Tribune Print Share Text

Treating a leading cause of blindness

Created date

December 21st, 2010

Age-related macular degeneration is one of the main causes of vision loss in older Americans, says Mark Samuelson, M.D. Although the disease, which gradually destroys your central vision, can occur in middle age, if you are over age 60 you are at a higher risk. One study shows that the risk of age-related macular degeneration (AMD) increased to nearly 30% in people 75 and older. Exact causes of the disease are unknown. Scientists have identified the genes associated with AMD, and they are related to the immune system, says Stephen Rose, Ph.D., chief research officer of the Foundation Fighting Blindness. But we still don t know exactly how the immune system and AMD interact.

The disease process

AMD affects photoreceptors [light-sensitive cells] in the macula the central portion of the retina that is responsible for daytime vision, color vision, and your ability to see fine detail, Rose says. The disease may advance slowly or quickly, and affect one or both eyes. Your central vision is affected first. As AMD progresses, vision loss may expand outward to include peripheral vision loss, Rose says. There are two forms of AMD dry and wet. Neither form is painful.

Dry AMD

Ninety percent of people with AMD have dry AMD, Rose says. Complex chemical reactions in your retina help to give you vision, Rose explains. But with all chemical reactions, there are resultant by-products. Dry AMD happens when toxic by-products build up. As you age, the cells responsible for removing this waste don t work as well as they should. People with the dry form of AMD need to see their ophthalmologist on a regular basis because they are at increased risk of developing the wet form, Samuelson says. Even in early stages, dry AMD can suddenly advance into wet AMD. If you have vision loss from dry AMD in one eye only, you may not notice any changes in your overall vision. With the other eye seeing clearly, you can drive, read, and see details.

Wet AMD

In the wet form [sometimes called advanced AMD], blood vessels that feed your eye begin growing under the macula and start leaking blood and fluid, Rose says. Damage to the macula and loss of central vision can occur rapidly. People who have wet AMD in one eye are at especially high risk of developing wet AMD in the other eye, Rose says. An early symptom of wet AMD is that straight lines appear wavy. In conjunction with other tests, an Amsler grid may be used to diagnose it.

Dealing with dry AMD

There are currently no standard treatments for dry AMD, but what s good for your heart is good for your eyes, Rose says. Research shows that eating a diet high in leafy green vegetables and fish may help slow the progression, Rose says. A clinical trial in progress is testing an oral medication calledfenretinide for dry AMD, Rose continues. Preliminary results have shown that it may slow or even stop the progression to wet AMD in some people.

Treating wet AMD

The National Eye Institute s Age-Related Eye Disease Study (AREDS) found that taking a specific supplement significantly reduces the risk of wet AMD and its associated vision loss. The AREDS supplement is available over-the-counter and contains antioxidants, minerals, and compounds known as carotenoids. All of these are particularly good for your eyes, Rose says. If your ophthalmologist recommends the AREDS supplement, be sure to notify your primary doctor. You may need an adjustment in other medications or supplements that you are taking, Samuelson adds. An especially good treatment for wet AMD is an FDA-approved drug called Lucentis [ranibizumabinjection]. It stops the blood vessel growth in approximately 90% of people who use it, and it can restore a small amount of vision in some people if the disease has been caught and treated early, Rose says. The downside to Lucentis is that it is expensive (about $2,000 per treatment) and typically administered monthly, which can be inconvenient. Medicare pays for some of the cost of Lucentis. Not all supplemental insurances will pay for it. Another clinical trial is testing a much less expensive drug for wet AMD, but it s not yet known if it is as effective as Lucentis, Rose says. Wet AMD can also be treated with laser surgery or photodynamic therapy. None of these treatments are cures, and loss of vision may progress despite treatment. The sooner you start treatment, the better, Samuelson says. If you have been diagnosed with AMD, it s not harmful to use your eyes for everyday activities, Rose says. Ask your eye care professional about low vision services and devices that may help you make the most of your remaining vision. A low vision specialist may also be able to help. Many community organizations and agencies can help with low vision counseling, training, and other services, Samuelson says.

Risk factors of AMD

  • Smoking
  • Obesity
  • Caucasian race
  • Family history
  • OF NOTE: Women and people with high blood pressure may be at higher risk.

Preventive measures

If you do all of the following you may have a lower risk of AMD:
  • Eat a healthy diet high in leafy green vegetables and fish.
  • Don t smoke.
  • Maintain normal blood pressure.
  • Watch your weight.
  • Exercise.

Resources for people with AMD

Foundation Fighting Blindness 1-800-683-5555 www.blindness.org Macular Degeneration Association 1-941-870-4399 www.maculardegenerationassociati...

Comments