How you prepare

Before cornea transplant surgery, you will undergo:

• A thorough eye exam. Your eye doctor looks for conditions that might cause complications after surgery.
• Measurements of your eye. Your eye doctor determines what size donor cornea you need.
• A review of all medications and supplements you're taking. You may need to stop taking certain medications or supplements before or after your cornea transplant.
• Treatment for other eye problems. Unrelated eye problems, such as infection or inflammation, can reduce your chances of a successful cornea transplant. Your eye doctor will treat those problems before your surgery.

Finding a donor cornea

Corneas used in cornea transplants come from people who have died. Corneas are not used from people who died from unknown causes or from donors who had certain conditions, such as diseases that can spread, previous eye surgery or eye disease.

Unlike with organs such as livers and kidneys, people needing cornea transplants don't require tissue matching. In the United States, donor corneas are widely available so there's usually not a long waiting list.

Procedures to transplant a portion of the cornea

A cornea transplant removes either the entire thickness or partial thickness of the diseased cornea and replaces it with healthy donor tissue. Your cornea surgeon will decide which method to use. These types of procedures include:

• Penetrating keratoplasty (PK) a full-thickness�� cornea transplant. Your surgeon cuts through the entire thickness of the abnormal or diseased cornea to remove a small button-sized disk of corneal tissue. A special instrument is used to make this precise circular cut.

  The donor cornea, cut to fit, is placed in the opening. Your surgeon then uses stitches (sutures) to stitch the new cornea into place. The stitches might be removed at a later visit with your eye doctor.

• Endothelial keratoplasty (EK). These procedures remove diseased tissue from the back corneal layers, including the endothelium and a thin layer of tissue that protects the endothelium from injury and infection (Descemet membrane). Donor tissue replaces the removed tissue.

  There are two types of endothelial keratoplasty. The first type, called Descemet stripping endothelial keratoplasty (DSEK), uses donor tissue to replace about one-third of the cornea.

  The second type, called Descemet membrane endothelial keratoplasty (DMEK), uses a much thinner layer of donor tissue. The tissue used in DMEK is extremely thin and fragile. This procedure is more challenging than DSEK and is commonly used.

• Anterior lamellar keratoplasty (ALK). Two different methods remove diseased tissue from the front corneal layers, including the epithelium and the stroma, but leave the back endothelial layer in place.

  The depth of cornea damage determines the type of ALK procedure that's right for you. Superficial anterior lamellar keratoplasty (SALK) replaces only the front layers of your cornea, leaving the healthy stroma and endothelium intact. A deep anterior lamellar transplant (DALK) procedure is used when cornea damage extends deeper into the stroma. Healthy tissue from a donor is then attached (grafted) to replace the removed portion.

• Artificial cornea transplant (keratoprosthesis). In some cases, if people aren't eligible for a cornea transplant from a donor cornea, they might receive an artificial cornea (keratoprosthesis).

Your doctor will discuss which method of corneal transplant surgery is best for you, what to expect during the procedure and explain the risks of the procedure.