During a cornea transplant, an eye surgeon removes a portion of your cornea and replaces it with a new section of cornea from a donor.
The procedure is also called a corneal transplant or a keratoplasty. About 40,000 cornea transplants are performed in the U.S. every year.
You may need a cornea transplant if your cornea no longer lets light enter your eye properly because of scarring or disease.
Role of a Healthy Cornea
Your cornea is a clear tissue that covers the front of each eye. Light entering your eye first passes through the cornea, then your pupil (the dark spot at the center of the colored iris), and then your lens.
The cornea must remain clear for you to see properly. However, a number of problems can damage the cornea, affecting your vision. These include:
- Corneal scarring from trauma and infection.
Keratoconus. A degenerative condition in which the cornea becomes thin and misshapen.
- Inherited corneal conditions (dystrophies) like Fuchs' dystrophy, Lattice dystrophy, and others.
Types of Cornea Transplants
The cornea contains five layers. Cornea transplants don't always transfer all the layers.
Types of cornea transplants include:
Penetrating (full thickness) cornea transplant. This involves transplanting all the layers of the cornea from the donor.
Lamellar cornea transplant. During this procedure, the surgeon only replaces some of the layers of the cornea with the transplant.
In a lamellar cornea transplant, selected layers are transplanted, which can include the deepest layer, called the endothelium (posterior lamellar cornea transplant). A commonly performed version of this procedure is the Descemet's Stripping Automated Endothelial Keratoplasty (DSAEK).
Or it can include layers closer to the surface (anterior lamellar cornea transplant).
Lamellar transplants may be more appropriate than full penetrating transplants when the disease process is limited to only a portion of the cornea.
How Full Thickness Cornea Transplants Are Performed
The surgery can be done using local anesthesia. This uses medication to numb the eye and stop it from moving. The patient stays awake although sedated during the surgery.
Another option is general anesthesia. In this case, the patient is put to sleep for the procedure.
The surgeon uses a special cutting instrument called a trephine, which works like a cookie cutter. It removes a round section of damaged cornea from the front of your eye.
The same process is used to remove a similar-sized circle of cornea from the donor's eye. The surgeon places the new section of cornea onto your eye. Then he or she sews it into place using ultra-thin stitches with the help of a microscope.
Success Rates of Cornea Transplants
Experts know more about the long-term success rates of penetrating cornea transplants, which use all the layers of the cornea.
Success rates are also affected by the problem that needed to be fixed with the transplant. For example, research has found that the new cornea lasts for at least 10 years in:
- 89% of people with keratoconus
- 73% of people with Fuchs' dystrophy
- 60% to 70% of people with corneal scarring