Macular degeneration is the leading cause of blindness in people over 55 in the United States. It affects more than 10 million Americans. The retina at the back of your eye receives light rays that have passed through the lens of this eye. Your retina's millions of cells then translate those light rays into images that it sends to your brain through the optic nerve. The macula is near the center of the retina and is the site of your most acute visual perception. It is used when you drive, see faces, read and do fine detail work.
Macular degeneration is associated with aging. It is present in equal numbers in men and women; whites are more affected than blacks. Smoking has been identified as a risk factor in the development of macular degeneration. Two major forms of macular degeneration have been identified. They are the atrophic or "dry" form and the exudative or "wet" form.
Between 85 and 90% of the cases of macular degeneration diagnosed are of the dry type. Small yellow deposits of a material called “drusen” form under the macula. This causes the macula to thin and dry out. Dry macular degeneration can sometimes deteriorate into the wet form.
Only 10 to 15% of cases of macular degeneration are of the wet or exudative type. In this form, abnormal blood vessels grow under the macula in a process called retinal or choroidal neovascularization. These abnormal vessels can bleed (intraretinal hemorrhage) or leak fluid under the retina. This can leave scars and can elevate the macula, which distorts vision.
At this time, there are no curative treatments for macular degeneration. The wet form can be treated with laser photocoagulation, which seals off the leaking blood vessels. Unfortunately, this treatment is not effective for everyone. It can slow the rate at which vision is lost, but it cannot prevent a recurrence.
Photodynamic therapy is a refinement of laser treatment. After infusion of a light-sensitive chemical, a laser focused on the abnormal vessels formed in macular degeneration is much more precise in its ability to cauterize those vessels, reducing the damage to surrounding retinal tissues that can occur with conventional laser treatment.
Very new surgical treatments to relocate retinal tissue away from the areas of damage are showing some promise. Still in the experimental phase, is the insertion of tiny prostheses into the retina that can stimulate the brain into producing visual images, taking over the function of the damaged eye tissue.
Nutritional treatments are touted for macular degeneration. Because zinc is present in high concentrations in the eye, and because many older people have low blood levels of zinc, some practitioners recommend zinc supplements for macular degeneration. In addition, because research has shown that oxidative damage is involved in the deterioration of the eyes in macular degeneration, some people advocate the use of antioxidants. In October 2001, a clinical trial from the Age-Related Eye Disease Study published in the Archives of Ophthalmology showed that persons 55 and older with moderate symptoms of age-related macular degeneration can reduce their risk of developing advanced macular degeneration by taking supplementary vitamins C and E, beta carotene, and zinc.
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