Prevalence and incidence of myopia and high myopia among children and adolescents in Qingdao, China (2022–2024): a longitudinal study

Myopia has emerged as a major global public health concern, especially among children and adolescents in China. This study assessed the prevalence and incidence of myopia and high myopia among school-aged children in Qingdao, examining associations with grade, sex, and district. From 2022 to 2024, 2,903,827 students (grades 1–12) from 1,674 schools underwent annual ophthalmic examinations. The spherical equivalent (SER) was measured via noncycloplegic autorefraction; myopia was defined as SER ≤ − 0.50 D and UDVA > 0 logMAR, and high myopia was defined as SER ≤ − 6.0 D. Prevalence was estimated annually. The cumulative incidence was calculated for students followed for two years. Logistic regression and Cox proportional hazards models were used to evaluate demographic and geographic risk factors. Between 2022 and 2024, the prevalence of myopia among Qingdao schoolchildren increased from 56.4% to 58.2%, whereas the prevalence of high myopia decreased slightly from 5.3% to 4.5%. Among students without myopia at baseline, the 2-year cumulative incidence of myopia was 48.8%; for those with high myopia, it was 4.1%. Both the prevalence and incidence of myopia rose rapidly in early grades and plateaued later: the prevalence increased from 24.6% in Grade 1 to 88.8% in Grade 11, and the incidence increased from 35.4% in Grade 1 to 67.3% in Grade 9. The incidence of high myopia remained low in primary school but accelerated in adolescence, with the prevalence exceeding 20% in Grade 12 and the incidence rising from 0.4% in Grade 1 to 11.0% in Grade 10. Girls consistently had higher risks than boys. The 2-year incidence was greater in girls (myopia: 51.5% vs. 46.6%; high myopia: 4.4% vs. 3.8%). Myopia prevalence was high across all district types; however, high myopia in both prevalence and incidence was disproportionately concentrated in rural and semi‑urban districts. Female sex, higher grade, and district location were independent risk factors. Myopia and high myopia show high prevalence and incidence among Qingdao students, with clear grades, gender, and regional disparities. Early identification and tailored gender, grade, and district-specific interventions are essential to reduce progression and future high myopia burden.