Macular degeneration, also known as age-related macular degeneration or AMD, is an eye disease that affects the macula, the part of the retina responsible for central vision. In many cases AMD develops slowly. In others the disease progresses rapidly and may lead to loss of vision in one or both eyes. AMD is the leading cause of vision loss in Americans over the age of 60.
Causes
The cause of age-related macular degeneration is unknown, although age, family history and environmental factors may explain why some older adults develop AMD and others do not. While it is likely that genetics and lifestyle contribute to the disease, a heightened immune response and resultant inflammation associated with most age-related diseases may be involved.
Types
The two categories of age-related macular degeneration are wet and dry. Dry AMD results when light-sensitive cells in the macula break down, and gradually blur central vision in the affected eye. Wet AMD occurs when abnormal blood vessels leak blood or fluid beneath the macula. All forms of macular degeneration begin as the dry form, but as the disease progresses, it may develop into the wet form at any time. Wet AMD is an advanced form and the major cause of blindness.
Risk Factors
Age is the greatest risk factor for macular degeneration. Research published in the January 2010 issue of the "American Journal of Ophthalmology" found that smoking in the older population is the second-most-identified risk factor for developing AMD. Studies of risk factors due to alcohol use are mixed, although smokers who consumed alcohol 30 days prior to the study were 60 percent more likely to develop AMD than those who did not drink. Lutein and Zeaxanthin, nutrients found in green leafy vegetables, and vitamins C and E are associated with reducing the risk of developing several eye diseases, including macular degeneration.
Diagnosis
A change in vision is often the first sign of macular degeneration. When straight lines appear wavy, wet AMD is suspected. Dry AMD may cause a blurry spot in the center of vision, making it difficult to recognize faces. A comprehensive medical examination of the retina and optic nerve detects both types of AMD.
Treatment
Treatment of AMD may slow progression of vision loss, but the disease is not curable. In a small percentage of wet MD patients, laser surgery is used to destroy the leaky blood vessels. Verteporfin, a type of photodynamic therapy, is sometimes prescribed to slow vision loss. New drugs injected into the eye slow the growth of abnormal blood vessels and may slow or improve vision loss. The Age-related Eye Disease Study sponsored by the National Eye Institute found supplementation with antioxidants and zinc significantly reduced progression of vision loss associated with advanced age-related macular degeneration.
