  Purpose: This study aimed to investigate the correlation between air
pollution and astigmatism, considering the detrimental effects of air pollution
on respiratory, cardiovascular, and eye health. Methods: A longitudinal study
was conducted with 127,709 individuals aged 4-27 years from 9 cities in
Guangdong Province, China, spanning from 2019 to 2021. Astigmatism was measured
using cylinder values. Multiple measurements were taken at intervals of at
least 1 year. Various exposure windows were used to assess the lagged impacts
of air pollution on astigmatism. A panel data model with random effects was
constructed to analyze the relationship between pollutant exposure and
astigmatism. Results: The study revealed significant associations between
astigmatism and exposure to carbon monoxide (CO), nitrogen dioxide (NO2), and
particulate matter (PM2.5) over time. A 10 {\mu}g/m3 increase in a 3-year
exposure window of NO2 and PM2.5 was associated with a decrease in cylinder
value of -0.045 diopters and -0.017 diopters, respectively. A 0.1 mg/m3
increase in CO concentration within a 2-year exposure window correlated with a
decrease in cylinder value of -0.009 diopters. No significant relationships
were found between PM10 exposure and astigmatism. Conclusion: This study
concluded that greater exposure to NO2 and PM2.5 over longer periods aggravates
astigmatism. The negative effect of CO on astigmatism peaks in the exposure
window of 2 years prior to examination and diminishes afterward. No significant
association was found between PM10 exposure and astigmatism, suggesting that
gaseous and smaller particulate pollutants have easier access to human eyes,
causing heterogeneous morphological changes to the eyeball.
