Macular degeneration is a progressive eye condition affecting as many as 15 million Americans and millions more around the world. The disease attacks the macula of the eye, where our sharpest central vision occurs. Although it rarely results in complete blindness, it robs the individual of all but the outermost, peripheral vision, leaving only dim images or black holes at the center of vision.

An eye is an organ that detects light. Different kinds of light-sensitive organs are found in a variety of creatures. The simplest eyes do nothing but detect whether the surroundings are light or dark. More complex eyes are used to provide the sense of vision. ...