Macular degeneration is a disorder that affects the retina, the light-sensitive lining at the back of the eye where images are focused. The macula—the area on the retina responsible for sharp central vision—deteriorates, causing blurred vision. This can cause difficulty reading and, for some, a blurry or blind spot in the central area of vision.
The most common form of age-related macular degeneration is known as non-exudative, or the "dry" form, in which vision loss usually progresses slowly. More rapid and severe vision loss comes from exudative, or the "wet" form, of macular degeneration. In the wet form, abnormal blood vessels develop under the macula and leak fluid and blood.
Both exudative and non-exudative forms of macular degeneration are age-related. They are the leading cause of blindness in people over 50. Recent studies estimate that over 1.6 million older Americans have age-related macular degeneration.
The exact cause is unknown. Although age is the primary contributing factor, cigarette smoking and nutrition can also play a role in the development of age-related macular degeneration. A hereditary juvenile form of macular generation called Stargardt Macular Dystrophy can also cause vision loss.