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Age Related Macular Degeneration (AMD)
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(click image for
larger view)
Drusen are white-yellow lesions
under the macula that occur in patients
with "dry" macular degeneration.
Vision may be normal or reduced.
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Age-related macular degeneration (AMD)
is the most common cause of irreversible visual loss after
age 60. The precise cause of AMD is unknown. Advancing age
is the most significant risk factor for developing AMD.
Heredity, blue eyes, high blood pressure, cardiovascular
disease, and smoking have also been identified as risk factors.
AMD accounts for 90 percent of new legal blindness in the
US.
Nine out of 10 people who have AMD have
the dry form, which results in thinning of the macula, the
area of the retina responsible for central reading vision.
Dry AMD takes many years to develop. Currently there is
no treatment for this form of AMD.
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(click image for
larger view)
This photo represents the appearance of an eye with "wet"
macular degeneration. Here abnormal
blood vessels grow and bleed underneath
the retina. Vision is often poor.
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The wet form of AMD occurs much less frequently
(one out of 10 people) than dry AMD, but is associated more
commonly with severe vision loss and sudden onset of symptoms.
The visual symptoms of AMD affect central
vision, peripheral vision is not affected. One loses the
sharp, straight-ahead vision necessary for driving, reading,
recognizing faces, and looking at detail. Imagine being
able to see a clock on the wall but unable to make out the
time or being unable to read because you could not see parts
of words on the page. It is very important to understand
that because peripheral vision is preserved in AMD, patients
maintain the ability to walk, dress, and care for themselves.
Short of losing the capacity to drive and read, patients
may maintain independent lifestyles.
Specialized laser surgery may be effective
in stabilizing vision loss in patients with the wet form
of AMD. The laser procedure usually does not improve vision
but prevents further loss of vision.
Promising AMD research is being done across
the country. In the meantime, high-intensity reading lamps,
magnifiers and other low-vision aids help people with AMD
make the most of remaining vision.
Prevention of AMD
Both doctors and the public have shown
growing interest in the relationship between diet and health.
Good nutrition depends on a healthy mixture of proteins,
carbohydrates, fats, vitamins and minerals. The eye, like
any other part of the body, benefits from a healthy diet.
Although the exact causes of macular degeneration are not
understood, there is some evidence that vitamins and minerals
may play a preventive role.
Zinc, one of the most common minerals in
our body, is very concentrated in the eye, particularly
in the retina and macula. Zinc is necessary for the action
of over 100 enzymes, including chemical reactions within
the retina. Studies show some older people have low levels
of zinc in their blood. Because zinc is important for the
health of the macula, some think that supplements of zinc
in the diet may slow down the process of macular degeneration.
Normal chemical reactions from light in
the eye activate oxygen that may cause macular damage. Some
vitamins function as antioxidants that prevent this potentially
damaging chemical reaction.
In a recent study conducted by the National
Eye Institute, scientists looked at the effects of zinc
and antioxidants in patients with cataracts, and in those
with varying stages and types of age-related macular degeneration
(AMD). Researchers also studied patients without evidence
of cataract or AMD to determine if zinc and/or antioxidants
can prevent the development of these conditions. The name
of this study is the Age-Related Eye Disease Study (AREDS).
Based on findings published in November
of 2001, AREDS makes the recommendation that you talk to
your ophthalmologist about taking nutritional supplements
if you have intermediate AMD in both eyes or advanced AMD
in one eye only. He or she can help you determine if they
may be beneficial-and safe-for you, and what types and doses
of supplements to take. The doses used in the study were:
- Vitamin C 500 mg
- Vitamin E 400 IU
- Beta-carotene 15 mg
- Zinc 80 mg, as zinc oxide
- Copper 2 mg, as cupric oxide (copper
should be taken with zinc, because high-dose zinc is associated
with copper deficiency.)
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