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(Reuters Health) – A new study suggests that small-particle air pollution called black carbon can increase the risk of developing glaucoma in people who already have genetic vulnerability.
According to a study published in the journal JAMA Ophthalmology, prolonged exposure to black carbon, a pollutant related to vehicle emissions and other combustion products, was badociated with higher eye pressures. ] Announcement
"Often, when we think of glaucoma, we think of risk factors such as age and genetic predisposition, but not to the environment," said Jamaji Nwanaji-Enwerem, lead author of the study, PhD candidate / PhD student at Harvard Medical School in Boston. "But one thing we are beginning to better understand is the impact of the environment on health outcomes."
The environmental impact on eye diseases is an area in which little research has been conducted, said Nwanaji-Enwerem. . So, he and his colleagues decided to examine the effect of tiny particles of black carbon, of a diameter less than 2.5 microns, able to penetrate deep into the lungs and from there, in the blood.
Researchers badyzed data from 419 elderly men in the Boston area who had been involved since the 1960s in a larger study on aging conducted by the US Department of Veterans Affairs. They underwent medical examinations every three to five years after joining the study and measuring intraocular pressure.
Glaucoma, which can eventually lead to blindness if it is not treated, is most often caused by elevated intraocular pressure.
"Eye pressure that is too high can damage the optic nerve, the cable that connects our eyes to the brain and the visual pathways," he says. Dr. Christopher Starr, ophthalmologist in New York York-Presbyterian / Weill Cornell Medicine in New York City, did not participate in the new research. "If you lose cells in this nerve, you lose vision, which usually starts with a loss of peripheral vision and, over time, you lose more and more."
For the study, the Nwanaji-Enwerem team determined men's exposure to pollution with the help of a modeling program including carbon levels black collected from 83 monitoring sites and meteorological data
. The researchers then badyzed the pollution results, as well as each man's ocular pressure values and many other health and lifestyle factors, including BMI, smoking, heart. disease, blood pressure and diabetes
Overall, they found no link between pollution and eye pressure. But when they just looked at men who had certain versions of genes that made them vulnerable to oxidative stress, the researchers found an badociation between higher levels of pollution and a slight increase in eye pressure. be duplicated, noted Starr, adding that although it was proven, the effects observed in this study are weak. "They may not even be clinically significant in the context of glaucoma," he said.
Differences in intraocular pressure may have been more striking if the men in the study had lived in a place heavily polluted with carbon black.
While it is clear that family history may increase the risk of glaucoma, studies of other possible variables are mixed, said Dr. Julia Polat, badistant professor of ophthalmology at the University of Ottawa. Medical Center of the University of Pittsburgh Pennsylvania, which has not been involved in the new research.
"When patients ask," what can I do to change my risk? "Unfortunately, I do not have much definitive information to give them," Polat said. "I tell them to eat healthy, exercise and quit, not necessarily because it will help fight glaucoma, but because these changes can make them healthier."
Glaucoma is particularly insidious because it usually develops without symptoms, Starr said. . That's why the pressures should be checked regularly, he added.
"One of the paradoxes, if you look at global surveys in almost every society and culture, is by far what people cherish and value the most," Starr says. "And yet, people consult their general practitioner every year, but do not regularly consult an ophthalmologist."
SOURCE: https://bit.ly/2JNqelK and https://bit.ly/2FlnQnE JAMA Ophthalmology, Online November 8, 2018.
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