Association Between Long-Term Ambient Air Pollution and Primary Open-Angle Glaucoma: A Nationwide Cohort Study in Taiwan

Abstract

Objective

Glaucoma is a leading cause of irreversible blindness worldwide, with incidence expected to increase with the aging global population. In this study, we aimed to investigate the association between long-term exposure to ambient air pollution and the risk of primary open- angle glaucoma (POAG).

Design

Retrospective, nationwide, population-based cohort study.

Participants

The study included 590,338 individuals aged 20 years and older who had no prior diagnosis of glaucoma and at least 10 years of air pollution exposure data. Seven air pollutants were examined: sulfur dioxide, carbon monoxide, particles less than 10 micrometers in diameter, particles less than 2.5 micrometers in diameter, nitrogen oxides, nitrogen monoxide, and nitrogen dioxide.

Methods

We utilized data from the National Health Insurance Research Database (NHIRD) in Taiwan. Participants were followed from January 1, 2000, to December 31, 2013. To assess the association between air pollutants and POAG risk, air pollution data were linked to patients' residential postal codes recorded in insurance registration records. The cumulative daily average level of each pollutant was calculated for each participant over the 10-year exposure period.

Main Outcome Measures

The primary outcome was incident POAG, which was defined as patients who received an ICD-9-CM diagnosis code for POAG confirmed by an ophthalmologist during at least 2 outpatient visits, along with POAG treatment. Hazard ratios (HRs) for exposure at each standard deviation increment over ten years were calculated using Cox regression models adjusted for confounding variables.

Results

During the follow-up period, 3158 patients with POAG were identified (0.53% incidence). A 1-standard-deviation increase in the 10-year average pollutant level was associated with a significant increase in POAG risk, ranging from 40% to 108%. This association was consistently observed across pollutants, with the highest risk linked to carbon monoxide exposure; meanwhile sulfur dioxide showed the lowest increase.

Conclusions

Long-term exposure to air pollution is significantly associated with an increased risk of POAG. These findings highlight the critical need for further research and public health interventions to mitigate this risk, particularly in regions with high pollution levels.