Age-related macular degeneration is a chronic eye disease that occurs when tissue in the macula, the part of your retina that's responsible for central vision, deteriorates. The retina is the layer of tissue on the inside back wall of your eyeball. Degeneration of the macula causes blurred central vision or a blind spot in the center of your visual field.

The first sign of macular degeneration may be a need for more light when you do close-up work. Fine newsprint may become harder to read and street signs more difficult to recognize. Eventually you may notice that when you're looking at a grid, some of the straight lines appear distorted or crooked. Gray or blank spots may mask the center of your visual field. The condition usually develops gradually, but may sometimes progress rapidly, leading to severe vision loss in one or both eyes.

Macular degeneration affects your central vision, but not your peripheral vision; thus it doesn't cause total blindness. Still, the loss of clear central vision critical for reading, driving, recognizing people's faces and doing detail work greatly affects your quality of life. In most cases, the damage caused by macular degeneration can't be reversed, but early detection may help reduce the extent of vision loss.

The condition tends to develop as you get older, hence the "age-related" part of its name. Macular degeneration is the leading cause of severe vision loss in people age 60 and older. More than 1.6 million American adults have the advanced form of age-related macular degeneration.