Factors influencing variability in vascular SO2 by retinal oximetry.

SD: Standard deviation; Un-IR: unirradiated group; IR: irradiated group.*Standard deviation of SO2 measurements in one patient co-variate category divided by another co-variate category.†Between-vessel SD in the irradiated group is 1.62 times the unirradiated group for vessels of the same type and width.‡Between-vessel SD for arterioles is 0.55 that of venules for vessels of same width and in the same group of patients.§The SD of repeated measurements of the same vessel is 0.71 fold smaller for arterioles than for venules in vessels of the same width and in the same group of patients.