Macular Degeneration

Macular degeneration is a chronic eye disease that affects the eye's central vision. It is associated with aging, and most often develops slowly and gradually. Millions of Americans are affected by macular degeneration.

The macula is the central portion of the retina and is the area where the most acute vision occurs. It is the area that makes reading fine print and seeing small object possible. In macular degeneration, the cells in the macula gradually cease to function, causing a person's central vision to become fuzzier and eventually making it impossible to read, drive or do close-up work. It can affect one or both eyes.

Age-related macular degeneration (AMD) appears in one of two forms: dry or wet. Both forms of AMD eventually result in loss of central vision. Most people with AMD retain their peripheral vision.

Dry AMD makes up about 90 percent of all cases of this eye disease. This form advances so slowly that a person may not notice any vision problems for years. Symptoms include the need for more light for reading or other close work; difficulty identifying faces; more difficulty adjusting to dimmer levels of light, such as when entering a darkened movie theater.

The wet form of AMD progresses rapidly. It initially causes straight lines to appear wavy. This is because blood vessels leak blood into the macula, distorting vision.

Causes

People ages 60 and older are at greatest risk for AMD. Women are more likely than men to develop AMD. Other risk factors include race (whites are more likely to develop AMD than African Americans), smoking, high cholesterol levels, light-colored eyes and having an immediate family member with AMD.

Although the cause of AMD is not known, genes and environmental factors both may play a role.

Diagnosis

An eye doctor can diagnose AMD with several tests. The doctor will check how well you can see at various distances, and also dilate your eyes to examine your retina directly by using a slit lamp. He or she may use an Amsler grid, which looks something like a checkerboard. If some of the straight lines of the grid seem distorted or broken, it may indicate you have AMD. If wet AMD is suspected, your doctor may order a test called fluorescein angiography, which helps determine if leaking blood vessels in the macula can be treated.

Treatment

There is no cure for AMD, and currently no treatment for dry AMD. Dry AMD develops so slowly, however, that many people are able to continue with a normal, active life for years.

Some cases of wet AMD can be treated with laser surgery or medication. Laser photocoagulation with a laser is used to seal leaking blood vessels. Two drugs have been approved to slow or block the growth of new blood vessels, thus preserving sight. Both are injected into the vitreous, the jelly-like substance in the back chamber of the eye. Pegaptanib (Macugen) is a drug that is injected every six weeks; ranibizumab (Lucentis) is injected monthly. Both drugs belong to a class of drugs that block a substance called vascular endothelial growth factor (VEGF) and stop the formation of new blood vessels and the leakage of blood.

The drug bevacizumab (Avastin), another VEGF, was originally approved to treat colorectal cancer, but it also appears to reduce leakage from abnormal blood vessels in the retina. This drug has not yet been approved for use in macular degeneration. Many other drugs are being studied.

Note that AMD is also sometimes referred to as age-related maculopathy (ARM).

What to Do

See your doctor if you notice any changes in your vision.

Self-care Steps for Macular Degeneration

• Get regular eye exams, particularly if you are 40 or older. If you have dry AMD, get a checkup at least once a year.

• Wear sunglasses that offer 100 percent protection against ultraviolet light and blue light.

• Eat low-fat, healthy meals that include five to 13 servings of fruits and vegetables, particularly green, leafy vegetables. (One serving is equal to 1/2 cup of chopped raw or cooked vegetables, or 1 cup of leafy raw vegetables.)

• Don't smoke.