Prevalence of strabismus among preschool, kindergarten, and first-grade Tohono O'odham children

Background: Although the prevalence of strabismus is 2% to 5% in European-based and African-American populations, little is known about the prevalence of strabismus in Native-American populations. We report the prevalence of strabismus in children who are members of a Native-American tribe with a high prevalence of astigmatism. Methods: Subjects were 594 children enrolled in Head Start and 315 children enrolled in kindergarten or first grade (K/1) in schools on the Tohono O'odham Reservation. Distance and near cover tests were performed on each child by an ophthalmologist or optometrist, and cycloplegic refraction was obtained. Results: Strabismus was detected in 9 Head Start children (1.5%) and 3 K/1 children (1.0%). Ratio of esotropia to exotropia was 1:3 in Head Start and 1:2 in K/1. Anisometropia ≥1.00 diopter (D) spherical equivalent was present in 2 children with strabismus, and anisometropia ≥1.00 D cylinder was present in 4 with strabismus. Conclusion: The prevalence of strabismus in Tohono O'odham children is at the low end of the prevalence range reported in studies of European-based and African-American populations.