Age-related decrease of the retinal vasculature area identified with a novel computer-aided analysis system

Fundus photographs enable non-invasive analysis of the status of the microcirculation by directly observing the retinal vasculature. Retinal microvascular abnormalities are important clinical markers of hypertension and arteriosclerosis, but retinal microvascular changes can be observed in older individuals without hypertension. In this study, our goal is to elucidate the effects of aging on fundus vessels in the retinal photograph. We analyzed retinal vessels of 161 healthy volunteers (49.5 ± 18.7 years, range 18-87) using in-house computer-aided measurement system to measure areas and diameters of all retinal vessels across the entire area of a retinal photograph. The vessels were segmented according to color, and then their area, size, length and thickness were measured by image processing. We also analyzed the correlation between total blood vessel area, age and mean arterial blood pressure (MABP). The decrease in total blood vessel area was dependent on both age and MABP. Moreover, decrease in blood vessel area was also correlated with age for the normotensive group. Furthermore, the slope of the regression line for retinal vessel area with MABP was significantly higher in participants aged ≤ 60 years than in those aged over 60 years. Changes in retinal vessel area with aging were observed in both arterioles and venules. In conclusion, we found the significant decrease in retinal vessel area that is correlated well with calendar age. Therefore, we need to carefully apply traditional classifications of fundus examination for hypertensive retinopathy in older individuals.