Macular Degeneration
Reviewed by Michael Fu, OD
What is Macular Degeneration?
Age related macular degeneration (AMD) is a disease that affects the macula, a part of the retina that allows you to see straight ahead and in fine detail. AMD is the most common cause of blindness because its main risk factor is age. Other risk factors include people who smoke, people who have bad eating habits and are obese, people of white race, family history of AMD, and women have greater risk of developing AMD.
Forms of Age Related Macular Degeneration, including Drusens
Dry AMD, the most common type, occurs when light-sensitive cells in the macula degrade and central vision begins to slowly fade. Dry AMD has three stages. Early AMD, the first stage, has a presence of drusens, yellow deposits under the retina, but usually no vision loss or problem is detected. In Intermediate AMD, there are many medium sized drusens or large sized drusens present. In this stage, blurry areas may be present and it is more difficult to do regular task. In Advanced Dry AMD, the light-sensitive cells begin to degrade dramatically and a blurred spot may appear in the central of your vision. Atrophy may also be a factor in advanced stages. This spot may appear larger and become darker and it becomes almost impossible to see with clarity and detail. Dry AMD can evolve into Wet AMD.
Wet AMD is more severe and vision loss occurs more rapidly. In wet AMD, small, abnormal blood vessels form. These new blood vessels are very thin and fragile and will begin to break and leak. The blood and fluids eventually causes damage to the macula and causes rapid loss in vision. Although Wet AMD is less common, loss of vision occurs faster so it is essential to get it diagnosed as quickly as possible.
Macular Degeneration - Symptoms and Detection
Symptoms of Dry AMD include the presence of drusens that begin to enlarge. Another symptom is blurry areas in central vision. A symptom of Wet AMD is seeing straight lines as wavy ones.
A visual acuity test can help an eye care professional determine if any central vision is lost. An Amsler grid may also be used to detect AMD. In this test you cover one eye and stare at a black dot that has patterns of straight lines. If these lines appear wavy or are missing then AMD could be present.
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Treatment and Prevention of Macular Degeneration
There is no treatment to restore vision once AMD has reached its advanced stage. However there are methods to prevent the advancement of AMD from immediate stage to advanced stage. Taking a high-dose formulation of antioxidants and zinc slows progression of AMD significantly. According to the research done by the NEI "The specific daily amounts of antioxidants and zinc used by the study researchers were 500 milligrams of vitamin C, 400 International Units of vitamin E, 15 milligrams of beta-carotene (often labeled as equivalent to 25,000 International Units of vitamin A), 80 milligrams of zinc as zinc oxide, and two milligrams of copper as cupric oxide. Copper was added to the AREDS formulation containing zinc to prevent copper deficiency anemia, a condition associated with high levels of zinc intake." This high level of antioxidants is virtually impossible to achieve with daily diets or multi-vitamins.
Wet AMD is treated with laser surgery to destroy the new blood vessels before they cause any more damage. This process can also cause more vision loss as it damages nearby tissue. New blood vessels may for and more treatments may be needed. Another process called Photodynamic Therapy (PDT), which was approved by the FDA in April 2000, uses a special drug that is injected into the body. This drug attaches itself to the new blood vessels in the eye. A special laser is then focused on the eye which activates the drug and destroys the abnormal blood vessels in a painless manor. There maybe some after surgery precautions with this method so it is best to ask your eye care doctor about specific details.
Prevention of AMD includes lowering risk factors and eating healthy diets of antioxidants and zinc. Quit smoking and eating foods with Vitamins A, C and E could help reduce chances of developing AMD. Exercising and keeping healthy are always good preventive methods for all diseases. For more information on nutrition and eye care visit our eye care nutrition pages.
For more information on Age related Macular Degeneration (AMD) visit your eye care doctor or visit http://www.amdalliance.org/ or http://www.nei.nih.gov for more research. Materials on this page have been researched from the national Eye Institute.
[Page updated 12/2010]
