Design and methodology of the Shanghai child and adolescent large-scale eye study (SCALE).

ABSTRACT

IMPORTANCE Nearly half of children suffering vision impairment reside in China with myopia accounting for the vast majority. BACKGROUND: To describe the design and methodology of the Shanghai Child and Adolescent Large-scale Eye Study (SCALE). DESIGN: The SCALE was a city wide, school-based, prospective survey. PARTICIPANTS: Children and adolescents aged 4-14 years from kindergarten (middle and senior), primary schools and junior high schools of all 17 districts and counties of the city of Shanghai, China were examined in 2012-2013. METHODS: Each enrolled child underwent vision assessment (distance visual acuity; uncorrected and with corrective device if worn) and their parent/carer completed a questionnaire designed to elicit risk factors associated with myopia. Additionally, non-cycloplegic autorefraction and ocular axial length was measured in a subset of the larger sample. MAIN OUTCOME MEASURES: Prevalence and the associated factors of vision impairment, myopia and high myopia in Shanghai. RESULTS: In 2012-2013, a total of 910 245 of the eligible 1 196 763 children and adolescents identified from census (76%, mean age 9.0 ± 2.7 years [4-14 years]) were enrolled with visual acuity screened in the city of Shanghai. Of these, 610 952 children (67% of the entire sample) underwent non-cycloplegic autorefraction and 219 188 (24% of the entire sample) had both non-cycloplegic autorefraction and axial length measurements. CONCLUSIONS AND RELEVANCE The study results will provide insights on the burden of vision impairment, myopia and high myopia in children and adolescents in a metropolitan area of China, and contribute to the policies and strategies to address and limit the burden.