Macular degeneration is a common cause of blindness and vision problems among people older than 50 in the United States. This condition also is called age-related macular degeneration, or AMD. AMD damages the macula, a small part of the eye's light-sensitive retina, the layer of tissue that sends vision signals to the brain. Because the macula is responsible for seeing sharp details directly in the center of the field of vision, damage caused by AMD can interfere with:

• The ability to see straight ahead, necessary for driving and viewing distances, such as when recognizing faces or watching television
• Fine, detailed vision, necessary for reading newsprint, sewing, working with crafts and making repairs

Most people with AMD have fluffy, yellow-white spots on the macula. These spots are called drusen. Not everyone who gets AMD has these spots, and the connection between drusen and AMD is not clear. There are two ways to lose vision as a result of AMD. Both occur during the early stage of the disorder.

• Dry (nonneovascular) AMD � About 90% of people who lose significant vision from AMD have this form of the illness. In dry AMD, the layer of cells under the retina stops functioning well, causing the light-sensing cells that overlie this area to malfunction or disappear over time, producing blank spots in an eye's central vision that are subtle at first then more noticeable later.



• Wet (neovascular) AMD � In wet AMD, delicate new blood vessels begin to grow beneath the retina and can leak blood and fluid into the macula, causing scarring. Damage from the blood vessels, blood and fluid, and scar tissue can occur in a very short period of time, causing rapid loss of vision over days to weeks and continued loss of vision over time. This is probably responsible for about 90% of the cases in which AMD has led to legal blindness. But it is less common than the dry form.

Age is the most important risk factor for AMD, and the early stage currently affects approximately 3.5 million to 10 million people in the United States older than 65. The exact number depends on how macular degeneration is defined. Only a small percentage of people in their 50s have AMD. This percentage increases dramatically in people aged 75 and older. In that age group, about 10% have the advanced form of AMD that causes vision loss. AMD also may be slightly more common in women and in those with a family history of AMD. Caucasians may be at greater risk of developing the wet form. Cigarette smoking and risk factors for cardiovascular disease, such as high levels of blood cholesterol, may be additional risk factors for AMD.

Dry AMD sometimes does not cause any symptoms, or it can make central vision a little less clear. In a small number of cases, it gradually advances to cause more significant blurring in the center of the field of vision. In these more advanced cases, faces and printed words become hard to recognize.

As a first symptom of wet AMD, straight lines or edges appear crooked and images become blurred. In some cases this is followed by a central blind spot, as in dry AMD. However, unlike in dry AMD, this vision loss usually happens rapidly.

AMD generally does not affect side vision, even in advanced cases, so most patients can function independently. Other people may not notice any problem with the person who has AMD. People who have AMD appear to see normally but actually may have difficulty recognizing friends. This can lead to social difficulties. About 15% of people with vision loss from AMD experience visual hallucinations. That is, they see things, such as people and patterns that are not there.

Your doctor will ask questions about your health history and about any risk factors you may have for AMD. He or she then will thoroughly examine your eyes, including tests of visual acuity and, in some cases, an Amsler grid test. An Amsler grid is a drawing of vertical and horizontal lines with a dot in the middle. You are asked to stare at the dot. If you have AMD, some of the lines will appear bent or distorted or even missing.

AMD is a lifelong illness. However, only a small fraction of people with early AMD develop advanced AMD with vision loss.

There is no proven way to prevent AMD. However, recent studies show that people with a history of smoking are more likely to develop AMD. Also, people who take cholesterol-lowering medications and people who eat a diet rich in leafy vegetables and nuts are less likely to develop AMD.

There is no effective treatment for dry AMD. Although some studies suggest that certain vitamins and minerals may help to prevent the development or worsening of the disease, it is still too early to tell for sure if there is any benefit, and the chance of causing harm is unknown. The disease may worsen more slowly in people who take cholesterol-lowering medications and people who eat a diet rich in leafy vegetables and nuts.

Some patients with wet AMD can be treated with thermal laser surgery, which burns the retina to prevent the damage from spreading. Another possible treatment is photodynamic therapy with verteporfin (Visudyne), which more precisely targets the blood vessels and causes less harm to the retina than may occur with thermal laser surgery. There are new types of medications being evaluated, as well as surgeries to remove the new blood vessels or to move the center of the macula to a healthier location.

Patients who have lost vision because of AMD may be able to use low-vision aids to read. Low-vision aids include:

• Optical devices, such as magnifying spectacles, handheld magnifiers, stand magnifiers and computer monitors with large type
• Nonoptical devices, such as books and newspapers with large print, talking computers, high-contrast watch dials and enhanced lighting

New research is being done to identify genes that may be responsible for AMD, to see how vitamins and minerals or laser may prevent or treat the disease, and to find new treatment regimens for wet AMD. Studies supported by the National Eye Institute, a part of the U.S. National Institutes of Health (NIH), also are investigating ways to operate on the retinal tissue in eyes affected by AMD.

Call your doctor immediately whenever you notice any change in your vision, especially if the change happens suddenly and interferes with your ability to read newsprint or to recognize people's faces.

Everyone older than 40 with no eye problems should have a thorough eye examination every two years. If your doctor believes that you are at high risk of vision loss from AMD, you may want to keep a copy of the Amsler grid at home so you can check your own vision periodically.

Because dry AMD develops slowly, most people who have it continue to lead normal lives, especially if only one eye is significantly affected. Only a small fraction of people with wet AMD, perhaps 5% to 10%, may be candidates for thermal laser surgery. An additional 20% to 30% are candidates for photodynamic therapy with verteporfin (Visudyne).

National Eye Institute
2020 Vision Place
Bethesda, MD 20892-3655
Phone: 301-496-5248
http://www.nei.nih.gov/