Table 2 shows the mean VNR in each crossing pattern and group. In all crossings, the VNR was significantly lower in the young group (15.5 ± 7.61%) than in the control (21.8 ± 9.02%,
P = 0.001), fellow (26.5 ± 12.1%,
P < 0.001), and BRVO eye groups (26.7 ± 11.0%,
P < 0 .001) and significantly higher in the fellow (
P = 0.005) and BRVO eye groups (
P = 0.005) than in the control group (
Fig. 4A). In arterial overcrossings, the VNR was significantly lower in the young group (16.0 ± 7.94%) than in the control (22.0 ± 8.81%,
P = 0.003), fellow (27.7 ± 11.1%,
P < 0.001), and BRVO eye groups (27.3 ± 9.76%,
P < 0.001) and significantly higher in the fellow (
P < 0.001) and BRVO eye groups (
P = 0.003) than in the control group (
Fig. 4B). No significant difference in the VNR of venous overcrossings was found among the four groups. In 378 arteriovenous crossings, 309 (81.7%) were arterial overcrossings and 69 (18.3%) were venous overcrossings. The VNR in arterial overcrossings (24.0 ± 10.5%) was higher than that in venous overcrossings (20.6 ± 13.0%,
P = 0.021). The ICC of the VNR measurements by two graders was 0.91 (95% confidence interval = 0.87 − 0.94).