Age-related ocular blood flow changes

Purpose. Pulsatile ocular blood flow (POBF is influenced by well-known parameters, such as intraocular pressure (IOP), heart rate, scleral rigidity, blood pressure, and posture. Age is also likely to influence POBF strongly. The purpose of this study was to evaluate POBF in relation to age in normal subjects. Methods. Relevant data were collected from a sample of 105 normal subjects, ranging in age from 10 to 80 years. To measure the effect of age on POBF, the subjects were divided into seven groups of 15 subjects each; the age range of each group spanned one decade, beginning with age 10. POBF and pulse amplitude (PA) were measured in sitting and supine positions and after suction cup application. Results. Using linear regression analysis, there was a significant correlation between PA and age in the supine position (P=0.012) and after suction cup application (P=0.002); in the sitting position, there was a borderline level of statistical significance (P=0.053). In the sitting position, POBF was 819+/-212 mu l/minute in the second decade and 630+/-194 mu l/minute in the eighth decade. In the sitting position and after suction cup application, but not in the supine position, a statistically significant correlation between POBF decrease and age was found with linear regression analysis (P <0.001 and P=0.004, respectively). Using multiple regression analysis, POBF values revealed a significant correlation with age (P <0.001), but not with systolic and diastolic brachial pressure. Considering all the subjects, analysis of variance for repeated measures highlighted a significant decrease of POBF from the sitting to the supine position and associated with an IOP increase (P <0.001) without significant changes of PA. After suction cup application, there was a significant reduction of both PA and POBF (P <0.001). Conclusions. The data revealed that as age increased, PA decreased in all three series of measurements. POBF decreased with age, and in subjects older than 50 years, the decrease was more evident. These findings are especially noticeable after IOP increase with suction cup. It must be considered that the age-related value of POBF is a fundamental parameter to evaluate correctly the hemodynamic aspects of the pathologies affecting the eye.