Wednesday, November 28, 2007

Macular Degeneration

Age-related macular degeneration (AMD) is the leading cause of blindness in the United States among people over 65 years old. Damage to the central retina (macula) and underlying tissue causes loss of central vision. People with macular degeneration often fear that they will lose all vision and be completely blind. This does not happen. Most people continue to have useful vision because the peripheral or side vision is not affected.

Macular degeneration occurs in older people as part of the aging process. Other risk factors include a family history of AMD, smoking, farsightedness, light iris color, high blood pressure, and cardiovascular disease. There are two types of macular degeneration. The more common dry form is due to atrophy of the tissue in the macula, and causes gradual loss of vision. The rarer wet or exudative form refers to abnormal blood vessel growth, or neovascularization, under the macula. These new vessels are fragile and can leak fluid or blood into the macula causing a sudden, profound loss of vision.

The degree of visual changes can range from mild to severe. People with AMD experience different symptoms, and even in the same person, each eye can be affected differently. Initially the central vision becomes distorted and blurry, making close work like reading more difficult. Straight lines may look bent or wavy, and small blind spots may appear. In the late stages, the center of vision may be completely dark or missing.

An examination of the retina to inspect the macula is necessary to make the diagnosis of macular degeneration. The disease can often be detected before the vision is affected. Therefore, it’s a good idea to have routine eye exams to screen for this and other conditions that occur with aging, especially if there is a strong history in your family.

Once macular degeneration is diagnosed, observation with periodic retinal exams and self-testing by looking at a grid pattern (Amsler grid) are recommended. Nutritional supplements may be beneficial for individuals who already have mild degrees of dry AMD. Low vision devices such as magnifiers, special computers, and large-print books, aid in daily activities and help improve visual functioning.

There are also a number of new treatments for the wet form of macular degeneration depending upon the size and location of the abnormal blood vessels. Therefore, any sudden change in central vision should be promptly evaluated. Special pictures of the macula help identify the neovascularization, and the leaking vessels may be sealed with medication or laser. Macular degeneration cannot be cured, but treatment often slows the rate of visual loss. New treatments are being investigated, and there is hope that one day we will be able to cure this disease.
Resources: AMD.org
Photo courtesy of Duke Medicine.

1 comment:

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