The cornea is the clear covering of the front of the eye which bends, or refracts, light rays as they enter the eye. For clear vision to occur, the cornea must have the correct shape and clarity to focus incoming light rays precisely on the retina at the back of the eye. When the cornea becomes cloudy or misshapen from injury, infection or disease, transplantation may be recommended to replace it.

Corneal transplantation, or keratoplasty, involves replacing the damaged cornea with a healthy one from a donor (usually through an eye bank). Keratoplasty is a low-risk procedure - it is the most common type of transplant surgery and has the highest success rate.

During the procedure, a circular incision is made in the cornea. A disc of tissue is removed and replaced with healthy tissue. The disc may be thin ("lamellar keratoplasty") or as deep as the entire cornea ("penetrating keratoplasty," the technique used in almost all corneal transplants). Local or general anesthesia may be used. The entire procedure lasts only 30-90 minutes.