The National Health and Nutrition Examination Survey is an on-going, national, comprehensive health survey of the civilian, non-institutionalized US population. A vision assessment was added in 1999 and is on-going. All sample persons aged 12+ years undergo a vision assessment in which measures of the eyeglass prescription in people who wear glasses for distance, tests the distance visual acuity of sample persons with and without correction (glasses/contacts) and an objective refraction (incorporating also an evaluation of the corneal curvature of the eye) are obtained. A visual acuity at near is assessed in persons age 50 years and over. In addition, personal interview data on functional measures related to vision are collected on people over the age of 49 years. Data from the vision component in NHANES will be used to estimate the prevalence of visual impairment in the U.S. population, describe the distribution of refractive error in the U.S. population, evaluate the impact of vision loss on functional abilities, and relate visual impairment to other health and disease measures. The prevalence data will be used as baseline measures for Healthy People 2010. Revisions to the vision interview protocol and modifications to its implementation were made last fiscal year. Close scrutiny of accruing data for quality control purposes in the early 2003 data collection prompted further refinements. Data collection is on-going. Vision data, collected since 1999, have not yet been released by the National Center for Health Statistics for analytic purposes. A release of data collected over the 1999-2002 time period is projected to occur in 2004.
