Age-related macular degeneration, or AMD, is one of the leading causes of blindness and vision loss among people over age 65 in the United States.

The macula is part of the retina. It is responsible for sharp central vision. A person with AMD has difficulty reading, driving, and performing other tasks that require clear central vision.

According to the "Archives of Ophthalmology", aprroximately 1.75 million people in the United States had symptoms of age-related macular degeneration in 2004, and this number is expected to grow to about 3 million by the year 2020.

There are two forms of macular degeneration - dry and wet. Dry AMD is the early stage of the disease. About 90 per cent of all AMD patients have the dry form, which is less severe and causes less vision loss than wet AMD.

As we age, the macular tissues may begin to thin. Pigment may be deposited in the macula. Yellowish spots called drusen begin to accumulate from these deposits. The central vision gradually deteriorates.

In about 10 per cent of the cases, dry AMD progresses into wet macular degeneration, a more severe form of the disease. The body tries to build new blood vessels to get more nutrients to the retina, but these blood vessels become abnormal and leakage and scarring occur in the back of the eye. Retina cells die and create blind spots in the central vision. Damage to the eye at this stage is permanent.

There are two forms of wet macular degeneration, classic and occult, with classic being the most severe.

A simple test called the Amsler grid can be used to screen individuals for macular degeneration. This test will show if AMD may be present, even if the person has no symptoms of vision loss. Ophthalmologists can also detect early stages of AMD through examination of the retina.

The individual with early stages of macular degeneration may experience blurry, fuzzy or distorted central vision. Anyone with these symptoms should visit their eye doctor for a professional examination.

Research at Duke and Columbia Universities has found possible links between certain defective genes and the presence of macular degeneration.

There is no cure for macular degeneration. Some studies by the National Eye Institute suggest that it may be possible to slow the progress of dry age-related macular degeneration by as much as 25 per cent by taking nutritional supplements of antioxidants and zinc, or zinc alone. These supplements of vitamins and minerals should be taken ONLY under a physician's care to be sure that they do not interfere with other medications or cause side effects.

Research indicates that the formation of blood vessels in wet AMD is activated by a protein called vascular endothelial growth factor (VEGF). VEGG is targeted in wet macular degeneration treatments by anti-VEGF drugs.

For more information, visit the National Eye Institute, Prevent Blindness America, or All About .Vision.com