KERATOCONUS - Cornea Transplant

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
  

Recovery From a Cornea Transplant

The risks of complications vary depending on how many layers of the cornea are transplanted. Your body is less likely to reject the transplant if only the outer layers are used, compared to using all the layers or the deepest layer. Rejection happens in about 20% of cases overall.

Other problems can include:

• Bleeding (rare)
• Scarring
• Cataract formation, retinal detachment, and damage to other parts of the eye
• Leakage of fluid from the transplant incision
• Infection (rare)
• Vision problems. Full thickness transplants can heal with large amounts of astigmatism, nearsightedness and farsightedness, requiring thick lenses on eyeglasses or contact lenses.

In addition, some ailments that damage people's original cornea can also harm the new cornea. For example, there is the possibility of recurrence of herpes simplex infection in the transplant.

The cornea tends to heal slowly. To help protect your eye in the days after the surgery, your doctor may ask you to wear a protective shield over it.

You will need to use eyedrops for several months after the transplant. The stitches may remain in your eye for months or years. Your eye doctor can remove them in a simple procedure during an office visit.

Your vision may improve slowly after the surgery. It's important to avoid any possible trauma to your eye, such as from sports. This can damage your new cornea. You should report new irritation or any decrease in vision to your corneal surgeon. These may be signs that your body is rejecting the donor cornea.

Rejection may even occur years after the surgery. If you notice any of these signs that last for more than six hours, call your eye doctor promptly. The doctor can give you medicine that can help prevent as well as treat rejection.

Source: http://www.webmd.com/