Age-Related Macular Degeneration
What Happens
Dry AMD
With dry age-related macular degeneration (dry AMD), vision gradually becomes worse over the years. As the cells and blood vessels beneath the macula age, they begin to thin and break down. When these cells and blood vessels stop working, the nerve cells in the macula that detect light cannot function properly. As more and more of the nerve cells in the macula break down, vision loss very slowly gets worse. At present, there is no treatment to prevent this vision loss. But a diet rich in zinc and antioxidant vitamins may slow the progression of vision loss.
Vision loss from dry AMD is often slow and gradual, allowing you to make adjustments over time. A small percentage of people who have dry AMD develop the abnormal blood vessels that lead to wet AMD.
The impact AMD has on your life will depend on the severity of your vision loss and your lifestyle. Even though AMD may affect central vision, it does not cause complete blindness, and most people keep good side (peripheral) vision. For information on adapting to reduced vision, see the Home Treatment section of this topic.
Wet AMD
With wet age-related macular degeneration (wet AMD), vision can suddenly become worse. Wet AMD begins with the growth of abnormal blood vessels under the macula, which is the part of the eye that is responsible for central vision. These blood vessels break easily. They leak blood and fluid and cause scar tissue, all of which push against the macula. They change the macula's shape and cause it to send distorted images to your brain. Straight lines begin to appear wavy or curved, and objects may seem oddly shaped or smaller.
Scar tissue also cuts off the macula from the normal support cells that it needs in order to work. Nerve cells in the macula begin to die, causing a loss of central vision.
When the nerve cell damage is contained in a small area, it causes a blank spot to develop in your field of vision. As this area expands, the blank spot also gets larger.
If not treated, the scar beneath the macula may continue to grow, affecting more and more of the nerve cells in the macula. Vision loss gets worse as more of the macula becomes involved. The entire macula may be destroyed by this process, resulting in a complete loss of central vision.
Treatment can sometimes delay or prevent further vision loss, but it cannot reverse vision loss that has already occurred. Normal use of the eyes (such as for reading or watching television) will not speed up vision loss or make the condition worse. Loss of vision from wet AMD may progress rapidly. This does not allow much time for those affected to adjust to the vision loss and find ways to live with it.
For information on adapting to reduced vision, see the Home Treatment section of this topic.
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| Author: | Alison Allen Robin Parks, MS | Last Updated: October 8, 2007 |
| Medical Review: | Kathleen Romito, MD - Family Medicine Carol L. Karp, MD - Ophthalmology Donald Sproule, MD, CM, CCFP, FCFP - Family Medicine | |
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