Objective: To determine the age-specific prevalence of strabismus in white and African American children aged 6 through 71 months and of amblyopia in white and African American children aged 30 through 71 months.
Design: Cross-sectional, population-based study.
Participants: White and African American children aged 6 through 71 months in Baltimore, MD, United States. Among 4132 children identified, 3990 eligible children (97%) were enrolled and 2546 children (62%) were examined.
Methods: Parents or guardians of eligible participants underwent an in-home interview and were scheduled for a detailed eye examination, including optotype visual acuity and measurement of ocular deviations. Strabismus was defined as a heterotropia at near or distance fixation. Amblyopia was assessed in those children aged 30 through 71 months who were able to perform optotype testing at 3 meters.
Main outcome measures: The proportions of children aged 6 through 71 months with strabismus and of children aged 30 through 71 months with amblyopia.
Results: Manifest strabismus was found in 3.3% of white and 2.1% of African American children (relative prevalence [RP], 1.61; 95% confidence interval [CI], 0.97-2.66). Esotropia and exotropia each accounted for close to half of all strabismus in both groups. Only 1 case of strabismus was found among 84 white children 6 through 11 months of age. Rates were higher in children 60 through 71 months of age (5.8% for whites and 2.9% for African Americans [RP, 2.05; 95% CI, 0.79-5.27]). Amblyopia was present in 12 (1.8%) white and 7 (0.8%) African American children (RP, 2.23; 95% CI, 0.88-5.62). Only 1 child had bilateral amblyopia.
Conclusions: Manifest strabismus affected 1 in 30 white and 1 in 47 African American preschool-aged children. The prevalence of amblyopia was <2% in both whites and African Americans. National population projections suggest that there are approximately 677,000 cases of manifest strabismus among children 6 through 71 months of age and 271 000 cases of amblyopia among children 30 through 71 months of age in the United States.