What is macular degeneration?
 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.
What causes macular degeneration?
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.
What are the symptoms of macular degeneration?
 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.
How is macular degeneration diagnosed?
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.
How is macular degeneration treated?
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.
How can I monitor for changes related to AMD?
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
photos provided by www.aao.org
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