Myopia appears to have become more common

"Myopia, or nearsightedness, is a common condition in which the image of an object seen in the distance is focused anterior to the retina and is consequently out of focus when it reaches the retina," according to background information in the article. "Blurred vision caused by myopia can be treated by corrective lenses (eyeglasses or contact lenses) or refractive surgery."

Susan Vitale, Ph.D., M.H.S., and colleagues at the National Eye Institute, National Institutes of Health, Bethesda, Md., compared U.S. population prevalence estimates for myopia from the National Health and Nutrition Examination Survey (NHANES) in 4,436 black and white participants from 1971 to 1972 and in 8,339 black and white participants from 1999 to 2004. Participants' ages ranged from 12 to 54. The same methods were used to determine myopia during 1971 to 1972 and 1999 to 2004.

"The prevalence of myopia for individuals aged 12 to 54 years was statistically significantly higher in 1999 to 2004 than in 1971 to 1972 (41.6 percent vs. 25 percent, respectively)," the authors write. "Prevalence estimates were higher in 1999 to 2004 than in 1971 to 1972 for black individuals (33.5 percent vs. 13 percent, respectively) and white individuals (43 percent vs. 26.3 percent, respectively) and for all levels of myopia severity."

Although myopia can be treated with corrective lenses, its high prevalence costs Americans billions of dollars every year. "The question of whether myopia prevalence is increasing is therefore important to health planners and policy makers," the authors conclude. "Identifying modifiable risk factors for the development of myopia could lead to the development of cost-effective interventional strategies."

The NHANES is sponsored by the National Center for Health Statistics, Centers for Disease Control and Prevention. Additional funding for the NHANES Vision Component was provided by an Intramural Research Program of the National Eye Institute, National Institutes of Health.