Air pollution may be the reason why people living in urban areas are 50 percent more likely to have glaucoma than those in rural areas. A new UCL-led study in the UK has found that living in a more polluted area is associated with a greater likelihood of having glaucoma, a debilitating eye condition that can cause blindness.
“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 from the UCL 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.”
Glaucoma is a neurodegenerative disease that is the leading cause of irreversible blindness and affects over 60 million people worldwide. Glaucoma is a disease of the eye in which fluid pressure within the eye rises, causing damage to the optic nerve that connects the eye to the brain. If left untreated, the patient may lose vision and even become blind.
“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,” said Foster.
For the study, medical records from 111,370 participants of the UK Biobank study cohort who underwent eye tests from 2006 to 2010 were analyzed. Participants underwent ocular testing to measure intraocular pressure, and spectral-domain optical coherence tomography imaging (a laser scan of the retina) to measure the thickness of their eye’s macula (central area of the retina).
The data were linked to air pollution measures provided by the Small Area Health Statistics Unit, with the researchers focusing on fine particulate matter (equal or less than 2.5 micrometers in diameter, or PM2.5).
Eye Pressure Not Affected
It was found that participants in the most polluted areas were at least six percent more likely to report having glaucoma than those in the least polluted areas. They were also found to have a significantly thinner retina, one of the changes typical of glaucoma progression. Eye pressure did not seem to be associated with pollution, suggesting that pollution may affect glaucoma risk through a different mechanism.
The study’s first author, Dr. Sharon Chua from the UCL 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.”
In previous studies, air pollution has been found to elevate the risk of pulmonary and cardiovascular disease as well as brain conditions such as Alzheimer’s disease, Parkinson’s disease, and stroke. This study shows how glaucoma can be added to this list.