Air pollutant exposure is associated with visual trajectories and visual impairment in children.

Air pollution is associated with vision loss in children, but the relationship with vision trajectories has not been explored. The study was conducted as a prospective cohort in 16 districts of Shanghai from 2021 to 2023, involving 5612 children with complete survey data. Each child underwent 3-4 eye tests, including unaided visual acuity and computerized refraction. Children's air pollutant exposure levels (PM2.5, PM10, O3, SO2, NO2, and CO) were assessed using school addresses and examination dates. Latent class mixture modeling was used to identify the trajectories of changes in vision-related measurements in children. Multinomial logistic regression and Cox proportional hazards regression were used to examine the association of air pollutant exposure and visual trajectories, as well as visual impairment outcomes. The study identified three trajectory categories for children's unaided visual acuity, spherical equivalent, and four trajectory categories for axial length. Increased levels of PM2.5, PM10, O3, and SO2 exposure are associated with an increased risk of categorizing vision-related measurements into the "poor" category trajectory in children. Increased exposure to PM2.5, O3, and NO2 was associated with an increased risk of visual impairment outcomes in children with normal vision at baseline, and the effect was more significant in female and older children.