The nation's twin epidemics of obesity and diabetes are beginning to rob more Americans of their sight, a new study shows.
The percentage of American adults who have uncorrectable vision loss spiked 21% in only about six years, rising to nearly 1.7% of the population, according to an analysis that compared the periods of 1999-2002 and 2005-2008.
Rates of visual impairment doubled among poor people and those who'd had diabetes for a decade or more, according to the study, published Tuesday in The Journal of the American Medical Association. Researchers defined impairment as anything worse than 20/40 vision that can't be corrected with glasses, a problem that disqualifies people from driving in many states.
"This is a dramatic change in eye disease in a small amount of time," says study author David Friedman, director of preventive ophthalmology at Johns Hopkins' Wilmer Eye Institute in Baltimore.
Typically, that kind of sight loss occurs in old age. Yet the biggest jump in visual impairment was in adults ages 20 to 39, when such sight problems are usually rare, notes David Musch, an epidemiologist at the University of Michigan Kellogg Eye Center, who wrote an accompanying editorial.
"I would hope this raises a flag for people," he says.
Musch notes that the ranks of Americans with this kind of vision loss swelled by nearly 700,000 people in the six-year study period. The number of people with visual impairment probably will grow, given that rates of diabetes more than doubled in 20 years, from 4.9% of Americans in 1990 to 11.3% in 2010.
Friedman says he's particularly concerned about children and teens, who are developing diabetes at younger ages because of being overweight and inactive. The longer people live with diabetes, the greater their chance of suffering serious complications, which can take a decade or more to develop.
"I think of this as a kind of canary in the coalmine," Friedman says. "It's the tip of something that is just starting to surface."
Health officials have warned for years of the consequences of obesity, which increases the risk of type 2 diabetes. About 27 million Americans have diabetes, and up to 80 million have "prediabetes," which puts them at high risk for the disease, says Vivian Fonseca, the American Diabetes Association's president for medicine and science.
Diabetese patients can reduce their risk of vision loss by keeping their disease under control, both with medications and lifestyle changes, and through annual eye exams, Fonseca says.
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