African Americans have a greater prevalence of open angle glaucoma (OAG) and exposure to traffic-related air pollution (TRAP). We investigated whether glaucomatous vascular changes were related to exposure of nitrogen dioxide (NO2) and particulate matter with aerodynamic diameter < 2.5 µm (PM2.5) in the African American Eye Disease Study (AFEDS).
The AFEDS is a cross-sectional, population-based cohort study conducted from 2014–2018 of 6,347 self-reported African Americans aged 40 years or older residing in 32 US census tracts of Inglewood, California. Participants completed in-home interviews and detailed eye exams including optical coherence tomography angiography (OCTA) imaging. Perfusion of radial peripapillary capillaries in healthy eyes was measured as vessel area density (VAD) calculated over 6x6 mm images centered on the optic nerve head. Exposures to NO2 (ppb) and PM2.5 (µg/m3) were estimated from spatiotemporal generalized additive models created using the EPA’s Air Quality System data. Hierarchical linear regression models of VAD on NO2 and PM2.5 were progressively adjusted for (1) sex and age; (2) education, employment, and income; (3) body mass index, glycated hemoglobin, duration of diabetes, systolic blood pressure, ever-smoking, and health insurance; and (4) axial length, OCTA signal strength, and vision insurance.
AFEDS participants (n = 1,009) were on average 58.3 years old, 64.2% female, 50% employed, 61% earned ≥ $40,000, and had 14.3 years of education. In the first three hierarchical models, lower VAD was associated with mean NO2 and PM2.5 exposure (P < 0.05). Associations in the fully adjusted models were not significant, but in the expected direction; VAD was -0.160 (95% CI: -0.377, 0.056) percent lower per 10-ppb increase in NO2, and -0.271 (95% CI: -0.588, 0.045) percent lower per 10 µg/m3 increase in PM2.5. Differences in VAD equated to an increased age of 1.6 years for NO2 and 2.7 years for PM2.5.
We found an inverse relationship between peripapillary perfusion and TRAP after adjusting for sociodemographic and clinical covariates. Associations further adjusted for ophthalmic measures were not significant, which may be due to a small true effect and overadjustment. These findings complement an emerging body of evidence that TRAP may be related to eye disease and could contribute to disparities in OAG for African Americans.