Macular degeneration, or age-related macular degeneration -- AMD -- is the leading cause of vision loss and legal blindness in Americans age 65 and older.

AMD is a chronic eye disease that gradually destroys sharp central vision. The eye-health organizations estimate that by 2020, Americans with moderate to severe AMD will number 17 million, more than double the current number.

Macular degeneration affects the central vision but not the peripheral vision; therefore, it does not cause total blindness. The progression of AMD can be slow or rapid, but the deterioration of central vision generally occurs over a period of a few years. Pain is not associated with AMD.

Early warning signs of AMD:

* Straight lines that appear wavy.

* Difficulty seeing at a distance.

* Decreased ability to distinguish colors.

* Inability to see details, faces, or words in a book.

* Dark or empty spots blocking the center of your vision.

Although the exact cause of AMD is unknown, several studies have shown that individuals over 50 with hypertension who smoke or have a family history of AMD have a high risk factor.

What can you do to prevent or lower your risk of AMD?

* Stop smoking. Smoking increases your risk two to five times.

* Control your blood pressure. The eye is a highly vascular organ and the rate of blood exchange in the eye is the highest in the body.

* Protect your eyes from exposure to harmful sunlight. Blue light and ultraviolet light can damage your retina. Wear sunglasses and a hat or visor outside.

* Eat a healthful diet. The diet widely recommended as beneficial for cardiovascular health seems to help people suffering from AMD.

Reprinted with permission from Alphapointe Association for the Blind.