Corneal transplant: Replacement of a portion of the clear window on the front of the eye (cornea) with a healthy cornea. The procedure is typically done under local anesthesia in an outpatient setting. Transplantation of the cornea may be indicated in cases of severe scarring of the cornea by injury or infection (as with corneal ulcers) and in genetic disorders such as keratoconus (inherited corneal thinning with visual distortion) and Fuchs' dystrophy (inherited corneal clouding with visual loss). The very limited blood supply of the cornea greatly reduces the risk of transplant rejection. Corneal transplants generally function effectively for many years.