Obtaining Donor Corneas

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When a doctor and his patient decide that it is time for a corneal transplant, the patient is placed on a waiting list. The waiting list is controlled by an “eye bank” that is responsible for storing and distributing corneal grafts.

When a donor becomes available, a skilled surgeon will harvest the cadaver’s corneas. The process that involves removing the corneas is called an “In Situ Corneal Excision.” During this twenty- thirty minute procedure, the cornea and the white part of the eyes called the sclera are excised from the whole eye of the cadaver.

  Contrary to many other organ grafts such as kidney and heart grafts, the sense of urgency in harvesting and placing cornea grafts is not extremely important. While other organs must be harvested and placed into a recipient within matters of minutes or hours, corneas may be harvested within twenty four hours of death from a cadaver, and may be stored for up to a month in an eye bank before going into a recipient. There are three possibilities of storage for corneal grafts in the eye bank. The first method consists of storing the whole eye at 4°C which lasts only forty eight hours. The second method of storage includes the graft as a corneoscleral disc in a chondroitin sulphate-based medium at 4°C and lasts for at most fourteen days.
Donated Corneas  
The final, and longest method of storage at eye banks is keeping the graft in a tissue culture as a corneoscleral disc at 37°C and can last for over a month. These storage methods promote great advantages for cornea transplants in contrast to other, more urgent grafts. This lengthened storage period allows for testing of the donor grafts for certain harmful diseases, and also allows a convenient surgery schedule for the doctor and the recipient.

Cornea grafts can come from almost anybody who is an organ donor. People who wear glasses, have diabetes, or have high blood pressure are all acceptable donors. Even people with cataracts are able to donate corneas because cataracts affect the lens of the eye not the cornea.

When the bank receives the graft, they test the grafts for harmful diseases, rate the grafts based on condition and clarity, and compile a detailed social history of the tissue donor. The bank then matches up a donor cornea and a recipient and sends the information to the doctor to review. If the doctor finds the graft acceptable, the surgery is scheduled. The cornea is delivered to the hospital where the doctor then transplants the cornea into the recipient.