Comparison of the perceptual threshold.

A, Summary of the thresholds by test 1, the control (n = 9), the early VD (n = 10) and the late VD (n = 8) groups, respectively from left to right: p = 0.012, the control vs. early VD; p = 0.75, the control vs. late VD and p = 0.0026, early VD vs. late VD. B, Similar to A, but by test 2: p = 0.027, the control vs. early VD; p = 0.93, the control vs. late VD and p = 0.014, early VD vs. late VD. C, Similar to A, but by test 3: p = 0.41, the control vs. early VD; p = 0.99, the control vs. late VD and p = 0.45, early VD vs. late VD. D, Similar to A, but by test 4: p = 0.021, the control vs. early VD; p = 0.51, the control vs. late VD and p = 0.0018, early VD vs. late VD. *, p p < 0.01, one-way ANOVA Turkey-Kramer post hoc test.