MONDAY, Aug. 11 (HealthDay News) -- About half of all American adults don't have the 20/20 vision physicians consider optimal because they are nearsighted, farsighted, or have an irregular corneal curve known as astigmatism, a large, new study reports.
The study revealed that such common eye-focus problems -- collectively known as "refractive errors"-- affect young, middle-aged and older adults of all races. Corrective care for such problems amounts to an estimated $3.8 billion to $7.2 billion annually, the researchers said.
"I think this study demonstrates that the problem of refractive eyesight errors is on the increase, particularly in terms of the amount of nearsightedness in the American population," said study co-author Dr. Frederick L. Ferris III, clinical director of the U.S. National Eye Institute.
"This is probably a worldwide problem," he added. "No one knows for sure what accounts for this. But it's a pretty smart hypothesis that the increased amount of near work that we're doing as a population may be increasing the incidence of nearsightedness. And it does suggest that we should be looking into ways to deal with it."
Rando Allikmets, a professor of ophthalmology, pathology and cell biology at Columbia University, said, "I would hazard to suggest that, in general, the widespread prevalence of refractive issues today could be related to environmental factors, like extensive use of TV and computers, and -- among the young -- video games. Because today we get much heavier loads on our eyes from all of that, and those are strenuous activities for our vision."
To take a current snapshot of American eye health, the study authors, led by Susan Vitale of the U.S. National Eye Institute, analyzed data collected by the U.S. Centers for Disease Control and Prevention's ongoing National Health and Nutrition Examination Survey. The survey, conducted between 1999 and 2004, involved more than 12,000 men and women 20 or older.
The authors found that 3.6 percent of those surveyed were farsighted, while about one-third were nearsighted. Slightly more than 36 percent were found to have some form of astigmatism.
Some modest gender differences were apparent. For example, in the 20-to-39-year-old bracket, more women (nearly 40 percent) than men (nearly 33 percent) were nearsighted. And in the 60-and-up age category, about two-thirds of men had some kind of refractive problem, compared with about 59 percent of women.
Age also played a role. While 46 percent of the 20- to-39- year-old group had some kind of refractive eye issue, that figure rose to nearly 51 percent among the 40-to-59-year-old group, and nearly 63 percent among those 60 and older. The study authors said farsightedness was more common than nearsightedness among the older group.
The findings are published in the August issue of the Archives of Ophthalmology.
Dr. Scott H. Greenstein, an ophthalmologist at the Massachusetts Eye and Ear Infirmary and an instructor at Harvard Medical School, called the findings "no surprise."
"Half the U.S. population needs glasses of some sort, so this does not strike me as unusual at all," he added. "And so even though many patients routinely come in concerned about having a surgical problem, it's much more often this sort of issue. I'm a surgeon, but I'm very happy to tell people, 'You don't need surgery.' And often they don't. They just need eyeglasses."