Age-related macular degeneration (ARMD) is the leading cause of untreatable legal blindness for older people. It involves a deterioration of the retinal cells that causes a loss of the central field of vision. The macula is the part of the retina that provides clear, sharp central vision. Approximately 3 million Americans suffer visual loss related to macular degeneration. While their central vision is impaired, people with ARMD rarely become totally blind. The prevalence of ARMD rises with age as shown in the graph below.

The exact cause of macular degeneration is not known. The major risk factors for ARMD are shown below. Other risk factors include cardiovascular disease, diabetes, ultraviolet light exposure, and diet.

Risk Factors for ARMD

Caucasian
Smoker
Hypertension

Symptoms of macular degeneration include a loss of central vision while the peripheral vision is unaffected. Other symptoms include difficulty reading or identifying faces, decreased color sensitivity, increased glare sensitivity, and distortion of objects (e.g. straight lines appear bent).

There are two types of ARMD:

Dry macular degeneration is the major type of ARMD and accounts for 80 to 90 percent of the cases. It causes a loss of central vision; peripheral vision is not affected. Early signs of the dry form include blurred or cloudy vision, a blind spot at the center of vision, dimmed color vision, and distortion in vertical lines.
Wet macular degeneration is more likely to result in severe visual impairment. Among older adults who are legally blind, 80 to 90 percent have this form of the condition. Wet macular degeneration leads to a separation of the retinal pigmented epithelium (RPE) from the retina. Early diagnosis is crucial since laser treatment may keep retinal lesions from spreading and is more effective when used early. An Amsler grid (see below) can help in the detection of wet AMD. When one eye is covered, those who have wet AMD see wavy lines rather than the straight lines that people with normal vision see.

Amsler Grid

Treatment

Currently there is no treatment for dry AMD, but this does not mean that you will lose your sight. Dry AMD develops very slowly and may affect only one eye. Over time you may lose some of your central vision. Only 10% of people with dry macular degeneration have vision loss severe enough to qualify as legal blindness.

Wet AMD may be treated with laser surgery. The laser treatment aims a high energy beam of light directly onto the leaking blood vessels and can help stop further vision loss. After surgery, frequent eye examinations are needed to detect any recurrence of leaking blood vessels. People who smoke have a greater risk of recurrence than those who don't.

Prevention

Some evidence suggests that certain vitamins and minerals may play a role in the treatment of AMD but more research is needed. Currently, the National Eye Institute is sponsoring the Age-Related Eye Disease Study to investigate whether vitamin or mineral supplements are beneficial. The possibility of transplanting healthy cells into a diseased retina is also being explored but is at a very early stage and still experimental.