Many elderly people in the United States suffer severe loss of vision and sometimes even blindness because of macular degeneration, a disease that affects the retina. Its cause remains unknown, but scientists think frequent exposure to sunlight and smoking may be involved.

Macular degeneration occurs when the cells of the macula (the central portion of the retina) become damaged and stop functioning. The macula enables us to focus on objects directly in front of us and see their fine detail during activities such as reading and driving. It also determines our capacity to distinguish color.

To work properly, the macula needs a host of nutrients and antioxidants including vitamins C and E, beta-carotene and lutein as well as zinc, selenium and copper. In addition to providing nourishment, these antioxidants protect against free radicals generated by the eye's constant activity.

The eye constantly processes light, particularly blue and ultraviolet, that can cause photodamage. Some researchers think melanin, present in the skin and partly responsible for eye color, helps absorb light and protect against free radical damage. Consequently, people with green or blue eyes are more susceptible to macular degeneration than people with dark eyes.