DOS_apr_2010

Contents

E5 ditorial 49 Current perspectives in New Endothelial Keratoplasty

Focus Procedures: DSAEK and DMEK
Deepender Chauhan, Dariel Mathur
7 Pterygium
55 Keratoconus
I11 ncoming President Address
Sri Ganesh
S13 ecretary’s Report 2009-2010
Refractive Surgery
H15 ighlights: Annual DOS Conference
61 Surgical Options for Lasik Rejects
Cataract
Sudhank Bharti
37 Toxic Anterior Segment Syndrome (TASS): Diagnosis
Miscellaneous
and Management
Kamaljeet Singh, Sanjeev Thapar, Pooja Lal 65 Faltering Practices-What is Lacking

Cornea Vipin Sahni

45 Corneal Hysteresis – A New Dimension in IOP Measurement F75 orthcoming Events

Sonam A. Bodh, Vasu Kumar, Basudeb Ghosh, U.K Raina, Columns
Meenakshi Thakar
77 Membership Form

Attention DOS Member 3

DOS Times is not published in the month
of May & June each year

www.dosonline.org

4 DOS Times - Vol. 15, No. 10, April 2010

Editorial

My Dear Friends and Valued Colleagues,
This is not my swan song, for i have one more year to go. The last issue of this DOS year and time to
take stock. Time for your feed back and time to think fresh new ideas for the coming year.
Looking Back;
We kept the ball rolling. The academic meets, the midterm conference, the DOST programme, and
the annual conference. Some new innovations-for eg the cultural programme by the DOS members
and a new look DOST. Amidst Kudos and Controversies; accolades and criticisms.
My Vision:
A fully networked society, in real time. I have tried to do what i envisioned. With qualified success.
We collected as many emails as possible as the first step.
And then we went on facebook.
Why?
Because facebook is popular and many of our members are already active on it. And because it is almost realtime-with
discussion forums and chatting facilities in addition to its now famous wall{almost like a ninth wonder of the world}.
And we worked hard and fast. Already we have uploaded more than 100 videos on the DOS wall which are there for all DOS
members to study and to discuss. All the members who are not yet part of the group are openly invited. Just send me an email,
and i’ll send you the invite. There are videos from the conferences and from the DOST programme. We are trying to kickstrart
discussions and take the whole idea forwards.
In the works:
We are requesting the reputed institutes of Ophthalmology to lend us the live video recordings of their lectures and case
discussions. We wish to upload them, so that all the residents from whichever institute have access to quality teaching. This will
be a quantum jump; a sea change -in the level of ophthalmology training in our country. Some thing like a level learning field.

We are a big society and we have made this big bold new start. I am sure of one thing, a whole lot more of our dear members
are going to be friends with each other very soon. And that my dear friends, would be a highly desirable sideffect.

Yours Truly.
Thanking you,

Dr Amit Khosla
Secretary,
Delhi Ophthalmological Society

www.dosonline.org 5

Pterygium Focus

Dr. Rajesh Sinha Dr. Ashu Agarwal Dr. Paras Mehta
MS, DNB, FIACLE, FRCS MS MS

Since the ancient age, pterygium has been recognized as a triangular sheet of fibro- vascular tissue that appears
on the epibulbar conjunctiva and cornea. Pterygium surgery is often treated as a minor procedure but an
optimal surgical management is necessary to prevent recurrence and potential vision threatening complications.
Here, we question distinguished corneal and ocular surface specialists to have their view-point on various aspects
of management of pterygium.

(DRS): Dr. Rajesh Sinha MD, DNB, FIACLE, FRCS, Assistant Professor of Ophthalmology, Cornea, Lens and Refractive
Surgery Services, R.P. Centre, AIIMS, New Delhi.

(AA): Dr. Ashu Agarwal MS, Cornea & Anterior Segment Perfect Sight Centre 21, LSC, C-Block Market, East of
KailashNew Delhi

(PM): Dr. Paras Mehta, MS, Cornea, External Disease & Refractive Surgery, Sameep Eye Hospital & Corneal Centre,
First Floor, Chaturbhaipark, Opp. Rajdhani Society, Harni-Warasia Ring Road, BARODA.

(RS): Dr. Ritika Sachdev, MBBS, MS, Cornea, Lens and Refractive Surgery Services, R.P. Centre, AIIMS, New Delhi.

RS: How frequently do you encounter cases of pterygium in tropical world. People who spend considerable time in the
your clinic? sun are much more likely to have pterygium. Apart from
U-V radiation, other environmental irritants, such as dust
DRS: Nearly 10% of the cases seen in the outpatient department and wind, may play a role as well.
at our centre have pterygium. Many of them may however
be small and asymptomatic. Risk factors include years of AA: The etiopathogenesis of Pterygium is still not well
working outdoors, increasing age and male gender. understood. The present, most widely accepted, concept
entails a localized Limbal Stem Cell deficiency arising out of
AA: I see a reasonable number of Pterygium, mine being a UV exposure due to sunlight or dry, dusty conditions. The
referred Cornea and Ocular Surface Disorder practice. Limbal Stem Cells prevent the conjunctival epithelium from
However most of them do not require any surgical growing over the cornea. The localized deficiency leads to
intervention. the absence of this “Contact Inhibition”. Pterygium is usually
seen in people spending a great deal of time outdoors
PM: Well, a pterygium is observed in about 4-5% of all fresh especially in sunny climates.
cases seen by us in a month.
PM: The most common cause of pterygium is exposure to UV-
RS: What is the etiology behind occurrence of pterygium? radiation, usually from sunlight. Hence, it is more common
in hot, dry, windy, smoky and dusty environments.
DRS: Pterygium is a common ultraviolet-induced degenerative Incidence of pterygium is higher in tropical country like
disorder of the limbal subconjunctival tissue. Because of India. It also affects people living in equatorial regions like
the localized stem cell loss, there is overshoot of conjunctival Australia and Africa.
tissue over the limbus and the cornea. It is a disease of the

www.dosonline.org 7

Now we have understood the role of Limbal stem cells, RS: What is your surgical procedure of choice in primary
and it is also believed that, localized limbal stem cell pterygium?
deficiency leads to occurrence of pterygium.
DRS: Simple excision of pterygium is associated with a high
RS: What are the common symptoms with which patients with recurrence rate ranging from 30 to 70%. To reduce this
pterygium present? high recurrence rate, different methods like, beta irradiation,
mitomycin C, and amniotic membrane have been used.
DRS: Some people with early pterygium have a constant foreign However, serious complications such as secondary
body sensation or itchy sensation and watering in their eye. glaucoma, uveitis, scleromalacia and corneal perforation
Some may come with a complaint of a fleshy mass in the may be associated with these methods. Contamination of
eye; however, many are asymptomatic. amniotic membrane is a potential risk that cannot be
overlooked despite low recurrence rate.
Because the lids can no longer spread the tears over a
smooth area, dry areas may result. Many patients may My surgical treatment of choice is pterygium excision with
present with congestion and cosmetic complaints. As the conjunctival autograft. In my experience, recurrence rate
pterygium progresses, it distorts the cornea leading to following this surgery is around 10% over a 12 month
occurrence of astigmatism and reduction in visual acuity. period.
Advanced cases progress onto the cornea, obscuring the
visual axis leading to decreased vision. AA: Pterygium excision with conjunctival autograft.

AA: Pterygium may often be asymptomatic except for a cosmetic PM: It is now established that amongst the various available
blemish. Symptoms include dryness, foreign body sensation surgical options, pyerygium excision with autologous
and localized redness. In advanced cases it may cause conjunctival graft is the best surgical method with a very
astigmatism and obscuration of vision by encroaching onto low recurrence rate.
the visual axis.
Hence, my choice of surgical technique for all primary
PM: Patients present with following symptoms: pterygia is Excision of Pterygium with Auto Conjunctival
Graft with application of Fibrin Sealant.
Redness of eye
RS: What is your surgical treatment of choice in cases of
Some growth on the side of the Cornea recurrent pterygium?

Irritation & watering DRS: Pterygium excision with limbal-conjunctival autograft
surgery, including stem cells is an effective surgical technique
Cosmetic Blemish in preventing pterygium recurrence and is my procedure
of choice in cases with recurrent pterygium. Recurrence
RS: What is your treatment protocol for a case of primary rate of less than 10% is seen with this procedure. Cases
pterygium? with extensive bilateral pterygia may not be amenable to
limbal conjunctival graft harvesting. These require
DRS: Artificial tears can be used to relieve the foreign body pterygium excision with cultivated limbal stem cells or an
sensation in the eye and to protect against dryness. A mild amniotic membrane transplantation with adjunctive use of
optical decongestant or, rarely, an anti-inflammatory agent mitomycin C to reduce recurrence.
may be prescribed.
AA: Pterygium excision with conjunctival autograft.
Surgery to remove the pterygium is advisable when the
effect on the cornea causes visual defects or when the PM: In Recurrent pterygium, I prefer to use MMC along with
thickening is causing excessive and recurrent discomfort or AutoConj Graft and AMT.
inflammation. Sometimes surgical removal is also
performed for cosmetic reasons. However, there is risk of RS: What will be your management protocol for pterygium
recurrence and other complications. involving the visual axis?

AA: If the Pterygium does not cause any visual symptoms, I DRS: My management protocol in such a situation will be in two
prefer to leave it alone. It is important to counsel the patient steps. Step 1 will include pterygium excision with
properly and explain the risk of recurrence (possibly autoconjunctival transplant. Once it heals up, Step 2 that
aggressive recurrence). Occasionally, one may take up for includes a 6-mm optic zone central phototherapeutic
cosmetic reasons if it is affecting the patient. keratectomy (PTK) will be done in most of the cases.
Occasionally in some cases, if the opacity in the centre of
PM: I prefer to operate the patient with primary pterygium if the cornea is deep, a lamellar keratoplasty may be needed
there is progression, If corneal involvement increases, If in place of PTK.
the pterygium is very flashy and cosmetically it is disfiguring.
AA: The patient needs to be counseled properly and given a
Initially I put them on topical lubricant and topical Anti guarded visual prognosis. The patient also needs to be
inflammatory drops. explained about the possibility of a Keratoplasty if the
underlying scarring prevents good visual recovery. However,
I also recommend them to use protective eye gear when many of these patients do well post excision with RGP
they are exposed to sun and windy situation.

8 DOS Times - Vol. 15, No. 10, April 2010

contact lenses. It should be noted that the cylinder induced normal post-operative fibrotic response and after
by the Pterygium may not recover fully after excision. dissolution of the fibrin glue the graft had not adhered to
the surgical bed. This suggests that Anti VEGF agents may
PM: I would prefer to excise the pterygium carefully maintaining alter wound healing after surgery and surgical techniques
the same corneal plane while working on visual axis. I will may need to be altered when they are used.
cover the corneal defect with AMT for minimizing the
corneal scarring and rest would be finished with Auto Conj RS: What are the common complications you encounter after
Graft with application of Fibrin Glue. AMT would promote pterygium surgery?
better surface healing with minimizing the scarring on the
visual axis. DRS: Recurrence remains a risk after pterygium surgery. The
rate of recurrence has decreased substantially with optimal
RS: What is your experience with fibrin glue as an alternative surgical techniques. A meticulous dissection of the limbal
to sutures in conjunctival autografts? tissue and use of a conjunctival autograft leads to recurrence
rates lower than 10% in my experience. Other complications
DRS: Fibrin glue is an effective alternative to sutures. Use of like infection, pyogenic granuloma, dellen formation, and
fibrin glue significantly reduces surgical time and improves corneo-scleral melting may be seen in a few cases.
post-operative patient comfort. The recurrence rate in my
cases of conjunctival autograft with glue remains less than AA: Recurrence- Although it has gone down significantly with
10%. Conjunctival Autografting, it is still seen.

AA: It is good. An elegant way to do the surgery. However, in Graft dehiscence in some cases where fibrin glue was used.
my experience there was no difference in the results. I get
the same results with sutures. Just takes a little longer for PM: The compication rate is much lower with my surgical
the surgery but it is more economical. technique. But I do see Retraction of the conjuctiva from
the graft edge some times. The size of the Graft should be
PM: Availability of Fibrin Sealant has revolutionized the surgical adequate to bridge the gap and one should be careful in
outcomes in Pterygium surgery. applying some amount of fibrin sealant to the free border
of the dissected conjunctival margin to achieve better
There are distinct advantages, cosmetically the results are apposition.
fabulous and very satisfactory to the patient as there is less
induced inflammation due to absence of sutures, there is Occasionally I do see haemorrhage under the graft.
rapid painless healing, early recovery and in turn early
rehabilitation and reduced chances of recurrence as well. RS: How frequently do you encounter corneo-scleral melting
as a complication of pterygium surgery? What would be
Subjectively patients are much more comfortable as there your approach in such cases?
is no irritation from sutures.
DRS: Being a referral centre, we do get cases of necrotising scleritis
Surgical chair time is less. and corneo-scleral melts following pterygium surgery. Such
complications highlight that pterygium surgery should not
RS: What in your opinion is the possible role of Anti-VEGF be treated as a minor procedure as it may be associated
drugs in the treatment of pterygium? with vision threatening complications. Risk factors for
corneo-sclera melt include excessive lamellar dissection,
DRS: Recent reports have suggested that topical and infection, use of Mitomycin C (MMC) and long term use of
subconjunctival preparation of Anti-VEGF drugs may be topical NSAIDS. Infection must be ruled out in all cases
effective in cases of pterygium. I have no personal and treated when present. Collagenase inhibitors such as
experience with anti-VEGFs in cases of pterygium. doxycycline along with Vitamin C are prescribed in these
cases. Systemic steroids may be necessary for controlling
AA: Anti- VEGF drugs are being tried out as an adjunct to the ocular inflammation. Amniotic membrane grafting
Pterygium excision and Conjunctival Autograft. They are may be performed for ocular surface reconstruction.
given as a subconjunctival injection. I have no personal Severe melts may require tectonic scleral/ corneo-scleral
experience and we will have to wait for the results of some grafts.
long term trials.
AA: None in my series (I only do conjunctival autograft).
PM: Recent studies have shown elevated levels of VEGF in However, I have managed 6 cases where Mitomycin was
Pterygium tissue compared with normal conjunctival tissue. used. I had to do a scleral graft for 2 patients and 4 were
So, inhibiting the action of VEGF, may provide a beneficial managed conservatively.
effect in reducing pterygium recurrence following excision
with Auto Conj Graft. Interestingly in a prospective, open PM: Personally I have not encountered this problem in my 17
lable phase 1 pilot study it was observed that Ranibizumab years of Cornea Practice, but I do see referred pts from
( Lucentis ) was injected subconjunctivally, the drug was diff. places with corneo-scleral melt. In most cases it can
well tolerated by all patients. Sudy results showed that occur due to excessive cauterization or due to improper
conjunctival grafts were well secured in most patients where dosage of MMC.
the graft were sutured while, the patient whose graft was
fixed with fibrin glue developed graft dehiscence. It is Primarily, I would rule out presence of infection, clinically
postulate d that this occurred as ranibizumab inhibited the and in cases where needed by microbiologic work up.

www.dosonline.org 9

I would put these pts on topical lubricants and stop topical RS: What would be your concerns in performing

steroids. keratorefractive surgery in a patient with pterygium?

Some, may need coverage of that area with AMT or a DRS: The pterygium should be removed before doing refractive
lamellar patch corneal or corneo-scleral graft. surgery. A pterygium if not removed may potentially
interfere with suction buildup during flap creation with a
RS: What is your opinion regarding the role of matrix microkeratome. Surface ablation may be useful in these
metalloproteinase inhibitors in the treatment of cases. The use of MMC is advocated as an adjunct following
pterygium? surface ablation as the ocular surface is inflamed with tear
film abnormalities leading to an increased risk of developing
DRS: Early reports have suggested that tissue matrix haze.
metalloproteinase inhibitors may contribute to pterygium
invasion inhibition. I have no personal experience regarding Another important reason to remove pterygium before
this. refractive procedure is the distortion of cornea caused by
it. Accurate assessment of the residual astigmatism after
AA: Sound good theoretically. Will need to wait for some large, complete healing (may be up to 3-4 months) would yield
long term studies. better results following refractive surgery. Wavefront guided
LASIK may be useful in these cases as the surface may be
PM: Recently it is shown that, MMPs and TIMPs may contribute more irregular than normal.
to the inflammation, tissue remodeling, and angiogenesis
that characterize pterygia. Hence, understanding the role Further, subclinical haze may be present in some cases.
of these proteins play may lead to novel therapies intended These may potentially complicate flap creation even with
to reduce the progressive nature of pterygia in future. the femtosecond laser.

RS: In a patient presenting with cataract and co-existing AA: This would depend upon whether the Pterygium has been
pterygium would you prefer a simultaneous or a sequential excised or not.
surgery?
If already operated upon:-
DRS: The pterygium must be addressed first, thus eliminating
induced astigmatism. Pterygia usually induce an adjacent a) Recurrence leading to change in refraction
wedge-shaped corneal flattening, causing asymmetric with-
the-rule astigmatism. Accurate assessment of the residual If not excised-
astigmatism after pterygium surgery would allow planning
for a toric IOL or limbal relaxing incisions. Correction of a) There could be a suction loss leading to flap complications
the residual astigmatism often leads to more gratifying
results. However, in the context of the Indian subcontinent b) In surface ablation, there could be significant errors induced
some patients may require simultaneous surgery which is and in addition there may be bleeding, again leading to
more cost-effective and time saving. induced errors.

AA: I would prefer to remove the Pterygium first and let the I would prefer to operate after a good Pterygium excision
astigmatism stabilize. After a few months I would take up and Conjunctival Autograft has been performed and the
for cataract surgery. This strategy helps me to take into patient has shown no sign of recurrence for sometime.
account the final corneal astigmatism. Today, cataract This would also enable me to account for the net refractive
surgery is all about giving the best refractive results and error with the Pterygium excised.
this method has worked well for me.
PM: This is a very tricky scenario. If possible I would prefer to
PM: I would prefer sequential surgery to achieve better surgical deal with pterygium first. If not may be newer agents like
outcome of each procedure. Pterygium surgery first anti VEGF can be tried before attempting kerato-refractive
followed by cataract surgery 4-6 weeks later. surgery in a patient.

DOS Correspondent
Ritika Sachdev MBBS, MS

10 DOS Times - Vol. 15, No. 10, April 2010

In-coming Presidential Address -2010

Respected Collogues,

As I take on the responsibility of this chair I acknowledge the trust bestowed on
me. I assure you on behalf of the executive of the best services we would like to
provide to the honorable members. There are many areas which come to my
mind where we plan to give more thrust. Diabetes, Glaucoma & Amblyopia have
long since being neglected by the physicians and the ignore at society. We plan to
associate bodies like DMA (etc.) to reach the physician and train them for proper
and timely referrals to the eye surgeon. Some awareness programmes could be
done to educate the general public. The increasing popularity of the conferences
in terms of delegates, scientific material and trade speaks of its high standard. We
look forwards to maintain these levels and do it more effectively.

The DOS teaching programme has shown increasing interest by own posts graduates can we make it more useful, I am
sure we shall work in the direction. DOS on line is one of the important tools of education in near future, lecture and
surgeons by world removed surgeon shall be available and this could be accessed by any DOS member any time.

Our executive and I do not would to make tall promise. But we commit to perform, perform and perform.

With best regards.

Dr. Prem V. Chadha
President, DOS

www.dosonline.org 11

Secretary’s Report 2009-2010

Dear Friends and Colleagues, 13

Honorable President Dr. Sharad Chandra Lakhotia, Incoming President Dr. P.V. Chadha,
respected Senior Members of the society and my dear friends. I welcome you all to this
General Body Meeting of Delhi Ophthalmological Society year 2010.

DOS is growing every year to this year we have record increase in members of 461 members
(out of which 31 are from Delhi) and now the total no of members is 5562.

The ophthalmic fraternity always looks forward to the academic quality of DOS which
includes the monthly meetings, Mid Term and Annual Conference, DOS Teaching
programme and the DOS Times and DJO.
The Mid Term Conference was organized on 14th to 15th November, 2009. The theme of the
conference was problem oriented management solutions. A live surgery was organized on
14th November from Sir Ganga Ram Hospital and Centre for Sight. It was sponsored by M/
s Bausch & Lomb, M/s Zeiss and M/s Appasamy.

The conference was attended by 1092 members and the academic content was well
appreciated. A run for diabetic retinaopathy awareness was held on 14th November with ISPAE which incidentally was also
world diabetic day and children’s day.

A musical nite was organized for the members and spouses. It was well attended and appreciated.

Nine monthly clinical meeting were held which were well attended were of high quality academic content.
DOS Teaching programme was held at Army Hospital (R&R) on 10th & 11th February, 2010. 128 students attended the meeting.
OSCE was held to give the DNB students and exposure to this mode of examination.

The DOS library has an online journal facility which was well – utilized by the members.

DJO – For the first time all DJO have published on time and of very high academic content.

The DOS travel Fellowship has been given to Dr. Ashu Agarwal and Dr. Prakash Chandra Agarwal.

This year we started guest faculty lectures by inviting foreign faculty. Many international faculty visit India, we used there
expertise, and invited them for guest lectures and interactive discussion with DOS members.

The highlights of this series were Dr. Harminder Dua a pioneer in corneal stem cell and editor in chief of British journal of
ophthalmology. The other invited speakers were Dr. Carlos Vera Cristo and Dr. Raman Malhotra.

A skill oriented programme was started to young ophthalmologists. A contact lens skill transfer programme was held for post
graduates at Sir Ganga Hospital and Shroff Charity Eye Hospital.
The Annual conference was held from 16th to 18th April, 2010. It was attended by 2872 delegates. The theme of the conference
was “Ophthalmology NOW” giving exposure to delegates for contemporary topics and latest cutting edge technology available.
Live surgery was held on 16th April, from four centre Bharti Eye Institute, Shroff Eye Centre, Centre For Sight, Chaudhary Eye
Centre and sponsored by M/s Alcon, M/s AMO, M/s Bausch & Lomb and M/s Zeiss.

The scientific session was spread across 8 halls with a total of 56 sessions 4 Instruction courses were held on FA and OCT, Visual field,
corneal topography and Basics evaluation in Strabismus. The total no scientific exhibitor’s were 105 which includes 11 video
presentation and 40 poster presentation.

The trade exhibition was well attended in the front lawns of the Ashok Hotel.

Obituary: With profound grief we inform the sad demise of Dr. R. Diwan on 17th July, 2009

Thanks.

Dr. Amit Khosla
Secretary
Delhi Ophthalmological Society
(2009-2011)

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Toxic Anterior Segment Syndrome (TASS): Cataract
Diagnosis and Management

Kamaljeet Singh MS, Sanjeev Thapar MS, Pooja Lal MS

Toxic anterior segment syndrome (TASS) is an acute, non Other residues:
infectious inflammation of the anterior segment of the eye
following cataract and anterior segment surgery. It is a rare, • Detergents, enzymes and tiny particulate matter can
potentially devastating complication that occurs when a contaminate instruments and tubing. They can get trapped
noninfectious toxic agent enters the anterior segment of the eye inside irrigating cannulas, which when introduced into the
causing an inflammatory reaction and resulting in toxic damage to eye, can cause TASS. Most of the enzymatic detergents contain
intraocular tissues. Cataract extraction is the most common form subtilisin, an exotoxin that causes corneal edema, marked
of surgery associated with TASS but it can occur after any kind of inflammation, and corneal decompensation.
anterior segment surgery. It was initially referred to as Sterile
Postoperative Endophthalmitis, accurately termed TASS by Monson • Intraocular lenses and phacoemulsification hand pieces that
et al. in 1992. When the damage is restricted to corneal endothelial are sterilized with ethylene oxide gas may have gas residue
cells, TASS cases are classified as toxic endothelial cell destruction left on them when they are not aerated completely. This gas
syndrome (TECDS). TECDS is a rare complication of intraocular residue can cause TASS.
operations. It causes unexpected severe corneal edema and opacity
within 24 hours of surgery. • Other particulate contaminants like talc from gloves, clothing
cotton fibers, rubber stopper pieces, metallic flecks, residual
Incidence lens cortex when introduced unknowingly in the eye can lead
to TASS. TASS may be associated with sulfate, copper, or zinc
Exact frequency of TASS is not known. Incidence of TASS is difficult residues found in autoclave steam used for sterilization.
to determine as milder cases can be missed because symptoms
may improve in a couple of weeks without treatment. At times Solutions and intraocular fluids: Any solution injected in or around
there is problem in diagnosing TASS. It can be mistaken for the eye during or after surgery can potentially cause TASS. Balanced
infectious endophthalmitis even in most experienced hands. salt solution (BSS) is a sterile physiological solution that contains
sodium chloride, potassium chloride, calcium chloride, magnesium
Causes chloride, sodium acetate, and sodium citrate dehydrate. BSS is
isotonic and is used for irrigation during eye surgery. BSS can be
Finding an etiological factor in TASS is a challenge. Often the cause a major contributing factor in TASS as it can act as a carrier for
cannot be found, even after thorough investigations. Many factors; toxic material in several ways. The solution may have an abnormal
prior, during, or after cataract surgery, may be responsible for ionic composition or pH. Refrigerated BSS has been associated
causing TASS. These are: with TASS outbreaks. Earlier, it was thought that colder

Bacterial endotoxin residues: Sterile does not mean non toxic.
Bacteria produce heat-stable endotoxins that are not destroyed
during the sterilization process. These endotoxins even in small
amount can cause an outbreak of TASS. Instruments, which are
cleaned using ultrasonic bath in same unchanged tap water, have
accumulation of debris which encourages the growth of gram-
negative bacteria. These bacteria with time produce heat-stable
endotoxins causing TASS.

Viscoelastic residues: Viscoelastic solutions are used in most Figure 1: Microscopic photograph of toxic
intraocular surgeries. Usually viscoelastic residues are nontoxic, anterior segment syndrome. Note limbal to
however if reusable irrigation and aspiration cannulas are not
cleaned properly after surgery, the viscoelastic residues are limbal corneal edema
denatured during the sterilization process.These denatured
viscoelastic residues are toxic to eye and also act as carrier for
detergents and enzymatic cleaners used in processing of
instruments before sterilizing them. These sterilized cannulas,
when used during subsequent procedures, may introduce these
toxic materials into the eye causing TASS.

M.D. Eye Hospital
Dr. Katju Road, Allahabad U.P

www.dosonline.org 37

Table: Differences between TASS and Endophthalmitis

Signs & Symptoms TASS Infectious Endophthalmitis

Lid Swelling Usually not significant Yes
Onset postoperatively 12 to 24 hrs. 4 to 7 days
Corneal edema Limbus to limbus Specific to the area of trauma
Pain Mild to moderate, if present Severe, considered diagnostic
Inflammation Immediate, marked ant. Increased cellular reaction
segment inflammation, with occurring over longer period
Pupil increased WBC, Flare and Fibrin of time
Culture Fixed and dilated Reactive
B-Scan Negative Positive
Anechoic Vitreous Echoes present

Figure 2: Microscopic photograph of toxic Figure 3: Microscopic photograph of toxic
anterior segment syndrome. Note limbal to anterior segment syndrome. Note corneal

limbal corneal edema with dilated pupil edema with irregular pupil,
and faint fundal glow hypopyon and faint fundal glow

temperature reduces postoperative inflammation and endothelial eye and cause TASS. Toxicity may also occur while using irrigating
cell loss. However, cold BSS reduces corneal swelling, leading to solutions containing antibiotic agents like gentamycin sulfate or
improper sealing of incision and thereby allowing potentially toxic when antibiotics are injected directly in the anterior chamber at
subconjunctival fluids to enter the eye causing TASS. the end of procedure for prevention of endophthalmitis.

Preservatives: Preservatives used in ophthalmic solutions like Intraocular lenses: Ethylene oxide residue may be left on IOL when
benzalkonium chloride, can damage corneal endothelium and it is not aerated completely. This IOL, when introduced into the
cause TASS. Other toxic preservatives include edetic acid, 0.1% eye causes TASS. IOL polishing compound, aluminum oxide is
sodium bisulfite, and 0.01% thimerosal. Anesthetics used also associated with chronic inflammation. Therefore, it should
intracamerally may also contain preservatives which can cause be thoroughly washed with BSS before implanting.
TASS.
Clinical Features
Medications: Medications like antimetabolites used during
glaucoma surgery, postoperative subconjunctival antibiotic Most patients with TASS develop symptoms within 12-24 hours
injections or postoperative application of antibiotic drops or of the surgery. Patients have decreased visual acuity, corneal edema
ointments may penetrate through the surgical wounds into the which is characteristically “limbus to limbus”, a nonreactive dilated

38 DOS Times - Vol. 15, No. 10, April 2010

pupil and moderate to severe anterior chamber reaction with postoperatively. The pressure may be as high as 40 mm Hg to
cells, flare, hypopyon and especially fibrin with eventual increased 70 mm Hg. Permanent damage to the trabecular meshwork
intraocular pressure. Pain is mild to moderate. can occur, thus creating a risk for glaucoma. Usually, the IOP
of a patient with infectious endophthalmitis is not elevated.
There is significant overlap between the clinical presentation of
TASS and that of infectious endophthalmitis. Differentiating TASS • Cultures: Cultures can determine whether the inflammation
from endophthalmitis may be difficult at times. Points of utmost is sterile or infectious. Vitreous involvement occurs more
importance are; TASS occurs within in 24 hours of surgery and on commonly in infectious endophthalmitis. With TASS, cultures
examination, there is always limbal to limbal corneal oedema. In of the anterior chamber and vitreous aspirates are negative.
addition B scan shows clear vitreous. The onset of signs and Usually, cultures are positive with infectious endophthalmitis,
symptoms, type of symptoms, and response to therapy are all although they can be negative in some cases.
very important factors in differentiating TASS from infectious
endophthalmitis. To differentiate between the two complete • B Scan: B scan is anechoic in TASS whereas in infectious
evaluation should be done including endophthalmitis, vitreous echoes are present.

• Slit lamp examination, Treatment

• Fundus examination, Hourly topical prednisolone acetate must be started immediately.
Cycloplegics should be frequently instilled. Oral steroids (1mg/kg
• Gonioscopy, body weight) should be prescribed. Antibiotics must be continued
till the diagnosis is clear.
• IOP measurement,
Toxic anterior segment syndrome may cause trabecular meshwork
• Aqueous and Vitreous needle aspiration and damage, so the patient’s IOP should be monitored daily for the
several days after the onset of symptoms. After beginning intensive
• B – Scan. topical steroid therapy, anything that could worsen inflammation,
such as prostaglandin analogues, usually is avoided. Prostaglandin
Following points are helpful in differentiating TASS from analogues, medications similar to naturally produced
endophthalmitis: prostaglandins, play a part in causing and increasing inflammation
and can adversely increase the inflammatory reaction in TASS.
• Onset: Usually, TASS occurs within 12 to 24 hours after surgery
whereas usual onset of infectious endophthalmitis is within Close monitoring for several days is necessary to ensure that the
4-7 days of surgery. inflammation does not worsen and to rule out an infectious etiology.
If infectious endophthalmitis is suspected, treatment includes
• Pain: Only mild to moderate pain occurs in TASS. Whereas in vitreous taps, cultures, and antibiotics.
infectious endophthalmitis, pain is more severe which is
regarded as diagnostic. Approximately 25% of patients Clinical outcome and prognosis
diagnosed with infectious endophthalmitis, however, do not
complaint of pain. If the reaction is mild, there is rapid improvement in signs and
symptoms of inflammation. Hypopyon resolves very fast. Within
• Corneal Edema: Although corneal edema exists in both 24-48 hours there is improvement in visual acuity. From hand
conditions, the edema in TASS is more profound and movement to counting fingers within a day is seen. Patient’s vision
characteristically described as diffuse, from “limbus to limbus”. improves remarkably thereafter. The inflammation usually clears
The corneal edema in infectious endophthalmitis is near or within one to three weeks. Moderate cases take between three to
opposite the wound. six weeks to resolve. In severe cases, TASS can cause permanent
damage. If severe symptoms are still present after six weeks, the
• Inflammation: Toxic anterior segment syndrome is eye is less likely to recover. Glaucoma may result if the trabecular
characterized by immediate and marked anterior segment meshwork is damaged, which may be resistant to treatment and
inflammation, with increased presence of white blood cells as may require multiple surgical procedures. In patients with very
a result of the marked breakdown of the blood-aqueous high IOP, the risk of chronic glaucoma is 50%. The corneal edema
barrier, flare and significant fibrin formation. Sometimes, the produced by TASS can permanently damage the corneal
hypopyon may be out of proportion with the quantity of cells endothelium, causing permanent and irreversible corneal
and amount of flare observed. In infectious endophthalmitis, decomposition. TASS may also cause profound cystoid macular
there is an increased cellular reaction in the anterior chamber, edema. If a fixed, dilated pupil is observed on the first postoperative
which occurs over a longer period of time than the day, it is less likely that it will come back to its original size.
inflammation in TASS.
Our experience of TASS (Presented at ESCRS, Barcelona
• Pupil: Iris atrophy may occur significantly in TASS. It damages 2009)
the iris sphincter causing pupillary distortion. As a result, it
reacts poorly to light. A fixed, dilated pupil, therefore, is more Our ten patients (six females; four males) with mean age of 63. 5
commonly observed in TASS than in infectious years, developed TASS after uneventful cataract surgeries on 12th
endophthalmitis. June 2009. Their chief complaints were pain, blurry vision, eye
redness on the second postoperative day. Visual acuity was 20/200
• Intraocular Pressure (IOP): With TASS, marked inflammation to counting fingers, diffuse limbal to limbal corneal edema (ten
may be initially associated with lower IOP. But gradually the
pressure rises as aqueous humor production increases

www.dosonline.org 39

patients), hypopyon (six patients), marked aqueous flare (ten References
patients), dilated non reactive pupil (seven patients), Faint fundal
glow in all patients, high Intraocular pressure (IOP) in three 1. Mamalis N, Edelhauser HF, Dawson DG, Chew J, LeBoyer RM,
patients. B scan revealed a clear vitreous in all patients. Vitreous Werner L. Toxic Anterior Segment Syndrome Review/Update. J
tap was negative. Cataract Refract Surg 2006; 32:324-333. Journal Club Terry J.
Alexandrou, MD Department of Ophthalmology and Visual Science
After diagnosing TASS, topical and systemic steroids and University of Chicago
Cycloplegics were started. Improvement in pain was noted within
24 hours of initiation of treatment. Corneal edema started 2. Holland SP, Morck DW, Lee TL. Update on toxic anterior segment
decreasing on third day and cleared in 15 days in eight patients. syndrome. Curr Opin Ophthalmol 2007;18:4.
Visual acuity gain started on third day. Nine patients attained 20/
30 in two weeks time. Hypopyon started disappearing on third 3. ASCRS Toxic anterior segment syndrome task force guidelines.
day. By one week, it resolved completely in all the patients. Recommended practices for cleaning and sterilizing intraocular
Improvement in fundal glow was seen on third day. IOP remained surgical instrumentsAvailable online at http://www.ascrs.org/TASS/
high in only one patient. upload/TASS_guidelines.pdf.

On prompt treatment with steroids, majority of the ten patients 4. ASCRS Toxic anterior segment syndrome outbreak final report.
diagnosed as TASS showed improvement beginning on third day. Available online at http://www.ascrs.org/press_releases?Final-TASS-
Outcome was good within a fortnight. Only one patient had Report.cfm.
secondary glaucoma at one month.
5. Department of Veterans Affairs Supply, Processing, and Distribution
Conclusion Training Manual. Available online http://www1.va.gov/vasafety/
docs/SPDLEVELONETrainingmanual.pdf.
Toxic anterior segment syndrome is a serious and potentially
devastating complication of cataract and anterior segment surgery. 6. Cohen AW, Oetting TA. Toxic Anterior Segment Syndrome (TASS):
When it occurs, the patient requires timely and appropriate A System’s Based View of a Day in the Life of a Canula. EyeRounds.org.
management. Moreover, TASS is an issue of environmental and May 7, 2008 [cited —insert today’s date here — ]; Available from:
toxin control. To prevent a recurrence, a multitude of issues must http://webeye.ophth.uiowa.edu/eyeforum/cases/85-Toxic-Anterior-
be evaluated including medication and fluid analyses, protocols, Segment-Syndrome-TASS-Systems-Based.htm.
cleaning and sterilization procedures, and surgical procedures. All
steps before, during, and after surgery must be reviewed. 7. AIOS Guidelines to prevent intraocular infection published by All
India Ophthalmological Society 2009.

8. Clinical Outcome of Toxic Anterior Segment Syndrome in an
Outbreak, Singh Kamaljeet, Suman Santosh, paper presented at
XXVII ESCRS, Barcelona, 2009.

First Author
Kamaljeet Singh MS

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40 DOS Times - Vol. 15, No. 10, April 2010

Corneal Hysteresis – A New Dimension Cornea
in IOP Measurement

Sonam A. Bodh MD, Vasu Kumar MD, Basudeb Ghosh MD, U.K Raina MD, Meenakshi Thakar MD

Early efforts to monitor IOP primarily involved indentation cornea. In other words, the ability of the tissue to absorb and
techniques e.g the Schiotz tonometer which essentially dissipate energy.
measured how easily the globe was compressed. These techniques
were highly dependent on rigidity of the ocular tissue. Thus, they Reichert Ocular Response Analyzer
typically overestimated true IOP in eyes with more rigid corneas
and underestimated true IOP in eyes with softer corneas. Principle

In the late 1940s, Jonas Stein Friedenwald, M.D, on the basis of the It utilizes a dynamic bi-directional applanation process to measure
Differential tonometry data developed the Friedenwald’s the biomechanical properties of the cornea and the Intraocular
nomogram referred to as the 1948 tables which estimated the Pressure of the eye. The basic output of the measurement process
coefficient of ocular ridgidity.1 is a Goldmann-correlated pressure measurement (IOPG), and a
new measure of corneal tissue properties called Corneal Hysteresis
With the advent of Goldmann applanation tonometry (GAT) in (CH).
the mid-1950s the previous methods fell out of favour as it is far
less affected by ocular rigidity. However, GAT assumed that there The CH measurement also provides a basis for two additional
was minimal variation in corneal biomechanical properties, new parameters: Corneal-Compensated Intraocular Pressure
including central corneal thickness (CCT), between individual (IOPCC) and Corneal Resistance Factor (CRF).
patients.2
Operation
Since then, research has shown that individuals demonstrate wide
variations in corneal biomechanical properties.3,4 Although GAT It utilizes a rapid air impulse to apply force to the cornea, and an
may be less prone to biomechanical influence than Schiotz advanced electro-optical system to monitor its deformation.
tonometry, it is clearly affected by ocular biomechanical influences Alignment to the patient’s eye is fully automated. A precisely-
as well.5 metered collimated-air-pulse causes the cornea to move inwards,
past applanation, and into a slight concavity. Milliseconds after
Thus it had long been suspected that biomechanical properties of applanation, the air pump shuts off and the pressure declines in a
the anterior segment, such as hydration, elasticity, hysteresis and smooth fashion. As the pressure decreases, the cornea begins to
rigidity, have substantial and widely variable influence on IOP return to its normal configuration. In the process, it once again
measurement. However, assessing the biomechanical properties passes through an applanated state. The applanation detection
of corneal tissue in-vivo had previously not been possible. Because system monitors the cornea throughout the entire process, and
of this, practitioners and researchers have been confined to two independent pressure values are derived from the inward
measuring purely geometrical aspects of the cornea, such as and outward applanation events.
thickness and topography. So, achieving accurate estimates of
intraocular pressure had been difficult. Newer modalities like the One might expect these two pressure values to be the same.
Ocular response analyzer developed by Reichert, Inc. have provided However, due to the dynamic nature of the air pulse, the viscous
a break through in the study of corneal biomechanics. damping in the cornea causes delays in the inward and outward

Corneal Biomechanics

Elastic materials are those for which strain (deformation) is directly
proportional to stress (applied force), independent of the length of
time or the rate at which the force is applied. Viscous materials are
those for which the relationship between strain and stress depends
on time or rate e.g. pushing a spoon into a jar of honey. The
resistance to the applied force depends primarily on the speed at
which the force is applied (greater speed = greater resistance).
Structures that are said to be “visco-elastic” contain characteristics
of both types of material. The response of such a system to an
applied load depends upon the material properties, the magnitude
of the force, and the rate at which the force is applied.

Human corneal tissue is a complex visco-elastic structure. The Corneal
hysteresis measurement is an indication of viscous damping in the

Guru Nanak Eye Centre,
Maharaja Ranjit Singh Marg,

New Delhi

www.dosonline.org 45

Figure 1: The difference between the “inward” Uses
applanation and the “outward” applanation is
Diagnosis and management of Glaucoma
called Corneal Hysteresis
Recently, the Ocular Hypertension Treatment Study (OHTS) and
applanation events, resulting in two different pressure values. The other studies on the subject have brought to light the importance
average of these two pressure values provides a repeatable, of CCT in diagnosing and managing glaucoma. These studies have
Goldmann-correlated IOP value (IOPG). The difference between suggested that low CCT may be an independent risk factor for the
these two pressure values is Corneal Hysteresis (CH). (Figure 1). development and progression of the disease. Clinical studies
The ability to measure this effect is the key to the understanding utilizing the Ocular Response Analyzer support this hypothesis.
the biomechanical properties of the cornea and their influence on Compared to normal subjects, glaucomatous subjects have a
the IOP measurement process. significantly lower average corneal hysteresis9,10.

CH-Corneal Hysteresis is a phenomenon that results from the IOPcc takes corneal biomechanical properties into account,
dynamic nature of the air pulse and the viscous damping inherent enabling the Ocular Response Analyzer to provide pressure
in the cornea and has been shown to be significant and useful in its measurements that are less affected by corneal properties.
own right, but in addition, the dynamic bi-directional applanation
process can be used to derive other valuable information; namely Ocular Response Analyzer’s has a unique ability to simultaneously
Corneal- Compensated IOP (IOPCC) and Corneal Resistance provide a Goldmann-correlated IOP measurement (IOPG) as well
Factor (CRF). Both of these parameters are the result of large- as the IOPCC value9,10,11. With this feature clinicians can observe
scale clinical data analysis and are derived from specific the difference between the two values for reference purposes.
combinations of the inward and outward applanation values using
proprietary algorithms. Identifying and classifying corneal conditions

IOPcc is an Intraocular Pressure measurement that is less affected Measuring biomechanical properties of the cornea with the Ocular
by corneal properties than other methods of tonometry, such as Response Analyzer gives us the potential, for the first time, to
Goldmann (GAT). IOPcc has essentially zero correlation with CCT identify various corneal conditions by means of a measurable and
in normal eyes and stays relatively constant post-LASIK. CRF repeatable metric. A comparison of CH values obtained from
appears to be an indicator of the overall “resistance” (viscous and eyes with known corneal conditions with normal-subject
elastic resistance) of the cornea, and is significantly correlated with measurement values reveals significant differences6, shown in
Central Corneal Thickness (CCT) and GAT, as one might expect, Figure 2.
but not with IOPCC.
It is easy to see that the Corneal Hysteresis and CRF measurements
in the eyes with corneal disorders are, on average, significantly
lower than in normal eyes.

Evaluation and follow up of LASIK patients

The potential clinical applications of the corneal hysteresis
measurement in the area of refractive surgery are evident.
Currently, CCT is the primary factor used for screening candidates
for refractive surgery. Patients with thinner corneas are considered
to be at higher risk for developing post-LASIK corneal ectasia.
This complication is a concern for both doctors and patients. Due
to the large and easily identifiable differences in hysteresis between
normal and compromised corneas, Reichert believes that this
metric provides a more complete characterization of the
biomechanical state of the cornea than does the measure of CCT.

Figure 2a: Typical signal from a normal eye. Figure 2b: Typical signal from a keratoconic
Corneal Hysteresis value of 12.5 mmHg eye. Corneal Hysteresis value of 6.4 mmHg

46 DOS Times - Vol. 15, No. 10, April 2010

Figure 3a: Typical signal from a normal subject’s eye Figure3b: Signal from the same subject’s eye one week
pre-LASIK. Corneal Hysteresis value is 11.4 mmHg post-LASIK. Corneal Hysteresis value is 8.4 mmHg

This observation, coupled with the fact that corneal hysteresis is Otolaryngol 1949 Jan-Feb;53:262-4.
only weakly correlated with CCT, leads Reichert researchers to 2. Ehlers N, Bramsen T, Sperling S. Applanation tonometry and central
believe that the corneal hysteresis measurement will be a useful
tool for eliminating LASIK candidates who are at risk of developing corneal thickness. Acta Ophthalmol 1975;53:34
post-LASIK ectasia. Studies investigating this subject are currently 3. Singh RP, Goldberg I, Graham SL, et al. Central corneal thickness,
ongoing.
tonometry, and ocular dimensions in glaucoma and ocular
The corneal hysteresis measurement also has potential uses in hypertension. J Glaucoma 2001 Jun;10(3):206-10.
post-LASIK follow up. Clinical trials have shown significant post- 4. Liu J, Roberts CJ. Influence of corneal biomechanical properties on
LASIK changes in corneal hysteresis6,7,8, (Figure 3). While these intraocular pressure measurement: quantitative analysis. J Cataract
results are preliminary and not yet fully understood, it appears Refract Surg 2005 Jan;31(1):146-55.
that the reduction in post-LASIK hysteresis is universal. Clinical 5. Doughty MJ, Zaman ML. Human corneal thickness and its impact
investigators are hypothesizing that the reduction in corneal on intraocular pressure measures: a review and metaanalysis
hysteresis is not primarily a function of reduction in corneal tissue, approach. Surv Ophthalmol 2000 Mar-Apr;44(5):367 408.
but rather a result of a weakening of the structure due to the flap. 6. Shah S, Laiquzzaman M. Comparison of corneal biomechanics in
The hysteresis measurement enables ophthalmologists to quantify pre and post-refractive surgery and keratoconic eyes by Ocular
this biomechanical material change, which may provide a more Response Analyzer. Cont Lens Anterior Eye. 2009 Jun;32(3):129-
complete understanding of lower post-LASIK measured IOP. 32; quiz 151. Epub 2009 Feb 23.
7. Shah S, Laiquzzaman M, Yeung I, Pan X, Roberts C. The use of the
Summary Ocular Response Analyzer to determine corneal hysteresis in eyes
before and after excimer laser refractive surgery. Cont Lens Anterior
The dynamic bi-directional applanation process employed in the Eye. 2009 Jun;32(3):123-8.
Reichert Ocular Response Analyzer facilitates the measurement 8. Kirwan C, O’Keefe M. Corneal hysteresis using the Reichert ocular
of Corneal Hysteresis (CH). The CH phenomenon is observable response analyzer: findings pre- and post-LASIK and LASEK. Acta
due to viscous damping in the cornea and permits the calculation Ophthalmol. 2008 Mar;86(2):215-8.
of Corneal Resistance Factor (CRF) which appears to reflect the 9. Shah S, Laiquzzaman M, Mantry S, Cunliffe I. Ocular response
overall resistance of the cornea. Both metrics are new analyzer to assess hysteresis and corneal resistance factor in low
measurements of the biomechanical properties of the cornea. tension, open angle glaucoma and ocular hypertension. Clin
The ability of the device to characterize the biomechanical Experiment Ophthalmol. 2008 Aug;36(6):508-13.
properties of the cornea enables the calculation of IOPCC, a 10. Chihara E. Assessment of true intraocular pressure: the gap between
measure of Intraocular Pressure that is less influenced by corneal theory and practical data. Surv Ophthalmol. 2008 May-
properties than Goldmann or other currently available tonometers. Jun;53(3):203-18.
IOPCC is unaffected by corneal properties such as CCT and 11. ElMallah MK, Asrani SG. New ways to measure intraocular pressure.
remains essentially unchanged after LASIK. Curr Opin Ophthalmol. 2008 Mar;19(2):122-6.

Published and preliminary results from clinical studies in process First Author
worldwide suggest these new parameters may be clinically useful Sonam A. Bodh MD
in a number of different areas including, but not limited to:
Identification of corneal diseases such as keratoconus and Fuchs’
Dystrophy, Glaucoma diagnosis and management, screening
potential LASIK candidates, and accurate IOP measurement.

References

1. Friedenwald JS. Clinical significance of ocular rigidity in relation to
the tonometric measurement. Trans Am Acad Ophthalmol

www.dosonline.org 47

Current Perspectives in new Endothelial Keratoplasty Cornea
Procedures: DSAEK and DMEK

Deepender Chauhan MS, DNB, FRCS, Dariel Mathur MS, FMRF

Corneal transplantation is one of the most successful forms of Table 2: Advantages of endothelial keratoplasty (DSEK /
human organ transplant. Though lamellar keratoplasty has DSAEK)
been in vogue, a full thickness / penetrating keratoplasty has
remained gold standard treatment for various corneal pathologies. 1. Use of sutures for host graft apposition is eliminated,
One of the reasons has been a high success rate of penetrating thus reduced postoperative astigmatism
keratoplasty. But it is often complicated by high irregular
astigmatism, a weak host graft junction, slow wound healing, suture 2. Spherical anterior corneal surface of the recipient is
related complications, corneal graft rejection, and, ultimately, by maintained
graft failure. Endothelial disorders such as pseudophakic bullous
keratopathy and Fuchs’ endothelial dystrophy are one of the major 3. Stable tear film
indications of corneal transplantation. Ideally, the corneal
endothelium is the only layer that requires transplantation in these 4. Tectonically stable globe, safe from injury and infection;
conditions. Thus, fewer complications may be expected when only
the diseased, posterior corneal layer is replaced with donor tissue. 5. Early visual rehabilitation & less frequent follow ups
Thus for conditions that primarily are endothelial diseases, a
selective corneal endothelial transplant is a more logical approach. 6. No epithelial and stromal rejection
As less tissue is transplanted, lower rejection rates may be expected,
esp. epithelial and stromal rejection. There are many other 7. Late wound dehiscence, frequently encountered with full-
arguments in favour of such an approach (Table 1) and the idea of thickness transplantation wounds becomes a rarity
a selective corneal endothelial transplant is not new.
8. Repeat procedures are less traumatic as host graft junction
It was in 1998 when Melles described a new surgical technique for is not progressively weakened and edematous, rejected
transplantation of the posterior corneal tissue that renewed the endothelial disc can be easily peeled off
interest in endothelial transplantation. The advantages of leaving
the anterior cornea intact were obvious (Table 2). They described ice slabs if they are rubbed with each other) which may contribute
it as posterior lamellar keratoplasty (PLK) in which an unsutured to fixation of the transplant. The fixation mechanism is so effective
posterior lamellar disc was transplanted through a 9.0-mm scleral that sutures are not required. If the graft remains apposed for the
incision. A similar procedure was described by Terry et al as Deep initial 48 hrs, graft dislocation is rare.
Lamellar Endothelial Keratoplasty (DLEK).
Despite the lower induced astigmatism and faster visual recovery
However, the most popular technique so far has been Descemet with the present day endothelial keratoplasty techniques, final
Stripping Endothelial Keratoplasty (DSEK) and its variations like postoperative visual acuity seems to be less than ideal. Many
Descemet’s Stripping Automated Endothelial Keratoplasty authors have attributed this limitation to problems with the
(DSAEK) and Femtosecond Laser assisted DSAEK. The posterior recipient-donor stromal interaction like initial keratocyte apoptosis
transplant consists of the endothelium, DM, and a thin layer of and a later hyperactivity and stromal regeneration as seen on
posterior stroma and it stays in position without suture fixation. histopathology. There is also proteoglycan deposition in the
This is due to the negative pressure induced by the pumping action interface. It leads to formation of interface haze, thus limiting the
of the endothelium that sticks the posterior transplant onto the visual potential to 20/30 or less in many patients and reduces the
posterior recipient stroma. It is further helped by the stickiness of contrast sensitivity. This problem has been reduced to some extent
the stromal interfaces (similar to spontaneous adhesion between by creating smoother interfaces in microkeratome assisted
procedures (DSAEK) but there is still some recipient-donor stromal
Table 1: Indications of endothelial keratoplasty (DSEK/ interaction. Also, the smoother interfaces obtained with automated
DSAEK) pre cut tissues may be associated with higher graft dislocation,
thus requiring a longer tamponade periods. As listed in Table 3,
1. Fuch’s endothelial dystrophy there are some other issues associated with DSEK technique.

2. Pseudophakic and aphakic bullous keratopathy To address these issues, a new technique, Descemet’s Membrane
Endothelial Keratoplasty (DMEK) was described by Melles.
3. Failed graft due to endothelial rejection or primary graft Basically in this technique, the donor Descemet’s membrane (DM)
failures and endothelial cells are transplanted and no stromal tissue is
transferred. Thus the recipient cornea retains its optical quality
Shroff Eye Centre with no interface and majority of these patients attain 20/20 vision.
A-9, Kailash Colony, New Delhi Though the concept is easy, the physiological properties of
Descemet’s membrane to roll over on itself make the procedure
more demanding.

www.dosonline.org 49

Table 3: Disadvantages of endothelial keratoplasty (DSEK / Table 4: Advantages of DMEK over present endothelial
DSAEK) keratoplasty techniques

1. Steep learning curve 1. Elimination of interface haze thus many patients achieve
20/20 vision
2. Higher endothelial cell loss rates in initial post op period
2. Less incidence of graft dislocation
a. Higher rates of primary graft failures esp. in the hands of
beginners 3. Shorter visual recovery as total corneal thickness remains
unaffected, thus there is practically no edema of donor
b. Need for grafts with higher endothelial counts lenticule in early post op period

3. Graft dislocation and migration 4. No crowding of peripheral anterior chamber

4. Pupillary block due to air tamponade and posterior 5. Larger (usually 9mm disc of donor decemets membrane
migration is used) donor surface provides more viable endothelial
cells
5. Shallow peripheral anterior chamber especially in eyes
with smaller corneal diameter, crystalline lens and pre- 6. Less strong host graft apposition at the interface allows
existing shallow AC easier removal of failed/rejected donor lenticule

6. Difficult graft manipulation in phakic eyes 7. No need for special and costly instruments for donor
lenticule preparation
7. Reports of graft dislocation in to vitreous cavity in aphakic
eyes Table 5: Disadvantages of DMEK over present endothelial
keratoplasty techniques
8. Interface haze limiting the probability of 20/20 visual
acuity 1. Difficult and more traumatic manipulation of rolled DM

9. Preparation of donor tissue to obtain consistent thickness 2. Higher endothelial cell loss rates with current techniques
of donor discs and a naïve surgeon

10. Hyperopic shift (usually related to thickness of donor
lenticule)

Harvesting the donor Descemet’s membrane

Descemet’s membrane (DM), the basement membrane of the
endothelium is a formed by the endothelial cells. These cells adhere
to DM by hemidesmosome binding complexes. However, DM
lacks strong adhesions with the stoma. For this reason, inadveratant
detachment of DM from the posterior stroma during cataract
surgery is not uncommon. Many techniques have been described
to harvest DM with minimal manipulation of the corneal
endothelium to prevent substantial cell loss and to preserve
endothelial cell viability for selective transplantation. A 9mm
diameter donor DM is often harvested. It is preferred because
compared to a standard 7.5mm corneal graft, 9mm donor lenticule
has 40% higher surface area and thus proportionally larger number
of endothelial cells.

Melles et al describe a technique in which the donor corneoscleral Figure 1: DSEK. Fig 1a. Clear graft at 3 weeks post op.
rims are mounted endothelial side up on a custom made holder Fig 1b. A well apposed posterior lenticule. Fig 1c. Early
with a suction cup. A 9 mm trephine is used for superficial
trephination just within the posterior stroma and DM is loosened interface scarring between optically clear recipient
at the scleral spur. Descemet membrane is then stripped from the stroma and posterior donor lenticule. Fig 1d. Persistent
posterior stroma by holding it with fine forceps at the periphery
so that a sheet of DM with the endothelial monolayer is obtained. haze at 3 months post op (BCVA 6/9).
Melles have reported 4% endothelial loss with this method.
Another modification is doing the steps in a water / saline bath so with the endothelium on the outer side (Figure 1). It is very delicate
that the endothelial cells don’t desiccate and also a thin fluid layer and transparent. This DM roll is better visualized by staining with
between the DM folds prevents cell loss. It has referred to as non toxic and reversible concentration of trypan blue dye (0.06%).
‘scuba’ technique. Because of the elastic properties of the
membrane, after immersion in saline a ‘‘Descemet roll’’ forms DMEK technique

The donor DM roll is stained with a 0.06% trypan blue solution
and sucked in to a custom-made injector. A clear cornea temporal

50 DOS Times - Vol. 15, No. 10, April 2010

Figure 2: Rotational importance of Descemet- Figure 3: DMEK technique. Fig 3a. A 3.5mm Clear
endothelium roll. Descemet roll with endothelial cells corneal incision is made.
lined on the outer side (Fig 2a). Air being injected to
unfurl the roll (Fig 2b). The roll has to be spread over Fig 3b. DM roll folded in a custom made injector
the iris with endotheliaium facing the iris followed by being placed in the anterior chamber.
air injection underneath the Descemet roll (as shown in
(Fig 2d). Failure to align the DM in correct position Fig 3c. Rolled up DM lying in the anterior chamber.
will lead to endothelium face upwards towards the Fig 3d. The DM roll is spread over the iris with
endothelium facing down.
recipient stroma (Fig 2c).

incision is placed in the recipient after recipient descemetorrhexis
and the donor DM is injected in to it. The DM roll has a unique
directional polarity so that endothelial cells are on its outer surface.
Thus injecting the air by placing the canula within the DM roll will
open it and push the endothelial cells towards host stroma. For
this reasons, the DM roll is gently spread out over the iris. The air
bubble is then injected underneath the donor DM (between the
DM and the iris) to lift the DM onto the recipient posterior stroma
(Figure 2,3,4). The anterior chamber tamponade is given with air
for 30 minutes followed by an air–liquid exchange.

Literature review of DMEK

PK and DSEK have a proven track record and there are umpteen
case series showcasing the advantages and disadvantages of these
procedures. I have, therefore, presented a literature review
pertaining to DMEK only.

In 2006, Tappin described the clinical transplantation of 7.5 mm Figure 4: ex vivo DMEK. Fig 4a. Harvested DM roll in
donor DM using a carrier device through a sutured 8mm incision. MK medium. Fig 4b. Corneoscleral rim placed on an
Most of the work in endothelial keratoplasty has been done by artificial anterior chamber. DM roll being injected
Melles et al and their first clinical case report was published in through a 3.5mm clear cornea incision. Fig. 4c. Donor
2006. In 2007, a case series of 10 patients reported by Melles et al, DM lying rolled up in the anterior chamber. Fig 4d. Air
3 cases showed primary graft failure due to graft dislocation. The bubble being injected underneath the donor DM roll.
preoperative endothelial cell density for these eyes averaged 2600
cells/mm2 and at 6 months, the endothelial cell density averaged eyes had persistent corneal edema (excessive endothelial cell loss).
2600 cells/mm2. These patients underwent DSEK and regained useful vision. All of
the eyes with a functional DMEK graft obtained a BCVA of 20/40
Another study of 11 eyes with primary donor failure in DMEK or better and 75% reached >20/25 at 6 months after surgery. Donor
showed that excessive tissue manipulation, upside-down ECD averaged 2641 (±163) cells/mm2 before, and 1551 (±765)
orientation of the graft (donor endothelium facing the recipient cells/mm2 after surgery
stroma) and incomplete graft adhesion were the most common
causes of graft failure.

The largest series so far reports clinical outcome in 50 cases of
Fuch’s endothelial dystrophy. 7 eyes had graft dislocation and 3

www.dosonline.org 51

Most of the present scientific information on DMEK has been 2. The technique for penetrating keratoplasty. In: Barraquer J, Rutllán
from a single centre and short term results. Though there are J, eds. Microsurgery of the Cornea: an Atlas and Textbook. Barcelona:
reports of successful DMEK surgeries by other surgeons, most of Ediciones Scriba, 1984:289–94.
them are isolated cases and not published in peer reviewed journals.
A high rate of primary graft failure in otherwise uncomplicated 3. Mohay J, Lange TM, Soltau JB, et al. Transplantation of corneal
cases of Fuch’s endothelial dystrophy is a concern with DMEK. endothelial cells using a cell carrier device. Cornea 1994;13:173–82.

Conclusion 4. Terry MA, Ousley PJ. Small-incision deep lamellar endothelial
keratoplasty (DLEK): six-month results in the first prospective clinical
In recent years, efforts have led to emergence of endothelial study. Cornea. 2005;24:59–65.
keratoplasty, as a promising alternative to conventional full-
thickness penetrating keratoplasty (PK) in patients with endothelial 5. Price FW Jr, Price MO. Descemet’s stripping with endothelial
disease. Present day techniques of endothelial transplant have keratoplasty in 200 eyes. Early challenges and techniques to enhance
proved that the concept of unsutured posterior corneal transplants donor adherence. J Cataract Refract Surg. 2006;32:411–418.
is surgically feasible; the best possible visual outcomes may be
obtained by selective transplantation of only DM and endothelium 6. Gerrit R. J. Melles. Descemet Membrane Endothelial Keratoplasty
by avoiding the interface haze and stromal – stromal interaction. (DMEK). Cornea 2006;25:987–990.
Though DMEK is a feasible procedure it requires further
evaluation and modifications in surgical technique. 7. Lange TM, Wood TM, McLaughlin BJ. Corneal endothelial cell
transplantation using Descemet’s membrane as a carrier. J Cataract
Conventional penetrating keratoplasty and DSAEK enjoy a better Refract Surg. 1993;19:232–235.
graft survival than DMEK in these patients. In present scenario,
automated or femtosecond assisted DSEK is a procedure of choice 8. Ignacio TS, Nguyen TT, Sarayba MA, et al. A technique to harvest
for conditions primarily affecting the corneal endothelium. Descemet’s membrane with viable endothelial cells for selective
transplantation Am J Ophthalmol. 2005;139:325–330.
References
9. Lissane Ham. Causes of Primary Donor Failure in Descemet
1. Irit Bahar, Igor Kaiserman, Penny McAllum, Allan Slomovic,David Membrane Endothelial Keratoplasty. Am J Ophthalmol
Rootman. Comparison of Posterior Lamellar Keratoplasty Techniques 2008;145:639 – 644.
to Penetrating Keratoplasty. Ophthalmology 2008;xx:xxx
10. L Ham. Descemet membrane endothelial keratoplasty (DMEK) for
Fuchs endothelial dystrophy: review of the first 50 consecutive cases.
Eye (2009), 1–9

Author
Deepender Chauhan MS, DNB, FRCS

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DR. ABHISHEK DATTA V-3683

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DR. ADVIN S-4067

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52 DOS Times - Vol. 15, No. 10, April 2010

Keratoconus Cornea

Sri Ganesh MBBS, MS, DNB

Keratoconus (conical cornea) is an bilateral non inflammatory There are various new treatment options available like Kerarings/
corneal ectasia with reported incidence being between 50 – C3R and Toric ICL’s
230 per 100,000 (approximately 1 per 2,000) in the general
population. It usually manifests after puberty. The cornea thins The various treatment options for the patient depends on the
near the center and progressively bulges forwards with the apex stage of keratoconus and is as per the following algorithm
of the cone usually being slightly below the centre of the cornea. “Keraring” intrastromal corneal ring segments are Implantable
devices implanted in the corneal stroma for correction of
The patient becomes myopic but the error of refraction cannot be morphological and refractive disorders. The device is manufactured
satisfactorily corrected with ordinary glasses owing to parabolic from PMMA and is implanted in the corneal stroma as per specific
nature of the curvature which leads to irregular astigmatism. surgical technique. The device acts upon the corneal tissue by
altering its central curvature and shape, thus reducing or eliminating
There are various modalities of treatment currently advocated: morphological irregularities and existing myopia and astigmatism.
The device is composed of one or two semicircular segments of
In early stages vision may be improved with spectacles but rigid variable arc lengths, variable apical diameters, variable thickness,
gas permeable lenses may be more beneficial. having a fixed triangular cross section of 600 micro base. Each ring
segment has a 0.2 mm diameter hole to facilitate manipulation
If however the disease progresses and the cornea becomes and implantation.
hydrated/scarred the most satisfactory treatment is corneal
transplantation (Keratoplasty). Keraring was specially designed for the treatment of corneal ectatic
disorders, providing greater and better corneal regularization and
refractive effects. Keraring implantation is intended to improve
the patient’s visual acuity, reduce or eliminate the refractive error
and stabilize the cornea, avoiding or delaying the need for corneal
transplantation.

Indications

• Keratoconus with poor BSCVA and contact lens intolerance.

• Progressing keratoconus.

Figure 1: Central corneal thinning

Figure 2: Munsen’s Sign in Figure 3: Dimensions of Kerarings
Keratoconus
55
Nethradhama Super Speciality Eye Hospital
7th Block Jayanagar, Bangalore, Karnataka

www.dosonline.org

• Pellucid marginal degeneration. • Irregular astigmatism following penetrating keratoplasty.

• Corneal ectasia following LASIK, PRK, LASEK, EPI-LASIK. • Corneal surface irregularities following trauma.

• Irregular astigmatism following radial keratotomy. Contraindications

• Acute keratoconus with K reading > 70 D.

• Severe central corneal opacities.

• Hydrops.

• Following penetrating keratoplasty with decentered graft.

• Severe atopic disease.

• Recurring corneal erosion syndrome.

Patient’s high expectation for uncorrected emmetropia

Advantages

• Clinically proven safety and efficacy

• Reversibility

• Adjustability

Figure 4: Keraring Segments • Quick visual recovery
• Exclusive prismatic design

• Greater refractive potential

Figure 5: Kerarings Implanted in the Figure 6: Mechanism of action of
Cornea Femtosecond Laser

56 DOS Times - Vol. 15, No. 10, April 2010

Figure 7: Riboflavin drops being Figure 8: UV exposure by special
instilled in the eye LED instrument

• Does not compromise corneal transplantation Figure 10: ICL Collamer Lens

Recently femtosecond laser technology has been introduced in
corneal refractive surgery opening a new frontier and providing a
new surgical technique for keraring implantation.The tunnel is
performed at 80% of corneal thickness with the aid of femtosecond
laser (intralase: femtosecond laser 15 KHz), which is a mode locked
diode pump infrared, neodymium glass femtosecond laser
(ultrafast 10-15) with a wavelength of 1053 nm. The laser beam of
3 micron diameter (spot size) is optically focused at a specific
predetermined intrastromal depth by computer scanner which
gives a focus (dissection) range between 90 and 400 microns from
the corneal anterior surface. This beam forms cavitations &
microbubbles of carbon monoxide and water vapour by photo

Figure 9: Location of ICL after disruption. The interconnecting of these bubbles forms a dissection
Implantation in posterior chamber plane.

www.dosonline.org A unique feature of femtosecond laser is the ability to produce
photo disruption of tissues at very low energy settings. This is due
to the short pulse width, or pulse duration (600-800 femtosecond)
and the very rapid pulse repetition or speed of the laser
(15,000 to 60, 000 pulses per second). Thus, energy settings are low
but high peak power is retained. Hence, postoperative
inflammation is reduced. Also the increased speed reduces suction
time thus providing enhanced safety and patient comfort. Tighter
spot placement produces better dissection quality.

The femtosecond laser has the following advantages over
conventional tunnel creation:

• Lesser discomfort to the patient and hence better patient
cooperation.

• Faster creation of tunnels with very little tissue disturbance
and faster postoperative recovery.

57

• Precise control of tunnel depth, width and centration. made of plastic or silicone materials, which are implanted into the
eye permanently to reduce a person’s dependence on glasses or
Corneal collagen cross linkage is a new treatment modality, the contact lenses. They are called as Phakic lenses as they are implanted
early results of which indicate that it may be the first treatment into the eye without removing the eye’s natural lens. The phakic
available to actually stabilize the keratoconic process. The aims of lens is inserted through a small incision and placed just in front of
the treatment are to increase the mechanical stability of the cornea or just behind the iris.
and its resistance to enzymatic digestion, by inducing cross linkage
between the corneal collagen fibres. Photochemical collagen cross- The lens is soft and tiny, much like the natural lens, but does not
linking by riboflavin/UVA appears to provide a simple, safe and replace it. The ICL is specially shaped to correct myopia/
technically easy to perform outpatient surgical procedure. hypermetropia/ astigmatism. Toric ICL’s correct the cylindrical
errors (also called as astigmatism) also thus providing a very sharp
The technique is performed as an outpatient procedure under vision
topical anaesthesia (eye drops). As riboflavin does not penetrate
the epithelium (corneal skin), this is removed using a blunt spatula Advantages of ICL/ Toric ICL
(although some surgeons advocate the use of minor epithelial
trauma only, as sufficient to allow riboflavin penetration into the Suitability for patients with keratoconus after stabilisation with
corneal tissue. Riboflavin eye drops 0.1% are applied to the corneal kerarings and/or C3R.
surface five minutes prior to the procedure and then every five
minutes during the procedure, which involves, exposing the corneal The lens is small foldable and injected through a tiny, pain free,
surface to ultraviolet A radiation (370nm) at a radiance of 3mW/ self healing incision in your eye. The ICL provides highly predictable
cm2 for 30 minutes. At this low energy level, UV wavelength and outcomes, excellent quality of vision and can be removed if
using this concentration of riboflavin, the technique has been shown necessary.
to be safe with no endothelial damage provided the cornea is
thicker than 400μm, with no loss of corneal transparency and no Quick Recovery post operatively
damage to deeper ocular structures.
Provides high patient satisfaction: The ICL provides high quality of
Implantable contact lens also called as ICL is a type of Phakic Lens. vision, is a highly precise and predictable treatment and provides
Phakic intraocular lenses, or phakic lenses, are specialized lenses exceptional patient satisfaction. The ICL was made available in
1997. Over 55’000 lenses have been implanted since then.

Author
Sri Ganesh MBBS, MS, DNB

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58 DOS Times - Vol. 15, No. 10, April 2010

Surgical Options for Lasik Rejects Refractive Surgery

Sudhank Bharti MS

Lasik is currently the most frequently performed refractive Alternatives for these Patients who are Lasik Rejects:
procedure. It is a practicable, convenient and efficacious
alternative and long- lasting treatment that eliminates dependency There are procedures, each with it’s own specific indications which
on spectacles and contact lenses. Conventionally Lasik is a marriage can be offered to these patients:
of a reasonably precise mechanical system to a very accurate laser
system. However this procedure is not available for all patients. For eyes with THIN CORNEA

There are multiple issues limiting the procedure availability. Apart • PRK/ LASEK/EPI-LASIK
from standard protocol demanding age >18 yrs along with stable
refraction for >1 yr, the other major issues include it’s safety in • SBK (Sub Bowman’s Keratomilleusis)
limited limit of correctible refractive error i.e. 6D of
Hypermetropia/6D of astigmatism/ 12D of myopia depending • Intra corneal Rings
upon the corneal thickness. A residual bed thickness of half of
original corneal thickness must remain after the flap has been cut • Blade Free Z-Lasik
and tissue ablated.
• Phakic IOL (ICL)
Keratoconus is an absolute contraindication for Lasik. Other ocular
conditions where Lasik should be avoided are corneal opacities, For eyes with ABNORMAL SHAPE
Irregular surface, previous eye surgery like aphakia/ pseudophakia/
Retinal detachment and Dry eyes. Other important considerations • Intra corneal Rings (INTACS,Kera rings )
before embarking upon Lasik are mesopic pupil diameter,
profession of the patient and high expectations. • Phakic IOL

A high refractive error correction and or large area of ablation PRK(Photo-refractive Keratectomy) is performed with an
requires more tissue to be ablated and thus is a limiting factor in excimer laser, which uses a cool ultraviolet light beam to precisely
thin corneas. remove (“ablate”) very tiny bits of tissue from the surface of the
cornea in order to reshape it. Improvement with PRK is gradual
Irregular surface and corneal opacities may remain in the flap and and takes days, weeks or even months. PRK is preferred in
ultimately result in a compromised vision. Previous eye surgeries circumstances such as when patients have thin corneas, Large
may preclude the eye from withstanding increase in IOP during mesopic pupil diameter, Steep corneal curvature and High
flap making or lead to cystoid macular edema and macular Refractive error.
hemorrhage. Some professions like boxers and sports persons
pursuing other contact sports make them prone to injury and to LASEK(Laser Epithelial Keratomilleusis) is modified PRK which
flap dislocation and Lasik is best avoided in these. People with involves separating the extremely thin epithelial layer by applying
unrealistic expectations and poor understanding of the technology 20% alcohol for 20 seconds and lifting it from the eye’s surface
should best be avoided. before laser energy is applied for reshaping. After the LASEK
procedure, the epithelium is replaced on the eye’s surface. LASEK
is used mostly for people with corneas that are too thin or too
steep for LASIK, when it may be difficult to create a thicker LASIK
flap.

Epi-LASIK is a newer laser eye surgery procedure that was
developed to solve some of the potential problems with LASIK

Figure 1: The EpiLASIK Keratome Figure 2: The One use plus SBK Keratome

Cataract, Cornea & Refractive Services 61
Bharti Eye Foundation,1/3 East Patel Nagar, New Delhi 110008

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Figure 3: OCT image showing the uniformity of
thickness in a flap created by Femtosecond laser

Figure 4: Electron microscope image showing uniform edge
at 55x magnification in a flap created by Femtosecond Laser

Figure 5: Intacs in place Figure 6: Topographic pictures showing
improvement in corneal curvature after PRK

+Crosslinking

and LASEK. It’s somewhat of a cross between the two, but differs thereby theoretically making it safer than conventional Lasik.A
in a few key areas. In Epi-LASIK the surgeon typically uses the Sub-Bowman’s Keratomilleusis flap compares favourably with a
plastic blade (and not alcohol), called an epithelial separator, to Femtosecond Laser flap in the possibility of reduced thickness of
separate the sheet from the eye. Classically the epithelium is the flap thereby offering an increase in the stromal thickness
replaced back on the surface of the cornea . Many surgeons now available for ablation. I am evaluating the Moria SBK-one use for
prefer to do away with the epithelium and it is documented that the same and have found it reasonably accurate. There are two
this hastens the epithelialisation and is called AST(Advanced thickness possibilities of 110 and 100 microns depending upon the
surface treatment) speed of the motor while creating the flap. A slow speed creates a
thicker flap. The flap configuration is good in all the cases done so
SBK(Sub-Bowman’s Keratomilleusis) SBK uses a new far.
mikcrokeratome that makes a flap with a thickness of 100 microns

62 DOS Times - Vol. 15, No. 10, April 2010

Blade Free LASIK (Z- Lasik, I- Lasik, All Laser Lasik) Blade free Safety issues: 400 μm corneal thickness to prevent endothelium
Lasik utilizes a Femto-second Laser for creation of the flap of a damage. Max K up to 57 or BCVA 6/24 or better.
precise thickness. The advantage of this flap is in the precision of
it’s thickness and size along with a hinge of a predetermined chord CXL +PRK- The compacting of the collagen fibers was observed
length. only in the absence of the epithelium, due to a limited penetration
of riboflavin through the epithelial tight junctions into the stroma,
I am using the Ziemer Femtosecond Laser for Z-Lasik. Therefore combining the two procedures yield much superior
results.
Ziemer Ophthalmic Systems received FDA approval in March
2008 for its portable femtosecond laser, known as the Ziemer ICL(Implantable contact lens)- is considered when other vision
Femto LDV. This femtosecond laser attaches to a movable arm correction procedures aren’t a good option, such as when a person
and can be combined with any approved excimer laser system to has thin corneas or myopia between -3.00 and -20.00D. Implantable
create a flap for bladeless LASIK. Bladefree LASIK creates hinged lenses are placed in eyes that retain their natural lens. Reversibility
flaps through infrared laser energy that inserts a precise pattern may be one of the procedure’s main advantages over laser vision
of tiny, overlapping spaces just below the corneal surface. The correction such as LASIK.
resulting corneal flap is created at a precise depth and diameter
pre-determined by the surgeon. With bladeless LASIK, people The ICL sits between the iris and crystalline lens and with the
with thin corneas who once were deemed unsuitable for LASIK current 4th generation design, does not touch either of them. Though
may now be candidates. It has a distinct advantage over it can cause an anterior sub-capsular cataract if it touches the
microkeratomes in terms of the ability to make thinner flaps, with crystalline lens and can lead to a low grade iris/ciliary body irritation
more defined, angled edges. People who have had previous corneal if it touches one of them, the current vault makes it reasonably
surgery often are candidates for bladeless LASIK. It results in safe on these accounts. The sizing and horizontal placement of
significantly fewer overall LASIK complications like buttonhole, ICL is very crucial and error in measuring the horizontal “white-
partially formed flaps. to-white” can lead to the 1. ICL rotation if the ICL is smaller and
then it has to be replaced or 2.An increased vaulting leading to
Intacs corneal inserts or implants are a minimally invasive surgical shallow anterior chamber and possibility of angle closure.
option primarily now used for correcting bulging (keratoconus)
caused by thinning of the eye’s front surface. Intacs are two tiny, The results of ICL are excellent, the refractive correction very
clear crescent-shaped pieces of a plastic polymer that are inserted accurate and visual quality very superior with very few instances
into the cornea.Intacs can be replaced with different-size implants of haloes, glare and reduced contrast sensitivity purely because of
or removed for good. You may be eligible for corneal ring a large optic size and maintenance of a prolate corneal shape.
implantation if you are an adult over 21, have keratoconus, have
stable vision. The ICL is available for correction of Refractive errors from +10
to -20 with astigmatism upto 6 diopters.
Corneal crosslinking (CXL) procedure increases the formation
of collagen covalent bonds by photosensitized oxidation, which CXL + ICL/Intacs
leads to a biomechanical stabilization of the cornea. Photosensitizer
riboflavin and UV irradiance lead to corneal tissue strengthening After stabilising the corneal curvature with Corneal Collagen
by increasing collagen covalent bonds. Corneal stiffness has been Crosslinking the residual refractive error can be corrected with
shown to increase by 300%. It is used to stop the progression of Toric ICL or Intacs.
keratoconus and pellucid marginal degeneration.

Author
Sudhank Bharti MS

www.dosonline.org 63

Faltering Practices-What is Lacking Miscellaneous

Vipin Sahni MS

Ophthalmology is the most rapidly developing medical branch surgery they never use to get the same quality of vision they have
in India. Eye surgeons in India are the most gifted and prior to surgery. But now, It has become a very demanding branch.
intensely trained professionals. Their numbers are limited (there As soon as we open the dressing or on the very first post operative
is approximately one for 65000 population), and barrier to enter visit patient complaints that he has not got good vision. So honing
practice is steep. Their customer base is abundant, and growing your skills with changing time is the utmost important. There
with increasing population. So, why many ophthalmic practitioners were few surgeons who could not upgrade themselves with the
are in trouble today? changing market environment and they soon became obsolete.
These were on top before the IOL came but failed to upgrade
Today medical or more precisely ophthalmic practice is not only themselves. Failed to learn new techniques and failed to provide
needs surgical skills; it also needs great business skills to market services according to market demand. Then came
the practice. If you see the top ophthalmologists in India they Phacoemulsification and SICS, some of the surgeon failed to learn
may/or may not be gifted surgeons but they are good marketers. or provide facilities for these in their setup, these are also becoming
In India ophthalmologists has to be producers and managers of or became failure. Now Multi-focals , MICS – MIOLs, Toric lenses,
their practice business. LRIs Accommodative lenses are becoming popular . And in times
to come everyone has to upgrade themselves in these technologies.
Ophthalmology is about control – in millimeters, even in microns, You have to upgrade your skills according to the need of hour. If
at a time. For most eye surgeons, it is a cruel professional contrast you cannot do that then you have to bring in visiting
to be this controlled clinically while having no control over fate of ophthalmologists who operates on your behalf.
their practice’s outcome. Earlier investments were low and expenses
were also less. Because of this even the bottom earners in private There are some second generation ophthalmologists who failed
practice once have viable business and were almost guaranteed to run the practice as their father/mentor did. These are neither
the ability to practice as they pleased and support their families. having the Charisma of their predecessor nor skills to improve
For past few years, as investments are increasing and with growing the practice that was once the top practice of the town. I have seen
number of corporate hospitals and chains of reputed eye institutes, a practice in town nearby where the father was the top practitioner
they must be noticing impact on their bottom line. They have to of the town. He made fortunes in ophthalmic practice and built a
pay more attention to the business side of their practice. Ride is big hospital. His son who is also an ophthalmologist could not
getting tougher day by day and they are starting to worry. keep pace with changing time and now he sees very few patients
and all the practice has been lost.
These practitioners do not get into the trouble in one day; they
become trapped slowly. Practice downturn happens over the Population – ophthalmologist ratio are out of balance. If you work
months or the years. Here are some common reasons for failures: in a place with less than 1 lac population of normal age distribution
per ophthalmologist, you may be in danger. It does not mean that
When the ophthalmologist becomes old or is chronically ill or he every ophthalmologist who is settled in low population area is in
is giving less time to practice as the productivity is falling or he/she danger. I have seen an ophthalmologist settled in a village has led
turns more towards spirituality, practice slows immediately. The ophthalmologists of nearby big towns to run for their money.
resulting profit drop is much more than degree of withdrawal by Until recently this has been the big city problem (like Delhi) but
the ophthalmologist. It is Important to have good physical and more doctors settling in middle class cities the problem is also
mental health to treat and manage patients properly. If you are rapidly spreading to small town markets in which one or two can
physically not fit you will not be able pay proper attention to thrive – third sputters and fourth starves.
patient or become irritated when patients repeatedly ask questions.
If you are mentally ill you will not pay attention to patients The most enlightened service providers long ago discovered that
complains or you can misbehave to him or his/her attendants, this the “customer rules” Earlier consultants use to see patients
has very bad impact on the patients. However good you are but according to their convenience. And patient use to wait for the
nobody can tolerate misbehavior. There were times when doctor/ doctors for hours. Even after the consultant has seen, the patient
ophthalmologists behavior, however rued it was not even use to wait for the optometrist or staff to provide treatment. But
considered as a factor. But now in the modern world of now world has been changed, consultants give prior appointments
ophthalmology if you misbehave even with one patient, it may be to patient according to their convenience. As soon as patient arrives
dangerous for your practice. I have seen some gifted surgeons in clinic optometrist starts his/her examination. Seeing patients at
when they entered the private practice could not do well because doctors convenience or staff ’s will rather than patient’s convenience
of their behavior. is a sure prescription for failure. Highly profitable practices are
most often run with strong service mission.
In past 25 years ophthalmology has completely changed. Earlier it
was considered luck that you get some vision or not. People use to Ratio of new to returning patient is falling. In India most of the
retire when they get cataract because even after the best of the patient comes by Mouth to Mouth publicity. Earlier practices use
to establish by this method only. It uses to take years to establish a
K.D. Eye Institute practice with hard work and proper treatments. But now nobody
Pilibhit, U.P.

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has that much time and everybody wants to get the maximum out before taking any decision on pricing you should know answers to
of the practice at the earliest, because investments are high and few questions-
you have to pay interest for the money, borrowed for establishing
practice. Every practice has its own mix of new to returning patient. In what type of locality you are practicing? A person practicing in
If your practice is having less than 20% satisfied returning patient Greater Kailash can charge double the amount a person of
or less than 50% patient who has come due to another patient Shahdara can charge. What type of clientele you have? A person
referring him, than you might be in danger. But if ratio of new whose most of patients are getting reimbursement can charge
patient is falling you need to be more active in your promotions. I much more than one whose patients are paying from their pocket.
have seen many practices which had gifted surgeons and all the How much is the competition? A doctor who does not have any
necessary top of the line equipment but failed due to lack of competition or have competitor who is not capable can charge
promotion or calibrated marketing efforts. more prices than the one who is sitting in fiercely competitive
market. There are many such points which should be taken into
Your dept is high. Unless your practice is new or rapidly growing, consideration before prices are decided. Making impulsive elective
your total liabilities to assets ratio should be well below 1.0. Most, price changes up or down without doing corresponding cost
older practices have no long term dept. But as ophthalmology is containment, promotion or level of service change could potentially
too much investment oriented branch you have to go to bankers cause your practice to fail at slower or faster pace.
too often. Even if you are a established general practitioner having
very good cataract practice one day you will be forced to buy New You may lack clear understanding of your performance and
Phaco machine, Nd YAG laser, Non contact tonometer, perimeter, practice goals. First try to understand what you want? If you are a
Fundus camera or retinal Laser. This will again force you to take established practitioner then you should decide what type of
loan. Sometimes this debt burden or interest load on you can practice you want in future? There are some practitioners who
force you to earn more by unfair means .This may lead to a bad know they can do better if they add few more facilities but they
image of you as ophthalmologist which in turn leads to failing don’t want to invest as they know nobody is going to look after
practice. their setup after them. So they know their future. There is another
type of practitioners who don’t know what their goal is. They are
You may be starving the practice of Investments. Under investment just doing it as they have to do it
in your clinic/hospital setup, new equipment, professional training,
staff development and training or marketing will lead to starving You may have “I have already tried that” mentality. Your practice is
your practice tree of vital manure which is required for your not doing well and you don’t want to take suggestions from your
practice to grow. Everything you invest in your setup in turn pays colleagues, seniors, well wishers or some consultant. You may be
you in the form of better return. If you are a Phaco surgeon and thinking you have read or got training from a much reputated
you have a seven year old peristaltic Phaco machine you have to Institute, and you have invested a lot and you are also a very good
invest for new top end state of the art Phaco system, because you surgeon but others are doing well or better than you. When
may be having problems with hard cataracts or one of your somebody suggests you something to improve your practice, you
competitor will buy it and you will be forced to follow the suit. may not be interested in that as you have become frustrated. You
say I have already tried that.It may be possible that that you have
You adhere to wrong pricing in the face of changing market. You tried that at the wrong time or for too short time. Remember
may be having premium pricing policy or you jump prematurely successful practitioners have one common factor of experimenting
to discounted pricing. Pricing strategy is an art. If you charge too new things again and again.
low then you are losing the money which you may be getting. If
your prices are high you may be losing your customers to your (This article has been written in view of standalone practicing
competitors who have kept prices low to get your patients. So ophthalmologists.)

Author
Vipin Sahni MS

66 DOS Times - Vol. 15, No. 10, April 2010

Life Time Achievement Award

1. Prof. Madan Mohan 2. Dr. D.K. Sen
Life Time Achievement Award Life Time Achievement Award

Various Trophies - 2010

Dr. B. Ghosh

Dr. Krishna Sohan Singh Trophy
for Best Clinical Talk in Monthly Clinical Meeting

Dr. Neha Goel

Dr. H.S. Trehan Trophy
for Best Case Presentation in Monthly Meeting

Guru Nanak Eye Centre

Dr. Bodh Raj Sabharwal Trophy
Institution for Holding Best Monthly Clinical Meeting

Dr. Saurabh Kamal

Dr. A.C. Agarwal Trophy
for Best Free Paper Presentation Session

Dr. Harbhajan Kaur

Dr. T.P. Agarwal Trophy
for Best Free Paper Presentation Session (Cornea)

Dr. Surbhi Khurana & Dr. Deepanker Mahajan

Dr. V.K. Kalra Memorial Trophy
Trophy for Quiz Winners

Dr. R.P. Centre for Ophthalmic Sciences

Dr. Minoo Shroff Trophy
for Most Popular Monthly Clinical Meeting

Certificates of Merit

1. Dr. Shina Mahajan and Dr. Tufela Shafi 4. Dr. Manju Mina

for Best Free Paper Session – 2(b) For Best Free Paper Session – 5

2. Lt. Col. Shailesh Kumar 5. Dr. Sujithra H.

for Best Free Paper Session – 3 for Best Video Presentation

3. Dr. Col. Ashish Saksena 6. Dr. Lokesh Jain

For Best Free Paper Session – 4 for Best Poster Presentation

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