What ocular and systemic variables affect choroidal circulation in healthy eyes

The aim of the study was to investigate the relationship between choroidal blood flow and systemic and ocular variables in patients with healthy eyes.In this prospective cross-sectional study, we examined 241 eyes of 241 healthy Japanese subjects (92 males and 149 females; mean age, 37.8 ± 17.0 years). The mean blur rate, a measure of the relative blood flow of the choroid, was determined using laser speckle flowgraphy. The total cross-sectional choroidal, luminal, and stromal areas of the choroid were determined by the binarization method. We investigated the correlation between choroidal MBR and systemic and ocular variables.Choroidal mean blur rate correlated with age (r = -0.385, P < 0.001) and choroidal thickness (r = 0.264, P < 0.001). The choroidal area correlated with choroidal mean blur rate (r = 0.374, P < 0.001), age (r = -0.184, P = 0.004), axial length (r = -0.251, P < 0.001), and choroidal thickness (r = 0.468, P < 0.001). The luminal area correlated with choroidal mean blur rate (r = 0.403, P < 0.001), age (r = -0.244, P < 0.001), axial length (r = -0.218, P = 0.001), and choroidal thickness (r = 0.435, P < 0.001). On multiple stepwise regression analyses, age (β = -0.321, P < 0.001) and luminal area (β = 0.320, P < 0.001), heart rate (β = 0.136, P = 0.018), and mean ocular perfusion pressure (β = 0.126, P = 0.045) were independent factors indicating the choroidal mean blur rate. Furthermore, axial length (β = -0.352, P < 0.001), choroidal mean blur rate (β = 0.273, P < 0.001), age (β = -0.247, P < 0.001), gender (β = -0.226, P < 0.001), and mean ocular perfusion pressure (β = 0.193, P = 0.002) were independent factors indicating the luminal area.The choroidal blood flow positively correlated with the luminal area and negatively correlating with age. In addition, the luminal area was negative correlated with age. It is suggested that aging causes a reduction in choroidal blood flow and luminal area, and as a result of aging effect, decreased choroidal blood flow would correlate with decreased luminal area.