Feature Archive

Tracking a Vision Thief

Science still searches for the cause of sight-robbing AMD.

WebMD Feature At first, the only clue might be slightly distorted or blurry vision, or difficulty reading. When it gets worse, you decide to see your eye doctor.

In doing so, you might learn you have a condition called age-related macular degeneration, or AMD. In AMD, the macula -- the area of the retina that is responsible for your sharpest central vision -- deteriorates.

According to the National Eye Institute (NEI), one million people have AMD, the leading cause of blindness in people over the age of 60. Every year, 200,000 new cases are reported -- a number expected to increase as the baby boomer population ages.

In "dry" AMD, the tissues of the retina thin and the cells of the macula "drop out." If this progresses enough, the resulting washed-out appearance of objects can make fine details on items, such as the letters on street signs, difficult to make out. Distortions or warping of images can also occur.

About 10% of patients have the "wet" form of the disease, in which abnormal blood vessels develop in the layer of tissue under the retina and leak blood and fluid, usually causing scar tissue, which creates a central blind spot. This more aggressive version of AMD accounts for about 90% of severe vision loss from the disease, according to the NEI.