Effect of aging on retinal circulation in normotensive healthy subjects

Although it is important to investigate the effects of normal aging on the ocular circulation, few studies have examined the effects of aging on the retinal microcirculation in healthy subjects. The purpose of this study was to evaluate the effects of aging on the retinal microcirculation in healthy men. Forty-five healthy men were divided into three groups based on age (young, middle-aged, elderly). We measured vessel diameter and blood velocity and calculated the retinal blood flow (RBF) and wall shear rate (WSR) in the retinal arteries. We performed pulse wave analysis obtained from the retinal blood velocity measurements. We also divided the subjects into two groups based on the presence or absence of prehypertension defined as 120-139/80-89 mmHg. No significant differences in vessel diameter, blood velocity, RBF, and WSR were seen among the groups. Pulse wave analysis showed significant increases in upstroke time (UT) in elderly men compared with young men (P < 0.05). Multiple regression analysis showed that the UT was correlated with age in all subjects. A significant difference was seen only in the UT between subjects with and without prehypertension. The UT calculated from the retinal blood velocity profile is associated significantly with aging, suggesting that measurement of the UT may detect the changes in the retinal and the systemic vessels with increasing age. The UT is the only parameter that increased significantly in subjects with prehypertension compared with those without prehypertension, suggesting that the UT may indicate the effects of prehypertension on the retinal arterioles.