Safety of eyeglasses wear for visual acuity among middle school students in northwestern rural China: a cluster-randomised controlled trial

OBJECTIVE: To assess the effect of free eyeglasses provision on visual acuity among middle school students in northwestern rural China. METHODS AND ANALYSIS: Among 31 middle schools randomly selected from 47 middle schools in northwestern rural China, students were randomly allocated by school to one of two interventions: free eyeglasses (intervention group), and eyeglasses prescriptions given only to the parents (control group). The main outcome of this study is uncorrected visual acuity after 9 months, adjusted for baseline visual acuity. RESULTS: Among 2095 students from 31 middle schools, 995 (47.5%) failed the visual acuity screening, 515 (51.8%, 15 schools) of which were randomly assigned to the intervention group, with the remaining 480 students (48.2%, 16 schools) assigned to the control group. Among these, a total of 910 students were followed up and analysed. Endline eyeglasses wear in the intervention group was 44%, and 36% in the control group. Endline visual acuity of students in the intervention group was significantly better than students in the control group, adjusting for other variables (0.045 LogMAR units, 95% CI 0.006 to 0.084, equivalent to 0.45 lines, p=0.027), and insignificantly better only for baseline visual acuity (difference of 0.008 LogMAR units, 95% CI −0.018 to 0.034, equivalent to 0.08 lines). CONCLUSION: We found no evidence that receiving free eyeglasses worsened visual acuity among middle school students in northwestern rural China. TRIAL REGISTRATION NUMBER: ISRCTN17141957.