Corneal Transplantation is one of the most successful organ transplant surgeries. Diseased corneas can now be replaced successfully by transplanting a human donor cornea to the diseased eye. Replacing the unhealthy cornea with a healthy cornea is the only way of restoring vision.
PENETRATING KERATOPLASTY (PKP) FOR OPTICAL AND THERAPEUTIC PURPOSES
Corneas for transplant come from individuals who have donated their eyes for use after death who is free from transmissible diseases like HIV, Hepatitis, and Syphilis. The donor cornea is itself screened for any pathology and then stored in a nutritive medium temporarily till use.
The donor cornea is secured on the patient’s eye with fine thin sutures made of nylon; about 8 to 16 sutures are put. These sutures can be removed later on after a period of 3 to 6 months. The corneal transplant procedure can be combined with cataract surgery and lens implantation when it is called “triple procedure”.
The success rate of a corneal transplantation procedure is over 90% in the majority of cases. However, the patient needs to come for regular follow-up after surgery for the early management of complications if they arise. The most common cause of failure of corneal transplant procedure results from graft rejection which can be successfully managed if recognized early.
The cornea is a transparent dome-shaped structure covering the front of the eye. It consists of 5 layers, and a recently added 6th layer called Dua’s layer. The cornea is peculiar in that it does not have any blood supply and hence is the only structure of the eye that can be transplanted.
Traditionally, corneal transplants involved removing the full thickness of the affected person’s cornea, and replacing it with a healthy donor cornea.
With advances in techniques of surgery, now a single cornea can be divided into at least 2 parts – the front and back being used for different indications. This is called Lamellar Corneal Surgery. The biggest advantage of lamellar surgeries is that since only a part of the donor cornea is implanted, the chances of rejection are much lesser.
DSEK OR DESCEMET’S STRIPPING ENDOTHELIAL KERATOPLASTY
Involves replacing the affected endothelium of the patient with a healthy one from a donor cornea. The endothelium is the innermost layer of the cornea.
DALK OR DEEP ANTERIOR LAMELLAR KERATOPLASTY
Involves removing the outer or front layers of the damaged cornea and replacing them with corresponding healthy layers from the donor.
Depending on the extent of damage to the patients’ cornea and the level up to which the layers have been affected, any of the above procedures may be advised.