The condition of small (micro) blood vessels is critical to good health. Retinal blood vessels provide a unique opportunity to study microvascular health noninvasively and have been linked to cardiovascular disease risk factors and blood pressure. Narrowing of retinal arterioles is a marker of hypertension in both adults and children, however prior to this study there had been no study to examine the relationship between physical activity and retinal microvasculature. The purpose of this study by Gopinath and colleagues was to examine relationships between children's physical activity, sedentary behaviors, and retinal microvascular size.
Researchers had the parents of almost 1,500 6-year-old children from 34 different schools in Sydney, Australia complete surveys regarding their children's physical activity (outdoor and indoor) and sedentary behavior. Researchers also took digital photographs of children's eyes and measured retinal vessel diameter.
In analyzing the data, Gopinath and colleagues found that, on average, children spent 36 minutes per day engaged in physical activity and 1.9 hours per day engaged in screen time. In examining relationships between children's physical activity, sedentary behaviors, and retinal microvascular size, researchers found that children who engaged in more physical activity outdoors had better retinal vascular diameter (wider arterioles), while children who engaged in more screen time had worse retinal vascular diameter (narrower arterioles). Interestingly, researchers did not find a significant relationship between indoor sporting activities and children's retinal vascular diameter. Gopinath and colleagues also discovered that the size of arterial narrowing associated with each daily hour children watched TV was fairly comparable to a 10-mm Hg increase in systolic blood pressure.
While additional research is needed to understand these relationships, the study results suggest that lifestyle factors may influence microcirculation in children. Researchers discuss how retinal arteriolar narrowing could be a potential indicator of future cardiovascular disease and thus efforts to decrease the amount of time children watch TV and increase the amount of time children spend in outdoor activities could be particularly valuable to improving children's health. Their findings suggest that approximately 30 additional minutes per day spent by the children in outdoor physical activity could be beneficial.
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