The cornea is the most frequently transplanted part of the human body, and more than 95 percent of cornea transplants performed in the United States are successful.
What is a cornea and what is a corneal transplant?
The cornea is the front clear part of the eye that covers the iris, pupil and anterior chamber. Together with the lens, the cornea refracts light, accounting for approximately two-thirds of the eye’s total optical power. It imparts the greatest focusing power of all the ocular media. The cornea is composed of five distinguishable layers: epithelium, Bowman’s membrane, the stroma, Descemet’s membrane and the endothelium.
A corneal transplant, also known as corneal grafting, is a surgical procedure that replaces a damaged cornea with a donor cornea either in its entirety (penetrating keratoplasty) or in part (lamellar keratoplasty). If the cornea is injured, it may become swollen or scarred, and its smoothness and clarity may be lost. Scars, swelling or an irregular shape can cause the cornea to scatter or distort light, resulting in glare or blurred vision.
What happens before the transplant?
In most cases, the patient will consult with his or her ophthalmologist for an examination prior to the surgery. During the exam:
- The eye is examined and diagnosed
- Different treatment options, as well as the risks and benefits of these options, are discussed
- A physical examination and other lab tests, such as blood work and X-rays, may be performed
- A date, time and location will be set
The surgery only takes place when the very best corresponding donor tissue is found.
Before a donor cornea is released for transplant, the eye bank performs serological screening and ocular evaluation. Usually the wait for a donor cornea is short. Most eye banks are able to provide tissue for transplant surgery scheduled in advance for a specific day.
What can you expect from the transplant?
This is a painless procedure and is often an outpatient surgery. The patient is given a brief physical examination and is then taken to the operating room. Once inside the operating room, the patient is given either general anesthesia or local anesthesia and a sedative. The ophthalmologist carefully removes the damaged or diseased cornea. The donor cornea is then brought into the surgical field and maneuvered into place with forceps, and the clear donor cornea is sewn into place. When the operation is over, the ophthalmologist will usually place a shield over the eye that has just received the transplanted cornea. Because there are no blood vessels in the cornea, rejection of the new cornea is very rare.
Why would you need a transplant?
People need transplants for many reasons. Some infants are born with congenital birth defects. Other people suffer blunt injuries, burns or infections of the eye that damage one or both corneas. Most people suffer from a variety of ocular diseases that affect the corneas. A disease may cause the cornea to become clouded and distorted in shape. When the cornea is clouded, no light can pass through and blindness sets in.
A corneal transplant is needed if:
- Vision cannot be corrected satisfactorily with eyeglasses or contact lenses
- Painful swelling cannot be relieved by medications or special contact lenses
- What could have caused the need for a transplant?
- Corneal failure after other eye surgery, such as cataract surgery
- Keratoconus, a steep curving of the cornea
- Hereditary corneal failure, such as Fuchs’ dystrophy
- Scarring after infections, especially after herpes
- Rejection after a first corneal transplant
- Scarring after injury