One eye donor can help not two persons without vision, but now, four people, thanks to techniques that exist to split each cornea into two layers, and skilled surgeons, to use these split layers on different patients. In a scenario where organ shortage is a reality, this also allows more corneas to be available for transplant.
Earlier, surgeons were using the entire donated cornea on the recipient’s eye, making the graft stay with sutures. However, with advanced equipment, each cornea is now being split into its anterior and posterior layers, and only the layer appropriate to the diseased part is being used. For instance, if the lower layer, endothelium, is damaged, only that layer can be replaced.
Dr. Prashant Garg, Consultant, Cornea and Anterior Segment Services, L.V. Prasad Eye Institute, Hyderabad, explains that the cornea has three zones — anterior, middle, deeper —each of them is affected by different classes of diseases. “Earlier, we were sacrificing healthy endothelial (posterior segment) cells when the disease was in the upper zones. We can now treat each zone separately. If the endothelium is healthy, we don’t have to sacrifice it anymore.”
The endothelium is key, says Bhaskar Srinivasan, consultant, Sankara Nethralaya. “The most common cause of graft (in corneal transplants) failure is endothelial rejection. So if the endothelium is healthy, we will prefer to keep it intact, merely replacing the other parts.” Additionally, there are more advantages too: smaller incisions, avoidance of seizures, and, thereby, complications, better recovery for patient. If the endothelium is unhealthy, it is removed and the anterior segment is retained.
Dr. Garg says L.V. Prasad Eye Institute has also started an eye bank to provide split cornea for surgeons across the country. Amar Agarwal, of Agarwal Eye Hospitals, says that the recovery time is quick. A 50-year-old patient, who recently received an endothelial keratoplasty (the posterior layer was replaced) could actually get back to work within a week. “This would be impossible in full corneal transplant, as it would take months,” he says. Additionally, it would take a skilled surgeon only 15 minutes to perform the procedure.
Not every one can benefit, Dr. Srinivasan explains. Currently, though the procedure was introduced in India around 2004, it still remains the surgeon’s decision to go in for part corneal transplant. Of the total number of transplant procedures, about 30 per cent are now endothelial keratoplasties.