Ambient air pollution exposure and incidence of cataract surgery: the prospective 3City-Alienor study

Abstract

Purpose : Cataract is the leading cause of blindness and is responsible for the visual impairment of 65.2 million people worldwide. It is a multifactorial disease, involving oxidative stress mechanisms. Air pollution is associated with increased mortality and chronic diseases, in particular through oxidative stress processes. To date, few studies, including none from Europe, have explored the link between air pollution and cataract. The aim of our study was to investigate the relationship between air pollution exposure and incidence of cataract surgery.

Methods : The 3C-Alienor study is a population-based cohort of residents of Bordeaux, France, aged 65 years or more, recruited in 1999-2000 and followed every 2-3 years until 2017. Cataract surgery was self-reported and checked at slit-lamp. Air pollution exposures (particulate matter <= 2.5 microns (PM_2.5), black carbon (BC), nitrogen dioxide (NO₂)) during the 10 years preceding the inclusion were estimated at the participants’ geocoded residential address using Land-Use Regressions models. Associations of air pollution exposure with incidence of cataract were estimated using multivariate Cox proportional hazard models adjusted for sex, deprivation index, corticosteroid use, asthma, diabetes, hypertension, body mass index, ultra-violet exposure, smoking status, with age as time-scale.

Results : The study included 829 subjects without prior cataract surgery; the mean age at inclusion was 72.6 years (Standard deviation (SD): 4.2) and 61% were women. The median (Interquartile-range (IQR)) [Minimum-maximum] follow-up duration was 7.7 years (5.8) [0.01-17.3] during which 507 participants underwent cataract surgery. The 10-year median (IQR) of average of NO2 concentrations was 34.1 µg/m3 (7.5) with range from 25.6 to 73.3 µg/m3. Participants exposed to a concentration ≥40 µg/m3, which corresponds to the current regulatory limit value in Europe, had a 50% increased risk of incident cataract surgery during follow-up compared to those exposed to <40 µg/m3 (HR=1.50, CI (1.19, 1.90), p<0.001). No statistically significant association was found of PM2.5 and BC with risk of cataract surgery.

Conclusions : Exposure to a NO2 concentration ≥40 µg/m3, was associated with a 50% increased risk of cataract. Although this regulatory limit value has been ratified since 2008 in Europe, it is still not achieved in several cities.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.