# Climate change and ocular health: temperature-pollution synergies amplify uveitis burden

## TL;DR

Cold and hot temperature extremes, especially when combined with pollution or humidity, are linked to increased uveitis outpatient visits in Shanghai.

## Contribution

This study identifies synergistic effects of temperature and pollution on uveitis, revealing non-linear and lagged associations.

## Key findings

- Cold temperatures (-4°C) with high humidity and PM2.5 increase uveitis visits up to 35%.
- Hot temperatures (33–34°C) under low humidity raise uveitis visits by up to 162%.
- The strongest associations occur at lags of 0–1 and 12–14 days after temperature exposure.

## Abstract

Uveitis, an inflammatory eye disease, exhibits seasonal patterns, which suggest environmental influences. This study examines the link between average temperature and uveitis outpatient visits, considering air pollution’s modifying effects.

We analyzed uveitis outpatient data (n = 8,090) from a major hospital in Shanghai between 2017 and 2023, along with meteorological and air pollutant data. A distributed lag non-linear model (DLNM) was used to assess the associations between temperature and outpatient visits, adjusting for humidity, pollutants, and temporal factors.

A non-linear relationship exists between temperature and uveitis visits. Lower temperatures increased visits, with peak relative risk at −4°C lagged by 1 day (RR = 1.351, 95%CI: 1.069–1.706). Significant associations were found at lags 0–1 and 12–14, with the highest risk at lag 14 (−4°C, RR = 1.257, 95%CI: 1.113–1.420). Stratified analyses showed stronger associations in males and individuals under 60 years. High humidity and elevated PM2.5 levels strengthened the cold temperature association, while extremely high temperatures (33–34°C) increased visits under low humidity (RR = 2.625, 95%CI: 1.034–6.668 at 34°C).

Temperature extremes are linked to increased uveitis outpatient visits in Shanghai, particularly with cold temperatures in high-humidity and high-PM2.5 environments, and hot temperatures under low humidity.