Retinal circulation time/arm-to-retina time ratio in the fluorescein angiography to evaluate retina-specific hemodynamics

To evaluate dynamic circulatory flow in the retinal or choroidal circulatory disease, we retrospectively reviewed medical charts of 128 eyes of 128 patients who underwent video recorded fluorescein angiography (FA), at Department of Ophthalmology, St Luke’s International Hospital, between April and September 2020. Mean age was 64.2 ± 14.0 (range 37–93) years, and 87 (67.9%) patients were men. Mean arm-to-retina (AR) time was 16.2 ± 4.1 s, and mean retinal circulation (RC) time was 10.9 ± 3.3 s. Mean RC time/AR time (RC/AR) ratio was 0.69 ± 0.22. AR time was correlated with age, whereas RC time was not. RC time was positively correlated with AR time (R = 0.360, P = 0.017). Moreover, mean RC time was significantly longer, and RC/AR ratio was greater, in the retinal-disease group after adjusting for age and sex. Patients who had an RC/AR ratio ≥ 0.8 more frequently presented with retinal diseases. RC time and RC/AR ratio were negatively correlated with systolic blood pressure only in the retinal-disease group. Given that AR time reflects systemic hemodynamics, RC time, which reflects local circulatory fluency, was influenced by the systemic circulatory condition. Moreover, RC/AR ratio revealed that circulatory changes peculiar to the retina may also be involved in retinal-disease pathogenesis. This study may help elucidate the mechanisms of retinal diseases and assist in diagnosis, although further studies are required.