Effect of a Local Vision Care Center on Eyeglasses Use and School Performance in Rural China - A Cluster Randomized Clinical Trial

2,613 children screened in all 31 rural primary schools of one county; 1,200 met vision criteria (543 early referral, 657 late referral); 949 completed

Grades 4-6 (aged ~10-12) with uncorrected visual acuity 6/12 or worse, Yongshou County, Shaanxi Province, rural western China, 2014-15

Investigator-masked cluster RCT of early vs late referral to a newly established hospital-based vision centre - a waitlist design, so the contrast is timing of correction, not correction vs none. Graded C for three reasons: the outcome was a study-administered mathematics test (researcher-designed), significance rests on a ONE-SIDED test (P = .04; the 95% CI lower bound of 0.01 means a two-sided test would be borderline), and the trial covers a single county.

Adjusted effect on mathematics score comparing early with late referral was 0.25 SD (95% CI 0.01 to 0.48, one-sided P = .04), which the authors describe as equivalent to half a semester of additional learning. Only 27.7% of eligible children owned eyeglasses at baseline. At study end, 80% of the early group reported owning and 75% reported wearing eyeglasses versus 61% and 55% in the late group. The point estimate is the largest in this topic and also the least statistically robust.

Low for the treatment contrast (school-level randomization to referral timing).