April 20, 2011 -- The eyes are said to be windows to the soul, but a new study suggests they may also provide a glimpse into a child's future risk for heart disease.

Researchers in Australia found that 6- and 7-year-olds who spent the most time in front of TVs or computer screens had narrower eye arteries in the back of their eyes than those children who spent less time.

Also, children who spent the most time in outdoor sporting activities had wider eye arteries compared to those who participated in outdoor sports the least.

Studies in adults suggest that narrowed blood vessels in the eyes indicate increased cardiovascular risk since they are part of the brain's vascular system and respond as other vessels do to stress and disease.

By analyzing digital pictures of the blood vessels of the retina, researcher Tien Wong, PhD, and colleagues from the University of Melbourne were able to predict whether adults would develophigh blood pressure or heart disease.

In the new study, which appears today in the American Heart Association journal Arteriosclerosis, Thrombosis and Vascular Biology, Wong and researchers from the University of Sydney report a link between total screen time and retinal artery width in children.

TV Time and Blood Vessel Width

The study included close to 1,500 6- and 7-year-olds living in Sydney, Australia.

The children's parents completed questionnaires designed to assess how much time the kids spent watching TV or using other electronic equipment and how much time they spent engaging in physical pursuits.

Digital photographs were taken in the back of each child's eyes to determine the width of the retinal blood vessels.

On average, the children spent just under two hours each day watching TV or in front of a computer or gaming device and just 36 minutes engaged in physical activity.

Kids who spent the most time in front of a screen had the narrowest retinal arteries. Those who engaged in the most outdoor physical activity had significantly wider retinal arteries than those who were the least active.

The association remained even after the researchers considered known risk factors for narrowed arteries, including obesity and high blood pressure.

Study researcher Bamini Gopinath, PhD, of the University of Sydney, says a sedentary lifestyle even very early in life appears to affect blood vessel health and increase cardiovascular disease risk.

She adds that the findings are preliminary and further research is needed to confirm them.

"We don't really know what this means, from a clinical standpoint," she tells WebMD. "Certainly it is suggestive of future cardiovascular risk, but we can't say that with certainty."

Message for Parents

Pediatric cardiologist and American Heart Association spokeswoman Dianne L. Atkins, MD, says the preliminary findings add to the evidence suggesting that lifestyle can influence cardiovascular risk even early in childhood.

Atkins is a professor of pediatrics at the University of Iowa Carver College of Medicine in Iowa City.

"This is another opportunity to send the message to parents that they need to limit the time their children spend in front of a screen, whether it is a TV, computer, or video game," she tells WebMD. 

According to the American Academy of Pediatrics (AAP), the average child and teen in the U.S. spends seven hours a day watching television or using computers, phones, and other electronic devices.

That's four more hours than the average time children spent watching TV each day in 1999, and five hours more than the two-hour limit recommended by the AAP for children over age 2 (younger children should not watch TV at all, the group says).

"Kids should be encouraged to be more active, and the best way to do that is for parents to lead by example," Atkins says.