Macular Degeneration is a a physiological breakdown of the sharp central focusing point of the retina, called macula of the eye.
The most common type of age-related macular degeneration is dry or atrophic degeneration caused by build up of undigested eye mater which forms yellow spots and patches in the macular of the eye. This causes a gradual vision loss of central vision. The dry type generally cause blank spots in your vision.
Another common type is wet or hemorrhagic macular degeneration, a condition in which abnormal blood vessels form at the back of the eye and they leak fluid or blood, causing the macula to bulge and distort your vision. This type may result in rapid vision loss and distorted vision.