Prevalence and incidence of myopia among children and adolescents aged 6–19 years: a prospective cohort study

Myopia is a significant public health concern worldwide, especially in China. While previous studies have primarily focused on prevalence, incidence data remain limited. Therefore, this study aimed to estimate the prevalence and incidence of myopia among school-aged children and adolescents in Guangdong Province (a southern part of China), and to examine demographic factors associated with incident myopia. This prospective cohort study was based on the Surveillance for Common Disease and Health Risk Factors among Students in Guangdong Province from 2019 to 2023. Screening-defined myopia was defined as uncorrected visual acuity < 5.0 and spherical equivalent (SE) < − 0.50 diopters (D) in either eye, and high myopia as SE < − 6.00 D in at least one eye. Age-standardized prevalence, cumulative incidence, and incidence rate (per 1,000 person-years) of myopia were calculated based on the 7th National Census population. Associations between demographic factors and incident myopia were assessed using multivariable logistic and Poisson regression models. A total of 197,685 participants were included, with mean age of 10.82 (standard deviation, SD, 3.31) years and 104,117 boys (52.67%). The baseline crude and age-standardized prevalence of screening-defined myopia were 45.64% (95% confidence interval (CI): 45.42%, 45.85%) and 55.14% (95% CI: 54.75%, 55.54%), respectively. High myopia prevalence was 3.27% (crude) and 5.13% (age-standardized). During 5-year study period, 32,012 (29.79%) new screening-defined myopia cases were identified, with an age-standardized cumulative incidence of 28.00% (95% CI: 27.53%, 28.49%) and incidence rate of 77.98 cases per 1,000 person-years. Girls, younger children (aged 6–9 years), students in grades 4–9, and urban students showed significantly higher cumulative incidence and incidence rate, while students from minority ethnic groups had a lower risk. Myopia burden among school-aged populations was substantial, with high prevalence and incidence, particularly among girls, younger students, and urban students. These findings support the urgent need for early, school-based prevention and intervention strategies targeting high-risk groups.