According to the World Health Organization (WHO), climate change presents a “fundamental threat to human health,” affecting the physical environment as well as all aspects of both natural and human systems—including social and economic conditions and the functioning of health systems. All aspects of health are affected by climate change, WHO noted, from clean air, water and soil to food systems and livelihoods. In fact, research shows that 3.6 billion people already live in areas highly susceptible to climate change.

In addition, by 2050, climate change will place an immense strain on global health care systems, causing $12.5 trillion in economic losses and over 2 billion healthy life years lost. This was the warning from the Quantifying the Impact of Climate Change on Human Health report published in January 2024 by the World Economic Forum.

But is climate change a threat to eye health? The answer may depend on who you ask and to what degree climate change can be directly attributed to eye disease.

For example, according to an article from the World Economic Forum and the Centre for Health and Healthcare, because of the loss of the ozone layer and increased UV rays that affect the eye, global warming can contribute to the onset and acceleration of cataracts. Furthermore, it noted, traffic-related air pollution is linked to severe allergic eye diseases, glaucoma and age-related macular degeneration.

Environmental factors, including climate change, have a strong influence on both human well-being and the stability of health systems, the article noted. Finally, the predicted rise in eye diseases and disruption of ocular health services may increase the number of people who are suffering from vision impairment.

Dr. Louis Pasquale

But is climate change directly responsible for changes in eye health and eyecare services or is it part of a bigger problem? “Climate change refers to a long-term shift in temperatures and weather patterns. In this respect, climate change per se does not impact ocular health,” Dr. Louis Pasquale, chair of the Department of Ophthalmology at The Mount Sinai Hospital and the director of the Eye and Vision Research Institute of New York Eye & Ear Infirmary of Mount Sinai, told Vision Monday. “It is reasonable to ask, ‘What factors contribute to climate change and how do they impact ocular health?’ Accumulating carbon dioxide, nitrous oxide and methane—the so-called gasses in the atmosphere—contribute to climate change. Again, none of these greenhouse gasses impact ocular health directly to the best of my knowledge. So, the effects of climate change on ocular health are indirect and difficult to quantify.”

He further explained, “Extreme climate conditions can affect ocular health. For example, excess ocular UV exposure has been linked to pterygium formation, photokeratitis, cataracts and exfoliation glaucoma. Sunglasses that afford UV protection help maintain good ocular health.”

Viola Kanevsky, OD.

“Aside from increases in dry eye from a hotter, harsher climate, the main concern would be conditions that arise from overexposure to UV rays,” said Viola Kanevsky, OD.

“A loss of the ozone layer increases exposure, and areas of the planet where the ozone is thinnest certainly show higher rates of comorbidities such as skin cancer, pterygium, macular degeneration and cataracts.”

To better understand eye health care needs of the future, the National Eye Institute (NEI) convened a panel of experts last April to discuss the potential effects of a changing climate on eye health and vision. The session described estimates for future eye disease burden and population changes, gaps in health care resiliency and the ability to provide care in diverse regions, and the need for more research into environmental drivers of eye disease.

Speakers at the event included Hugh Taylor, MD, University of Melbourne; Nisha Acharya, MD, University of California, San Francisco; Cassandra Thiel, Ph.D., New York University; and Serge Resnikoff, MD, Ph.D., University of New South Wales. The session was moderated by Gyan Prakash, Ph.D., NEI associate director for International Research.

Dr. Taylor noted that aging populations around the globe will lead to more blinding eye disease, including cataract, glaucoma and age-related macular degeneration (AMD). Rising temperatures will drive populations away from the equator, according to Dr. Resnikoff, increasing the eye health care burden in other areas.

Dr. Acharya noted that there is a poor understanding of how particulate air pollutants, like those emitted by wildfires, drive chronic eye inflammation and contribute to diseases like uveitis, cataract and AMD. In addition, she said, most programs exploring the impacts of climate change on health don’t cover eye health.

Of course, prevention plays a huge role in maintaining ocular health, regardless of the environment or other contributing factors. “Periodic eye exams and sunglass wear are good strategies to maintain ocular health, regardless of the changing climate,” said Dr. Pasquale. “Don’t underestimate how much sun your eyes are exposed to when you are at the beach, on a boat, or even out in the snow on a sunny day. It is not hat wear that will protect your eyes, it will be a good pair of sunglasses.”

“UV protective eyewear, headwear and skin lotions should be used when outdoors. Also, outdoor activity during periods when the sun is high over the horizon should be limited,” added Dr. Kanevsky.