Macular
degeneration is a degenerative disease of the central retina.
“Macular”
refers to the Macula – the small area in the central retina that
is responsible for producing fine details in vision. This fine
detailed
vision, in turn allows you to perform activities such as reading and
driving.
When the macula does not function correctly, this fine central vision can be impaired or even lost. Macular degeneration affects your ability to see near and far, and can make some activities—like threading a needle, driving or reading—difficult or impossible.
While macular degeneration reduces vision in the central part of
the
retina, it does not affect the peripheral vision. For example, you
could
see the outline of a clock, but not be able to tell what time it is.
Macular degeneration alone does not result in total blindness. Even
in more advanced cases, people continue to have some useful vision
and
are often able to take care of themselves. In some cases, macular
degeneration’s
impact on your vision can be minimal, but in others it can be
devastating.
Many older people develop macular degeneration as part of the body’s natural aging process. There are different kinds of macular problems, but the most common is age-related macular degeneration (AMD). Exactly why it develops is not known, and no treatment has been uniformly effective. Macular degeneration is the leading cause of severe vision loss in Caucasians over age 65.
The two most common types of AMD are “dry” (atrophic) and “wet” (exudative).
· “Dry” or “atrophic” macular degeneration
Most people have the “dry” form of AMD. It is caused by aging and thinning of the tissues of the macula. Vision loss is usually gradual.· “Wet” or “exudative” macular degeneration
This form refers to blood vessels that form underneath the retina and leak fluid, hence the term “wet”. This wet form of macular degeneration accounts for only about 10% of all AMD cases, but it can result in rapid and severe vision loss.
Early
in the course, symptoms are often barely noticeable. In fact, if
only
one eye is significantly affected, the patient may remain unaware
despite
significant visual loss in that eye. When both eyes are affected,
the
loss of central vision may be more profound and noticed more
quickly.
Patients may complain of a variety of symptoms due to AMD. Words may be blurry when reading or central spots that are blurry or missing in the vision can be encountered. Commonly, distortion of straight lines, such as door jams or lines on paper, bring cause for concern.
Unfortunately, AMD is often not found until significant visual symptoms have occurred. Harbin Clinic Eye Center physicians can detect early stages of AMD during a comprehensive eye examination, highlighting the need for frequent eye exams.
Sometimes, when there is suspicion of AMD, but it is difficult to tell by exam alone, a special test called a fluorescein angiogram (FA) can be done in our office. An FA is done by injecting a small amount of fluoroscein dye into a vein in your arm and taking special photos of your retina with a camera. This can show abnormal blood vessels under the retina.
There is no treatment to reverse damage already caused by AMD. Therapies listed below are aimed at stopping or slowing the progression of the disease in an attempt to preserve vision not yet lost to AMD.
· Nutritional Supplements
Recent studies, most importantly the Age Related Eye Disease Study (AREDS), have shown that antioxidant vitamins and zinc may reduce the impact of AMD in some people. The risk for developing advanced stages of AMD has been shown to be lowered by about 25% when treated with a high-dose combination of vitamin C, vitamin E, beta carotene and zinc. There was no advantage, however, for patients without AMD or in patients with very early AMD.
· Laser surgery and photodynamic therapy
Another treatment that can preserve vision in some patients is laser surgery. Certain types of “wet” macular degeneration can be treated with this technology. Laser surgery and another form of treatment called photodynamic therapy use a focused beam of light to slow or stop leaking blood vessels that damage the macula.
· Low Vision Aids
Unfortunately, despite advanced medical treatment, many people with macular degeneration still experience some vision loss. For those with advanced loss of vision, low vision aids may be necessary to perform basic functions. These aids range from simple magnifiers to advanced computer monitors. Your doctor can help refer you to a low vision specialist if needed.
Testing your vision with the Amsler grid (see figure above) can
be
helpful in discovering early changes related to AMD. By checking
your
vision daily with an Amsler grid, like the one pictured here, you
may
find changes in your vision that you wouldn’t notice otherwise.
Putting the grid on the front of your refrigerator or on a bathroom
mirror is a good way to remember to look at it each day. Your doctor
can review this with you during your visit to the Harbin Clinic Eye
Center.
For more information, please
contact:
The American Macular Degeneration Foundation
P.O. Box 515
Northampton, MA 01061-0515
Phone: 413-268-7660
www.macular.org
Foundation Fighting Blindness
11435 Cronhill Drive
Owings Mills, MD 21117-2220
1-888-394-3937
www.blindness.org