(Reuters Health) – In people who already have a genetic vulnerability, small-particle air pollution known as black carbon may increase the risk of developing glaucoma, a new study suggests.
Researchers found that in older men with changes that made them particularly susceptible to oxidative stress, long-term exposure to black carbon, a pollutant related to vehicle emissions and other combustion products, it was associated with higher eye pressures, according to the study published in JAMA Ophthalmology.  Advertising
"When we think about glaucoma, we often think about risk factors such as age and genetic predisposition and we do not think about the environment," said the study's lead author. , Jamaji Nwanaji-Enwerem, an MD / PhD candidate at the Harvard Medical School in Boston. "But one thing we are starting to appreciate the most is the way the environment affects health outcomes."
One area in which there has been much research is the impact of the environment on eye diseases, Nwanaji-Enwerem said. Thus, he and his colleagues decided to examine the effect of the tiny particles of black carbon, which are less than 2.5 microns in diameter and can penetrate deep into the lungs and from there into the bloodstream.
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Glaucoma, which can eventually cause blindness if not treated, is often caused by a high intraocular pressure, or high fluid pressure inside the eye.
"When the eye pressure is too high, it causes damage to the optic nerve, the cable that connects our eyes to the brain and the visual pathways," explained Dr. Christopher Starr, an eye specialist of New York-Presbyterian / Weill Cornell Medicine of New York, who was not involved in the new research. "If you lose cells in that nerve, you lose your sight, usually it starts with loss of peripheral vision and over time you lose more and more."
For the study, the Nwanaji-Enwerem team determined the modeling program exposure that included the black carbon levels collected from 83 monitoring sites and meteorological data.
The researchers then analyzed the results of pollution together with each man's eye pressure readings and a range of other factors of health and lifestyle, including BMI, smoker status, heart disease, and blood pressure. diabetes.
Overall, they found no link between pollution and ocular pressure. But when they only looked at men who had certain gene versions that made them vulnerable to oxidative stress, the researchers found an association between higher levels of pollution and a slight increase in eye pressure.
Although interesting, the results of the new study will need to be duplicated, notes Starr, adding that although proven, the effects observed in this study are small. "They may not even be clinically significant in the context of glaucoma," he said.
Differences in intraocular pressure may have been more surprising if the men in the study lived in a place that had high levels of black carbon pollution, Starr said.
While it is clear that family history may increase the risk for glaucoma, studies of other possible variables have been mixed, said Dr. Julia Polat, an assistant professor of ophthalmology at the University of Pittsburgh Medical Center in Pennsylvania, who was not involved in the new research.
"When patients ask," what can I do to change my risk? "I unfortunately do not have much definitive information to give them," Polat said. "I tell them to eat healthy, exercise and stop smoking, not necessarily because it will help with glaucoma, but because these changes can make them healthier in general."
Glaucoma is particularly insidious because it generally develops without symptoms, Starr said. That's why people should regularly monitor their pressures, he added.
"One of the ironic things, when looking at global surveys in almost all societies and cultures, vision is by far what people appreciate and value the most," Starr said. "Still, people see their general practitioner for annual checks, but they do not see an eye doctor regularly."
SOURCE: https://bit.ly/2JNqelK and https://bit.ly/2FlnQnE JAMA Ophthalmology, online, 8 November 2018.