ScienceDaily (Aug. 12, 2008) — About half of U.S. adults age 20 and older have refractive errors, or eye problems that result in less than 20/20 vision, according to a report in the August issue of Archives of Ophthalmology, one of the JAMA/Archives journals.

Refractive error accounts for nearly 80 percent of vision impairment in U.S. residents 12 years and older, according to background information in the article. It occurs when the eye cannot properly focus light, resulting in nearsightedness, farsightedness or astigmatism, an irregular curve of the eye's cornea. Providing eye care to individuals age 12 and older who need glasses or contacts is estimated to cost between $3.8 and $7.2 billion per year.

Susan Vitale, Ph.D., M.H.S., and colleagues at the National Eye Institute, Bethesda, Md., analyzed data from the National Health and Nutrition Examination Survey (NHANES), an ongoing nationally representative survey conducted by the Centers for Disease Control and Prevention. Demographic characteristics were collected during in-person interviews and a vision examination was conducted.

Among 12,010 participants age 20 and older who completed the survey between 1999 and 2004 and had complete data available, about half had some type of refractive error. This included 3.6 percent who were farsighted, 33.1 percent who were nearsighted and 36.2 percent who had astigmatism. The researchers also found that:

• Nearsightedness was more common in women (39.9 percent) than in men (32.6 percent) among 20- to 39-year-olds
• Individuals age 60 and older were less likely to have nearsightedness and more likely to have farsightedness and astigmatism than younger participants; in the older age group, men (66.8 percent) were more likely to have refractive error than women (59.2 percent)
• Mexican-Americans were less likely to have any type of refractive error (44.4 percent) than were non-Hispanic whites (53.4 percent) or non-Hispanic blacks (49.3 percent)
• The prevalence of any refractive error increased with age, from 46.3 percent among those age 20 through 39 to 50.6 percent among those age 40 through 59 and 62.7 percent among those age 60 and older

"Refractive error is, therefore, the most common condition affecting the ocular health of the U.S. population, involving young adults, middle-aged persons and older adults of all ethnicities," the authors conclude. "Accurate, current estimates of the prevalence of refractive error are essential for projecting vision care needs and planning for provision of vision care services to the many people affected."

Journal reference:

1. Susan Vitale, PhD, MHS; Leon Ellwein, PhD; Mary Frances Cotch, PhD; Frederick L. Ferris III, MD; Robert Sperduto, MD. Prevalence of Refractive Error in the United States, 1999-2004. Archives of Ophthalmology, 2008; 126 (8): 1111 DOI: 10.1001/archopht.126.8.1111

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