The cornea is the eye’s outermost layer. It is clear and dome shaped and covers the front of the eye. It helps with focusing of the vision, along with the lens, on the retina so that the things we look at are clearly visible.
A corneal transplant serves to replace diseased or scarred corneas with a new, healthy one from a tissue donor.
Approximately 40,000 corneal transplants are performed every year in the United States, according to the National Eye Institute (NEI). This procedure, also known as keratoplasty, is performed when a diseased cornea is removed and replaced with a healthy one.
There are essentially two types of keratoplasties –
- Penetrating keratoplasty (PK) is the traditional procedure that replaces the entire thickness of the cornea during the transplant procedure.
- Endothelial keratoplasty (EK), when the inner layer of the cornea is replaced with a healthy one in certain medical conditions when the inner layer is diseased and is not functioning well.
This procedure can usually be performed under either local or general anesthesia. After measuring the affected corneal area, a circular, button-shaped, full-thickness section of tissue is removed and replaced with a matching button from the donor tissue and sutured in place. Traditional PK surgeries could take upto two hours to perform and are usually done on an outpatient basis. A protective shield covers the eye during the healing process
Almost anyone can be a cornea donor today. Approximately 75 % of donated corneas come from persons between 34 and 70 years old, with one third coming from people aged 61 to 70. Success rates of 75 % after 10 years has been shown for these donor corneas after they are transplanted.