|Year : 1967 | Volume
| Issue : 4 | Page : 139-144
Corneal surgery in India
Corneal Surgery Unit and Regional Eye-Bank, M.G.M. Medical College and M. Y. Hospital, Indore (M.P.), India
|Date of Web Publication||21-Jan-2008|
R P Dhanda
Corneal Surgery Unit and Regional Eye-Bank, M.G.M. Medical College and M. Y. Hospital, Indore (M.P.)
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Dhanda R P. Corneal surgery in India. Indian J Ophthalmol 1967;15:139-44
Corneal blindness is a national problem in India when we realise that of the 3 million estimated blind in the country, 650,000 are corneally blind due to the ravages of small pox and malnutrition and sequelae of trachoma and infective conjunctivitis. Worse still, these are mostly preventable causes.
To an ophthalmic surgeon it poses two problems. Either he has to surgically treat these cases or he has to guide them on proper lines which might help their rehabilitation.
The purpose of this talk is to avoid wrong conventions in keratoplasty in this country as has happened say for example in relation to cataract surgery. It takes 5 years for a new thing to be accepted but it takes 25 years for old conventions to die out.
It is ironical that unlike other sciences, technical advances in keratoplasty preceded the scientific understanding of the subject. That is why it is often mentioned as corneal carpentry. The WHY and HOW of graft failures have only started being understood very recently. That cornea isolated from the donor eye and before being finally accepted or rejected by the host can live on its own reserve of nutrition even upto 15-20 days, explains that grafts unless technically complicated mostly remain transparent during the first 15 days. The critical period of life and death of donor graft from a physiological point of view is therefore the end of the third week when tissue exchanges with the host surroundings have started and donor cornea becomes dependent on the mercy of the host. Any reactions of tissue incompatibility are therefore most frequently observed about this time. It is correctly said that if a graft has remained transparent for one month after operation it is most likely to remain so for the rest of the life.
| Etiological Considerations|| |
The common etiological factors for corneal pathology in India, you will appreciate, are radically different from those in Western countries. If one went through the literature, a lamellar keratoplasty is most frequently done for herpetic keratitis and epithelial dystrophy and a penetrating graft for keratoconus and Fuch's endothelial dystrophy, interstitial keratitis having been excluded from the clinical picture by steroids and antibiotics. The problem that you and I have to face are however radically different. We in India know that infected corneal ulcers, trachoma, small pox and malnutrition are the conditions for which corneal grafting is most frequently required.
| Age considerations|| |
Nearly 60% of the causes of corneal opacity have their origin before the acre of 12 years, and this poses a question, how soon can corneal grafting be safely done. It is commonly advised that a child with corneal opacity should better wait till he grows up to adolescence but it is little realised that the introduction of nystagmoid movements and a concomitant squint will seriously jeoparadise the visual recovery in that case. To be more precise, 113 out of 571 recipients during 1963-64 i.e. 19.5% were considered unsuitable by us because of associated squint or nystagmus. I may emphasize that the history of onset of pathology is extremely important because a pathology developing after the age of 15 years and ocular deviation if present is likely to be a heterophoria temporarily converted to heterotropia but of a reversible nature and therefore of good visual prognosis.
| Depth and Density of the Corneal Opacity|| |
Another difficulty is the preoperative assessment of the depth of corneal opacity. You will often experience that you plan a lamellar surgery for a superficial looking opacity but on dissection leave behind an unexpectedly large amount of deeper extension. There are occasionally pleasant surprises also that a dense looking opacity may not have extended more than 0.3 mm. in depth, so that a slit lamp examination is imperative for a proper assessment of this point. One should of course realise that in total corneal opacity judgment may have to depend more on intuition or observations during actual surgery.
I may also emphasize the falacy of applying a tonometer on a scarred cornea. This is still more undependable in adherent leucomata and partial staphylomata. It is therefore wise to presume a raised intraocular tension in all cases where more than half the angle of anterior chamber is narrowed.
| Vascularisation|| |
70% of long standing corneal opacities in India are vascularised, trachomatous or non-trachomatous. Vascularisation therefore is a matter of consideration in the assessment of suitability of corneal surgery. A pre-operative intensive antitrachoma therapy in trachomatous cases, help of steroids and peritomy in more pronounced vascularisation should adequately help making the case more suitable and operable. It may be mentioned that radiation as a pre-operative therapy is now considered a disadvantage.
It is thus to be appreciated that advice for keratoplasty cannot be very lightly given. Observations that I have made should help my ophthalmic colleagues to study the case before undertaking a corneal surgery or advising the same.
Accurate projection of light in all directions of gaze is imperative for consideration of corneal grafting or for that matter any surgery on the eye. Similarly it is important to widely disseminate to the lay public that corneal transplantation is not transplantation of the eye ball as a whole. It will relieve us of a great strain and avoid disappointment to the patient if it was well understood that transplantation of an eye ball is not a practical proposition nor is it likely to be in near future because of the peculiar physiology of the optic nerve.
"When to do and when not to do a keratoplasty".
In the sea of corneal blindness in this country, the most deserving indication of corneal grafting is a patient with bilateral corneal scars of an active corneal pathology. Corneal grafting will not be rewarding surgery even if successful in long standing uniocular pathology if the vision in the other eye is 6/12 or better because the binocularity of the vision in such cases is a difficult and slow process. Again in cases with one eye totally blind, phthisical or staphylomatous, and the other with a gross leucoma adherens, penetrating kerotoplasty should be undertaken with great hesitation and only after carefully balancing the prospect of good visual recovery if all goes well, and losing what the patient has if an unexpected complication ruins the graft. Prudence may sometimes lead us to an optical iridectomy rather than a penetrating surgery in such cases. Except this one indication, an optical iridectomy should be considered misplaced eye surgery. An enthusiastic iridectomy of a big size is a great hazard during penetrating surgery responsible for anterior dislocation of lens through a large ragged coloboma and difficulty in injection of air and restoration of anterior chamber at the end of operation. It is important to emphasize that iridectomy should not be done in any case where corneal grafting can be a consideration at the time or in future. The gravity of the problem will be evident to you when I tell you that 66 out of 571 cases referred to us, (11.5 0%) had a big iridectomy coloboma and this was a cause for our hesitation for surgery in those cases.
I may also explain what I have often called and which is being more often accepted, "mercy keratoplasty". Who can refuse surgery when one eye is incurably blind and the other eye has a partial or a total staphyloma with perfect projection of light. A situation like this particularly in a developing child is an every day challenge in India and will need a total penetrating keratoplasty which means replacement of the whole cornea, removal of all tags of iris and extraction of lens even if transparent. It is a surgery which has a prospect of improvement in not more than 10-15% of cases. Often the graft may remain perfectly transparent, but a deeply cupped atrophic disc discovered after surgery may explain the failure in improvement of vision. However the excitement of an occasional success is an ample reward where nothing else could have been done.
There is also a distinct place for cosmetic keratoplasty in India where rehabilitation in life may be as important as the rehabilitation of blind. Cosmetic surgery must however be limited to lamellar surgery because penetrating surgery may in some give positive results while in others may make it cosmetically worse.
| Surgical Consideration|| |
The days of 4 and 5 mm. size grafts are a past history and in the pathologies like the one we face in this country, it should have still less consideration. These small grafts were done when means of securing a graft were the cris-cross overlying stitches or support by an amniotic membrane or a conjunctival flap. The common size of a penetrating graft should be 6.5 or 7 mm. and may have to be even 8 or 9 mm. or even more in cases of subtotal and total penetrating grafts. A lamellar graft should preferably be 8 mm. in size and 9 to 11 mm. is an equally practical possibility. These large sized grafts can however be secured only by direct edge to edge stitching because that alone can help attaining the final step of surgery, that is restoration of anterior chamber on the table by injection of air or saline, a step if not attained will account for at least 50% failures. To accomplish this, a stitch every mm. in a penetrating graft is necessary and is an acceptable possibility with the fine needles and finer silk now available. The importance of this statement can be assessed from the following table:
A lamellar graft can however be more lightly undertaken. In properly selected patients lamellar graft should be the first choice when it can serve even a limited purpose as compared to the risky penetrating surgery. A lamellar dissection is surgically a more intricate procedure but a fascinating piece of surgery in conditions like epithelial dystrophies, scarred trachomatous corneas in quiet eyes and in cosmetic indications. A donor therapeutic tissue effect on the resolution of the deeper opacity that may not have been included in lamellar dissection of recepient cornea is a known biological phenomenon. An eye operated by lamellar keratoplasty may look very much different 6 months to a year later.
Surgery for a recurrent pterygium of a malignant type has taxed the ingenuity of eye surgeons for long the patients having been operated repeatedly by best of eye surgeons. There is no final answer. A deep dissection of the pterygium and a partial peripheral corneo-scleral lamellar grafting followed by repeated doses of β-radiation is, I think, best when everything else fails.
| Post-operative Complications and Results|| |
Anterior synechia to the graft margin is a most potent danger to the transparency of a graft. A larger incidence of post-operative iridocylitis in India should be anticipated because of flaring up of hidden septic foci in the body which are difficult to detect and often impossible to erradicate. A persistent iridocylitis will cause endothelialitis leading to a very disturbing complication like a bullous keratoplasty.
| Results of Corneal Grafting|| |
Results of corneal grafting depend on the clinical condition of the cornea for which it is planned and on the type of surgery that is undertaken.
Penetrating surgery will undoubtedly have a better outlook in simple partial leucomatous opacities with minimal or no anterior synechia and where a round pupil can be maintained after synechiotomy. More extensive the iris incarceration, poorer will be the result. Other intraocular changes like a cataractous lens and degenerative changes in posterior segment NOT discovered before surgery will materially influence the results. Lamellar grafting however is very safe surgery and carries, where suitably indicated and performed, a high degree of success.
I want to emphasize that the statement `Graft has taken' is not only misplaced but is deceiving one's own self. Every graft `takes', stitches or no stitches because of the gluing secretions of the raw corneal edges. What is important is whether the graft remains transparent or has become cloudy. Kerato-plasty could be as confidently undertaken in children as in adults, provided a good anesthesia is available and the surgical considerations are appropriate and where possible, a lamellar surgery should be preferred in children.
| Eye Bank and the Donor Material|| |
An eye bank is an incompletely understood term. It is an organisation where donor human eyes are received, processed and made available to corneal surgeons. An eye bank is also a research organisation in experimental studies aimed at prolonging the viability of donor cornea. It is also a centre of training to the paramedical staff, and a nucleus of organisation for publicity of donation of eyes. The position till todate is that a fresh donor cornea removed soonest after death and used within 24 hours, occasionally longer is alone a suitable donor material for penetrating keratoplasty. The viability of donor cornea depends on the viability of its endothelial layer which in turn is influenced by factors like the cause of death of donor, the environmental conditions in which the body was lying till the eyes were enucleated, the seasonal variations of tropical climate and the interval between death and enucleation and between enucleation and surgery. For lamellar surgery however, a donor eye can be used after much longer periods of preservation. Excised corneas preserved in glycerine and molecular sieve can be used for lamellar surgery even after 6-9 months of preservation at room temperature or ever longer.
Having made the long subject a really short story indeed it is not for me to say, "who should do corneal grafting?" I would only state that dexterity in cataract surgery, special instrumentation and practice in their use and willingness to face and handle complications are the foundations of a good corneal surgeon. The rewards of corneal surgery are as great as the stakes and it should be a profession rather than fulfiling a curiosity. No surgery is more unpredictable preoperatively, no surgery involves more uncertainties on the operation table, no surgery is more out of control of the eye surgeon once the patient has left the operation table and no surgery is more uncertain in the final outcome. The surgery invites popularity but it should be a popularity which is not run after but which is born of justice in pursuit of noble ends by noble means.
| Summary|| |
In this lecture the following aspects of keratoplasty have been dwelt upon:
1. Etiological and age considerations with special reference to Indian conditions.
2. Indications for penetrating and lamellar keratoplasty with reference to vascularization and depth of opacity, and their limitations.
3. Cosmetic and "mercy" keratoplasty.
4. Techniques and results.
5. Eye banks and requisites of a good corneal surgeon.
[Table - 1], [Table - 2]