Your eye is a complex organ connected to your brain by the optic nerve. The optic nerve sends visual signals from the eye to the brain, where they are interpreted as images. The optic nerve is relatively small, varying in length between 1.3 and 2.2 inches, and at its widest point, inside your cranial cavity, it is still less than one-fifth of an inch wide. Yet the optic nerve is made up of more than one million tiny nerve fibers, much like a fiber optic cable. Once these nerve fibers are cut, they cannot be reconnected. That is why it’s impossible to transplant a whole eye. Even if a surgeon could implant the eye into the eye socket, the eye still would not be able to transmit signals to the brain through the optic nerve and thus would not provide sight.

CORNEAL TRANSPLANTS

Cornea transplants are the most common use of donated eye tissue. Each year, nearly 47,000 cornea transplants are performed to restore vision in people with corneal injuries or keratoconus. But it is important to remember that other parts of the eye are equally vital in the mission to save sight.

Corneal transplantation is more than a century old. A healthy, clear cornea is necessary for good vision. If your cornea is injured or affected by disease, it may become swollen or scarred. A cornea with scarring, swelling or an irregular shape can cause glare or blurred vision. In a corneal transplant, a surgeon removes the damaged or unhealthy cornea tissue. She puts a clear donor cornea in its place. There are several corneal transplant surgery options available, depending on the situation.

OTHER EYE-RELATED TRANSPLANTS

Amniotic membrane transplantation (AMT) has a well-established history. For problems affecting the sclera or the conjunctiva, doctors can transplant amniotic membranes. These membranes are taken from donated placental tissue and can be grafted on the surface of the eye as needed or used as a dressing or bandage of sorts. They can be temporary or permanent. These membranes help heal and regenerate surface tissues of the eye. Surgeons have also been able to successfully perform eyelash transplantation. This can restore eyelashes lost due to burns, injury and other medical conditions. Doctors continue to explore whether it is possible to transplant other parts of the eye. In July 2010, French doctors transplanted eyelids and tear ducts as part of a full-face transplant. Eyelids have been included in other face transplants in recent years as well.Today, researchers are replacing damaged retinal cells with healthy transplants. In clinical trials, researchers have used human stem cells to grow retinal pigment epithelium (RPE) cells. In the near future, we can expect RPE transplants. This is good news for people suffering from macular degeneration and Stargardt disease.