High levels of air pollution may increase your chances of developing the vision-robbing illness glaucoma, a new study suggests.
Researchers analysed data from more than 111 000 people across Great Britain who underwent eye tests from 2006 to 2010. They found that the risk of glaucoma – the leading cause of irreversible blindness – was at least 6% greater among those who lived in areas with the highest levels of fine particulate matter (PM2.5) air pollution.
No causal association
The participants were also much more likely to have a thinner retina, one of the eye changes that occur in glaucoma progression.
"We have found yet another reason why air pollution should be addressed as a public health priority, and that avoiding sources of air pollution could be worthwhile for eye health alongside other health concerns," said study author Dr Paul Foster, from the Institute of Ophthalmology at University College London (UCL) and Moorfields Eye Hospital in London.
The study was published in the journal Investigative Ophthalmology & Visual Science.
"While we cannot confirm yet that the association is causal, we hope to continue our research to determine whether air pollution does indeed cause glaucoma, and to find out if there are any avoidance strategies that could help people reduce their exposure to air pollution to mitigate the health risks," Foster said in a UCL news release.
Glaucoma affects more than 60 million people worldwide. The most common cause is a build-up of pressure from fluid in the eye, which damages the optic nerve that connects the eye to the brain.
Constriction of blood vessels
"Most risk factors for glaucoma are out of our control, such as older age or genetics. It's promising that we may have now identified a second risk factor for glaucoma, after eye pressure, that can be modified by lifestyle, treatment or policy changes," Foster said.
"Air pollution may be contributing to glaucoma due to the constriction of blood vessels, which ties into air pollution's links to an increased risk of heart problems. Another possibility is that particulates may have a direct toxic effect damaging the nervous system and contributing to inflammation," said study first author Sharon Chua, also from the UCL Institute of Ophthalmology and Moorfields Eye Hospital.
Previous research has shown that glaucoma rates are 50% higher in urban areas than in rural areas, and these new findings suggest that air pollution may be a factor in that difference.
Given that the study was conducted in the United Kingdom, "which has relatively low particulate matter pollution on the global scale, glaucoma may be even more strongly impacted by air pollution elsewhere in the world. And as we did not include indoor air pollution and workplace exposure in our analysis, the real effect may be even greater," Foster said.
Air pollution has also been linked with an increased risk of heart and lung diseases, and brain conditions such as Alzheimer's disease, Parkinson's disease and stroke.
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