Refractive error causes most vision problems in US

By Karla Gale

NEW YORK (Reuters Health) - In a survey of visual impairment in the US, researchers at the National Eye Institute (NEI) found that more than four out of five individuals with impaired vision could achieve good visual acuity if their refractive error was corrected.

Dr. Susan Vitale and her associates in Bethesda, Maryland, obtained data from the National Health and Nutrition Examination Survey for 1999-2002, and report their findings for visual impairment in the Journal of the American Medical Association.

Approximately 13,000 individuals, age 12 years or older, had their vision assessed, with visual impairment defined as distance visual acuity of 20/50 or worse in the better-seeing eye. Visual impairment due to uncorrected refractive error referred to acuity that could be improved to 20/40 or better, the standard criterion for obtaining a driver's license in most states.

A total of 1190 persons (6.4 percent) had with visual impairments, and most of these cases (83.3 percent) could be corrected with eyeglasses or contact lenses.

Based on these data, the authors estimate that 14 million residents in the US have visual impairment, and more than 11 million could achieve good visual acuity with appropriate correction.

The data were standardized by age and within the racial and ethnic categories described in the 2000 census, co-author Dr. Mary Frances Cotch told Reuters Health.

Rates of visual impairment were highest among Hispanics, Asians, and individuals of mixed race, as well as those with diabetes, people without private health insurance, and those with fewer years of education. Individuals with incomes at least twice as high as the poverty level were less likely to have uncorrected refractive error.

The assessments did not include retinal examinations, Cotch noted, so they were unable ascribe the cause of impairments other than uncorrected visual acuity.

"Our job at NEI is to uncover conditions that affect the health of the American public," she continued. "Then we rely on other federal agencies and other local, state and national organizations that could develop programs to respond to the unmet need."

She added that the NEI has information on their Web site (http://www.nei.nih.gov/health/financialaid.asp) for organizations that assist in providing glasses to children or other individuals who can't afford them on their own, such as Vision USA and Sight for Students.

SOURCE: Journal of the American Medical Association, May 10, 2006.