Choked Up

Air pollution carries significant health risks: lung cancer, heart disease, acute respiratory infections… but what about glaucoma? A UK study found that those living in neighborhoods with higher amounts of fine particulate matter pollution were 6 percent more likely to have glaucoma than those in less polluted areas (1). The researchers focused on particles smaller than 2.5 in μm diameter – widely recognized as having major adverse effects on health – in the study of 111,370 individuals. The team compared participants’ IOP and macula thickness with the number of toxic particulates reported at their home address, to find the association.

Paul Foster, Professor of Ophthalmic Epidemiology and Glaucoma Studies at UCL and Consultant Ophthalmic Surgeon at Moorfields, who led the study, likens the effect to that of a migraine. “It is well known that migraines increase the risk of developing glaucoma two- to three-fold. This is because they cause spasms in blood vessels in the eye and around the optic nerve – and we believe that pollution may act by a similar mechanism,” he says. “Glaucoma has two broad mechanisms by which damage is thought to occur: constricting blood vessels and exacerbating inflammation. At the moment, we think that the blood vessel mechanism probably has the greater impact. Although the neurotoxicity mechanism is still rather speculative, there is good reason to believe that this actually does happen.”

The findings echo prior studies that found people in urban areas are 50 percent more likely to have glaucoma than those who live in rural areas, which also suggests that air pollution may be a key contributor to glaucoma risk. Though Foster cannot confirm yet that the association is causal, his team plans to continue the research to explore whether air pollution causes glaucoma, studying the short- and longer-term effects of air pollution on ocular blood flow, while trying to understand the toxic effect of micro particles of metals on the retina. He offers this advice to those hoping to reduce their exposure and mitigate potential health risks: “The first step is awareness that air pollution is ranked as the world’s number one environmental threat to health. Each of us needs to make choices around transport, heating, cooking, and energy consumption, and try to live cleaner, greener lives. By creating clearer evidence around the risks of pollution, we can hopefully influence national and international policy.”