Macular Degeneration

The part of the retina (the light-sensitive membrane that lines the back of the eye) that provides sharp sight in the center of the field of vision is called the macula. You need this sharp central vision to see fine details. It is essential for driving, reading, and recognizing faces. As you age, the tissue of the macula can become damaged, leading to a loss of central vision. Age-related macular degeneration is the leading cause of blindness in the United States.

There are two general types of macular degeneration: dry and wet. The dry form accounts for about 90 percent of all cases of the disorder. In this form, the macula slowly thins until vision becomes dimmed. Although only about 10 percent of all people with macular degeneration have the wet form, they are at much higher risk of losing their sharp central vision than are those with the dry form. New blood vessels grow under the retina in the wet form of the disease. These



Concerns blood vessels bleed and leak fluid, creating a large blind spot in the center of the field of vision.

The greatest risk factor for macular degeneration is age. Although symptoms can appear when a person is in his or her 40s or 50s, they usually occur in people over age 60. Women tend to be at greater risk than men, and whites have a higher risk than people of other races. Smoking also appears to increase the likelihood of developing macular degeneration.

Neither form of macular degeneration causes pain. The most common early symptom is blurred vision. As fewer cells in the macula are able to function, affected people are less able to see details—for example, in faces or on printed pages. The blurred vision may lessen in more brightly lit areas, but once the light-sensing cells degenerate, a small but growing blind spot appears in the middle of the field of vision. Another symptom is that objects in straight lines, such as telephone poles or sentences on a page, appear crooked. This phenomenon can occur because fluid from the leaking blood vessels collects and lifts the macula, distorting vision.

To diagnose macular degeneration, an ophthalmologist will use eyedrops to dilate your pupils and an ophthalmoscope (a handheld viewing instrument that projects a very bright light onto the back of the eye) to view the retina. The doctor also may ask you to look at a pattern called an Amsler grid, which looks like a checkerboard. If your central vision is affected, the lines of the grid will appear wavy or distorted.

Currently there is no proven treatment for dry macular degeneration. Some doctors believe that taking antioxidant vitamins (see page 9), zinc supplements, or lutein (an antioxidant found in plants such as spinach, kale, and collard greens) may be helpful in slowing the progression of the disease. A number of low-vision aids, such as magnifying glasses or bright lights, can help affected people continue to participate in activities they enjoy and to lead independent lives.

Some cases of wet macular degeneration can be treated with laser surgery, in which a highly concentrated beam of light is used to destroy the new blood vessels under the retina. Laser surgery is less successful when the abnormal blood vessels have grown beneath the center of the macula. Laser surgery is usually performed in a doctor's office or in an outpatient facility, and the person is allowed to go home the same day.

0 0

Post a comment