April 12, 2004.
By Salynn Boyles,
Medical News Reviewed By Brunilda Nazario, MD.
As baby boomers morph into senior citizens over the next two decades, the number of Americans who are legally blind will grow by millions, according to new figures from the government's top vision research group.
Nearly 3 million Americans aged 40 and over are now considered either blind or have low vision, but a report released today by the National Eye Institute projects an estimated increase of 70% in the numbers of blind persons in the U.S. and an increase in the numbers of adults with low vision to a total figure that will grow to 5.5 million by the year 2020.
The report on age-related blindness is published in the April issue of the journal Archives of Ophthalmology.
Macular degeneration (AMD), glaucoma, and cataracts were found to be the leading causes of visual impairment especially among older Americans. Researchers say that these conditions are predicted to increase rapidly in the future because older Americans represent the largest growing segment of the population.
"Developing blindness prevention strategies could help address the potentially devastating impact of the increased prevalence of eye diseases in the next few decades," Paul A. Sieving, MD, PhD, said in a news release.
National Eye Institute director of epidemiology Frederick Ferris III, MD, tells WebMD that the age-related blindness projections, derived from studies conduced during the past 15 years will help investigators identify areas for future research.
In the study, AMD was more commonly found among white Americans, accounting for 54% of all blindness. Glaucoma and cataract were the leading causes of blindness among blacks and Hispanics.
"We don't really know why African Americans have a much higher risk of blindness from glaucoma and why whites have a much higher risk from macular degeneration," he tells WebMD. "These are certainly questions that deserve further study."
The findings will also help health professionals and public officials prioritize public health programs over the coming years, Ferris says.
Glaucoma was almost three times as common among blacks as whites, and the condition occurred earlier in life. For this reason, Ferris says, African Americans should have regular dilated eye exams beginning soon after they turn 40, while healthy whites can wait until age 60. People with diabetes should have regular eye exams, he says, because one in every 12 people with the disease over age 40 develops diabetic retinopathy.
Other significant findings from the study include:
1 in 10 white Americans over the age of 80 has vision loss caused by AMD.
The prevalence of glaucoma rises rapidly in Hispanics over the age of 65.
Cataracts are the leading cause of low vision among all Americans. They are responsible for about half of all cases of low vision, which is defined as a person's best vision -- even with a correction lens -- that is significant enough to impede the ability to drive or conduct everyday activities.
Macular degeneration is of particular concern, Ferris says, because it is the least treatable of the age-related eye conditions. Cataracts can now be removed with a quick and relatively simple, outpatient surgical procedure. More than 2 million Americans each year have the surgery, and more than 95% achieve improved vision as a result. Glaucoma and diabetic retinopathy are also highly treatable if identified early.
Strategies for the prevention or treatment of macular degeneration have been few, but this is beginning to change, Ferris says. Treatment with vitamins and zinc has been shown to prevent blindness in about 25% of people with AMD, and studies also show that the antioxidant lutein, found in dark, leafy vegetables such as spinach and kale, can protect against the disease, as can eating fish.
"For the first time we have treatments that can reduce the risk of further vision loss in people with macular degeneration," he says. "I think the major message is that there are now treatments for the four leading age-related causes of blindness, and for three of the four, the treatments are very effective. But people won't know they have these conditions if they don't have regular eye exams."
SOURCES: Ferris, F.Archives of Ophthalmology, April 2004; vol 122: pp - 477-485. Frederick Ferris III, MD, director of clinical research, National Eye Institute; National Institutes of Health. Paul A. Sleving MD, PhD, director, National Eye Institute.
© 2004 WebMD Inc. All rights reserved.
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