Association between outdoor air pollutant exposure and refractive error changes: A retrospective clinical practice study

In recent decades, the impact of air pollution on eye health has been emphasized, but the effect of air pollution on changes in refractive error is still unknown. A comprehensive retrospective cohort study was conducted to address this, utilizing the China Medical University Hospital Clinical Research Data Repository (CMUH-CRDR). It included 4,399 participants aged 6-12 years, with 2,166 females and 2,223 males, who visited the ophthalmology department between 2003 and 2019, ensuring a robust and representative sample. The mean age was 7.04 years (± 2.20), and the change in refractive error was highest in subjects aged between 7 and 9. Cumulative exposure to delicate particulate matter (PM_2.5), carbon monoxide (CO), nitrogen oxides (NOx), ozone (O₃), and sulfur dioxide (SO₂) from the index date to the end of the follow-up was calculated to examine the association between air pollutants and myopia progression. The study found a clear dose-effect relationship, as the change in refractive error progressively increased with higher levels of PM_2.5, CO, and O₃, with exposure to the highest levels resulting in a considerably significant change (p < 0.05). For every quantile increase in PM_2.5, CO, NOx, O₃, and SO₂, the average change in refractive error decreased by approximately 0.3 D. Among the five air pollutants analyzed, CO had the most significant effect with just one unit increase. PM_2.5 had the most significant impact on refractive error in patients among different age groups (age 5-6, β: - 0.40; age 7-9, β: - 0.47; age 10-12, β: - 0.35). In conclusion, exposure to air pollutants, including PM_2.5, CO, SO₂, NOx, and O₃, increases the risk of myopic progression in children aged between 6 and 12 years old, emphasizing the need for better air quality control measures to protect children's eye health and prevent myopia progression.