Overview
Chinese children are some of the most short-sighted in the world, but only one in five children in poor areas who needs glasses has them. Our team has already shown in other trials that giving children free glasses leads to better grades and that free glasses have a bigger impact on grades than factors like parents' education level and the amount of money a family has. The effect on grades from glasses is greater than from other health services in school, like giving vitamins. Only about one in three children in rural China goes on to a regular, non-vocational high school. The investigators would like to show the Chinese government strong evidence of what glasses can do to help children continue their education, in order to help convince the government to carry out national programs to provide free glasses for children who need them.
Study Plan: The investigators will choose 111 middle schools at random in Liaoning, northern China, and all children in Year 1 at each school will go at random into one of two groups: either a group getting free glasses, with support from teachers to push them to wear the glasses ("Intervention") or a group getting just glasses prescriptions ("Control.") The main study outcome will be the proportion of children going on to academic (as opposed to vocational) high school, and the study is powered to detect a 10% difference in this figure between groups.The study will also assess whether children wear their glasses at school and how often they use blackboards (which disadvantage short-sighted children) vs textbooks to learn from. These other outcomes will help us to better understand the causal pathway between vision and high school attendance. We will also study the total cost of providing glasses and the teacher support to wear them per additional student attending academic high school, as well as student mental health outcomes. We will also collect data on the progression of nearsightedness. The hypothesis of this study is that providing glasses will increase academic high school attendance.
Description
Research question: Will providing free glasses to myopic rural Chinese students, with a teacher incentive to promote use, increase academic high school attendance?
Design: Cluster-randomised controlled trial
Rationale: Rural Chinese children have high myopia prevalence, but poor access to glasses. Our previous trials show giving free glasses significantly improves academic performance, with greater effect size than parental education or family income, equaling or exceeding other classroom-based medical interventions. Non-vocational (academic) high school attendance is only 30% in rural western China. Strong evidence of educational benefit from glasses is needed to spur adoption of national distribution programs.
Methods: Children in Year 1 at 111 randomly-selected middle schools in Liaoning, Northern China, will be randomized by school to receive free glasses and a trial-proven teacher-based incentive to promote wear (Intervention) or prescriptions only (Control). The main outcome 3 years later will be high school attendance (powered to detect 10% difference between study groups); secondary outcomes of compliance and use of near versus distance classroom learning aids will elucidate biological plausibility of a causal pathway between myopia correction and learning. Local knowledge and attitudes about myopia and spectacle use and intervention cost-effectiveness will be studied.
Statistical methods to be employed in the analysis and justification for the choice of sample size:
Adjusted- and unadjusted-comparison of the difference between study groups
Principal analyses for the main trial will include:
- Of attendance at academic high school after Year 3 of middle school (as opposed to following a vocational pathway or leaving school).
- of observed spectacle wear at un-announced examinations at school and for self-efficacy scores.
- of mental health outcomes after Year 1 year of intervention
Sample size: Assuming 120 students per school undergoing vision screening, 50% of children failing vision screening, 30% of these needing glasses, α=0.05, intra-class correlation=0.10, explained variation by covariates=0.40, difference between the groups in the main study outcome=10%, high-school attendance rate in the Control group=50%, a sample size of 111 middle-schools (55 or 56 in each group) will provide power=80%.
Loss to follow-up in our previous school-based trials in China, SWLW I and II, was approximately 4% over the course of one school year, and so our calculations here assume a loss to follow-up of 10% over 2-3 years. However, we have not adjusted for non-compliance because we will use a strict intention-to-treat analytic approach where children in schools allocated to the Intervention group will be analysed as such irrespective of compliance and because our intention is to test the policy of making free glasses available to those students who need them, rather than the effect of those students actually wearing the glasses. Further, our expected effect size is based conservatively on previous trials with compliance rates of approximately 40%, which we feel can be improved on in the current trial with teacher incentives as above.
Eligibility
Inclusion Criteria:
- Year 1 classes (likely age 12-13 years) at the recruited schools
- Have uncorrected (without glasses) visual acuity of ≤6/12 in both eyes;
- Refractive error meets cut-offs shown to be associated with significantly greater improvement in visual acuity when corrected (myopia ≤-0.75 diopters (D, or astigmatism (non-spherical refractive error) ≥1.00 D);
- Visual acuity can be improved to >= 6/7.5 in at least one eye with glasses.
Exclusion Criteria:
- Presence of visually-significant ocular condition besides refractive error