'A uniquely direct route that might cause damage': Scientists uncover link between air pollution and eye diseases like glaucoma

Aging is one of the biggest risk factors for developing glaucoma or cataracts — but as scientists look more closely at what happens to the eyes over a lifetime, they are finding that people's exposure to air pollution also plays a role in whether they develop these eye conditions.

Glaucoma, which affects about 80 million people worldwide , is a group of diseases that damage the optic nerve, which carries visual information from the eye to the brain.

It can lead to permanent vision loss, usually affecting peripheral vision at first and later central vision.

Cataracts are even more common, affecting more than 94 million people globally ; the condition occurs when the eye's lens becomes cloudy, causing blurred vision and, eventually, blindness.

Aging raises the risk of both diseases, as do certain medical conditions, such as diabetes.

But now, a review of 41 studies suggests that people who are exposed to higher levels of air pollution may also face a greater risk of these diseases.

The research, presented in September at the 44th Congress of the European Society of Cataract and Refractive Surgeons in London, brought together evidence from dozens of studies collectively involving millions of people across East Asia and the U.K.

The studies were observational, meaning they can only draw a link between air pollution and the eye conditions, rather than prove that air pollution causes the diseases.

But still, "this reframes glaucoma and cataract as conditions shaped by where you live and breathe, not just how long you've lived," said study co-author Dr.

Ahmed Alnabihi , an ophthalmologist at King Khaled Eye Specialist Hospital and Research Center in Saudi Arabia, who presented the findings.

These environmental exposures may compound age-related decline in the eye as they do in cardiovascular disease, he said.

PM2.5 shows the clearest links The researchers examined exposure to several pollutants, including different sizes of particulate matter (PM), such as fine PM2.5 and larger PM10.

They also looked at nitrogen dioxide, sulfur dioxide, ozone and carbon monoxide.

Most studies included in the review estimated people's long-term exposure based on the pollution levels around their homes and in their communities.