What is macular degeneration?
Macular degeneration is a deterioration or breakdown
of the macula. The macula is a small area in the retina at the back of the eye that allows you to see fine details clearly
and perform activities such as reading and driving. When the macula does not function correctly, your central vision
can be affected by blurriness, dark areas or distortion. Macular degeneration affects your ability to see near and far,
and can make some activities difficult or impossible.
Although macular degeneration reduces vision
in the central part of the retina, it usually does not affect the eye's side, or 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 many cases, macular degeneration's impact on your vision can be minimal.
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 65.
The two
most common types of AMD are "dry" (atrophic) and "wet" (exudative):
"Dry" macular degeneration (atrophic):
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" macular degeneration
(exudative): The "wet" form of macular degeneration accounts for about 10% of all AMD cases.
It results when abnormal blood vessels form underneath the retina at the back of the eye. These new blood vessels leak
fluid or blood and blur central vision. Vision loss may be rapid and severe.
Deposits under
the retina called drusen are a common feature of macular degeneration. Drusen alone usually do not cause vision loss,
but when they increase in size or number, this generally indicates an increased risk of developing advanced AMD. People
at risk for developing advanced AMD have significant drusen, prominent dry AMD, or abnormal blood vessels under the macula
in one eye ("wet" form).
What are the symptoms of macular degeneration?
Macular
degeneration can cause different symptoms in different people. The condition may be hardly noticeable in its early stages.
Sometimes only one eye loses vision while the other eye continues to see well for many years. But when both eyes are
affected, the loss of central vision may be noticed more quickly.
Following are some ways vision
loss is detected:
- words on a page look blurred;
- a dark or empty area appears in the center of vision;
- straight lines look distorted.
How is macular degeneration diagnosed?
Many people do not realize that have a macular problem until blurred vision becomes obvious. Your ophthalmologist
can detect early stages of AMD during a medical eye examination that includes the following:
- a simple vision test
in which you look at a chart that resembles graph paper (Amsler grid);
- viewing the macula with special lenses;
- taking
special photographs of the eye called fluorescein angiography to find abnormal blood vessels under the retina.
How is macular degeneration treated?
Nutritional Supplements
Although the exact causes of macular degeneration are not fully understood, antioxidant vitamins and zinc may reduce the
impact of AMD in some people.
A large scientific study found that people at risk for developing advanced stages
of AMD lowered their risk by about 25% when treated with a high-dose combination of vitamin C, vitamin E, beta carotene and
zinc. Among those who have either no AMD or very early AMD, the supplements did not appear to provide an apparent benefit.
It is very important to remember that vitamin supplements are not a cure for AMD, nor will they restore vision that
you may have already lost from the disease. However, specific amounts of these supplements do play a key role in helping
some people at high risk for advanced AMD to maintain their vision. You should speak with your ophthalmologist to determine
if you are at risk for developing advanced AMD, and to learn if supplements are recommended for you.
Laser surgery, PDT and anti-VEGF treatments
Certain types of "wet" macular degeneration can be
treated with laser surgery, a brief outpatient procedure that uses a focused beam of light to slow or stop leaking blood vessels
that damage the macula. A treatment called photodynamic therapy (PDT) uses a combination of a special drug and laser
treatment to slow or stop leaking blood vessels.
Another form of treatment targets a specific chemical in your
body that is critical in causing abnormal blood vessels to grow under the retina. That chemical is called vascular endothelial
growth factor (VEGF). Anti-VEGF drugs block the trouble-causing VEGF, reducing the growth of abnormal blood vessels
and slowing their leakage.
These procedures may preserve more sight overall, though they are not cures that restore
vision to normal. Despite advanced medical treatment, many people with macular degeneration still experience some vision
loss. Early detection and treatment may minimize vision loss.
Adapting to
low vision
To help you adapt to lower vision levels, your ophthalmologist can prescribe optical devices or refer
you to a low-vision specialist or center. A wide range of support services and rehabilitation programs are also available
to help people with macular degeneration maintain a satisfying lifestyle. Because side vision is usually not affected,
a person's remaining sight is very useful. Often, people can continue with many of their favorite activities by
using low-vision optical devices such as magnifying devices, closed-circuit television, large-print reading materials and
talking or computerized devices.
