title: Influence of physical activity and screen time on the retinal microvasculature in young children.
abstract: OBJECTIVE
  It is not clear whether physical activity and sedentary behavior affect retinal microvascular caliber. We investigated associations among physical activity (outdoor and indoor sporting activities), sedentary behaviors (including screen time, television [TV] viewing, and computer and videogame usage), and retinal microvascular caliber in schoolchildren.
  
  
  RESULTS
  Six-year-old students (1765/2238) from a random cluster sample of 34 Sydney schools were examined. Parents completed questionnaires about physical and sedentary activities. Retinal images were taken, and retinal vessel caliber was quantified. After adjusting for age, sex, ethnicity, eye color, axial length, body mass index, birth weight, and mean arterial blood pressure, children who spent more time in outdoor sporting activities (in the highest tertile of activity) had 2.2 μm (95% CI 0.65 to 3.71) wider mean retinal arteriolar caliber than those in the lowest tertile (Ptrend=0.004). Increasing quartiles of time spent watching TV were associated with narrower mean retinal arteriolar caliber≈2.3 μm (95% CI 0.73 to 3.92), Ptrend=0.003.
  
  
  CONCLUSIONS
  These data suggest that physical activity could have a beneficial influence, whereas screen time has a potential adverse influence on retinal microvascular structure. The magnitude of arteriolar narrowing associated with each hour daily of TV viewing is similar to that associated with a 10-mm Hg increase in systolic blood pressure in children.
authors.affiliation: Centre for Vision Research, Department of Ophthalmology, University of Sydney, Westmead Hospital, Hawkesbury Rd, Westmead, New South Wales 2145, Australia.
authors.forename: Bamini
authors.initials: B
authors.lastname: Gopinath
authors.forename: Louise A
authors.initials: LA
authors.lastname: Baur
authors.forename: Jie Jin
authors.initials: JJ
authors.lastname: Wang
authors.forename: Louise L
authors.initials: LL
authors.lastname: Hardy
authors.forename: Erdahl
authors.initials: E
authors.lastname: Teber
authors.forename: Annette
authors.initials: A
authors.lastname: Kifley
authors.forename: Tien Y
authors.initials: TY
authors.lastname: Wong
authors.forename: Paul
authors.initials: P
authors.lastname: Mitchell
mesh_terms: D001794:Blood Pressure; D002648:Child; D002652:Child Behavior; D003201:Computers; D015444:Exercise; D005260:Female; D005451:Fluorescein Angiography; D006801:Humans; D016014:Linear Models; D008297:Male; D008833:Microcirculation; D055806:Microvessels / Q000033:anatomy & histology / Q000502:physiology*; D009517:New South Wales; D012171:Retinal Vessels / Q000033:anatomy & histology / Q000502:physiology*; D018570:Risk Assessment; D012307:Risk Factors; D057185:Sedentary Behavior; D011795:Surveys and Questionnaires; D013690:Television; D013997:Time Factors; D018910:Video Games