Air pollution could be linked to a higher risk of glaucoma, according to a new study.
Scientists observed that living in a more polluted area was associated with a greater likelihood of having the debilitating eye condition that can cause blindness.
The research team found that people in the most-polluted 25% of areas were at least 6% more likely to report having glaucoma than those in the least-polluted quartile.
They were also significantly more likely to have a thinner retina, one of the changes typical of glaucoma progression.
Experts suggest particulates may damage the nervous system and contribute to inflammation.
According to the study published in Investigative Ophthalmology & Visual Science, eye pressure was not associated with air pollution.
The researchers say this suggests air pollution may affect glaucoma risk through a different mechanism.
Lead author Professor Paul Foster, of University College London’s Institute of Ophthalmology, said: “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.
“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.”
The findings were based on 111,370 participants of the UK Biobank study cohort who underwent eye tests from 2006 to 2010 at sites across Britain.
The participants were asked whether they had glaucoma and underwent ocular testing which measured intraocular pressure, and a laser scan of the retina.
Their data was linked to air pollution measures for their home addresses, from the Small Area Health Statistics Unit, with the researchers focusing on fine particulate matter – equal or less than 2.5 micrometres in diameter, or PM2.5.
The study’s first author, Dr Sharon Chua of UCL’s Institute of Ophthalmology and Moorfields Eye Hospital, 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.”
Particulate matter exposure is one of the strongest predictors of mortality among air pollutants, scientists say.
Prof Foster added: “We found a striking correlation between particulate matter exposure and glaucoma. Given that this was in the UK, 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.”