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Nutritional
Supplementation for
Age-Related Macular Degeneration
Age-related
macular degeneration (AMD) is an acquired ocular disorder
and a leading cause of legal blindness in persons over age
60.(1) AMD affects the macula, the central part of the retina
that is responsible for providing clear, sharp vision needed
for reading, writing, driving and other daily activities.
The
nature and severity of this condition vary with individual
patients. Approximately 90 percent of patients with AMD have
the non-exudative form of the disease, which results in the
development of dry atrophic scars of the macular area. These
patients generally experience a gradual loss of central vision.
Only 10 percent of patients with AMD will develop the exudative
form which results in the leaking of fluid beneath the retina
and a greater and more rapid loss of vision. Effective laser
photocoagulation treatment for the disease is limited to small
numbers of patients with exudative AMD who are identified
early.
Some
research now suggests that the development of AMD may be the
result of free radical oxidative damage to the retina due
to antioxidant enzyme depletion. Therefore, antioxidant nutritional
supplementation (e.g., vitamins C, E, beta-carotene and zinc)
may help to prevent or impede the progression of AMD. It is
theorized that antioxidants may function as defense mechanisms
that convert free radicals (highly reactive by-products of
cellular metabolism) into stable compounds before they interact
with cell membranes to produce damage.(3) The results of animal
studies have supported this theory.(4-6) However, several
human clinical studies have had inconclusive results.(7-9)
One study did suggest that a higher dietary intake of carotenoids,
especially those obtained from dark green leafy vegetables
(e.g., spinach and collard greens), was associated with a
significantly lower risk for AMD.(10) An 18-month study of
individuals with advanced AMD found that a twice-a-day use
of antioxidant supplements did not improve vision, but did
keep it from getting worse.
The
use of antioxidants cannot reverse the damage caused by AMD;
however, they may be able to prevent or slow its progression
in some patients. If dietary supplementation of antioxidants
is undertaken as a preventive measure, its use may be most
appropriate for the following individuals:
- Over
age 50
- Family
history of AMD
- Insufficient
dietary intake of vitamins and minerals
These
preliminary findings are indeed hopeful, but more data is
needed to define nutritional and antioxidant therapies for
the prevention of AMD. Until these study results are available,
the American Optometric Association recommends patients stop
smoking, consume a nutritionally balanced diet and regularly
see their optometrist for early detection of AMD.
Related
Links
Macular
Degeneration: What Is It?
http://www.marylandeyes.com/maculardegenerationstory.htm
Amsler
Grid Test
http://www.marylandeyes.com/maculardegeneration-amsler.htm
Nutrition
and Age Related Macular Degeneration
http://www.marylandeyes.com/maculardegeneration-nutrition.htm
Take
a Look at the Causes and Risks
http://www.marylandeyes.com/maculardegeneration-risk.htm
Antioxidant
Vitamins and Zinc Reduce Risk of Vision Loss
http://www.marylandeyes.com/maculardegeneration-antioxidant.htm
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