Exposure to air pollution with a higher NO2 concentration was associated with a larger possibility of developing cataracts. Photo: Getty Images.

Oxidative stress figures prominently in cataract formation. Air pollution has been associated with increased mortality and numerous chronic diseases, in particular through oxidative stress processes. At ARVO 2023, researchers from France presented a study investigating the relationship between air pollution exposure and incidence of cataract surgery. The team determined that exposure to a nitrogen dioxide (NO₂) concentration ≥40µg/m³ was associated with a 50% increased risk of cataracts.

The work comes from a larger study, called Alienor-3C, that was a population-based cohort analysis of residents of Bordeaux, France, aged 65 years or older, recruited in 1999 to 2000 and followed every two to three years until 2017. Cataract surgery was self-reported and checked at the slit lamp. Air pollution exposure levels—defined here by the presence of particulate matter ≤2.5µm (PM_2.5), black carbon and NO₂—during the 10 years preceding the inclusion were estimated at the participants’ geocoded residential address. The study included 829 subjects without prior cataract surgery; the mean age at inclusion was 72.6 years, and 61% were women. The median follow-up duration was 7.7 years, during which 507 participants underwent cataract surgery.

Associations of air pollution exposure with incidence of cataract were estimated and adjusted for sex, deprivation index, corticosteroid use, asthma, diabetes, hypertension, body mass index, ultraviolet exposure and smoking status, with age as a time-scale.

The 10-year median of average NO₂ concentrations was 34.1µg/m³ with a range from 25.6µg/m³ to 73.3µg/m³. Participants exposed to a concentration ≥40µg/m³, which corresponds to the current regulatory limit value in Europe, had a 50% increased risk of incident cataract surgery during follow-up compared with those exposed to <40µg/m³ (hazard ratio: 1.50). No statistically significant association was found of PM_2.5 and black carbon with risk of cataract surgery.

Although this regulatory limit value regarding exposure to a NO₂ concentration ≥40µg/m³ has been ratified since 2008 in Europe, the researchers emphasized that this has still not been achieved in several cities.

Original abstract content © Association for Research in Vision and Ophthalmology 2023.