Study results have shown that sedentary behaviour in children, such as watching television or playing video games, is associated with a narrowing of the retinal arteriolar caliber – a marker of future cardiovascular risk.  Bamini Gopinath, PhD, senior research fellow at the Center for Vision Research at the University of Sydney, and colleagues studied 1,492 children aged 6-7 years. The researchers took digital photographs of the vasculature in the back of each child's eye, and measured their height, weight, body mass index (BMI), and blood pressure. Parents were asked to answer a questionnaire, providing the number of hours spent each week in indoor and outdoor physical activity and sedentary activity such as watching television, videogames, computer time, and reading. Results showed that the children spent an average of 1.9 hours per day participating in sedentary activities, compared with just 36 minutes a day of physical activity. Those with the highest levels of physical activity (just over an hour each day) were found to have a significantly wider average retinal arteriolar caliber than those with the lowest level of physical activity (half an hour or less per day). The amount of time the children spent watching television and playing computer/video games each day was associated with a narrower average retinal arteriolar diameter, with each hour per day of such activities being associated with an average 1.53 micron narrower retinal arteriolar caliber. Gopinath concluded that the findings suggest that “unhealthy lifestyle factors may influence microcirculation early in life and increase the risk of cardiovascular disease and hypertension later in life."