by CU Anschutz Medical Campus

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Clinical visits by patients suffering ocular surface eye conditions more than doubled during times when ambient particulate matter from air pollution was in the atmosphere, signaling a possible association between climate change and ocular health, according to a new study from the University of Colorado Anschutz Medical Campus.

The study, published Wednesday in the journal Clinical Ophthalmology, is among the first to look into how climate change may affect the eyes.

"The World Health Organization has declared climate change to be "the single biggest health threat facing humanity," said the study's lead author Jennifer Patnaik, Ph.D., MHS, assistant professor of epidemiology and ophthalmology at the University of Colorado School of Medicine. "Yet there are limited studies on the impact of climate change-related air pollution on ocular health."

The researchers, including Associate Professor Katherine James, Ph.D., who directs the Climate & Human Health program at the Colorado School of Public Health, examined the associations between ocular surface irritation and allergy-related daily outpatient office visits with daily ambient particular matter (PM) levels in the Denver Metropolitan area.

They obtained data of PM concentrations that were 10 micrometers or less and 2.5 micrometers or less in diameter. The researchers found 144,313 ocular surface irritation and allergy visits to ophthalmic clinics during the study period. The daily visit counts were 2.2 times higher than average when PM₁₀ concentrations were 110. The clinic visit rate ratio increased as daily concentrations increased.

The study reported that conjunctivitis was the second most common eye disease among the clinic visits in the study, representing exactly one-third of all the visits. The prevalence of ocular allergic conjunctivitis has increased worldwide and varies across regions. Socioeconomic and environmental factors such as temperature, humidity and air pollution have been proposed as reasons for the increase.

Patnaik said the health risks of air pollution and climate change span a wide range of outcomes including infectious disease, weather-related morbidity and a variety of lung, kidney and cardiovascular maladies.

"Less studied chronic diseases such as dementia have also been shown to be associated with temperature and air pollutants," she said. "Research on the topic of ocular conditions and climate is still in its early stages; therefore, more studies are needed to better understand how climate and air pollutants impact eye health."

James agreed.

"This study highlights the systemic health impacts of climate stressors including air quality, wildfires, temperature, and drought conditions and the continued need to for transdisciplinary research," she said.

The researchers hope to build and expand on these initial discoveries, said the study's senior author Malik Kahook, MD, professor of ophthalmology at the CU School of Medicine.

"These findings open the door to a deeper understanding of how environmental factors affect eye health. From a clinical standpoint, we're now seeing more evidence suggesting that particulate matter in the air isn't just affecting respiratory or cardiovascular health but also directly impacting ocular surface health," Kahook said. "Our next steps are to investigate how other air pollutants might influence eye health and to expand our focus to areas outside of Colorado. By doing so, we aim to identify preventive strategies and consider new treatment protocols tailored to address these environmental influences, ultimately protecting the most vulnerable patients in areas heavily affected by pollution."

Amy Dye-Robinson, from the Department of Biostatistics & Informatics at CU Anschutz, is a study co-author.

More information: Jennifer Patnaik et al, Association Between Particulate Matter Pollutants and Ophthalmology Visits for Ocular Surface Irritation and Allergy, Clinical Ophthalmology (2024). DOI: 10.2147/OPTH.S485199

Provided by CU Anschutz Medical Campus