Researchers have found a link between glaucoma and air pollution. Glaucoma is an eye disease that can make you blind if it is not treated. Fluid builds up in the front part of your eye. This increases the pressure in your eye, and damages the optic nerve.
Glaucoma is the second most frequent cause of blindness in the US. Almost 3% of the US population above 40 years of age have the disease. Around half of them are most likely not aware of it yet. Globally, the number of cases have been projected at around 80 million in 2020, almost half of them in Asia.
Glaucoma and the city
A research team from University College London matched the glaucoma status of 111,370 participants within the UK Biobank study for the period between 2006 and 2010 with the PM2.5 levels at their address. In an article in the prestigious journal Investigative Ophthalmology & Visual Science, they now conclude that those living in areas with higher concentration of fine particulate matter (PM2.5) have a higher risk of developing glaucoma.
The researchers found that people living in urban areas had 6% greater chance of developing glaucoma than those living elsewhere. Also, people living in the 25% most-polluted areas were 18% more likely to report that they had glaucoma than people living in the 25% least-polluted areas. They were also more likely to have a thinner retina. This can be a symptom of glaucoma. So there is a correlation between glaucoma and air pollution, but it is too early to say that air pollution causes glaucoma.
It's not the pressure, darling, it's the intoxication
People in the most polluted areas were not more exposed to eye pressure - usually associated with glaucoma - than others. The researchers therefore think air pollution affects glaucoma risk through constricting our blood vessels, or that it has an inflammatory or toxic effect on our nervous system. As we discussed in a recent blog, ultra-fine particles likely increase such risks.
Visible threat in developing countries
In an interview regarding this research, the authors said air pollution levels are far lower in the UK than many other places globally. They also highlighted that their study did not cover indoor air pollution or workplace exposure. It is possible, of course, that UK air is particularly harmful (even outside its pubs). However, chances are that glaucoma risk is much higher in many urban areas in developing countries. There, both outdoor, household and workplace air pollution can be much higher than in the UK. As if smog hadn't reduced visibility there enough already.