Epidemiology of Myopia Occurrence, Development, and Correction in Primary School Students in China: A Retrospective Cohort Study.

Background: The purpose of this study is to assess the occurrence, progression, and correction of myopia in primary school students in China over the past few years. Methods: This longitudinal cohort study was based on a 5-year follow-up sample of first-year students enrolled in 2019. Data were collected from students' regular physical examinations conducted between September and December every year. Results: A total of 6790 primary students were included in this analysis, of whom 3658 (53.8%) were boys. The spherical equivalent of students' binocular vision demonstrated a marked annual decline. The myopia rate gradually escalated from 23.4% in Grade 1 to 80.1% in Grade 5. The largest increase, amounting to 30%, occurred during the grade 1-2. A negative correlation was found between the spherical equivalent values and students' height, particularly among girls in grades 4 and 5. In grades 4 and 5, the rate of myopia among girls was approximately 5% higher than that among boys. Among students with moderate to severe myopia, the rate of spectacle wear for vision correction were 21.9%, 47.9%, 58.0%, 67.1%, and 71.5% in grades 1-5, respectively. Among students with spectacle wear, the rate of those with qualified vision correction reaching about 85%. Conclusions: Over 5 years from 2019 to 2023, the myopia rate among observed primary school students, particularly moderate and severe cases, has been alarmingly high, with inadequate vision correction. Additionally, myopia rates differ among students of various genders and heights.