Visual acuity and refraction by age for children of three different ethnic groups in Paraguay

Purpose: To characterize refractive errors in Paraguayan children aged 5-16 years and investigate effect of age, gender, and ethnicity. Methods: The study was conducted at 3 schools that catered to Mennonite, indigenous, and mixed race children. Children were examined for presenting visual acuity, autorefraction with and without cycloplegia, and retinoscopy. Data were analyzed for myopia and hyperopia (SE <= -1 D or -0.5 D and >= 2 D or >= 3 D) and astigmatism (cylinder >= 1 D). Spherical equivalent (SE) values were calculated from right eye cycloplegic autorefraction data and analyzed using general linear modelling. Results: There were 190, 118, and 168 children of Mennonite, indigenous and mixed race ethnicity, respectively. SE values between right/left eyes were nonsignificant. Mean visual acuity (VA) without correction was better for Mennonites compared to indigenous or mixed race children (right eyes: 0.031, 0.090, and 0.102 logMAR units, respectively; P<0.000001). There were 2 cases of myopia in the Mennonite group (1.2%) and 2 cases in the mixed race group (1.4%) (SE < -0.5 D). The prevalence of hyperopia (SE >= 2 D) was 40.6%, 34.2%, and 46.3% for Mennonite, indigenous and mixed race children. Corresponding astigmatism rates were 3.2%, 9.5%, and 12.7%. Females were slightly more hyperopic than males, and the 9-11 years age group was the most hyperopic. Mennonite and mixed race children were more hyperopic than indigenous children. Conclusions: Paraguayan children were remarkably hyperopic and relatively free of myopia. Differences with regard to gender, age, and ethnicity were small.