye). Patients may give a good history of this,
although some patients are unaware of its presence. If the
cataract is not too severe confirmation of normal
binocular vision is helpful. However binocular tests
become unreliable if cataract is advanced or unilateral.
The second potential is the presence of a manifest strabismus. This may not be obvious from initial ins-
pection and again a history of strabismus is sometimes not present. Confirmation of aligned eyes with a cover test is reassuring. Further workup, for example assess-ment of suppression, binocular vision and ocular alignment would be encompassed by an orthoptic
report. Cataract surgery in the presence of binocular vision
abnormalities can lead to large angle strabismus or
intractable double vision. As a general rule, operate on
the better potential eye and warn patients of these
risks.
Vol. 22, No. 1, 2016
14
Calculated lens implant choices: Right eye
Hoffer Q AL 21.5
31.0 -1.50
30.5 -1.20
30.0 -0.81
29.5 -0.45
29.0 -0.11
28.5 +0.23
28.0 +0.59
Refractive planning This patient gives no history of strabismus surgery or
patching so probably has normal binocular vision. In
addition her refraction is equal (axial lengths should
be checked to exclude axial anisometropia masked by
index myopic shift).
In the absence of a large corneal astigmatism, the
choice of a 29.0 D lens would seem to be appropriate.
Note the use of Hoffer Q formula because of the short
axial length (1).
Case 6 65 year old female complains of reduced vision in the
left eye. She gives a history of reduced vision in the
left eye all her life. She has had no strabismus surgery.
Refraction and best corrected acuity:
-0.25/+0.75x180 6/18 +4.00/+2.00x180 6/60
Biometry Right eye: Biometry Left eye:
SRK-T Hoffer Q
Axial length 22mm Axial length 20mm
24.0 -1.2 29.5 -1.2
23.5 -0.81 29.0 -0.81
23.0 -0.52 28.5 -0.52
22.5 -0.12 28.0 -0.12
22.0 +0.35 27.5 +0.35
21.5 +0.72 27.0 +0.72
21.0 +1.1 26.5 +1.1
In this case the suggestion is that the left eye is amblyo-
pic. If so it should have a shorter axial length, which is
confirmed. As outlined above, the risk of proceeding to
cataract surgery in the left eye first would be intractable
double vision. This is less of a problem if the eyes are
aligned with binocular functions. Any manifest de-
viation would be a contraindication to proceeding to
cataract surgery in the left eye first. This is because
improving the acuity in the left eye to a level superior to
the right eye could anti-suppress the left eye leading to
intractable double vision, i.e. double vision that persists
even after subsequent cataract surgery to the right eye.
The right eye has reduced vision. If we assume this is due
to cataract, the recommendation would be to proceed to
cataract surgery for the right eye first. Refractive planning The right eye is planned first, as outlined above, and the aim would be emmetropia. The K readings are not presented, but the spectacle astigmatism power is low so let us assume that the K readings reveal less than 1 dioptre of corneal astigmatism. As the patient is likely to have been hypermetropic until the onset of cataract, a lens choice of 22.5 might be reasonable. For planning the left eye, the pre-existing anisometropia should be respected and the fact that the left eye is probably amblyopic makes the choice less critical. A 27.5 or 27 power lens could be chosen to maintain the direction of the pre-existing anisometropia, if not its magnitude. Although it is tempting to push up the myopic end result in some patients if they wish for a reading vision outcome, it is often not tolerated well in patients who have always been hypermetropic.
Case 7 A 54 year old female presents with worsening vision in the left eye. She has worn single vision glasses for driving since early adulthood, and more recently changed to full time varifocal glasses wear. She wishes to have uncorrected distance vision. Refraction and best corrected acuity
-2.00/+2.00x85 6/6 -1.75/+2.00x95
6/12
K1 42.00 D K2 44.00 @95 left eye
Calculated lens implant choices: Left eye
22.5 -1.20
22.0 -0.81
21.5 -0.45
21.0 -0.1
The Journal of the College of Ophthalmologists of Sri Lanka
Refraction planning in cataract: Avoid creating an unhappy patient
Refractive planning This case is similar to Case 2, although there is more
astigmatism which is reflected in the K readings. The
patient’s preference is for good uncorrected distance
vision but this is unlikely to be achieved with 2 D of
corneal astigmatism. While on-axis incisions or toric
lens implants are options, let us assume that these are
unavailable.
This patient’s most positive meridian is +0.25 D in the
left eye, zero in the right eye. The initial lens to choose
might appear to be 21.5 D for a post operative
spherical equivalent of -0.45 D. However, given her
degree of astigmatism, this would create a
hypermetropic meridian. Therefore selecting a 22.0 D
lens would be more logical.
This same principle applies if the overall myopia is
greater. See next case.
Case 8 A 60 year old patient presents with reducing vision as
a result of cataract. He has worn contact lenses for
many years and reading glasses over the top. He
requests good unaided visual acuity at distance in the
operated eye and understands that he will need
reading glasses, which he will use while continuing
with his contact lens in the un-operated eye. Refraction and best corrected acuity Right -10.00/+2.00x90 6/18 Left -10.00/+2.00x90 6/9 K1 42.00 D K2 44.00 @90 each eye
Refractive planning Aim for a myopic spherical equivalent of half the
corneal astigmatism power which, in this case, is -
(+2.00/2) = -1.00. Remember that biometry is less
accurate in higher axial lengths so it is wise to leave
more room for error and counsel the patient
accordingly.
This case is uncommon and most myopes have a degree
of anisometropia. By reflecting this in the refractive
planning, a useful all round uncorrected acuity can be
achieved, assuming the degree of astigmatism is not
large. Some patients prefer to continue in glasses and
have used their myopia on occasion to see close up
(perhaps unlikely if -10 but always worth asking). If this
is the case aiming for a spherical equivalent of between -
1.0 and -2.0 (depending on corneal astig-matism and
anisometropia) may be a better option. A set of varifocals
is usually well tolerated.
15
Some moderately myopic presbyopic patients (around
-4.00 D), have adapted to enjoy the unaided near
magnification that their refractive error enables. It is
worth checking that they would not miss this
magnified near vision if given an emmetropic outcome
with cataract surgery. A clue to this pitfall is to
observe whether they look over the top of their glasses
when they are given fine detail to examine.
Case 9 A 64 year old man presents with reduced vision as a
result of cataracts. He has worn glasses since age 7
years and currently wears varifocals. He has no strong
preference about glasses post operatively.
Refraction and best corrected acuity -10.00/+1.00x180 6/12 -
6.00/+1.50x160 6/9
Right Left
Axial length 26.5mm Axial length 24.50mm
17.0 -3.19
19.5 -3.19
16.5 -2.84
19.0 -2.84
16.0 -2.51
18.5 -2.51
15.5 -2.22
18.0 -2.22
15.0 -1.9
17.5 -1.9
14.5 -1.58
17.0 -1.58
14.0 -1.23
16.5 -1.23
13.5 -0.81
16.0 -0.81
13.0 -0.52
15.5 -0.52
12.5 -0.12
15.0 -0.12
Refractive planning The pre-existing refraction is reflected in the different
axial lengths of the two eyes. An option is to aim to
preserve this difference in the planning and aim for
approximately -2.5 in the right eye and -0.3 in the left
eye. With these measurements a 15.5 D lens in each
eye would probably be ideal. Note the symmetry in
the intraocular lens choice.
In this case, one danger is in doing the right eye first
and leaving the spherical equivalent at zero or
minimally myopic. This leaves no room for maneuver
for the left eye as a hypermetropic error on the left is Vol. 22, No. 1, 2016
16
undesirable, and leaving the same degree of low
myopia or emmetropia as on the right may lead to
binocular intolerance, as the pre-existing anisome-
tropia is eliminated.
Case 10 A 55 year old lady presents with symptomatic early
cataract. She does not wear glasses or contact lenses at
all and prior to the cataract developing was happy
with her unaided vision.
Refraction and best corrected acuity -0.5/+0.25x90 6/9
-0.75DS 6/12 Left eye K1 38.0 D K2 39.0 D@90
24.5 -2.0
24.0 -1.9
23.5 -1.58
23.0 -1.23
22.5 -0.81
22.0 -0.52
21.5 -0.12
21.0 +0.23
Beware in this case because the patient is young and
very symptomatic and expects not to be needing any
refractive aids. She has not told you that she had laser
refractive surgery for low myopia 10 years ago. A clue
is available as the K readings (in diopters) are low.
Her presbyopia has developed coincident with the
small and asymmetric index myopic change that has
been preserving her unaided near vision on the left
and distance vision on the right remains well
preserved. Her left eye now has sufficient nuclear
cataract to interfere with her reading and interfere
with the clarity of vision in the right eye for distance.
The assumptions in the lens implant calculations are
invalidated with prior refractive surgery and adjust-
ments must be made (which we are not within the
remit of this paper) (2). Following the calculations
without adjusting for the prior surgery is likely to lead
to a hypermetropic outcome and an unhappy patient.
Counselling the patient about the increased chance of
a refractive surprise is crucial prior to surgery. The
patient should be prepared for the possibility that a
second procedure might be needed to correct any
postoperative refractive error once the refraction has
stabilized. Multiple postoperative visits will also be
necessary.
Conclusion This article has aimed to point out some of the
common scenarios that lead to a patient unhappy with
the refractive outcome after cataract surgery. The cases
are not exhaustive, and sometimes multiple factors are
present in one patient. We have chosen not to discuss
toric lens implants or multifocals, as it would
overcomplicate the discussion and there are many
circumstances where such premium lenses are
unavailable. We aim to assist surgeons in their early
careers rather than experienced refractive cataract
surgeons. In any cataract surgical plan, always
consider the patient and their preferences as a whole,
and the way in which both eyes function together.
Recognise for each individual their needs and desired
outcome. Often small adjustments to lens power
choices, combined with the multifocality of low
astigmatism and preservation of small amounts of
anisometropia, can lead to very happy patients free
from refractive aids. Managing expectations is
extremely important as even the best plan may not
produce the desired outcome.
Follow the acynom RACkUP
Refractive history Myope, hypemetropia,
Anisometropia astig, presbypia, contacts,
Corneal astigmatism laser old refractions/axial
lengths power, axis (k’s)
And their significance, eg Understand the
loss of near sight in myopes patients wishes
double check for amblyopia,
Plan Lens choice primary position tropia, low
myopia or myopic astigma-
tism, anisometropia, glasses
dependence, and reading
aids
References 1. RCOphth guidelineshttps://www.rcophth.ac.uk/wp-
content/uploads/2014/12/2010-SCI-069-Cataract-
Surgery-Guidelines-2010-SEPTEMBER-2010.pdf accessed
25/5/2016. 2. Kalyani SD, Kim A, Ladas JG. Intraocular lens power
calculation after corneal refractive surgery. Curr Opin
Ophthalmol. 2008; 19(4): 357-62. doi: 10.1097/ICU.0b013e3282fec43e.
The Journal of the College of Ophthalmologists of Sri Lanka
17
Dr. P. Sivasubramanium Oration – 2015
Vascular endothelial growth factor (VEGF): Its role in ocular
neovascularization
Saliya Pathirana1
The Journal of the College of Ophthalmologists of Sri Lanka 2016; 22: 26-45
Dr. P. Sivasubramaniam DO, MS, FRCS, FRCOphth, FCS (SL, HON)
Dr. Ponniah Sivasubramaniam was the most respected Ophthalmologist
who lived in Sri Lanka. He passed away at the age of 86 years on 3rd
December 2002.
He was born on the 31st of August in 1916 in Kandegamuwa. He had his
early education in Jaffna and later at St. Josephs College, Colombo and
graduated at Ceylon Medical College with a 1st class at the final
examination.
From the day he returned to Ceylon in 1950 after the postgraduate
training in Britain he began to work in Jaffna as a consultant
Ophthalmologist. He was posted to Victoria Memorial Eye Hospital in
1955 and continued working until his retirement. He was the 1st Sri
Lankan to pass the final FRCS Ophthalmology examination in 1950.
His biography indicates that he carried a good record during his undergraduate period that he carried away all
the prizes at the London Matriculation at St. Patrick College in Jaffna and won the exhibition prize for Botany and
Zoology.
He held many positions in various professional organizations and was the founder member of the
Ophthalmological Society in Ceylon in 1957. He was also the President of the Sri Lanka Association of
Advancement of Science in 1957, President of the Ophthalmological Society Ceylon in 1962, President of SLMA in
1976, President of 5’ congress of the Asia Pacific Academy of Ophthalmology and founder President of College of
Ophthalmologists of Sri Lanka in 1992.
He was awarded Jose Rizal award 1974 for a outstanding contribution to Ophthalmology in the Asia Pacific
region. He completed his 50 years of service on 30th November 1993. He was a member of the board of study,
examiner for DO, MS examinations. He had numerous publications in national and international journals mainly American Journal of Ophthalmology, Archives of Ophthalmology, British Journal of Ophthalmology, Oriental Archives of
Ophthalmology, Transactions of Asia Pacific Ophthalmology, Ceylon Medical Journal and Transactions of Ophthalmological
Society. His book “text book in Ophthalmology” written in 1960 was the book for medical students.
He also took leadership in preparing national plan for the prevention of blindness in 1990 and to establish eye care
in Sri Lanka and carried out a landmark survey of blindness.
In considering the clinical work half a century ago in addition to cataract surgery he performed DCR, glaucoma
Surgery, and squint surgery.
His variety of interest within the chosen field affected almost every facet of Ophthalmology as he contributed
greatly to important clinical and lab advances in disease areas. He had incredible wisdom and ability to stimulate
his colleagues and students to do the right thing and to follow the accepted norms. The Journal of the College of Ophthalmologists of Sri Lanka
Vascular endothelial growth factor (VEGF): Its role in ocular neovascularization 18 Neovascularization and edema in retinal disorders Leading causes of blindness in the world are, in people aged over 50 years-age-related macular degeneration
(AMD), diabetic retinopathy.
Major cause of blindness in both disorders is related to neovascularization and edema. VEGF is implicated in
pathologic neovascularization.
Central vision loss with neovascular AMD
Milestones in VEGF research
1948-1958 Michaelson, Ashton, and Wise contribute to “factor X” hypothesis 1971
Folkman publishes “tumor angiogenesis factor” hypothesis
1983 Dvorak demonstrates tumor secretion of vascular permeability factor (VPF)
1989 Ferrara clones VPF and identifies it as an angiogenesis factor; VPF is rechristened VEGF 1997
First clinical trials of anti-angiogenic therapy in cancer patients initiated
1999 First anti-VEGF therapy tested in humans with AMD
2003 VEGF164 (165) found to be required for pathologic, but not physiologic, retinal neovascularization
2003 Optimal methods of long-term controlled delivery of an anti-VEGF agent evaluated in
animal studies
2004 First FDA-approved anti-VEGF therapy for colorectal cancer
Vol. 22, No. 1, 2016
19
Properties of VEGF
1. Stimulator of angiogenesis
2. Potent inducer of vascular permeability
3. Vessel survival factor
4. Fenestration factor
5. Proinflammatory effects
6. Neuroprotective effects
VEGF stimulates angiogenesis Triggers degradation of basement membrane of endothelial cells. Endothelial cells then change shape and invade
surrounding stroma, proliferate and form migrating column. Then cease proliferation, change shape, and adhere
to each other and form new capillary tube. Sprouting tubes fuse into loops, creating circulation.
VEGF is a potent inducer of vascular permeability 50,000 times more potent than histamine in inducing vascular permeability. Induces vessel leakage via multiple
mechanisms. Causes leukocyte-mediated injury of endothelial cells, formation of fenestrae, dissolution of tight
junctions, transcellular bulk flow. Vascular permeability may be antecedent and necessary step for
neovascularization.
Proinflammatory effects of VEGF VEGF receptors present on inflammatory cells. Inflammatory cells make and release VEGF, participate in blood-
retinal barrier breakdown and neovascularization.
VEGF in normal physiology Essential for normal embryonic development. Role in female reproductive cycle. Expressed in tissues in the brain,
kidney, and gastrointestinal mucosa. Corrective role in wound healing and bone repair. Promotes new vessel
growth following myocardial ischemia.
VEGF is present in the healthy eye VEGF receptors primarily located on vascular endothelial cells. High concentrations of VEGF found in retinal
pigment epithelium (RPE). VEGF may play a protective role in maintaining adequate blood flow to RPE and
photoreceptors. It’s trophic for choriocapillaries. Also required for maintenance of choriocapillaries fenestrae.
VEGF in pathologic ocular neovascularization VEGF is implicated in neovascular AMD, diabetic retinopathy, retinal vein occlusion, retinopathy of prematurity,
corneal neovascularization, and iris neovascularization.
Preclinical evidence of VEGF in pathologic ocular neovascularization VEGF and neovascularization are linked in experimental models (cornea, iris, retina, choroid), is necessary and
sufficient to produce pathologic neovascularization. Selective VEGF inhibition suppresses vessel growth in these
models.
Pathophysiology of neovascular AMD Evidence for role of VEGF
VEGF present in surgically excised neovascular choroid membranes of patients with neovascular AMD. Also
present in CNV membranes of autopsied eyes of patients with neovascular AMD. Other growth-stimulating and
growth-inhibiting factors may be implicated in neovascular AMD, but their roles are not as well understood.
The Journal of the College of Ophthalmologists of Sri Lanka
Vascular endothelial growth factor (VEGF): Its role in ocular neovascularization 20
VEGF – the common denominator in AMD CNV membranes have demonstrated expression of both VEGF and VEGF receptors
Predominantly classic neovascularization
Occult neovascularization
Left: FAs of choroidal neovascularization Right: Immunohistochemistry for VEGF expression
VEGF in diabetic retinopathy Retinal VEGF levels elevated in experimental diabetes. Blocking VEGF prevents pathology.
VEGF injected in primates induced vascular leakage and produced conditions similar to diabetic retinopathy.
VEGF levels elevated in vitreous of eyes with diabetic macular edema and with proliferative diabetic retinopathy. Vol. 22, No. 1, 2016
21
Pathologic VEGF activates CNV cascade
VEGF is an important target for therapeutic intervention. It is secreted, diffusible, and mitogenic for endothelial
cells. Multiple retinal cell types produce VEGF; retinal endothelial cells have receptors for VEGF. Blood-retinal
barrier breakdown is both prevented and reversed through VEGF inhibition. Extensive data support role of VEGF
in ocular neovascularization and vascular permeability.
The Journal of the College of Ophthalmologists of Sri Lanka
Vascular endothelial growth factor (VEGF): Its role in ocular neovascularization 22
Blocking VEGF does not affect underlying stimuli In neovascular AMD, blockade of pathologic VEGF does not block stimuli underlying VEGF cascade sustained
blockade of pathologic VEGF may be required.
VEGF164(165) preferentially elevated in pathologic neovascularization In murine model, VEGF levels were higher in pathologic versus physiologic processes. Expression ratio of
VEGF164/ VEGF120 was ~12 higher in pathologic neovascularization
Expression VEGF164/ VEGF120 in retinal neovascularization
Pathologic 25.3 8.7
Physiologic 2.2 1.1
VEGF164(165) blockade preferentially inhibits VEGF164(165) blockade has no significant effect on
pathologic retinal neovascularization physiologic retinal vascularization
Pathologic neovascularization Revascularization
Murine VEGF 164
equivalent to human VEGF Murine VEGF164 equivalent to human VEGF165 165
Control
VEGF164 selective blockade
Non selective VEGF blockade
Evidence suggests VEGF164(165) is not required for normal retinal vessel growth and function
Retinal vessels in normal mouse Retinal vessels in VEGF164 knockout mouse
Vol. 22, No. 1, 2016
23
Summary VEGF and neovascularization are linked in experimental models (cornea, iris, retina, choroid). VEGF is necessary and sufficient to produce pathologic neovascularization. Based on animal models preferential role of VEGF164(165)
suggested in pathologic neovascularization and blocking VEGF164(165) inhibits abnormal vessel growth while sparing normal vessels.
What is wet AMD? No. 1 cause of non-reversible blindness worldwide! Aging is the most important triggering factor. VEGF is the
most important factor for its development. Who is affected 1. >65 years – Age most important factor 2. Smoking 3. Whites and Chinese more commonly affected 4. Runs in families
The pathology is in – RPE & Bruch's membrane at macula
It presents as painless loss of central vision. Loss can be gradual or acute depending on type. Dry AMD – Gradual loss (5-10 years or more) Wet AMD – Sudden loss of vision (day or days)
The Journal of the College of Ophthalmologists of Sri Lanka
Vascular endothelial growth factor (VEGF): Its role in ocular neovascularization 24
Dry AMD Accumulation of yellow extracellular deposits adjacent to retinal pigment epithelium – drusens.
Wet AMD Generally develops in people with Dry AMD. New blood vessels grow below macula. Leads to sudden loss of
vision. Can see sub retinal hemorrhage or sub retinal fluid or both at the macula.
How is it diagnosed ? Dry type – Detected on routine testing by opticians/ ophthalmologists on ophthalmoscopic examination to look
for drusens. Does not need any further investigations.
Wet type needs further tests to confirm diagnosis such as optical coherence tomography (oct), fluorescein
angiography (confirm diagnosis) and amser grid is useful to detect the distortion of the figures with affected eye.
Amsler grid
Vol. 22, No. 1, 2016
25
Optical coherence tomography (OCT)
Treatment of AMD So far no drug to completely cure AMD. Anti VEGF drugs – ranibizumab, bevacizumab, aflibercept (Wet AMD only stops progression) Injected intravitreally works well to achieve relatively quick resolution of exudative signs in most patients. This
will stop the growth of CNV and improve the vision up to a certain extent. Other treatment methods include photodynamic therapy and laser photocoagulation for non central lesions.
Reassure the patient and inform him that he will not go completely blind, and also his peripheral vision is going to
be normal. Affected patients can be helped with magnifying lenses and large prints for reading.
Vitamins and green leafy vegetables to supply anti oxidants.
Currently used Anti VEGF agents
The Journal of the College of Ophthalmologists of Sri Lanka
Vascular endothelial growth factor (VEGF): Its role in ocular neovascularization 26
Bevacizumab Alibercept Ranibizumab RTH 258
Baseline lesion characteristics Size of CNV > 5DA poor prognostic indicator Classic CNV or minimal classic CNV are poor prognostic indicators. Occult CNV – untreated show slow decline of VA Persistent active lesions Less responsive to treatment Presence of RAP Presence of GA Any PED – height and width Drying of the exudative or “wet” macula in neovascular AMD can usually be accomplished safely, effectively and relatively quick with an initial series of frequent, continuous therapy with one of these drugs in the so-called INDUCTION PHASE. In most patients, the signs of exudation are brought under good control within 3-4 injections in this phase. It is what to do thereafter, how to keep the macula dry and obtain the best visual outcome in the long run -THE
MAINTENANCE PHASE, that is the challenge and where clinicians practices can vary considerably.
Compartments fluid Sub retinal fluid Intraretinal fluid
Various clinical trials done to compare and to find best treatment methods
MARINA (Clinical trial one)
ANCHOR STUDY (Clinical trial two)
HORIZON extension study
PIER study
EXCITE study
PrONTO
SAILOR
SUSTAIN
CATT
Vol. 22, No. 1, 2016
27
Anti-VEGF induction methods Fixed and variable regimens There are three basic approaches to maintenance dosing regimens.
1. The first is a fixed continuous, monthly or bi-monthly injection schedule.
2. The second is an individualized discontinuous variable approach, also called as - needed or pro re nata
(PRN) dosing. 3. The third is an individualized continuous variable approach commonly known as treat – and - extend
(TAE) strategy.
Ocular and systemic adverse effects of anti-VEGF’s Ocular adverse effects
• Enodophthalmitis • Cataract, raised IOP, glaucoma • Vitreous hemorrhage, retinal detachment • Systemic adverse effects • CVA • Cardiovascular events • GIT and renal disorders
Determining disease activity Functional and morphologic features, improvement of vision. disappearance or appearance of haemorrhages.
OCT morphology
• SRF – sub-retinal fluid • IRF – intra-retinal fluid • PED – pigment epithelial detachment • Sub-retinal hyper-reflective material: SRHM
Any sub/ intra retinal fluid indicates inadequate treatment.
TREAT UNTIL DRY Impact of sub-retinal fluid
1. SRF at baseline no impact on outcome
2. Persistence of SRF compatible with good outcome
3. Recurrence of SRF negative impact on outcome
Impact of intra-retinal fluid
1. Associated baseline worse VA
2. Predictor of worse VA outcomes
The Journal of the College of Ophthalmologists of Sri Lanka
Vascular endothelial growth factor (VEGF): Its role in ocular neovascularization 28
Treatment refractory CNV the “Non responder” Revisited diagnosis, consider PCV, check ICG and allow time for recovery if not other alterative are laser, PDT,
steroids.
Patient treated with anti-VEGF for ARMD R/EYE L/EYE
CNV treated with Anti-VEGF
Vol. 22, No. 1, 2016
29
Conclusions 1. Wet AMD causes irreversible damage to the macula and permanent visual impairment if treatment is delayed
and/or not provided adequately or stopped prematurely. 2. However, macula scar and macular atrophy may occur despite timely treatment and regression of CNV based
on baseline characteristics.
Diabetic retinopathy ETDRS classification of diabetic retinopathy
• None
• Non- proliferative (NPDR) +/- Clinically significant macula edema (CSME)
Mild
Moderate
Severe
Very severe
• Proliferative (PDR)
Without high risk characteristics (HRC)
With HRC
Focal DME Localize retinal thickening often surrounded by exudates usually with cluster of microaneurysms.
The Journal of the College of Ophthalmologists of Sri Lanka
Vascular endothelial growth factor (VEGF): Its role in ocular neovascularization 30
Diffuse DME Generalized thickening of the central macula with no obvious source of leakage.
Ischemic maculopathy Normal FAZ
Vol. 22, No. 1, 2016
31
The pathogenesis of DME
OCT classification of DME
The Journal of the College of Ophthalmologists of Sri Lanka
Vascular endothelial growth factor (VEGF): Its role in ocular neovascularization 32
VEGF Concentration in nAMD, BRVO, CRVO & DME Vol. 22, No. 1, 2016
33
Treatment of DME
1. Laser photocoagulation
2. ANTI-VEGF intra vitreal injections
3. Dexamethazone intra vitreal injections
Many patients lose vision despite laser
year data 2‐line loss with laser 3‐line loss with laser
DRCR.net: grid laser vs. IVTA 17% 13%
DRCR.net: mod. macular grid 13% 7 – 10%
DRCR.net: ranibizumab vs. prompt/deferred 13% 8%
laser/IVTA
DRCR.net: ranibizumab vs. prompt/deferred 13% 8%
laser/IVTA
RESTORE 13% 8%
BOLT: Bivacizumba vs. laser Not reported 26%
Laser helps to reduce severe visual loss in 50% of DME patients. Progressive visual loss experienced in 19% of
DME in spite of laser treatment.
Various anti-VEGF agents have been investigated for the treatment of DME The Journal of the College of Ophthalmologists of Sri Lanka
Vascular endothelial growth factor (VEGF): Its role in ocular neovascularization 34
Studies conducted to investigate anti-VEGF treatment for DME The study conducted by DRCR.net showed the patients treated with 0.5mg ranibizumab plus prompt or deferred
laser had better VA outcomes at 1 year than patients who received sham injections plus prompt laser treatments. Two year primary outcomes of the RISE and RIDE studies clearly demonstrated monthly injections ranibizumab
significantly improved VA. 40 – 45% of patients gained 3-more line of vision. In the READ 3 study patients treated with 0.5mg or 2mg ranibizumab. Increasing VA was 8.7 letters for the 0.5mg
group and 7.5 letters for 2mg group. In 2011 RESTORE study demonstrated superior gain in VA with ranibizumab with or without laser.
Patient treated with anti-VEGF for DME
Exam. date: 2 8/4/20 1 5
Exam. date: 18/5/2 0 1 5
Exam. date: 2 0/6/2 0 1 5
No improvement with anti VEGF Improvement with anti VGEF
OD OS
Vol. 22, No. 1, 2016
35
Non-center involved DME treated with laser only
RETINAL VEIN OCCLUSION
CRVO BRVO
FFA in BRVO and CRVO
Treatment of RVO BRVO study showed that macula photocoagulation is superior in improving VA compared with observation.
CRVO study demonstrated grid laser treatment of macula edema of no visual benefit
Intravitreal anti-VEGF agents for RVO In the BRAVO and CRUISE studies published in 2010 evaluated the effect of ranibizumab for macula edema
secondary to CRVO and BRVO.
The Journal of the College of Ophthalmologists of Sri Lanka
Vascular endothelial growth factor (VEGF): Its role in ocular neovascularization 36
In six months both ranibizumab groups showed significant different in improvement of BCVA (+18.3 letters for
the 0.5mg group, +16.6 letters for the 0.3mg group, +7.3 letters for the sham group p<0.5)
It appears that some eyes stabilize after a few consecutive monthly injection and require few injections thereafter.
Findings from SD-OCT is used to predict VA. Anti-VEGF treatment for CME following BRVO
Exam. date: 0 4/0 8/2015
Exam. date: 11/09/2015
Exam. date: 17/06/2015
Exam. date: 07/08/2015
Exam. date: 11/09/2015
My experience during the past 8 years using anti VEGF therapy for wAMD, DME, RVO has proved that anti
VEGF therapy is very effective in managing macula edema in these vascular-retinal diseases. Vol. 22, No. 1, 2016
37
The role of anterior segment OCT in glaucoma
J. K. Dilruwani Aryasingha1
The Journal of the College of Ophthalmologists of Sri Lanka 2016; 22: 46-48
Introduction A comprehensive evaluation of the drainage angle is critical for accurate diagnosis and appropriate therapeutic intervention in glaucoma. There is a wide spectrum of anatomical variations in the drainage angle in normal and affected eyes. Furthermore, forces at different anatomic levels in the eye may be responsible for the pathogenesis of angle closure, the iris (pupillary block), the ciliary body (plateau iris), the lens (phacomorphic glaucoma) and posterior to the lens (malignant glaucoma). Therefore, assessing anterior chamber angle anatomy and surrounding structures with anterior segment imaging is of tremendous importance for identifying individuals in the early stages of the disease and guiding therapeutic decisions.
Gonioscopy Gonioscopy remains the reference standard for assessing anterior chamber angle in the eye. It is inexpensive and can be rapidly performed at the slit-lamp. Gonioscopy permits dynamic visualization of the entire angle quadrant and allows indentation differentiating between appositional and synaechial angle closure. As this is a subjective technique, this can be affected by patient’s cooperation, examiner's skill, type of lens used, direction of gaze, inadvertent pressure on the cornea and environmental illumination. Different classification systems may also cause variability in angle assessment. Furthermore, it does not provide quantitative evaluation of the angle and is also limited in visualizing structures posterior to the iris.
Imaging of the anterior segment Imaging of the anterior segment offers an objective
method for visualizing the angle and adjacent anatomical
structures. In addition to qualitative analyses, some
imaging modalities permit quantitative analyses that can
be used to monitor change or progression over time.
Several imaging devices are available such as ultrasound
biomicroscopy (UBM), scheimpflug photography, eye
cam and anterior segment optical coherence tomography
(AS-OCT).
Anterior segment OCT Anterior segment OCT is a non-contact method
providing high resolution tomographic cross-sectional
imaging of anterior segment structures. AS-OCT uses
the principle of low-coherence interferometry instead
of ultrasound. The technique measures the delay and
intensity of the light reflected from the tissue structure
being analyzed and compares it with the light
reflected by a reference mirror. The combination of
these two signals results in interference phenomenon.
The signal intensity depends on the optical properties
of the tissues and the device uses these signals to
construct a sagittal cross-section image of the structure
being analyzed. OCT technology was initially used to
produce images of the posterior segment of the eye by
using a wavelength of 820nm. In 2001, the wavelength
was altered to 1310nm to allow better penetration
through light-retaining tissues such as the sclera and
limbus and to improve visualization of the anterior
segment.
Figure 1.
Compared with UBM, AS-OCT provides a higher axial
resolution (18um versus 25um in 50 MHz UBM) and
faster sampling rate (2.0 kHz versus 0.8kHz). Another
main clinical advantage over UBM is its ability to
provide noncontact scanning in a seated, upright
position (Figure 1). But in AS-OCT lack of a coupling
medium may affect the image quality due to abnor-
malities in the anterior surface of the eye. The major
drawback for AS-OCT is its inability to visualize
structures posterior to the iris due to blockage of
1Consultant Ophthalmologist, Golden Key Eye & Ent Hospital, Rajagiriya, Sri Lanka.
The Journal of the College of Ophthalmologists of Sri Lanka
The role of anterior segment OCT in glaucoma
wavelength by pigment. This limits its application in
discerning several secondary causes of angle closure,
such as plateau iris, ciliary body cyst or tumor, lens
subluxation or ciliary effusions (Figure2).
38
the ARA is defined as the triangular area with boun-daries including the angle recess (apex), iris surface and the inner corneoscleral wall (sides) and AOD (base). The anterior chamber angle is defined in degrees, in which the angle recess forms the apex and the two sides of the angle are formed by drawing the lines through the points defining the AOD 500.
Figure 2.
AS-OCT can be used as an adjunct to gonioscopy as
well as a substitute when gonioscopy is not feasible
due to corneal pathology or lack of patient co-
operation. It is extremely useful as a patient education
tool, especially when laser peripheral iridotomy is
being recommended. Being a non-contact technique
and can be performed under dark conditions, it allows
angle assessment during physiological mydriasis.
OCT-Goniometry Anterior segment OCT plays an important role not only
in identifying the angle structures qualitatively, but also
in providing quantitative measurements by using special
software to determine the extent of apposition in cases of
angle closure. OCT-Goniometry is the new term given for
objective measurement tools obtained by the AS-OCT to
quantify angle opening. After the scleral spur is located
by the technician, several parameters can be measured.
Anterior chamber depth is defined as the axial distance
between the posterior surface of the cornea and anterior
lens surface. One important parameter for angle anatomy
is the angle opening distance (AOD): the length of line
drawn perpendicular from a point on the corneal
endothelial surface (either 500 or 750um anterior to the
scleral spur) to the iris surface. Theoretically, a distance of
500um from the scleral spur approximates the location of
the trabecular meshwork and a longer distance of 750um,
covering a more extensive region, may be less affected by
local iris surface irregularities.
Because AOD measurements are made in the iris plane,
they can be influenced by the presence of peripheral
anterior synechiae or other irregularities of iris contour
and curvature. To overcome these limitations and to
account for the whole contour of the iris surface, Ishikawa
et al. devised the angle recess area (ARA), which borders
the anterior iris surface, corneal endothelium, and AOD
500 or AOD 750. Therefore,
AOD750
Scleral
AOD50 Spur Angle (SSA)
TISA75
TISA500
Figure 3.
Because of poor visualization of the angle recess near the
scleral spur and inability to measure the ARA properly
with AS-OCT, Radhakrishnan et al, proposed calculating
the trabecular-iris space area (TISA), which does not
require clear visualization of the angle recess (Figure 3).
The researchers described this parameter to be a better
indicator than ARA for actual filtering area and a more
sensitive identifier of narrow angles in eyes with deep
angle recesses. The TISA excludes the nonfiltering area
via its posterior border outlined by a line drawn from the
scleral spur to the opposing iris perpendicular to the
plane of the inner scleral wall. Therefore, the TISA is the
trapezoidal area with AOD anteriorly, inner scleral wall
posteriorly, inner corneos-cleral wall superiorly, and iris
surface inferiorly. Clinical applications of AS-OCT Anatomically narrow angles can be diagnosed with AS-OCT both qualitatively and quantitatively. Widening of the angles after laser iridotomy in eyes with narrow angles or pupillary block glaucoma has been demonstrated with both UBM and AS-OCT. Serial monitoring of the angle since approximate alignment with ocular landmarks (such as iridotomies, iris naevi, conjunctival blood vessels etc.) can be performed with AS-OCT by utilizing the video image during OCT scan acquisition. Although AS-OCT is limited due to blockage of infrared
light by iris pigment with incomplete visualization of the
ciliary body, it can visualize iris cyst, iris melanoma or
ciliary effusions in some cases. AS-OCT has been
described to differentiate cystic and solid lesions of the
iris. However, these pathologies and others including
plateau iris, phacomorphic glaucoma, or malignant
glaucoma are better detected with UBM. In
Vol. 22, No. 1, 2016
39
contrast to AS-OCT, UBM better demonstrates the
anterior rotation of the ciliary body with loss of ciliary
sulcus in plateau iris syndrome.
AS-OCT can be used to assess the iris contour in
pigment dispersion syndrome (PDS). In this condition,
pigment liberation is secondary to rubbing between
the iris pigment epithelium and lens zonules because
of increased iridolenticular contact.
AS-OCT is a useful tool to evaluate filtering blebs or
glaucoma drainage devices in the postoperative
period. Clinically, blebs can be described as diffuse,
cystic, encapsulated or flat. However, these
descriptions are subjective and there may be cases in
which clinical appearance does not correlate with bleb
function. Therefore, visualizing intrableb morphology
with anterior segment imaging may enhance our
under-standing of different surgical outcomes and
wound healing. Encapsulated blebs have a thick wall,
high reflectivity because of dense collagenous
connective tissue present in the bleb wall and an
enclosed fluid-filled space. Flat blebs demonstrated
high scleral reflectivity with no bleb elevation. AS-
OCT allows visualization of the glaucoma drainage
devices in the anterior chamber to assess their position
or potential occlusion.
The noncontact nature of AS-OCT makes it a valuable
tool in identifying angle pathology in posttraumatic
eyes. Angle recession or cyclodialysis cleft may be
documented.
Summary Anterior segment imaging is an important facet of glaucoma care. The various devices have their own advantages and disadvantages and the decision to use these modalities depends on their cost, technicians’ expertise, and medical professionals’ clinical pre-ferences. References 1. Ritch R, Liebmann J, Tello C. “A construct for unders-
tanding angle-closure glaucoma: the role of ultrasound
biomicroscopy”. 2. Dandona L, Dandona R, Mandal P, et al. “Angle-closure
glaucoma in an urban population in Southern India. The
Andhra Pradesh Eye Disease Study. Ophthalmology 2000;
107: 1710-16. 3. Radhakrishnan S, Rollins AM, Roth JE, et al. Real-time optical
coherence tomography of the anterior segment at 1310 nm.
Arch Ophthalmol 2001; 119: 1179-85.
4. Radhakrishnan S, Goldsmith J, Westphal V, et al.
Comparison of coherence tomography and ultrasound
biomicroscopy for detection of narrow anterior chamber
angles. Arch Ophthalmol 2005; 128: 1053-9. 5. Fukuda S, Kawana K, Yasuno Y, et al. Repeatability and
reproducibility of anterior ocular biometric
measurements with 2-D and 3-D optical coherence
tomography. J Cataract Refract Surg 2010; 36: 1867-73. 6. Tan AN, Sauren LD, de Brabander J, et al. Reproducibility of
anterior chamber angle measurements with anterior segment
OCT. Invest Ophthalmol Vis Sci 2011; 52: 2095-9.
The Journal of the College of Ophthalmologists of Sri Lanka
Lamellar dissection technique in deep anterior lamellar keratoplasty (DALK) – does it matter in postoperative progression 40
Lamellar dissection technique in deep anterior lamellar keratoplasty
(DALK) – does it matter in postoperative progression K. H. Wickramasinghe1, S. K. G. S. Kurera2, C. J. Kumarage3, W. M. C. M. Andradi4, D. H. H. Wariyapola5
The Journal of the College of Ophthalmologists of Sri Lanka 2016; 22: 49
Introduction Success of DALK depends on postoperative graft
behavior. Factors that might influence this are graft
size, lamellar dissection and suturing techniques.
Method DALK done from 2009 December to 2014 October
were enrolled. 90 eyes were included in the analysis.
Topography and refractive data were collected at 3
monthly intervals starting at postoperative 3rd month.
Data was analyzed using SPSS.
Results Average age of the patients was 25 years. 52.9% were
females. Preoperative average keratometry (Avrg-K)
in the operated eye was 57. Preoperative best corrected
visual acuity(BCVA) in 4.3% was 6/9 or better and
91.4% had 6/18 or less. 72.4% of surgeries used
Anwar’s big bubble technique (ABB) and 26.7% were
layer by layer dissections (LL). Postoperatively pooled
data showed 6/9 or better vision in 46.5% at
postoperative 3rd month. It increased to 67.2% at 6th
month, 78.1% at 9th month and 77.8% at 12th month.
Postoperative Avrg-K was 43.
In patients who had ABB, preoperative BCVA in 4.9%
was 6/9 or better. 85.4% had 6/18 or less BCVA. Avrg-
K in the operated eye was 57. Postoperatively BCVA
was 6/9 or better in 42.9% at 3 months, 65.5% at 6
months, 79.3% at 9 months and 88.8% at 12 months.
Postoperative Avrg-K was 43.
In patients who had LL, Preoperative BCVA was less
than 6/18 in all patients (n=15). Avrg-K in the
operated eye was 62. Postoperatively BCVA was 6/9
or better in 45.5% at 3 months, 57.1% at 6 months, 75%
at 9 months and 66.7% at 12 months. Postoperative
Avrg-K was 43. There was no statistically significant
correlation between the lamellar dissection technique
and post operative progression of Average
Keratometry and BCVA parameters.
Discussion There was improvement in BCVA in both methods
until 1 year of post op follow up. Average keratometry
was corrected by DALK. In our setting there was no
difference in post operative progression until one year
follow up between the two lamellar dissection
techniques.
1Registrar in Ophthalmology, 2Post Graduate Trainee in Ophthalmology, 3Senior Registrar in Ophthalmology, 4Research Assistant, 5Consultant Ophthalmologist, Sri Jayawardenapura General Hospital, Kotte, Sri Lanka.
Vol. 22, No. 1, 2016
41
The effect of preservatives on the ocular surface and success of glaucoma
filtration surgery Nuwan Niyadurupola1
The Journal of the College of Ophthalmologists of Sri Lanka 2016; 22: 50-53
Abstract The preservatives in topical glaucoma medication can have a
detrimental effect on the ocular surface. The use of preserved
antiglaucoma drops has been shown to lead to poor
trabeculectomy outcomes. Reducing the amount of preser-
vatives and switching patients to preservative-free eye drops
improves comfort and tolerability of topical medication.
Introduction Preservatives are everywhere these days; from the food that we eat, to the paints on our walls and the varnish on our floors. They are principally used to kill microbes and extend the shelf life of the product. The majority of topical antiglaucoma eye drops contain preservatives. The role of the preservatives in topical medication is also to kill microbes and extend the shelf life of the drops. There is some controversy that the preservatives in topical medication may help enhance drug penetration into the eye, but this appears not to be the case since non-preserved varieties of the medication have been shown to have the same efficacy as the preserved variety. The most common preservative used in topical antiglaucoma medication is benzalkonium chloride (BAK). Other preservatives used in topical anti-glaucoma medication include polyquaternium-1 (Polyquad), Purite and sofZia. Benzalkonium chloride is a cationic detergent and a highly effective anti-microbial. The mechanism of action of BAK as an anti-microbial is to cause dissolution of bacterial cell walls, disruption to cellular junctions and dissociation of lipid bilayers. The problem, however, is that the effect of BAK on cells is non-selective and healthy host tissue can also be damaged. The BAK content of commonly used topical anti-
glaucoma eye drops are shown in Table 1. The highest
concentrations of BAK (0.02%) are contained in
bimatoprost, latanoprost and fixed combination
latanoprost/timolol. The available generic varieties of
latanoprost contain the same concentration of BAK
(0.02%). Travaprost and fixed combination travaprost/
timolol contain polyquaternium-1 (Polyquad) rather than
BAK. In some countries travaprost is available
preserved with sofZia and brimonidine is available
preserved with Purite.
The effect of BAK on the ocular surface Benzalkonium chloride from topical medication has been shown to accumulate in the corneal and conjunctival epithelium (1,2). Benzalkonium chloride can be retained in the epithelium for up to 1 week, with a half-life of 20 hours (1). From the corneal and conjunctival epithelium, BAK can penetrate into the deeper structures within the eye. Following topical instillation, BAK has been found in the trabecular meshwork, iris, lens capsule, retina, choroid and the optic nerve of rabbit eyes (2,3). Topical BAK (0.01%) has been shown to halve the tear break-up time (a measure of dry eye) within minutes of application in healthy volunteers (4). The detergent action of BAK is thought to dissolve the superficial oily lipid layer of the tear film leading to dry eyes (4). Benzalkonium chloride has been shown to reduce the number and function of conjunctival goblet cells compromising the tear film further (5). Dissolution of the lipid layer of the tear film causes excessive evaporation of the aqueous layer of the tear film and mucin precipitation. This can then lead to corneal epithelial defects and risk of ulceration.
Benzalkonium chloride is detrimental to the cornea. Low
concentrations of BAK have been shown to inhibit corneal
epithelial cell pseudopod growth and impair corneal
epithelial regeneration (6). Keratectomies performed in rabbit
cornea have failed to heal in the presence of 0.02% BAK (7).
In patients, the density of superficial corneal epithelial cells
was found to be reduced in those receiving preserved
antiglaucoma eye drops in comparison to those receiving
non-preserved antiglaucoma eye drops and control subjects
on no topical treatment (8). Patients receiving preserved anti-
glaucoma eye drops also had decreased corneal sensi-tivity
compared to those receiving unpreserved antiglaucoma eye
drops or control subjects (8,9). The num-bers of sub-basal
corneal nerves was lower in patients taking preserved
antiglaucoma eye drops than those taking preservative-free
antiglaucoma eye drops (8).
1Consultant Ophthalmic Surgeon, Department of Ophthalmology, Norfolk and Norwich University Hospital, United Kingdom.
The Journal of the College of Ophthalmologists of Sri Lanka
The effect of preservatives on the ocular surface and success of glaucoma filtration surgery 42
Table 1. Concentration of benzalkonium chloride (BAK) in antiglaucoma eye drops
Antiglaucoma eye drop BAK content (%)
apraclonidine 0.01
betaxolol 0.01
bimatoprost 0.02
brimonidine 0.005
brinzolamide 0.01
carteolol 0.005
dorzolamide 0.0075
metipranolol 0.004
latanoprost 0.02
levobunolol 0.005
pilocarpine 0.01
timolol 0.01
Fixed combination bimatoprost/timolol 0.005
Fixed combination brimonidine/timolol 0.005
Fixed combination brinzolamide/brimonidine 0.003
Fixed combination brinzolamide/timolol 0.01
Fixed combination brinzolamide/timolol 0.01
Fixed combination dorzolamide/timolol 0.0075
Fixed combination latanoprost/timolol 0.02
Fixed combination pilocarpine/timolol 0.01
In the conjunctiva, BAK has been shown to cause a dose-
dependent loss of epithelial cells. Low concen-trations of
BAK (0.0001% to 0.01%) have been shown to cause
apoptosis of conjunctival cells in culture (10). Higher
concentrations of BAK (0.05% to 0.1%), however, caused
immediate conjunctival cell lysis (10). Chang conjunctival
cells in vitro have shown immediate cell lysis following
addition of 0.01% BAK (11). In a study of conjunctival
histology, patients using multiple topical medication
showed more inflammatory changes and fibroblastic cells
within the conjunctiva compared to control subjects (12).
Benzalkonium chloride was found to be the cause of this
inflammatory infiltrate since topically applied preserved
0.5% timolol (containing 0.01% BAK) and topically
applied 0.01% BAK alone caused an increase in
inflammatory cell counts in the conjunctiva of rat eyes
compared to controls (12). The conjunctival cell profile of
rats treated with topical preservative-free 0.5% timolol,
however, was similar to controls (12). Long-term
antiglaucoma
therapy with at least two agents for a mean of 7.7 years
has been shown to significantly increase the number of
fibroblasts and inflammatory cells in the conjunctiva. (5). The inflammatory and fibroblastic infiltrate of the
conjunctiva may be the cause of significant fore-
shortening of the inferior fornix that has been found in
patients using topical anti-glaucoma therapy
containing preservatives for three or more years (13).
The effect of preservatives on trabeculectomy
outcomes A pivotal study published in 1994 by Broadway D. C. and
co-workers (14), examined the conjunctival cell profile of
topically treated and untreated glaucoma patients and
compared the success rates of trabeculectomy in these
groups. The control patients were patients undergoing
primary trabeculectomy who had not had any previous
surgery and had minimal previous topical therapy. The
study group were
Vol. 22, No. 1, 2016
43
patients on topical antiglaucoma therapy with preserved
eye drops for at least 6 months prior to undergoing
trabeculectomy and were divided into three groups;
those taking beta-blockers alone, those taking a beta-
blocker and a miotic and those taking a beta-blocker, a
miotic and a sympathomimetic. The success rate of
trabeculectomy in patients taking a beta-blocker alone
(90%) was similar to that of controls (93%) (14). However,
the success rates of trabeculectomy were lower in those
on multiple topical medication, and therefore those that
had more exposure to preser-vatives. Those on two
medication (beta-blocker and miotic) had a lower
trabeculectomy success rate of 75% compared to controls
and those on triple therapy had a markedly lower success
rate of only 45% (14). The triple therapy group, that fared
the worst, had increased numbers of fibroblasts,
macrophages, lymphocytes, mast cells and Langerhan’s
presenting cells within the conjunctiva compared to
control eyes (14,15). The increased inflammatory infiltrate
in the conjunctiva of treated triple therapy patients was
presumed to be the cause of trabeculectomy failure in
this group. The triple therapy group also had lower
numbers of goblet cells within the conjunctival epi-
thelium compared to controls (15). The prior duration of
treatment with preserved antiglaucoma drops was also
found to be important for trabeculectomy success. A
duration of antiglaucoma treatment of greater than three
years and hence a greater than three year expo-sure to
preservatives was found to significantly reduce
the success of trabeculectomy surgery in patients
compared to those treated for less than three years or
controls (14).
The effect of preservatives on patients A large study of 4107 patients by Pisella P. J. and co-
workers (16), showed that symptoms of discomfort upon
instillation, foreign body sensation, stinging or burning,
dry eye sensation, tearing and eye lid itching and signs of
dry eye disease were significantly higher in the patients
taking preserved antiglaucoma eye drops compared to
those taking preservative-free eye drops. The prevalence
of symptoms and signs of dry eye disease increased with
the number of preserved eye drops used and switching
patients to preservative-free antiglaucoma eye drops
reduced both symptoms and signs of dry eye disease (16).
Quality of life has been shown to be reduced in those
suffering from burning, itchy eyes, dry eyes and redness
as a result of topical medication (17). It is not surprising
that the patients who reported worse quality of life and
were unsatisfied with their treatment were the ones who
often missed doses of their medication and had poor
adherence (17). Those patients who reported a good
quality of life and were satisfied with their eye drops had
good adherence (17). Furthermore, patients who reported
that they were unsatisfied with their treatment had
significantly more visits to the eye clinics than patients
who reported being ‘rather satisfied’ with their
Table 2. Preservative-free topical antiglaucoma medication
Antiglaucoma eye drop Class
betaxolol β-blocker
levobunolol β-blocker
metipranolol β-blocker
timolol β-blocker
dorzolamide carbonic anhydrase inhibitor
pilocarpine miotic
bimatoprost prostaglandin analogue
latanoprost prostaglandin analogue
tafluprost prostaglandin analogue
Fixed combination dorzolamide/timolol carbonic anhydrase inhibitor/β-blocker
Fixed combination bimatoprost/timolol prostaglandin analogue/β-blocker
Fixed combination latanoprost/timolol prostaglandin analogue/β-blocker
Fixed combination tafluprost/timolol prostaglandin analogue/β-blocker
The Journal of the College of Ophthalmologists of Sri Lanka
The effect of preservatives on the ocular surface and success of glaucoma filtration surgery 44
treatment (17). Therefore, reducing the amount of
preservative load on the ocular surface of patients is
beneficial to reducing adverse symptoms and signs,
improving adherence and reducing unnecessary visits
to eye clinics.
Preservative-free antiglaucoma medication There are a number of preservative-free topical
medications available for treatment of glaucoma (Table
2). All preservative-free topical antiglaucoma medi-
cations have been shown to be non-inferior to the
preserved varieties, suggesting that the preservative is
not required for drug penetration into the eye.
Preservative-free antiglaucoma medications have also
been shown to be better tolerated than the preserved
varieties (16). The increasing use of preservative-free
antiglaucoma therapy will hopefully help improve
patient adherence by improving tolerability of the
medication. The improved adherence to antiglaucoma
medication is important to achieve effective intraocular
pressure lowering and reduce glaucoma progression for
our glaucoma patients.
6. Hendrix DV, Ward DA, Barnhill MA. Effects of anti-
inflammatory drugs and preservatives on morphologic
characteristics and migration of canine corneal epithelial
cells in tissue culture. Vet Ophthalmol 2002; 5: 127-35. 7. Collin HB, Grabsch BE. The effect of ophthalmic preservatives on
the healing rate of the rabbit corneal epithelium after
keratectomy. Am J Optom Physiol Opt 1982; 59: 215-22. 8. Martone G, Frezzotti P, Tosi GM, et al. An in vivo confocal
microscopy analysis of effects of topical antiglaucoma
therapy with preservative on corneal innervation and
morphology. Am J Ophthalmol 2009; 147: 725-35. 9. Van Went C, Alalwani H, Brasnu E, et al. [Corneal
sensitivity in patients treated medically for glaucoma or
ocular hypertension]. J Fr Ophtalmol 2011; 34: 684-90. 10. De Saint Jean M, Brignole F, Bringuier AF, Bauchet A,
Feldmann G, Baudouin C. Effects of benzalkonium
chloride on growth and survival of Chang conjunctival
cells. Invest Ophthalmol Vis Sci 1999; 40: 619-30. 11. Debbasch C, Brignole F, Pisella PJ, Warnet JM, Rat P,
Baudouin C. Quaternary ammoniums and other preser-
vatives’ contribution in oxidative stress and apoptosis on
Chang conjunctival cells. Invest Ophthalmol Vis Sci 2001;
42: 642-652. References 1. Champeau E, Edelhauser H. Effect of ophthalmic
preservatives on the ocular surface: conjunctival and corneal
uptake and distribution of benzalkonium chloride and
chlorhexidinedigluconate. In: Holly, F (Ed), The preocular
tear film Dry Eye Institute, Inc, Lubbock, TX 1986; 292-302. 2. Brignole-Baudouin F, Desbenoit N, Hamm G, et al. A
new safety concern for glaucoma treatment
demonstrated by mass spectrometry imaging of
benzalkonium chloride distribution in the eye, an
experimental study in rabbits. PloS One 2012; 7: e50180. 3. Desbenoit N, Schmitz-Afonso I, Baudouin C, et al.
Localisation and quantification of benzalkonium chloride in
eye tissue by TOF-SIMS imaging and liquid chromatography
mass spectrometry. Anal Bioanal Chem 2013; 405: 4039-49. 4. Wilson WS, Duncan AJ, Jay JL. Effect of benzalkonium
chloride on the stability of the precorneal tear film in
rabbit and man. Br J Ophthalmol 1975; 59: 667-9. 5. Sherwood MB, Grierson I, Millar L, Hitchings RA. Long-
term morphologic effects of antiglaucoma drugs on the
conjunctiva and Tenon’s capsule in glaucomatous patients.
Ophthalmology 1989; 96: 327-35.
12. Baudouin C, Pisella PJ, Fillacier K, et al. Ocular surface
inflammatory changes induced by topical antiglaucoma
drugs: human and animal studies. Ophthalmology 1999;
106: 556-563. 13. Schwab IR, Linberg JV, Gioia VM, Benson WH, Chao
GM. Foreshortening of the inferior conjunctival fornix
associated with chronic glaucoma medications.
Ophthalmology 1992; 99: 197-202. 14. Broadway DC, Grierson I, O’Brien C, Hitchings RA. Adverse
effects of topical antiglaucoma medication. II. The outcome
of filtration surgery. Arch Ophthalmol 1994; 112: 1446-54. 15. Broadway DC, Grierson I, O'Brien C, Hitchings RA.
Adverse effects of topical antiglaucoma medication. I.
The conjunctival cell profile. Arch Ophthalmol 1994; 112:
1437-45. 16. Pisella PJ, Pouliquen P, Baudouin C. Prevalence of ocular
symptoms and signs with preserved and preservative free
glaucoma medication. Br J Ophthalmol 2002; 86: 418-23. 17. Nordmann JP, Auzanneau N, Ricard S, Berdeaux G. Vision
related quality of life and topical glaucoma treatment side
effects. Health Qual Life Outcomes 2003; 1: 75.
Vol. 22, No. 1, 2016
45
Knowledge, attitudes and practices of pre-intern doctors on the
management of emergency ophthalmological conditions M. M. Dissanayake1, S. Vithoosan2, S. A. A. Senevirathne2, N. Wickramasekara2, P. H. Dissanayake2
The Journal of the College of Ophthalmologists of Sri Lanka 2016; 22: 54-55
Abstract Objectives: To assess the knowledge, attitudes and practice
regarding ophthalmological emergencies among pre intern
doctors. Methods: One hundred (n=100) pre intern doctors who
have completed their final MBBS were studied using a self-
administered questionnaire which contained questions on
knowledge, attitudes and practices regarding ophthalmo-
logical emergencies. Data were analyzed using SPSSv20.0. Results: Mean age was 25.96±0.7236 (mean±SD) years
(n=100, males=60; females=40). Assessment of knowledge
revealed that mean knowledge on the diagnosis of ocular
trauma, acute loss of vision, red eye were 4.100±0.8103,
3.44±1.258, 3.28±1.0257 (mean±SD) out of five res-
pectively. Knowledge on the management of above
conditions were 3.82±0.9361, 3.26±1.0211, 3.26±1.1687
out of five respectively. 46% of the students haven't
encountered acute angle closure glaucoma during their
clinical practice. Similarly 56% and 42% haven’t
encountered retinal detachment and corneal foreign bodies.
50% were not confident regarding management of acute
angle closure glaucoma and 22% were not confident
regarding corneal foreign bodies management. 55% felt that
the current duration of 2 weeks for clinical appointment in
Ophthalmology is not adequate. 72% suggested that
increasing clinical exposure is the most suitable way to
improve the knowledge and confidence regarding
management of ophthalmological emergencies. Conclusions: Even though most pre intern doctors have
adequate theoretical knowledge regarding diagnosis and
management of common ophthalmological emergencies,
majority were not confident regarding management of the
emergencies as first contact doctors. Most suggested that
increasing the clinical exposure as the ideal way to improve
their confidence in managing ophthalmological emergencies.
Introduction Ophthalmological emergencies are among the
commonest presentations encountered by primary care
doctors. A sound knowledge of these conditions is essential for doctors to manage them appropriately. Diagnosis and treatment or referral to a center with better facilities will significantly affect the visual prognosis of the patient. However in the present day medical curriculum with so much of content for the undergraduate to cover there were discussions on reducing the time allocated for Ophthalmology. Studies done in various parts of the world regarding the knowledge of medical practitioners regarding ophthalmological emergencies showed that most medical undergraduates and first contact care doctors lack a sound knowledge regarding the diagnosis and management of ophthalmological emergencies.
Objective To assess the knowledge, attitudes and practices
regarding ophthalmological emergencies among pre
intern doctors
Methodology One hundred (n=100) pre intern doctors who have completed their final MBBS at a Sri Lankan medical school were studied using a self-administered questionnaire which contained questions on general information, knowledge on emergency ophthal-mological conditions and attitudes and practices regarding ophthalmological emergencies. Ethical clearance was obtained from the Ethics Review Committee of Faculty of Medicine, University of Colombo. Data were analyzed using SPSS v 20.0.
Results Sample size was 100 with 60% males. Mean age was
25.96±0.7236 years. All participants had undergone
two weeks of clinical training in ophthalmology. Data analysis was carried out to obtain a mean score
giving an assessment of each of the ophthalmological
emergencies.
1Senior Lecturer and Consultant Ophthalmologist, Faculty of Medicine, University of Colombo, 2Research Assistant,
Faculty of Medicine, University of Colombo, 3Senior Lecturer, Faculty of Medical Sciences, University of Sri Jayewardenepura, Sri Lanka.
The Journal of the College of Ophthalmologists of Sri Lanka
Knowledge, attitudes and practices of pre-intern doctors on the management of emergency ophthalmological conditions 46
Assessment of knowledge regarding ophthalmological
emergencies revealed mean scores of 4.100±0.8103,
3.44±1.258, 3.28±1.0257 (mean±SD) out of five for ocular
trauma, acute loss of vision, red eye respectively.
Figure 1.
Assessing the knowledge on management of ophthal-
mological emergencies revealed that mean knowledge
on management of ocular trauma was acute loss of
vision, red eye were 3.82±0.9361, 3.26±1.0211,
3.26±1.1687out of five respectively.
Figure 2.
Regarding the familiarity with emergency eye con-ditions
46% of the students have not gained adequate knowledge
on acute angle closure glaucoma during their clinical
appointment. Similarly 56% and 42% have not had
adequate exposure on practical manage-ment on retinal
detachment and corneal foreign bodies.
With regard to confidence in managing emergency eye
conditions, 50% were not confident regarding manage-
ment of acute angle closure glaucoma and 22% were
not confident regarding corneal foreign bodies
management.
Even though all have agreed ophthalmological training
should be a part of undergraduate curriculum 55% felt
that the current duration of 2 weeks for clinical
appointment in Ophthalmology is not adequate. 72% suggested that increasing clinical exposure is the
most suitable way to improve the quality of
knowledge regarding ophthalmological emergencies
Discussion Though the pre interns have satisfactory theoretical
knowledge most of them have not had adequate exposure
to most of the emergencies in clinical practice during their
student days. Most were not confident about their ability
to manage the emergencies themselves as first contact
doctors. This could also result from the recent changes in
the medical curriculum trying to incorporate more of core
clinical areas during the undergraduate period. Most of
the participants suggested that increasing the clinical
exposure as to improve the knowledge and skills on
diagnosis and management of ophthalmological
emergencies. At the same time it is the duty of the
ophthalmogist to act proactively assisting the curriculum
development committees to incorporate inputs from
ophthalmology in to core curricular material as they
make an essential component of the work of primary care
doctors. The International Council of Ophthalmology also
provides guidance to increase ophthalmology training in
medical schools. It recommends 40-60 hours of
ophthalmology exposure during undergraduate medical
education which is barely covered in most medical
schools.
Acknowledgements We would like to acknowledge Professor Rohan W
Jayasekara, Emeritus Professor and Former Dean,
Faculty of Medicine, University of Colombo for the
support and guidance.
References 1. Quillen DA, Harper RA, Haik BG. Medical student
education in ophthalmology: crisis and opportunity
Ophthalmology 2005; 112(11): 1867-8. 2. Jacobs DS. Teaching doctors about the eye: trends in the
education of medical students and primary care residents.
Surv Ophthalmol. 1998; 42(4): 383-9. 3. Manolopoulos J. Emergency primary eye care. Tips for
diagnosis and acute management. Aust Fam Physician
2002; 31(3):233-7. 4. Tong, Lili et al. Eye Day for medical students: delivering
ophthalmic undergraduate education through inter-
professional collaboration. Canadian Journal of Ophthal-
mology 2016; 51(4): 242-3.
Vol. 22, No. 1, 2016
47
Effect of axial length on accuracy of different types of biometry in
phacoemulsification surgery H. P. M. K. Gunewardena1, N.G. I. R. De Silva1, M. T. K. Perera2, W. M. C. M. Andradi3, D. H. H. Wariyapola4
The Journal of the College of Ophthalmologists of Sri Lanka 2016; 22: 56-57
Abstract Introduction: The target of cataract surgery is an ultimate
good vision with minimal refractive errors. Final outcome
will depend mainly on the accuracy of the biometry. Both
immersion and optical biometry are in use for biometry
world wide. Some studies have shown advantages and
disadvantages of each other. This study was done to find the
accuracy of final refractive outcome between IOL master
(OPT) and Immersion A scan in hypermetropes, myopes
and emmetropes and analyse which of the two biometry
methods would be better for each instance. Methodology: A retrospective longitudinal study was
carried out from March 2013 to September 2015 in Sri
Jayawardenapura General Hospital (SJGH) on 490 eyes-
which was conveniently selected. IOL Master biometry and
Immersion A biometry was performed randomly in these
patients before cataract surgery. Post-operative data was collected after one month and spherical
equivalent and the difference between the predicted refraction
and spherical equivalent was calculated. Finally comparison of
error in prediction was done in all groups. Results: In 490 eyes, IOL master, measurement was done
in 363 eyes which resulted in 331 emmetropes, 13 myopes
and 19 hypermetropes. In 127 eyes, measurement was done
by Immersion A scan which resulted in 106 emmetropes, 04
myopes and 17 hypermetropes. No statistically significant difference was seen in all three
groups, for the prediction of final refractive outcome (Paired
t test was done). Conclusion: Our study suggests that optical biometry [IOL
master] and immersion biometry are both clinically acceptable
in patients with hypermetropes, myopes and emmetropes.
Introduction A patient hopes for the best vision at the end of a
cataract surgery. Ultimate good vision depends on the
accuracy of biometry. Both immersion (IMM) and optical biometry (OPT, IOL
master) have been shown to have comparable
predictive ability in emmetropic eyes.
However this is often different with axial myopic and
hyperopic eyes, requiring greater refractive corrections
post operatively. There are some benefits of Immersion A scan over IOL
Master. Immersion A scan is useful in dense ocular
media with mature cataract, a patient who is unable to
sit on a table and those who are having fixation
disorders. There are some benefits of IOL master over Immersion
A scan too. IOL master is not dependant on the user. It
is extremely useful in patients with macular disorders
and extreme myopics.
Objectives
• To analyze the accuracy of final refractive outcome between IOL master (OPT) and Immersion A scan in hypermetropes, myopes and emmetropes.
• To analyse which of the two biometry
methods would be better for each instance.
Methodology A retrospective longitudinal study was carried out from
March 2013 to September 2015 in Sri Jayawardenapura
General Hospital (SJGH) on 490 eyes. Convenient
sampling method was carried out and axial length was
calculated randomly by IOL master or Immersion A scan
in groups of emmetropes, myopes and hyper-metropes
pre operatively and predicted refraction was calculated
by SRK/T formula.
All the cataract surgeries were done by a single
surgeon using 2.2mm incision. A single piece IOL was
implan-ted and complicated surgeries were excluded.
All the patients had an uneventful post-operative
period and after one month spherical equivalent and
1Post Graduate Trainee, 2Registrar, 3Research Assistant, 4Consultant Ophthalmologist, Sri Jayewardenepura General Hospital, Kotte, Sri Lanka.
The Journal of the College of Ophthalmologists of Sri Lanka
Effect of axial length on accuracy of different types of biometry in phacoemulsification surgery 48
the difference between the predicted refraction and spherical equivalent was calculated. Finally com-parison of
error in prediction was done in all groups.
Results In 490 eyes, IOL Master, measurement was done in 363 eyes which resulted in 331 emmetropes, 13 myopes and
19 hypermetropes. In 127 eyes, measurement was done by Immersion A scan which resulted in 106 emmetropes,
04 myopes and 17 hypermetropes.
Hypermetropes Myopes Emmetropes
IOLM IMM IOLM IMM IOLM IMM
PE 0.68D 0.54D 0.32D 0.20D 0.37D 0.52D
(+/-0.75) (+/- 0.44) (+/- 0.24) (+/- 0.19) (+/- 0.38) (+/- 0.46)
Axial length range PE
26-27mm -0.30
27-28mm -0.31
28-29mm -0.34
29-30mm -0.29
Conclusion This study suggests that optical biometry [IOL master] and immersion biometry are both clinically acceptable in
patients with hypermetropes, myopes and emmetropes.
Vol. 22, No. 1, 2016
49
Astigmatic change following suture manipulation after deep anterior
lamellar keratoplasty (DALK) S. K. G. S. Kurera1, K. H. Wickramasinghe2, C. J. Kumarage3, W. M. C. M. Andradi4, D. H. H. Wariyapola5
The Journal of the College of Ophthalmologists of Sri Lanka 2016; 22: 58-60 Abstract Introduction: A successful DALK requires both clarity and an acceptable refraction. A clear corneal graft may be an optical failure if high astigmatism limits visual acuity. Therefore post DALK suture manipulation is mandatory to minimize postoperative astigmatism. Method: Post DALK suture manipulations done from July 2010 to August 2015 were included. 87 patients were followed up. Patients had undergone removal of sutures (ROS) depending on astigmatism, starting from 3rd month post DALK. Before ROS and month after ROS, keratometry was checked. Results: 20.5% of single suture removals were done at 3 months and resulted in a surgically induced astigmatic change (SIAC) ranging between 0.29 -19.43. 10.3% were at 6 months and SIAC ranged between 0.13-2.76, 7.7% were at 9 months and SIAC ranged between 0.83-1.51, 12.8% were at 12 months and SIAC ranged between 0.50 -2.92, 10.3% were at 15 months and SIAC ranged between 0.28-1.50, 10.3% were at 18 months and SIAC ranged between 0.57-4.81, 15.4% were at 21 months and SIAC ranged between 0.50 - 8.66, and 5.1% were at 24 months and SIAC was 0.69. 7.6% were after 24 months. 13.9% of double suture removals were done at 3 months and
resulted in a SIAC ranging between 0.57-9.25. 32.5% were at
6 months and SIAC ranged between 0.39-10.69, 15.1% were at
9 months and SIAC ranged between 0.63-7.59, 15.7% were at
12 months and SIAC ranged between 0.51-14.50, 4.2% were at
15 months and SIAC ranged between 0.77-14.17, 10.2% were
at 18 months and SIAC ranged between 0.69-16.44, 3.6% were
at 21 months and SIAC ranged between 1.95 -5.97, 2.4% were
at 24 months and SIAC ranged between 1.33-1.86. 2.4% were
after 24 months. Conclusion: Astigmatic change per single ROS stabilises
after 6 months. For double ROS astigmatic change is higher
after 6 months than single ROS.
Methodology DALK was first introduced to SJGH in December 2009. It
is a single surgeon station where the same surgeon
performed all DALK and the decision to offer DALK was
taken by him. The patient’s pre-operative data was
collected and included with demographic data, preoperative refraction, BCVA, topography and pachymetry. Post DALK suture manipulations done from July 2010 to August 2015 were included in the study. 87 patients were followed up who had under-gone removal of sutures (ROS) depending on astig-matism, starting from 3rd month post DALK. Before ROS and a month after ROS, average keratometry was checked and surgically induced astigmatic change was calculated (SIAC) using internet based SIA calculator. Data was collected from clinical records and investigations and a data collection form was used to record the data. The patients included in the study had a routine post-operative review at 1 month. At this review data on refraction, BCVA and topography were collected. Data collection was done by ophthalmology trainees and data was analysed using SPSS. Loose suture removals and broken suture removals were not included in the study.
Results Of the removal of sutures 14.8% were done at 03 months, 27.4% were done at 06 months, 13.9% were done at 09 months, 15.3% were done at 12 months, 5.6% were done at 15 months, 9.7% were done at 18 months, 5.6% were done at 21 months, 2.8% were done at 24 months, and 4.9% were done after 24 months.
Figure 1. Distribution of ROS at each encounter
by percentage.
1Post Graduate Trainee in Ophthalmology, 2Registrar in Ophthalmology, 3Senior Registrar in Ophthalmology, 4Research Assistant, 5Consultant Ophthalmologist, Sri Jayawardenapura General Hospital, Kotte, Sri Lanka.
The Journal of the College of Ophthalmologists of Sri Lanka
Astigmatic change following suture manipulation after deep anterior lamellar keratoplasty (DALK) 50
For single suture removals, 20.5% of single ROS were
done at 3 months and SIAC ranged between 0.29-19.43
with a mean of 3.8, 10.3% were at 6 months and SIAC
ranged between 0.13-2.76 with a mean of 1.7, 7.7%
were at 9 months and SIAC ranged between 0.83-1.51
with a mean of 1.2, 12.8% were at 12 months and SIAC
ranged between 0.50-2.92 with a mean of 1.8, 10.3%
were at 15 months and SIAC ranged between 0.28 -
1.50 with a mean of 0.8, 10.3% were at 18 months and
SIAC ranged between 0.57-4.81 with a mean of 3.3,
15.4% were at 21 months and SIAC ranged between
0.50-8.66 with a mean of 4.2 and 5.1% were at 24
months and SIAC was 0.69. 7.6% were after 24 months.
Figure 2. Mean SIAC following single suture removals.
For double suture removals, 13.9% of double ROS
were done at 3 months and SIAC ranged between 0.57-
9.25 with a mean of 4.1, 32.5% were at 6 months and
SIAC ranged between 0.39-10.69 with a mean of 4.4,
15.1% were at 9 months and SIAC ranged between
0.63 - 7.59 with a mean of 3.6, 15.7% were at 12 months
and SIAC ranged between 0.51-14.50 with a mean of
3.9, 4.2% were at 15 months and SIAC ranged between
0.77- 14.17 with a mean of 5.3, 10.2% were at 18
months and SIAC ranged between 0.69-16.44 with a
mean of 5.1, 3.6% were at 21 months and SIAC ranged
between 1.95-5.97 with a mean of 3.9 and 2.4% were at
24 months and SIAC ranged between 1.33-1.86 with a
mean of 1.5. 2.4% were after 24 months.
For quadruple suture removals, 11.1% of quadruple ROS
were done at 3 months and resulted in a SIAC of 6.76,
22.2% were at 6 months and SIAC ranged between 5.28-
10.07 with a mean of 7.6, 22.2% were at 9 months and
SIAC ranged between 0.72-9.14 with a mean of 4.9 and
22.2% were at 12 months and SIAC ranged between 2.57-
6.45 with a mean of 4.5. 22.3% were after 12 months. Data
for quadruple suture removals were few after 12 months
and the data was scattered.
Figure 3. Mean SIAC following double suture removals.
Figure 4. Mean SIAC following quadruple
suture removals. Discussion The decision to offer DALK to patients, who cannot be
adequately treated with glasses and contact lenses, is
based on clinical judgement. Postoperative clinical
parameters may be influenced by the lamellar dissection
technique and suture tension and patient corneal
characteristics like central corneal thickness. It is
important to understand that a clear corneal graft may be
an optical failure if high astigmatism limits visual acuity
and post DALK suture manipulation is useful to
minimize postoperative astigmatism. In this study the
majority who had DALK are young patients with
keratoconus and had an average patient age of 26 years. It
is the most productive part of their lives in terms of
education and career development. Therefore the
decision to offer timely surgery becomes imperative. It
Vol. 22, No. 1, 2016
51
is still the patients’ visual requirement and tolerability
of eyewear that is considered when managing the
patient postoperatively. At the time when these
patients required surgery, majority had moderate to
severe keratoconus.
Of the single ROS, mean SIAC was minimal between 6
and 15 months, but significantly high between 18 and
21 months (3-4D). In double ROS group, the mean
astigmatic change was about the same from 6 to 21
months, but the variability is significant. In quadruple
ROS, the difference is not significant between 3 to 12
months.
Conclusion We were unable to see a definite pattern between early
ROS and late ROS. It is generally believed that early
ROS cause more change in astigmatism than late ROS.
Some believe that late ROS (> 2 years) would not have
much effect. In our study, we noted that at 3 months
the mean SIAC was only 3.8D, but there was a wide
range with a maximum of 19.43D. This would agree
with the commonly held beliefs that early ROS cause a
high astigmatic change. At least in the initial stages
(up to about 9 to 12 months), the astigmatic change is
higher in quadruple ROS than double and single and
higher in double than single.
The Journal of the College of Ophthalmologists of Sri Lanka
Conjuctival intraepithelial neoplasia 52
Conjuctival intraepithelial neoplasia – a case study G. J. N. Widanage, I. K. Devasurendra, B. Amarasinghe, S. Nanayakkara The Journal of the College of Ophthalmologists of Sri Lanka 2016; 22: 61-63
Introduction Ocular surface squamous neoplasia (OSSN) encompasses a wide and varied spectrum of disease involving
abnormal growth of dysplastic squamous epithelial cells on the surface of the eye (3).
Figure 1.1 Figure 1.2 Figure 1.3 Figure 1.4 Figure 1. Schematic representation of the progression of OSSN. The figure 1.1 represents normal epithelium with basement
membrane (pink line). In conjunctival intraepithelial neoplasia (CIN), a portion of the epithelium is replaced with dysplastic
cells. Carcinoma in situ is the complete replacement of epithelium by dysplastic cells, with the basement membrane still
intact. In invasive squamous cell carcinoma, note the invasion through the basement into the stroma (3).
Conjunctival intraepithelial neoplasia (CIN) is non-invasive by definition. The basement membrane and the
underlying substantia propria remain intact (1,2). It is a slow-growing tumour that arises from a single mutated
cell on the ocular surface (1). CIN is known by other names including Bowen’s disease, conjunctival squamous
dysplasia, intraepithelial epithelioma, and epithelial dyskeratosis (1). Case report A forty three years old male presented to the outpatient department at National Eye Hospital, Colombo with the
history of slow growing reddish fleshy growth over lateral aspect of left eye of 1 year duration. It was not painful
and did not affect his vision. He was a known diabetic patient on oral hypoglycemic drugs. No significant surgical
or ocular history noted. His visual acuity of left eye was 6/9. He had fleshy well circumscribed conjunctival lesion which was extending
from 11 o’clock to 7 o’clock position around the limbus spreading onto the peripheral cornea. The surface
appeared gelatinous with a prominent “corkscrew” vascular pattern. The adjacent conjunctiva appears injected
with prominent “feeder vessels” leading to the lesion. Rest of the anterior segment and fundus of left eye
appeared normal except for mild non proliferative diabetic retinopathy. There was no palpable lymph nodes or
evidence of distant metastases.
Vol. 22, No. 1, 2016
53
Investigations showed; FBC: WBC 6600, N-64, L-32, E-04, ESR 28mm in 1st hour, RBS-282mg/dl, Blood picure-
normal, CXR-normal, ANA-negative. Wide conjuctival excision with 4 mm margin and corneal epithelium excision with 3mm margin with complete
lamellar dissection was done. The edges of the excised conjuctival margins were treated with cryotherapy (-45°C
or 45 seconds). Amniotic membane graft was applied over the surface. Histology showed intraepithelial dysplasia
amounting to focal severe dysplasia suggesting close follow up.
Figure 2.
Figure 3.
The patient was explained about the condition with the importance of close follow up. As the excised tissue
margins were not involved with dysplasia patient is being following up 6 monthly after the surgery. No
recurrences noted upto now.
Discussion Conjunctival neoplasia is showed to make up 14% of all primary ocular and orbital tumors due to sun exposure (4). UV-B exposure in male gender with light complexion is known to be main risk factors and the prevalence is
higher in equatorial regions around the world (4). UV associated mutations in tumour suppressor genes such as
The Journal of the College of Ophthalmologists of Sri Lanka
Conjuctival intraepithelial neoplasia
p53 and hereditary deficiency of DNA repair such as in Xeroderma pigmantosa increases the risk of CIN. It is also associated with human papilloma virus infection subtypes 16 and 18 as well as HIV infection. Non HIV related immunosuppression, old age and smoking are other risk factors (3). Typically, patients present with a gelatinous or plaque like interpalpebral conjunctival gray or white lesion nasaly or temporaly (6). Approximately 95% of CIN lesions occur at the limbus, where the most actively mitotic cells reside (1). There are three major clinical variants of CIN: papilliform, gelatinous, or leukoplakic (1). The adjacent conjunctiva appears injected, with prominent “feeder vessels” leading to the lesion (3). The surface appears gelatinous or leucoplakia and a prominant “corkscrew” vascular pattern (3). Histologically, the epithelium exhibits hyperplasia, loss of
goblet cells, loss of normal cell polarity, nuclear
hyperchromasia, pleomophism, mitotic figures and mild
to moderate increase in nuclear to cytoplasm ratio (3). The most important assessment is whether the neoplasia contained by basement membrane or neoplastic cells have traversed the epithelial basement membrane and invaded the stroma (3). For lesions contained by basement membrane, the term con-junctival intraepithelial neoplasia (CIN) may be used. The neoplasia can be graded as mild, moderate or severe according to degree of cellular atypia. In cases with most severe atypia, full thickness involvement of the epithelium is seen, ofen with squamous eddies or keratin pearls/whorls which was noted in our patient (3). CIN that involves the entire epithelium is referred to
as carcinoma-in-situ (5). On pathology, there is a
characteristic sharp demarcation line between normal
and abnormal epithelium (5). Due to a barrier provided
by Bowman’s membrane, subepithelial cellular invasion
is almost exclusively limited to the conjunctiva (1). Surface keratinization and dyskeratosis can be seen oftenly (3). A chronic inflammatory response is often present in substantia propria. Excision margin at the time of surgery is the most important factor in predicting recurrences. The slow growth of the recurrent lesions with malignant potential leads to suggest that all patients with history of CIN warrant annual follow up for the remainder of their lives. Intraocular spread of squamous conjunctival neoplasia is
rare in developed countries (< 5% of cases). When
intraocular penetration occurs it is typically through the
limbus. Signs include neovascularization of the
54
iris and cornea as well as glaucoma, peripheral
anterior synechiae, thickening of the ciliary body, uvea
and blunting of the iridocorneal angle. High frequency
ultrasound is particularly helpful in these cases. Intra-
ocular penetration is typically treated by enucleation
of the eye or eye-wall resection (4).
The use of topical chemotherapeutic agents, including
Interferon- 2b, mitomycin C, and 5-fluorouracil have
the advantage of treating the entire ocular surface and
avoiding surgical complications such as positive
margins, scarring, and limbal stem cell deficiency (5).
Prognosis The recurrence rate of OSSN after surgical excision can
occur in over half of the cases and may occur years
later (7). The rate of recurrence is substantially higher
in the setting of positive surgical margins. Even if the
surgical margins are negative, up to one third of eyes
may experience a recurrence within 10 years (7). A recurrent OSSN can grow rapidly and be more
invasive, and thus needs to be treated with aggressive
medical, surgical or combination therapy (1). The
conjunctival lesions involving over half of the limbal stem
cells have very poor pronosis such as in our patient
highlighting the importance of long term follow up (1).
Overall, SCC is generally associated with local invasion
rather than widespread systemic metastases.
References 1. Krachmer JH, Mannis MJ, Holland EJ. Cornea:
Fundamentals, diagnosis and management. 2005. 2. Reidy JJ, Bouchard CS, Florakis GJ, et al. Basic and
Clinical Science Course 2011-2012; 2011: 226-33. 3. American Academy of Opthalmology – opthalmic
pathology and intra ocular tumors (Volume 2014-2015). 4. Squamous carcinoma and intraepithelial neoplasia of the
conjunctiva by Paul T. Finger, MD. https://eyecancer.com/
eye-cancer/conditions/conjunctival-tumors/squamous-
carcinoma-intraepithelial-neoplasia-conjunctiva/ 5. Ocular surface squamous neoplasia. http://eyewiki.
aao.org/Ocular_Surface_Squamous_neoplasia 6. Kiire CA, Srinivasan S, Karp CL. Ocular Surface
Squamous Neoplasia. International Ophthalmology Clinics
2010; 50: 35-46. 7. Tabin G, Levin S, Snibson G, et al. Late Recurrences and
the Necessity for Long-term Follow-up in Corneal and
Conjunctival Intraepithelial Neoplasia. Ophthalmology
1997; 104: 485-92.
Vol. 22, No. 1, 2016