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As the US population gets older,
more Americans than ever before are facing the loss of their vision.
One
million Americans over age 40 are blind now,
and that 2.4 million have some form of visual impairment. Those figures
will double over the next few decades, according to the analysis, conducted
jointly by the National Eye Institute, Prevent Blindness America and the
Wilmer Eye Institute at Johns Hopkins University.
The leading causes of blindness
are vision loss due to diabetes, age-related macular degeneration, cataracts
and glaucoma. Most of these conditions appear in older Americans and worsen
with age.
Nearly half of diabetics will
develop vision impairment due to retinopathy. In that condition, the retina's
blood vessels break down, leak or become blocked, impairing vision. The
risk of retinopathy increases with age and the duration of diabetes, especially
if blood sugar is not well controlled.
Diabetics can help prevent
vision loss by managing their disease with increased exercise and tight
blood sugar control, he said. Retinopathy can sometimes be treated with
laser surgery or vitrectomy, in which the jelly-like substance behind
the eye is removed.
Age-related
macular degeneration (AMD) is the most common cause of blindness and vision
impairment, affecting mostly people over age 60.
The disease, which has no
known cause, tends to run in families and affect women and whites more.
There is also evidence that smoking and high-fat, high-cholesterol diets
increase AMD risk, Sieving noted.
Ninety percent of those with
the condition have dry AMD, in which there is a gradual breakdown of light-sensing
cells. Only 10% have the wet form, but it is the leading cause of blindness.
Leaky blood vessels lead to rapid damage, causing total vision loss.
Lasers can destroy those vessels
and help slow impairment, but there is no treatment for dry AMD. A study
published by the National Eye Institute last fall showed that taking a
combination of zinc, vitamins C and E and beta-carotene may slow AMD progression.
Cataracts run in families also,
and increase with age. About 20 million Americans have cataracts, which
can be successfully treated. Clouded, diseased lenses are surgically removed
and replaced with artificial lenses.
National
Eye Institute March 20, 2002
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