|Year : 1979 | Volume
| Issue : 4 | Page : 131-132
Modern trends in keratoplasty
Shyam S Prasad
5-4-71, Murlidhar Bagh, Hyderabad., India
Shyam S Prasad
5-4-71, Murlidhar Bagh, Hyderabad.
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Prasad SS. Modern trends in keratoplasty. Indian J Ophthalmol 1979;27:131-2
When cataract and corneal scarring co-exist, it is customary to perform a keratoplasty in the first instance and proceed to cataract extraction six months to two years later. This two stage procedure has a number of obvious disadvantages.
The results of a combined operation are now excellent (80%). Nevertheless, some special problems remain.
(1) Chronic herpetic kerato-uveitis, with cornea and cataract.
(2) When regrafting is necessary, e.g., after rejection or when there is recurrence of infection in the graft and cataract formation.
(3) Interstitial keratitis and cataract.
(4) Fungal keratitis and cataract.
(5) Some cases of ammonia burn with ensuing cataract and vascular keratopathy.
(6) Fuchs' endothelial dystrophy and cataract.
Reasons for success
There are three reasons why this operation is now so successful:
(1) Profound hypotony which can be obtained with hyperosmotic agents, combined with modern anaesthetic techniques.
(2) The ease of extraction of lens with cryoapplicator.
(3) Better methods of dealing with vitreous loss, should it occur.
| Materials and methods|| |
Most operations are carried out under general anaesthesia. Osmotic agents (manitol-I.V. or glyceroloral) is routinely used.
Operative microscope is a must. The globe is fixed by sutures under superior and inferior recti. Fleringas ring is often used.
Preparation of the Donor eye
The donor eye is removed within 8 hours of death and should be used within 24 hours post-mortem. The donor eye must be examined with a slit lamp microscope to exclude any endothelial disease.
Donor disc trephination should be complete so as to obtain clear cut edge, and produce as little damage to the endothelium as possible. Minimal handling of the disc is advisable.
The host cornea is trephined and excision completed with scissors. It should be aimed to obtain a clean cut edge. If iris is adherant to the cornea, it should be gently dissected free, failing which the adherant iris should be excised.
In vascularised cornea, partial trephination causes bleeding to stop after sometime. Persistant bleeding from the stromal vessels should be cauterised.
If posterior synechiae are present they can be gently freed using a narrow spatula. A sphincterotomy can be performed at this stage. Usually four iridotomies are performed. The disc may be loosely attached to the host cornea by four direct 8-0 virgin silk sutures at 12.3,6, and 9'O clock meridia before lens extraction. It gives best possible alignment because the sutures arc preplaced. The lens is removed using a cryo probe, either by tumbling or by an open sky technique.
If vitreous prolapses into the anterior chamber, anterior vitrectomy is performed using absorbent sponge until the vitreous sinks behind the iris. This method is preferable to aspiration of vitreous through the pupil or a posterior sclerotomy.
When suture is complete, A.C. is reformed with saline or ringers solution and the wound is inspected for leaks. A water seal is more effective than air seal. The use of air should be avoided as it may go behind the iris and push it forwards with danger of formation of P.A.S. and secondary glaucoma.
The graft is dressed the day after surgery and antibiotic and mydriatic drops are applied. Patient is mobilised the first post-operative day and the eye is examined daily by slit-lamp microscopy. Topical steroids are administered from the time the graft is covered with epithelium (usually the 2nd or • 3rd post-operative day); the dosage is judged on the basis of clinical apearance of the eye and continued for a variable period of time. Diamox is given whenever there is tendency for I.O.P. to rise.
Corneal wounds heal slowly. Firm scar is frequently delayed by the use of monofilament nylon, early administration of steroids. It is advisable, therefore, not to remove sutures until four to six months post-operative, unless the sutures are loose or cause irritation.
Recurrence of the original host pathology in the graft.
Role of tissue typing in keratoplasty
A retrospective survey of 100 full thickness grafts reveal the following:
When the donor and the recipient shared two antigens, there were few irreversible rejections and they occur quite late, compared to the ones where no antigens were shared. The overall pattern shows little influence on the incidence of rejection but there is a definite effect on the incidence of reversibility.
Cases with marked vascularisation are the ones most likely to undergo irreversible rejection. So, it is in these cases that HL A compatibility should have the greatest influence.