Age-related Macular Degeneration (AMD)

The macula is the central area of the retina and is responsible for detail vision. As opposed to RP, macular degeneration (MD) affects the center of the retina first, while peripheral vision remains largely intact; as a result, general orientation is still possible. Macular degeneration (MD) usually occurs in people over the age of 70; in this group it is known as age-related macular degeneration (AMD).

There are two types of age-related macular degeneration: dry (atrophic) and wet (neovascular) MD. In dry MD, which is the more common form, drusen deposits accumulate in the retinal pigment epithelium. These deposits can cause progressive degeneration of the central retina which in turn leads to a loss of central vision. Initially, the patient may recognize a gradual blurring of central vision or a grayish spot in the center of the visual field that gradually increases. Sometimes the dry form of MD develops into wet MD, which is characterized by abnormal blood vessel growth underneath the macula with blood and fluid leaking into the macula and damaging photoreceptor cells. The resulting warp of the retina can make straight lines appear distorted. AMD can be detected using the Amsler grid (see below): one eye is covered while the other eye focuses on the black dot in the center of the grid. AMD patients will perceive blank, dark or distorted areas on the grid.

Macular degeneration is the single most important cause of legal blindness in people over 55 years of age. It affects about 6% of people aged 65-74 and 20% of those between the ages of 75 and 84. While some of the juvenile forms of macular degeneration (e.g. Best's disease, Stargardt's disease and inverse RP) are inherited, the causes of age-related macular degeneration (AMD) are still largely unknown.

You can find useful information on how to cope with AMD on the website of the international patient organization AMD Alliance www.amdalliance.org.

The website of the Foundation Fighting Blindness www.fightingblindness.org also offers comprehensive information on AMD and other degenerative diseases of the retina.