Scientists find that air pollution causes glaucoma
The eye ailment joins a host of other diseases associated with air pollution
Just a quick note before this week’s science article. I turned on Substack “boost” today, a marketing program run by this platform. If you start to get a lot of extra spam because of this, please let me know. If the feature floods you with spam, I will turn it off.
Air pollution has been associated with a number of human ailments, including asthma, bronchitis, cardiovascular disease, and even heart attacks. Now, scientists in China have found a link between air pollution and glaucoma.
Previous studies have found that exposure to air pollution causes high blood pressure. Studies have also found an association between high blood pressure and glaucoma, so it seems like the connection between air pollution and glaucoma would be an obvious topic for a health study. The scientists published their results in BMC Public Health, a peer-reviewed journal that focuses on environmental, behavioral, and occupational causes of ailments and disease. Their paper was published in September.
Glaucoma is the world’s leading cause of blindness. More than 70 million people between the ages of 40 and 80 suffering from this condition that damages the optic nerve.
Glaucoma is one of the most insidious of ailments, as it usually has no warning signs. The eyeball is sort of like a water balloon, filled with fluid that keeps the structure of an eyeball a ball. Too much fluid pressure in the eyeball causes damage to the optic nerve, the neural connection from the eye to the brain. This damaged nerve condition is glaucoma. Vision loss is so gradual that most people don’t notice until the disease is in its later stages and has already robbed them of much of their vision. Anyone can develop glaucoma, but it is most common in folks over the age of 60.
There are two main types of glaucoma. Open-angle glaucoma has no early symptoms, but as it advances, patchy blind spots develop in a person’s peripheral vision, advancing to difficulty seeing things in their central vision. The symptoms for acute glaucoma, or acute angle-closure glaucoma, on the other hand, develop quickly, making it an emergency. Those afflicted with acute angle-closure glaucoma experience headaches, nausea, and vomiting. Their eyes can turn red and be severely painful. Vision is decreased and cloudy. Sufferers often see halos around lights.
The investigators gathered data on glaucoma patients at a university-associated medical center in Shanghai, concentrating on those suffering from acute glaucoma and a similar ailment known as glaucomatocyclitic crisis. The data collection started in 2015 and continued through 2021. Their study procedure was pretty straightforward. They gathered the addresses of the more than 14,000 glaucoma patients treated at the medical center and, using the data from air quality monitoring stations throughout the city, assessed how much air pollution each patient was exposed to.
They found that exposure to soot, what scientists call particulate matter, led to an increase in a person’s chances of developing acute glaucoma. Exposure to other pollutants, such as nitrogen dioxide and carbon monoxide were less of a causative factor for the disease. Previous science has found that soot can lodge in the lungs and even enter the bloodstream. Another recent study found that particulate matter could enter the cornea. The scientists in this study theorize that the soot entering the eye triggers the glaucoma crisis.
Modest improvements for Shanghai residents
Pearl S. Buck’s depiction of early 20th Century life in China, The Good Earth, was published in 1931. The novel contains no mention of automobiles, airplanes factories, or just about anything we associate with the industrial modern world, including air pollution. After the passing of Mao in 1976, however, China raced full steam ahead to join the rest of the industrial world. Loose regulations led to pollution levels that paralleled or exceeded those of mid-20th Century Pittsburgh or Los Angeles. By the 1990s, Beijing, Hong Kong, and Shanghai were known to be among the most polluted cities in the world.1
Starting in 2013, Shanghai commenced a series of programs to mitigate the city’s air pollution, including restrictions on high-polluting vehicles and changing out new government vehicles to run on renewable energy. Even still, air pollution problems still exist for the city that is home to 25 million people. Extra-fine soot is particularly bad, even worse than that of Beijing, which is known for having some of the worst urban pollution in the world.
This study interested me because of what I know personally of glaucoma and pollution. Later in his life, my father was diagnosed with glaucoma. Lucky for him, it was caught early and treatment kept his vision until he died at the age of 89. Through most of his life he lived a block or two from a factory. When he was a child, the factory processed zinc. Later, it changed to producing graphite. When I was a child, I remember smoke, soot, and ash billowing from the factory smokestacks. The grime settled over everything: trees, grass, cars, and houses. With the findings of this new study, I’m left to wonder how much of that soot and pollution contributed to my father’s eye problems. Do you think you might know someone whose glaucoma resulted from their exposure to air pollution?
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Mark Landler. "Choking on China's Air, but Loath to Cry Foul: Legendary Vistas are Lost to View as Pollution Engulfs Hong Kong." New York Times (1923-), Feb 12, 1999, pp. 1. ProQuest, https://www.proquest.com/historical-newspapers/choking-on-chinas-air-loath-cry-foul/docview/110126091/se-2.