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Age-Related Macular Degeneration
Age-related macular degeneration (AMD or ARMD) is a disease associated with aging that causes vision loss in the center of your vision. The disease affects the center of the retina called the macula. The retina is the light sensitive tissue which lines the back of the eye like the film in the back of a camera. The macula is used for fine central vision such as reading, recognizing faces, and recognizing colors. Any damage to the macula may have a profound effect on one’s central vision and daily functioning.
In many cases, AMD advances so slowly that people notice little or no change in their vision. In others, the disease progresses faster and may lead to a significant loss of central vision in both eyes. AMD is a leading cause of vision loss in Americans 60 years of age and older.
Macular degeneration occurs in two forms, “dry” and “wet.” Dry macular degeneration is by far the more common (85-90% of all instances) and is typically the milder form of the disease. It is caused by a build-up of waste products under the macula which damage the cells of the macula. As dry AMD gets worse, you may see a blurred or distorted area in the center of your vision. Dry AMD typically does not result in severe central vision loss, but can in some cases.
A small percentage of patients with dry AMD will progress to develop wet AMD. In this form, there is a growth of abnormal blood vessels underneath the macula. These vessels can quickly leak fluid or blood underneath the macula resulting in scar tissue and leaving permanent blind spots if left untreated.
Macular degeneration almost NEVER totally blinds a patient. Typically, peripheral or side vision remains unaffected. Nonetheless, the effect on a person’s lifestyle from damages to central vision can be very troubling and can limit the ability to read or drive or recognize faces.
The cause or causes of macular degeneration is unknown. Research has shown several risk factors for macular degeneration:
There is definitely a hereditary pattern in some families, although we often see AMD in some patients with no family history. Current research is investigating multiple genes and genetic markers which may places some patients at higher risk.
People who smoke have a higher risk of developing significant macular degeneration. We encourage and strongly recommend smoking cessation.
A strong association seems to be a lack of certain nutritional factors, particularly anti-oxidants (e.g. Vitamin E, beta-carotene, Vitamin C) and minerals (zinc and copper). Other research has suggested the benefit of certain other nutrition supplements such as lutein, zeaxanthine, and omega 3 fatty acids.
Some feel that ultraviolet light (sunlight) exposure may play some role in damaging the retina.
Much more work remains to be done to fully understand this disease.
Examination and Testing
Sometimes, early vision changes can be subtle. This effect may be most noticed on a grid pattern, such as tiles or windowpanes. Your eye doctor may provide you with a small paper chart that has crossed lines printed on it called an Amsler Grid. This grid can be used at home so that you may test yourself to find early changes. If you notice any sudden change in your vision, especially distortion, you should contact your eye doctor immediately. You can go here to download an Amsler Grid.
In order to diagnose AMD, your eye doctor will need to perform a dilated examination of the retina. Sometimes it is an easy matter to determine the extent of macular degeneration by simply looking at the retina. Those patients with early stages of the disease may require regular visits to the eye doctor to monitor any progression. In some patients, further testing is required. The most common test is scanning a cross section of the retina with laser light, called Optical Coherence Tomography (OCT). This quick and painless test can help to distinguish between the dry and wet type of the disease. Less commonly, a series of special photographs following an injection of dye into a vein in the arm called a fluorescein angiogram can be helpful.
Treatment of Macular Degeneration
A major national trial called the Age Related Eye Disorder Study (AREDS), sponsored by the National Institutes of Health and National Eye Institute, showed that a combination of high dose vitamins and minerals (Beta-carotene, Vitamin C, Vitamin E, Copper and Zinc) slowed down the progression of dry AMD in those patients who already have moderate AMD. The therapeutic dosage for these supplements is very high, there are potential side effects, and not everyone will benefit from this regimen. You and your eye doctor should discuss if these vitamins are right for you; nonetheless, we recommend a healthy diet with green leafy vegetables in everyone when possible.
A second phase to this study is underway (AREDS2) which is testing other supplements (lutein, zeaxanthine, and Omega 3 fatty acids); however, the results are not yet known.
The most exciting and effective treatment of wet AMD are the new biologic therapies. These drugs are administered by intra-ocular injection and work by blocking vascular growth factors (Vascular Endothelial Growth Factor or VEGF). Over the past five years a series of these drugs have provided a significant improvement in the visual outcomes in wet AMD. The two most commonly used drugs currently are Lucentis and Avastin. A recent study (the Comparison of AMD Treatments Trials or “CATT”) showed both of these two drugs stabilizing vision in over 90% of patients, and over 30% of patients experienced significant improvement in vision. Another drug named Eylea was recently approved for use in wet AMD and shows similar visual results.
These drugs offer much more hope for patients with wet AMD than we were able to provide in the recent past. However, they require monthly visits to a retina doctor and frequent injections into the eye. There are multiple new exciting treatments under investigation, and we are very hopeful the recent progress of new treatment options will continue.
Living with AMD
AMD is a very frustrating disease. Although it is not always possible to prevent vision loss in some patients with AMD, one can still have a productive life. Vision aids are available to enable people with AMD to better utilize their remaining vision. These aids and devices are varied and may involve the use of magnifying lenses or glasses, small telescopes, large print books and large print appliances, closed circuit TV enlargers, electronic devices, computer software etc. If your vision is poor due to macular degeneration, you should discuss with your doctor getting a referral to a vision rehabilitation specialist. This is a team of doctors and therapists who can work with you to help you get the most out of your remaining sight.
Age Related Macular Degeneration is the most common cause of vision loss in people over 60. There are effective prevention strategies and new treatments for the severe wet type of the disease. We recommend a healthy diet and lifestyle and regular, comprehensive eye exams to screen for this and other eye diseases.