Association between building density and screening myopia in children and adolescents: a 5-year longitudinal study from China.

BACKGROUND

This study explored the relationship between school-level built environment factors (building density and height) and myopia prevalence.

METHODS

In all 16 districts of Shanghai, students from public schools and kindergartens underwent visual acuity testing and non-cycloplegic refraction between 2019 and 2023. Building density and height within 500-metre and 1,000-metre buffers around the schools were obtained using GIS (Geographic Information System)-based spatial and network analyses from the Tianditu database. Demographic and behavioural covariates, such as age, gender, outdoor activity time and near-work time, were collected through questionnaires. Logistic mixed-effect models were used to analyse the association between the building environment and myopia, adjusting for relevant demographic and behavioural factors.

RESULTS

Data from 8 647 375 participants were analysed, with 1 116 851 followed consistently. The myopia rate among students was significantly higher during 2020-2021 compared with 2019, 2022 and 2023 (p<0.05). Myopia was more prevalent in students aged 6 to 12, with a higher average age for myopic individuals (8.13 vs 6.64 years). The average building density was higher at schools of myopic students (15.70%) versus non-myopic students (14.90%) (p<0.001). Building density near schools was negatively correlated with spherical equivalent (p<0.05), while no significant association was found with building height. The risk of myopia increased with higher building density (OR: 1.143-1.202, p<0.05), particularly in boys over 12 years old. A stronger association was observed in inner suburban areas (p<0.001).

CONCLUSIONS

Prolonged exposure to high building density may accelerate myopia progression. Urban planning should consider vision health, with regulations on building density near schools to reduce myopia risk.