Objective: To study for the first time using a clinical trial the effect of free glasses on academic performance in rural Chinese children, among whom uncorrected myopia is the leading cause of visual impairment.

Participants: Among 19,934 children in grades 4 and 5 randomly selected for visual acuity screening, 3177 (15.9%, mean age 10.5 years) had visual acuity < 6/12 in either eye without glasses correctable to > 6/12 with glasses, and were eligible for allocation. Among these, 3052 (96.0%) completed the study.

Interventions: Children were randomized by school (84 schools per arm) to one of three interventions at the beginning of the school year: free glasses provided in class, vouchers for free glasses at a local facility or glasses prescriptions only (Control group).

Results: Among 3177 eligible children, 1036 (32.6%), 988 (31.1%) and 1153 (36.3%) were randomized to Control, Voucher and Free Glasses respectively. All eligible children would benefit from glasses, but only 15% had them at baseline. Intention-to-treat analyses were performed on all 1002 (96.8%), 946 (95.9%) and 1104 (95.8%) children completing final testing in Control, Voucher and Free Glasses groups. Effect on test score was 0.11 SD (95% Confidence Interval [CI] 0.01 to 0.21, p = 0.03) comparing the Free Glasses and Control groups. Adjusted effect of providing free glasses (0.10 SD, 95% CI 0.01 to 0.20; p = 0.04) was greater than parental education (0.03, 95% CI -0.03 to 0.10) or family wealth (0.002, 95% CI -0.07 to 0.07). Closeout glasses wear was 41% (observed), 68% (self-reported) in the Free Glasses group.

Conclusions: Providing free glasses improves children's performance on mathematics testing to a statistically significant degree, despite imperfect compliance. Myopia is common and rarely corrected in this setting.

PURPOSE. We assessed the prevalence and predictors of inaccurate refractive error among rural refractionists in western China.