Environment/Climate Change
Long-term Ambient Air Pollution Exposures in Relation to Glaucoma, Dry Eye Disease, and Chronic Conjunctivitis: Nationwide Cohort Study in Taiwan Yu-Kai Lin* Yu-Kai Lin Kuei-Zuo Lai Chih-Da Wu Hou-Wei Chu Chin-Kuo Chang
Long-term exposure to ambient air pollution has been associated with acute and chronic health disorders. Our eyes, the organs directly exposed to ambient air pollutants, attract special research interest regarding their susceptibility and vulnerability. Glaucoma is the second leading cause of blindness globally, right after cataracts, revealing a significant public health challenge. Additionally, ocular surface diseases, mainly referring to dry eye disease and chronic conjunctivitis, rarely cause blindness but still significantly impact sufferers’ daily lives. Previous studies explored the association between these three eye conditions and air pollution. However, the findings were inconsistent. There was a particular lack of research focusing on long-term exposures assessed with cohort study design.
The Taiwan Biobank collected data from Taiwanese-representative residents aged 20 years or older in community from 2008. We utilized data from participants at their initial enrollment between 2008 and 2020, linking to the National Health Insurance Research Database with coverage of outpatient/emergency claims and inpatient claims to determine disease diagnoses in ICD-9/-10 codes. Cumulative exposure to six major ambient air pollutants (i.e., PM2.5, PM10, NO2, SO2, CO, and O3) assessed by air pollution stations in Taiwan for a decade preceding their enrollment was estimated, standardized, and categorized into tertiles. Cox proportional hazards regression was used to examine the hazard ratios for disease risk associated with air pollution exposure in tertiles for univariable and multivariable analyses with adjustment for potential confounders.
After excluding ineligible cohort members, Cohort 1 (glaucoma as the outcome) included 130,784 individuals, among whom 1,525 developed glaucoma. Cohort 2 (dry eye disease as the outcome) included 124,590 individuals, with 3,767 cases of dry eye disease identified. Cohort 3 (chronic conjunctivitis as the outcome) consisted of 100,651 individuals, with 6,606 cases detected in follow-up. Multivariable analysis by Cox regression revealed that in Cohort 1, NO2 and CO were positively associated with glaucoma risk (aHR [95%CI]: 2nd tertile NO2=1.29 [1.14-1.47]; 3rd tertile NO2=1.51 [1.32-1.70]; 2nd tertile CO=1.29 [1.15-1.47]; 3rd tertile CO=1.62 [1.42-1.84]), while O3 was inversely associated (aHR [95%CI]: 2nd tertile O3=0.71 [0.62-0.79]; 3rd tertile=0.76 [0.67-0.86]). In Cohorts 2 and 3, all six pollutants showed significant positive associations with the risk of dry eye disease and chronic conjunctivitis after confounding control, with potential dose-response relationships observed for specific pollutants.
Our findings suggest that vehicle-related air pollutants may increase the risk of glaucoma, while ocular surface diseases of dry eye disease and chronic conjunctivitis are pervasively sensitive to major air pollution. These results highlight the need to further explore the etiology of specific pollutants that increase the risk of these diseases in future.