A new study found a significant association between higher ambient particulate matter levels and increased ophthalmology clinic visits for ocular surface irritation and allergy.
Climate change and air pollution are known to contribute to a variety of health risks, from lung health and communicable or non-communicable diseases, to cardiovascular and renal conditions and extreme weather event-related morbidity and mortality. This research contributes to a developing body of literature on how eye health is affected by air pollution and climate.
In a recent article in Clinical Ophthalmology, researchers highlighted findings from a US survey indicating higher temperatures are linked to increased rates of severe visual impairment. They noted ultraviolet radiation, intensified by ozone depletion, plays a significant role in eye health, with the National Eye Institute estimating that approximately 20% of cataracts are caused by UV overexposure. Air pollutants like nitric oxide, sulfur dioxide, and particulate matter (PM) also can trigger symptoms including itching, redness, swelling, and blurred vision. Environmental factors such as temperature, humidity, wind, and dust further exacerbate eye irritation, potentially disrupting the tear film and leading to dry eye disease and other chronic conditions.
While the eyes are organs that are consistently exposed to the environment and are known to be susceptible to the elements, research into specifically how they are affected by environmental changes is currently limited.
This study analyzed 144,313 visits for ocular surface irritation and allergy at the University of Colorado Sue Anschutz Eye Center from October 2015 to January 2023. Researchers examined the effects of PM 10 micrometers or less in diameter (PM10) and PM 2.5 micrometers or less in diameter (PM2.5) in cumulative exposure data. Distributed lag nonlinear models were used to assess the relationship between PM levels and visit counts. The researchers also evaluated the influence of temperature as a potential modifier.
Dry eye syndrome accounted for 47% of visits (67,510 visits), followed by conjunctivitis (47,093 visits). Higher PM10 levels were strongly associated with increased visits. For PM10 concentrations of 110 µg/m³, visit rates were 2.2 times higher than baseline. Visit rates also rose with increased exposure for PM2.5, though the gradient effect was less pronounced. The effect of PM10 on visit rates was significantly greater on days with below-average temperatures, with a rate ratio of 3.78 at 110 µg/m³ compared to 2.63 at 80 µg/m³. PM2.5 effects were not significantly influenced by temperature variations.
Health effects occurred at pollutant levels below the U.S. Environmental Protection Agency’s air quality standards, suggesting that even moderate pollution levels may adversely affect eye health.
“Visual health is a significant determinant of quality of life,” the researchers wrote. “Additional research in this field is needed, with the incorporation of more pollutant types, larger population sizes, and broader geographic areas.”
A full list of author disclosures can be found in the published research.
