Climate change could increase risk of visual impairment: study

As climate change continues to warm the planet, another consequence could arise: according to a new study, higher temperatures are associated with a higher likelihood of visual impairment.

Canadian researchers found that American adults aged 65 and older were much more likely to have severe visual impairment if they lived in warmer regions than their peers who lived in colder regions.

This is the first large-scale study to examine the association between higher temperatures and vision problems, according to the authors.

They looked at average temperatures in US counties and found that the risk of having serious vision problems was 44% higher for those who lived in counties where the average temperature was above 15.5°C, compared to compared to those who lived in the cooler counties.

“This link between visual impairment and average county temperature is very concerning if future research determines that the association is causal,” said Esme Fuller-Thomson, director of the Institute of Life Course and Aging at the University of Toronto. and first author of the study. said in a statement. “With climate change, we expect global temperatures to rise. It will be important to monitor whether the prevalence of visual impairment in the elderly increases in the future.

The study, published last month in the peer-reviewed journal Ophthalmic Epidemiologytapped into a data pool of more than 1.7 million Americans.

The association between temperature and visual impairment persisted even when the researchers took into account participants’ age, gender, income and education.

“It was impactful to see that the link between visual impairment and temperature was consistent across many demographic factors, including income,” said Elysia Fuller-Thomson, a graduate student at the University of Toronto and one of the co-authors of the study. release.

To track visual impairment and cross-reference it with temperature, researchers looked at the American Community Survey, looking at data collected between 2012 and 2017 through mail, phone, and in-person interviews. The survey, which surveyed adults aged 65 and over who lived in the same state as they were born, included a question about severe visual impairment, allowing participants to indicate whether they were blind or had hard to see even with glasses.

The researchers then took temperature data from the National Oceanic and Atmospheric Administration to create averages for the included counties, and compared that data to vision data.

Counties with an average temperature below 10 C were the coolest counties in the data set. The researchers found that, compared to those in the coldest regions, the risk of severe visual impairment was 14% higher for those living in countries where the average temperature is between 10 and 12.7°C, and 24% higher for those living in counties between 12.7 and 12.7°C. 15.4 C.

Although the link existed in all demographics, there were populations for which the association was even stronger. Higher temperatures seemed to correlate more with the risk of severe vision loss in men, people aged 65 to 79 compared to those aged 80 or older, and white Americans compared to black Americans.

Co-author ZhiDi Deng, a recent pharmacy graduate from the University of Toronto, pointed out that vision loss and impairment can have a huge impact on the lives of those who have to struggle with it.

“We know that vision problems are a leading cause of disabilities and functional limitations,” Deng said in the statement. “Severe visual impairment, for example, can increase the risk of falls, fractures and have a negative impact on the quality of life of older people. Caring for visual impairments and their consequences also costs the US economy tens of billions every year. So this link between temperature and visual impairment was quite concerning. »

Although research seems to show a strong association, how temperature actually affects our vision is still unknown.

Researchers hypothesize that the cause could be due to increased exposure to ultraviolet rays, air pollution, or the degradation of folic acid that comes with higher temperatures.

However, as this study was designed solely to determine if there was an association, further research needs to be conducted to unravel the mechanisms by which soaring heat affects our eyeballs, especially since temperatures averages on the planet continue to rise.

The authors noted in their conclusion that “projected increases in global temperatures could impact older Americans affected by severe visual impairment and the associated health and economic burden.”

Fuller-Thomson said he was “very surprised” by the strong association they found.

“But this new finding raises more questions than it answers, including what the connection is between the county’s average temperature and visual impairment.”

She added that the next step for this specific team will be to determine whether heat is associated with “other disabilities in older people, such as hearing problems and limitations in daily activities.”