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October 21, 2019

Secondhand smoke exposure may harm children's developing eyesight

Researchers in Hong Kong studied the portion of the eye that supplies oxygen and nutrients to photoreceptors

There is evidence that secondhand smoke can cause damage to children’s still-developing eyes.

According to the study published in JAMA Ophthalmology, researchers in Hong Kong examined the effects of second hand smoke on the eye's choroid, a layer of tissue located between the sclera and retina that “supports the photoreceptors with oxygen and nutrients,” according to Robert F. Mullins, at the University of Iowa.

Scientists measured choroidal thickness in 1,400 children, ages 6 to 8. Of that group, 459 had been exposed to secondhand smoke. Dr. Jason Yam, an associate professor of ophthalmology and visual sciences at the Chinese University of Hong Kong, found that the children exposed to secondhand smoke had thinner choroids on average.

Yam told US News & World Report that a causal relationship still needs to be established, but there was a definite link between the degree of thinning and the amount of exposure to secondhand smoke. He also said in his study that the amount choroid thinned was dependent on the volume of secondhand smoke a child was exposed to.

One of the concerns of a thinning choroid, he said, is that it could lead to maculopathy, a progressive disease that causes blindness.

Dr. Luxme Hariharan, a pediatric ophthalmologist at Nicklaus Children’s Hospital in Miami told US News & World Report that these findings are important because the eyesight of children ages 6 to 8 is still developing.

“Once you’re 10, changes can be permanent," Hariharan said. "Anything abnormal can cause a permanent problem in the visual pathway as it’s forming – that’s why this age group is key.”

She added that while more research is needed to establish a causal relationship that it generally is better to not have children around secondhand smoke.

Secondhand smoke is already associated with increased risk for cancer and stroke in adults, and asthma, lung infections and sudden infant death syndrome (SIDS) in children.

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