Associations of Physical Activity and Television Viewing Time with Retinal Vascular Caliber in a Multiethnic Asian Population

PURPOSE. The aim of this study was to examine the relationship of physical activity and television (TV) viewing time with retinal vascular caliber in a multiethnic Asian population. METHODS. Chinese, Indian, and Malay participants (n = 3866) were examined cross-sectionally in the Singapore Prospective Study Program (2004-2007). Leisure-time physical activity and TV viewing time were assessed by the use of an interviewer-administered questionnaire. Retinal arteriolar and venular calibers were measured from digital retinal photographs. RESULTS. After adjusting for demographic, behavioral, and medical factors, those in the lowest quartile of leisure-time physical activity had a wider venular caliber (by 1.51 mu m; 95% confidence interval [CI], 0.01-2.92) compared with those in the highest quartile. Using sex-and ethnicity-specific quartiles, stronger associations were noted in males (2.23 mu m; 95% CI, 0.10-4.38) and Chinese (2.52 mu m; 95% CI, 0.44-4.59) participants. Females who watched > 2 hours of TV per day had a narrow arteriolar caliber (by 1.28 mu m; 95% CI, -2.56-0.03), compared with the arteriolar caliber of those who watched less TV. CONCLUSIONS. Lower physical activity and higher TV viewing time (in females) were adversely associated with retinal microvascular caliber among Asian adults. Additional cross-sectional and longitudinal studies are needed to further clarify the potential mediating role of the microvasculature in the relationship between these behavioral risk factors and poor cardio-metabolic health outcomes. (Invest Ophthalmol Vis Sci. 2011; 52: 6522-6528) DOI: 10.1167/iovs.11-7324