Macular degeneration is a degenerative disease affecting the macula or center of the retina of the eye. It results in progressive loss of central vision. Occurring most often among older people, it is the most common cause of vision loss in people over age 55. It is believed that both genetic and environmental factors influence this disease.
The development of this disease is usually gradual. The first sign may be a need for more light when reading or doing close work.
There are two types of macular degeneration: dry and wet. In most cases, the disease starts out as dry macular degeneration. Wet macular degeneration refers to leaking of fluid or blood from blood vessels under the macula.
Symptoms of dry macular degeneration may include a need for greater illumination when reading, difficulty recognizing faces, blurriness of printed words, and difficulty adjusting to dim lighting such as in restaurants.
Symptoms of wet macular degeneration may include loss of central vision and visual distortion. For instance, a straight line may appear wavy or a small object may seem to be farther away than it really is.
In either the wet or dry forms of the disease, one eye may seem to be affected while the other remains unaffected for a period of time. During that time, the healthier eye may compensate for the affected eye. However, in most cases, if one eye is affected the other eye will develop macular degeneration in time, too.
Macular degeneration doesn’t cause total blindness. Peripheral vision may not be affected, but central vision, which is used for activities such as reading, watching television, and doing close work, is.
The retina is a thin lining of nerve tissue on the inside back wall of the eye. The macula is the center of the retina. It is the part of our vision process that makes possible recognizing faces, reading, and driving a car.
Light-sensing cells in the macula known as photoreceptors convert light into electrical impulses that are sent to the brain. When those photoreceptor cells degenerate, central vision loss occurs.
Early-onset forms of macular degeneration are genetic. Age-related macular degeneration is believed to be influenced by both genetic and environmental factors.
Although the exact cause of macular degeneration is now known, the following are considered risk factors for this disease: age (60 years or older), family history of the disease, obesity, cigarette smoking, and having light-colored eyes.
Macular degeneration affects both males and females, although women appear to be more frequently affected by severe vision loss, perhaps because they live longer. It is the leading cause of blindness in adults over 55. Wet macular degeneration is the most severe form of the disease.
The U.S. Food and Drug Administration (FDA) has approved (April 2000) verteporfin (Visudyne), a type of photodynamic therapy, for treatment of the wet form of age-related macular degeneration. This is the first FDA approved treatment for wet macular degeneration. Photodynamic therapy involves the use of a light-activating drug in combination with a "cool" laser to destroy abnormal blood vessels with minimal damage to surrounding healthy tissue. Visudyne therapy cannot restore lost vision, but prevents further loss. Therefore, early diagnosis through regular ophthalmic examination is important.
Macugen, a drug that works by blocking vascular endothelial growth factor, a protein that promotes blood vessel growth, received approval from the FDA in 2005 for the treatment of wet (neovascular) age-related macular degeneration. The web form of macular degeneration is caused by the abnormal growth of fragile blood vessels in the retina that leak blood and cause damage to the light-sensitive photoreceptor cells. For information on Macugen, contact the American Health Assistance Foundation, a sponsor of research on age-related and degenerative diseases, at www.ahaf.org or (tollfree) 800-437-AHAF. Macugen is manufactured by Eyetech Pharmaceuticals, Inc., 3 Times Square, New York, NY, 10036; telephone: (212) 824-3400; www.eyetech.com.
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Online Mendelian Inheritance in Man (OMIM).Victor A. McKusick, Editor; Johns Hopkins University, Last Edit Date 6/26/97, Entry Number 248200.
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