In a corneal transplant, or keratoplasty, healthy corneal tissue from a human donor replaces a damaged part of the cornea. Corneal transplants help restore corneal clarity lost through injury, inflammation, ulceration, or chemical burns. They may also correct corneal dystrophies such as keratoconus, the abnormal thinning and bulging of the central portion of the cornea.

A corneal transplant can take one of two forms: a full-thickness penetrating keratoplasty, involving excision and replacement of the entire cornea, or a lamellar keratoplasty, which removes and replaces a superficial layer of corneal tissue. The full-thickness procedure, the more common of the two, produces a high degree of clarity and restores vision in 95% of patients.

A lamellar transplant is used if damage is limited to the anterior stroma or if the patient is uncooperative and may be expected to exert pressure on the eye after surgery. The degree of clarity produced by a lamellar transplant rarely matches that of a full-thickness graft. As a treatment for dystrophies, its success depends on the type and extent of the abnormality.

Because the cornea is avascular and doesn’t recover as rapidly as other parts of the body, healing may take up to a year. Usually, sutures remain in place and vision isn’t completely functional until healing is complete.