Air pollution is linked to irreversible vision loss, study finds



Air pollution could cloud your vision later in life, according to a large study that found a link between fine particle air pollution and macular degeneration, an age-related eye disease that can lead to irreversible blindness.

The results are a clear reminder of the many ways air pollution can be harmful to our health, even though this research is still in its early stages.

“Our findings add to the growing evidence for the harmful effects of ambient air pollution, even at relatively low exposure to ambient air pollution,” the study authors explain. write in their paper.

Air pollution is a global problem that many cannot escape, with the World Health Organization (WHO) saying more than 90 percent of the world’s population live in places where air quality levels exceed limits set for pollutants that pose health risks.

The biggest public health concerns about poor air quality are pollutants such as particulate matter (dust, soot, etc.), ground-level ozone, nitrogen dioxide, sulfur dioxide and others. gases, which are emitted by motor vehicles, heavy industry and wood fires.

Fine particles, called PM2.5 in short, are of particular concern. These microscopic particles smaller than 2.5 microns can penetrate deep into the lungs and enter the bloodstream, causing inflammation around the body.

Repeated exposure to such pollutants can irritate people’s eyes and throat, causing breathing difficulties. In addition, ambient air pollution is responsible for 43% of deaths from chronic obstructive pulmonary disease and more than a quarter of all deaths from chronic obstructive pulmonary disease. lung cancer, heart disease or stroke.

In this study, the focus was on Macular degeneration (AMD), a condition in which a person’s vision worsens with age, leading to increased vision loss and potentially even blindness.

The disease is linked to leaky blood vessels at the back of the eye and small patches of fat and protein that build up on the macula, the part of the eye in the center of the retina. Genetics and being a smoker are among the main risk factors for this disease.

For their analysis, the researchers extracted data on thousands of people enrolled in the British Biobank and estimated annual levels of air pollution around their homes using other publicly available datasets.

As of 2006, nearly 116,000 people were asked to report whether their doctor had diagnosed them with macular degeneration.

Of this larger group, 52,062 people also had an eye exam and retinal thickness measurement, as an indicator of any changes in their eye health.

What the study found was that people who were exposed to higher levels of fine particle air pollution had higher rates of self-reported AMD.

Exposure to other pollutants, including nitrogen dioxide but not coarse particles, was also associated with changes in retinal thickness, detected by imaging.

But don’t be swayed by the big numbers alone. Only a tiny fraction of people were actually diagnosed with AMD during the study – and remember, while this observational study may draw our attention to the trends and patterns seen in a population, it cannot. establish the cause.

In other words, researchers are doing what they can in population-wide studies like these to account for other factors, such as lifestyle, that influence disease risk, but suffice to say, trying to unravel the precise health impacts of exposure to air pollution in a world where everything is interconnected is not always clear.

Researchers to suggest that air pollution can affect the eye in a roundabout way through inflammation and oxidative stress, two defense mechanisms where the body fights foreign matter and tries to detoxify chemical species, respectively. But more research will be needed to examine this plausible link.

This is not the first time, however, that air pollution has been linked to eye disease. A Study 2019 examine the global burden of glaucoma found that higher average fine particle levels were associated with more cases of glaucoma, which affects the optic nerve.

“The good news is that indoor air pollution can be controlled and the diseases it causes prevented”, writing Philip Landrigan, a public health physician and epidemiologist at the Icahn School of Medicine in Mount Sinai, New York, who was not involved in the study.

Applying air quality standards and reducing emissions from coal-fired power plants – by switching to clean fuels and ultimately renewable energy sources – would both be effective strategies for reducing pollution. atmospheric.

We saw how quickly the skies cleared in the early months of the coronavirus pandemic, which blocked air traffic and pulled cars off the road as people stayed at home. While such drastic changes were ultimately not sustainable, the momentary relief from the air pollution that typically blankets cities has shown us what is possible.

“Cities and countries will have to switch to non-polluting energy sources, encourage active travel, improve their transport networks, [and] rethinking industrial processes to eliminate waste ”, writing Landrigan.

“These changes will not be easy. They will have to overcome strong opposition from powerful vested interests. But fortunately, the technical, institutional and policy tools needed to control air pollution are already at hand.”

In the meantime, more research will be needed to gather evidence on the long-term risks that air pollution poses to eye health.

The research was published in the British Journal of Ophthalmology.



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