Effect of Eyeglasses on Student Academic Performance: What Matters? Evidence from a Randomized Controlled Trial in...

Although eyeglasses have been considered a cost-effective way to combat myopia, the empirical evidence of its impacts on improving learning outcomes is inconsistent. This paper provides empirical evidence examining the effect of providing eyeglasses on academic performance between provinces with a different economic level in western China. Overall, we find a significant impact in Intention-to-Treat analysis and a large and significant local average treatment effect of providing free eyeglasses to students in the poor province but not in the other. The difference in impact between the two provinces is not a matter of experimental design, implementation, or partial compliance. Instead, we find that the lack of impact in the wealthier provinces is mainly due to less blackboard usage in class and wealthier households. Our study found that providing free eyeglasses to disadvantaged groups boosted their academic performance more than to their counterparts.