Influence of Neighbourhood and Schooling on Myopia: Learnings from the Shanghai Child and Adolescent Large-Scale Eye Study (SCALE)

Abstract

Background: Environmental factors are associated with myopia but their role is not well elucidated. Little is known about the variation in prevalence by district/neighbourhood within a region and the effect of schooling. Such data may provide information on socioeconomic risk factors and/or schooling environment. We used the baseline data from the Shanghai Child and Adolescent eye study to address these questions. Methods: In a prospective, school-based, survey (2012-2013), we examined 910,245 school children (four to14 years old) across all 17 districts of Shanghai and administered non-cycloplegic auto refraction, visual acuity check, and questionnaire. We plotted age-gender standardized prevalence of myopia (≤1•0D) and high myopia (≤-5•0D) across the districts, used a regression discontinuity design to determine the impact of school entry cut-off date (1 September) by comparing refractive errors at each age, for children born pre-September to post 1-September, and performed a multivariate analysis to explore risk factors associated with myopia. Findings: Data for 606,476 children was included. Prevalence of myopia and high myopia was 32∙9% (95% CI:32•8-33•1) and 4•2% (95% CI:4•1-4•2) respectively. Myopia prevalence was twice in the inner (43•5%; highly urbanized) compared to outer districts (21•6%). From 6 years of age onwards, children born pre-September were more myopic compared to those born post 1 September (ahead in school by one year, discontinuity at 6 yrs:-0•19D (95% CI: -0•09 to-0•30D);14 yrs:-0•67D (95% CI: -0•21 to-1•14D)). Interpretation: Vision of children is influenced by schooling. In Shanghai, more children were myopic in inner district schools and, at any given age, those ahead in schooling by one year had a more myopic refractive error. Funding: 1. Three-year Action Program of Shanghai Municipality for Strengthening the Construction of the Public Health System (2011-2013) (Grant NO.2011-15) 2. Key Discipline of Public Health –Eye health in Shanghai (Grant No. 15GWZK0601) 3. High-end Research Team–Eye Health in Shanghai (GWTD2015S08; Shanghai, China) 4. Municipal Human Resources Development Program for Outstanding Young Talents in Medical and Health Sciences in Shanghai（Grant No.2017YQ019）5. Brien Holden Vision Institute. Declaration of Interest: XH- None; PS- None; SX-None; WL- None; SL- None; TN- None; RW- None; ML-None; YM None; LL- None, JW-None, RZ- None, LW- None; SR- None, JZ-None, HZ- None, XX-None. Ethical Approval: The Institutional Ethics Committee of Shanghai General Hospital, Shanghai Jiaotong University approved the protocol and the study followed the tenets of the Declaration of Helsinki for experimentation on humans. Written consent were obtained from each parents or guardians or carers of each participant.