Health & Nutrition
Age Related Macular Degeneration
Age Related Macular Degeneration (AMD) is a common eye disease associated
with aging that gradually destroys sharp, central vision. Central vision is
needed for seeing objects clearly and for common daily tasks such as reading and
driving. In some people, AMD advances so slowly that it will have little effect
on their vision as they age. But in others, the disease progresses faster and
may lead to a loss of vision in one or both eyes.
AMD is the leading cause of vision loss and legal blindness in people over
65. It causes gradual but painless damage to the macula. The retina is a
paper-thin tissue that lines the back of the eye and sends visual signals to the
brain. In the middle of the retina is a tiny area called the macula. The macula
is made up of millions of light-sensing cells that help to produce central
vision. People with AMD continue to have peripheral vision but gradually find it
difficult or impossible to read, drive a car, or identify faces.
AMD occurs in two forms:
- Dry AMD--Ninety
percent of all people with AMD have this type. Scientists are still not sure
what causes dry AMD. Studies suggest that an area of the retina becomes
diseased, leading to the slow breakdown of the light-sensing cells in the
macula and a gradual loss of central vision.
- Wet AMD--Although
only 10 percent of all people with AMD have this type, it accounts for 90
percent of all blindness from the disease. As dry AMD worsens, new blood
vessels may begin to grow and cause "wet" AMD. Because these new
blood vessels tend to be very fragile, they will often leak blood and fluid
under the macula. This causes rapid damage to the macula that can lead to the
loss of central vision in a short period of time.
The greatest risk factor is age. Although AMD may occur during middle age,
studies show that people over age 60 are clearly at greater risk than other age
groups. For instance, a large study found that people in middle-age have about a
2 percent risk of getting AMD, but this risk increased to nearly 30 percent in
those over age 75.
Other AMD risk factors include:
Gender--Women tend to be at greater risk for AMD than men.
Race--Whites are much more likely to lose vision from AMD than
Blacks.
Smoking--Smoking may increase the risk of AMD.
Family History--Those with immediate family members who have AMD are
at a higher risk of developing the disease.
Both dry and wet AMD cause no pain. The most common early sign of dry AMD is
blurred vision. As fewer cells in the macula are able to function, people will
see details less clearly in front of them, such as faces or words in a book.
Often this blurred vision will go away in brighter light. If the loss of these
light--sensing cells becomes great, people may see a small--but growing-blind
spot in the middle of their field of vision.
The classic early symptom of wet AMD is that straight lines appear crooked.
This results when fluid from the leaking blood vessels gathers and lifts the
macula, distorting vision. A small blind spot may also appear in wet AMD,
resulting in loss of one's central vision.
Your eye care professional may suspect AMD if you are over age 60 and have
had recent changes in your central vision. To look for signs of the disease, he
or she will use eye drops to dilate, or enlarge, your pupils. Dilating the
pupils allows your eye care professional to view the back of the eye better.
You may also be asked to view an Amsler grid, a pattern that looks like a
checkerboard. Early changes in your central vision will cause the grid to appear
distorted, a sign of AMD.
No treatment now exists for dry AMD. Some studies have suggested that taking
certain extra vitamins and minerals may slow the progress of the disease. But
this treatment needs much more research before scientists can know for sure if
it's helpful.
Eye care professionals can treat some cases of wet AMD with laser surgery.
This treatment involves aiming a strong light beam onto the new blood vessels to
destroy them. Laser surgery is done in a doctor's office or in an eye clinic and
lasts a short period of time. Although a person may go home the same day, he or
she will need to return for follow-up exams.
Although there is no effective treatment for dry AMD at this time, it is
crucial that those who progress to wet AMD and need laser surgery have it before
the disease destroys central vision. For this reason, if you have dry AMD or are
age 60 or older, you should have your eyes examined through dilated pupils at
least once a year. You may also want to get an Amsler grid from your eye care
professional to check your vision at home.
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