A recent study shows that older Americans (age 65 and older) who live in warmer areas are at higher risk for severe vision impairment than those who live in cooler areas. The reasons behind this correlation between temperature and vision damage are unclear, but potential causes include UV exposure, air pollution, and infection.
In a study involving 1.7 million older Americans, those who lived in counties with average temperatures above 60°F had a significantly higher risk of severe vision problems than those who lived in cooler areas.
U.S. adults age 65 and older who live in warmer areas are at higher risk for serious vision problems than those who live in cooler areas, according to a recent study published in the journal Ophthalmic Epidemiology.
Residents living in areas with average temperatures between 50 and 54.99 degrees Fahrenheit have a 14% increased risk of severe visual impairment compared with areas with average temperatures below 50 degrees Fahrenheit (<10°C). The risk rises to 24% for residents in counties with average temperatures between 55 and 59.99 degrees Fahrenheit, and jumps to 44% for residents in areas with average temperatures of 60 degrees Fahrenheit (15.5°C) or higher.
"This link between visual impairment and average county temperatures is very concerning if future studies determine that this association is causal," said lead author Professor Esme Fuller-Thomson. "It will be important to monitor whether the incidence of visual impairment increases in older adults in the future. Dr. Fuller-Thomson is director of the Institute for Life Course and Aging at the University of Toronto and a professor in the Factor-Inwentash School of Social Work and the Department of Family and Community Medicine."
"We know that vision problems are a leading cause of disability and functional limitations," said co-author Zhidi Deng, a recent pharmacy graduate from the University of Toronto. "For example, severe vision impairment increases the risk of falls and fractures and negatively impacts the quality of life of older adults. Care for vision impairment and its consequences also costs the U.S. economy tens of billions of dollars each year. So the link between temperature and vision impairment is quite concerning."
The relationship between average temperature and severe visual impairment was strong regardless of participants' age, gender, income and education.
"It's compelling to see that the link between vision impairment and temperature is consistent across so many demographic factors, including income," said Elysia Fuller-Thomson, a graduate student at the University of Toronto.
The association between rising county temperatures and severe vision impairment was stronger among people aged 65 to 79 compared with those aged 80 or older, among men compared with women, and among white Americans compared with black Americans.
The observed link between average temperatures and severe visual impairment may be strong, but the mechanisms behind this relationship remain a mystery.
The study's authors hypothesized several potential causes for this relationship, including increased UV exposure, air pollution, infection, and the degradation of folate with increasing temperatures. However, the study's design does not provide precise insights into how temperature affects vision.
The study is based on six consecutive American Community Surveys (2012-2017), an annual survey of a nationally representative sample of U.S. respondents aged 65 and older. The sample analyzed included 1.7 million community-dwelling and institutionalized older adults in the United States who lived in the same state in which they were born. The question about visual impairment was: "Is this person blind, or does he/she have difficulty seeing clearly even with glasses?" Average temperature data came from the National Oceanic and Atmospheric Administration and were combined with American Community Survey data.
"We were very surprised to find such a strong link between temperature and visual impairment," said Esme Fuller-Thomson. "But this novel finding raises more questions than it answers, including what is the link between average county temperatures and visual impairment. In the future, we plan to investigate whether county-level temperatures are also associated with other disabilities in older adults, such as hearing problems and limitations in daily activities."