Prevalence and causes of visual impairment in African-American and Hispanic preschool children: the multi-ethnic pediatric eye disease study.

Purpose: To determine the prevalence and causes of decreased visual acuity (VA) in a population-based study of minority preschool children.
Design: Population-based, cross-sectional study.
Participants: Children 30 to 72 months of age in 44 census tracts in Los Angeles County.
Methods: A population-based sample of children underwent comprehensive ophthalmic evaluation including monocular VA testing, cover testing, cycloplegic autorefraction, anterior segment and fundus evaluation, and VA retesting with refractive correction. The prevalence and etiology of decreased VA were determined, for both presenting and best-measured VA, and better eye and worse eye.
Main Outcome Measures: Prevalence of decreased presenting and best-measured VA with an identifiable ophthalmic etiology.
Results: Presenting VA was assessed in 3207 children and best-measured VA in 3364 children. Although nearly one third of cases of worse-eye decreased presenting VA were without an identifiable ophthalmic etiology, this proportion decreased with increasing age. Decreased presenting VA that resolved with retesting and was associated with uncorrected refractive error was present in the worse eye of 4.3% of African-American children and 5.3% of Hispanic children, and in the better eye of 1.9% of African-American children and 1.7% of Hispanic children. Decreased best-measured VA that was not immediately correctable with spectacles and that was because of ocular disease, unilateral or bilateral amblyopia, or probable bilateral ametropic amblyopia, was seen in the worse eye of 1.5% of African-American and 1.9% of Hispanic children, and in the better eye of 0.8% of African-American and 0.6% of Hispanic children. Amblyopia related to refractive error was the most common cause.
Conclusions: More than 5% of African-American and Hispanic preschool children in Los Angeles County have either correctable visual impairment from uncorrected refractive error or visual impairment from amblyopia related to refractive error.