Air pollution linked to blindness as scientists say particles may hinder blood vessels in eyes

Sarah Knapton
Particles may damage the blood vessels in eyes and increase the change of glaucoma  - PA

Air pollution could be contributing to one of the leading forms of blindness in Britain, scientists fear, after discovering the risk of glaucoma rises in smoggy areas.

Around half a million people in Britain suffer from glaucoma, which occurs when the optic nerve which connects the eye to the brain becomes damaged, usually by a build up a fluid, which leads to vision loss if not caught early.

It is estimated that in the UK about one in 50 of people older than 40 have glaucoma, and this rises to almost 10 per cent in people older than 75.

Previously, the condition has been linked to high blood pressure and eye injury, but a new study by University College London (UCL) suggests that air pollution may also play a role. 

People living in neighbourhoods with higher amounts of fine particulate matter pollution - such as from engines - were at least six per cent more likely to suffer glaucoma than those in the least-polluted areas.

Highly polluted areas had particulate matter levels between 10.46 to 19.69 micrograms per cubic metre, while the lowest 8.17 - 9.38.

World Health Organisation guidelines say that levels exceeding 10 micrograms per cubic metre pose a health risk, Britain’s cities regularly pass that.

“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 the study’s lead author, Professor Paul Foster of UCL’s  Institute of Ophthalmology and Moorfields Eye Hospital.

“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.

“And as we did not include indoor air pollution and workplace exposure in our analysis, the real effect may be even greater.”

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 data was then 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.

Although the study is only observational, and it would be unethical to test whether pollution could damage eyes in laboratory conditions, the researchers say there are biological reasons why the particles could damage sight. 

“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,” said first author Dr Sharon Chua, of UCL.

“Another possibility is that particulates may have a direct toxic effect damaging the nervous system and contributing to inflammation.”

Air pollution has been implicated in elevated risk of pulmonary and cardiovascular disease as well as brain conditions such as Alzheimer’s disease, Parkinson’s disease and stroke. 

The research was published in the journal Investigative Ophthalmology & Visual Science.