Clouded Vision

Ambient air pollution is a major problem across the globe, causing many short- and long-term health problems. To put the issue into perspective, the WHO estimates that 91 percent of the world’s population live in areas that exceed the recommended safe air pollution exposure levels. And although many pollution-related diseases are caused by inhalation, the eyes are also prime victims of harmful emissions from vehicles, households, and industries.

But not all air is the same – so how does the rate of eye disease change for those who live with different levels of air pollution? This is what researchers from the University of Ottawa, Canada, have deciphered, with findings suggesting that there is an association between certain air pollutants and AMD, glaucoma, and cataracts (1).

The group compiled studies that looked into associations between air pollutants and age-related eye diseases, forming a systematic review and meta-analysis of the available data. This resulted in a collection of risk data for specific pathologies along with the pollutants associated with changes in risk. For example, carbon monoxide and particulate matter under 2.5 micrometers in diameter (PM_2.5) were associated with an increased risk of AMD; PM_2.5 was also associated with increased glaucoma risk. Interestingly, although PM₁₀ pollutants were associated with an increased risk of cataracts, ozone exposure appeared to have a protective effect.

The researchers noted that their work was limited by the information available. The number of available studies was low – and many of those studies couldn’t be pooled into the meta-analysis because of vast differences in methodology. Issues included inconsistencies between classifications of disease in separate studies, locations limited to a handful of countries, and the use of a single pollutant model in a number of studies. It’s clear that there’s a need for robust, systematically consistent research in this area to yield a full understanding of the effects of air pollution on eye health. In the meantime, the University of Ottawa study offers a compilation of recent evidence with large sample sizes – and gives us one more good reason to keep an eye on the quality of our air.

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