Macular Degeneration (Atrophic or Exudative)

Macular degeneration entails gradual destruction of the macula, the tissue that makes up the central portion of the retina. It generally strikes the elderly, and among older Americans, it is one of the most common causes of legal blindness.

Researchers believe that a hereditary predisposition is involved, but the precise cause of the condition is unknown. Typically, both eyes will be affected -- either at the same time or sequentially. Because the disorder tends to develop very slowly and is painless, a person may not realize that there is a problem until considerable vision has been lost.

There are two types of the disease. In the most common form, known as exudative (wet) macular degeneration, small blood vessels grow abnormally in the macular region beneath the retina. As these blood vessels become narrowed and hardened, the blood supply to the macula is impaired. If these vessels leak blood, the retinal cells in the macula can be damaged, resulting in blurred and distorted central vision.

The second type, atrophic (dry) macular degeneration, is caused by a disturbance of pigment cells in the macular region, without the hemorrhaging that occurs in the wet type.

Both types lead to increasingly impaired central vision. Initially, a person may notice difficulty in reading or in seeing distant objects such as street signs. If both eyes are affected, any activities that require sharp central vision eventually become impossible.

Diagnostic Studies and Procedures

Macular degeneration can be detected easily by an ophthalmologist (eye specialist) as part of a regular examination with an ophthalmoscope. This instrument has a bright light and a magnifying device that allows a doctor to view the inside of the eyes. By focusing on the macula, the doctor can detect any abnormalities in the pigment, as well as pinpoint small areas of bleeding and scarring. With another procedure called fluorescein angiography -- a special X-ray study of the blood vessels in the retina -- a doctor can also detect an overgrowth of blood vessels.

Medical Treatments

Until recently, little could be done to treat macular degeneration. Now, laser surgery has brought dramatic advances in treating the exudative type, but to prevent vision loss, therapy must begin early in the course of the disease, preferably even before symptoms occur.

To seal off newly formed abnormal blood vessels, doctors use a technique called laser photocoagulation. They focus the laser, a very narrow beam of extremely intense light, on the retina, where it makes a tiny circular burn that blocks the blood vessels crossing that area. Depending on the number of abnormal blood vessels, a doctor may make dozens or even hundreds of such minute bums on the retina. Drops are inserted into the eye to prevent movement during the procedure, but it is entirely painless. The patient remains conscious, and will see a bright flash of light with each burn.

Alternative Therapies

There are no alternative therapies that can restore vision lost to macular degeneration, but research indicates that zinc may help prevent the disease or slow its progress. Some nutritionists also recommend extra vitamin C for the same purpose.

Self-Treatment

If you have been diagnosed with the exudative, or wet, form of macular degeneration, you should check your vision daily for any further deterioration. To do this, your ophthalmologist will give you a card that is imprinted with the Amsler grid. Even if you have normal vision, the periodic use of an Amsler grid can detect some early signs of vision loss.

During the early stages of macular degeneration, magnifying glasses may be prescribed to help you read. Even if vision deteriorates markedly, special eyeglasses and other devices can significantly improve the quality of life.

Contact your local association for the blind for information on counseling and training to adapt to impaired vision. People who lose their central vision completely can be helped by retraining their eyes to more fully use their side vision. This should be taught by an occupational therapist who works with the visually impaired.

Other Causes of Vision Loss

Poorly controlled diabetes can cause a loss of vision due to an overgrowth of blood vessels in the retina, a condition called diabetic retinopathy. Vision loss similar to that of macular degeneration can result from a detached retina, although the onset will be sudden.