Age-Related Macular Degeneration: Cause

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Cause

Vision loss from age-related macular degeneration (AMD) is caused by damage to the light-detecting nerve cells in the macula. The cause of this damage to the nerve cells is unknown.

Dry AMD

In dry AMD, cells in the macula break down, resulting in vision problems. No one knows why some people get AMD but others do not. In the early stages of dry AMD, a type of debris called drusen, which comes from cells, builds up in the area under and around the macula. When viewed with ophthalmoscopy, which is a way of seeing inside the eye, drusen appear as yellowish white spots under the retina. Although some small drusen can usually be found in the macula as a normal result of aging, the development of numerous large drusen is associated with AMD.²

Wet AMD

Wet AMD is caused by the growth of abnormal blood vessels under the macula. Experts are still studying why this happens. The blood vessels break easily and leak blood and fluid under the macula. The excess blood and fluid, along with abnormal scar tissue that forms under the macula, distort and damage the macula.

Last updated:	August 13, 2007
Author:	Robin Parks, MS
Reviewed By:	Kathleen Romito, MD - Family Medicine, Carol L. Karp, MD - Ophthalmology
Editors:	Kathleen M. Ariss, MS, Pat Truman, MATC