Abstract

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.

Design: Cluster-randomized, investigator-masked, controlled trial carried out in the 2012-2013 school year.

Setting: Primary schools (n=252) randomly selected on a population basis in two prefectures in western China.

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).

Main Outcome: Main study outcome was year-end score on a specially-designed mathematics test, adjusted for baseline score, expressed in units of standard deviation (SD).

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.