Characteristics of subjects are given in
Table 1.
The average ± standard deviation (range) of the minimum, median, and maximum gradient was 5.5 ± 3.0 (2.9–14.3); 10.0 ± 4.0 (4.0–17.1); and 21.2 ± 5.3 (7.8–20.0) dB/deg interval, respectively. On average, the measurement duration of the 24-2E test was 14 minutes and 29 seconds, whereas it was 12 minutes and 5 seconds with the 24-2 grid.
Figures 5A and
5B illustrate a linear interpolation of VF sensitivities in two patients. The distributions of calculated VF gradients for each patient are depicted in
Figure 6. The boxplot in
Figure 7 shows the intra- and intervisit reproducibility of the thresholds of the added 10 test points. The reproducibility tended to be worse where gradients were steeper. The boxplots in
Figure 7 illustrate the relationship between the gradient of the plane and Δ
ave. As shown in these boxplots, Δ
ave increases as the gradient of the plane becomes steeper. These boxplots are in agreement with the results of MLM where there was a significant positive relationship between the gradient of sensitivity and Δ
ave in each of the four VF test results (
P < 0.001); Δ
ave = 0.20 × gradient + 2.7 (day 1, measurement 1); Δ
ave = 0.20 × gradient + 3.2 (day 1, measurement 2); Δ
ave = 0.17 × gradient + 3.8 (day 2, measurement 1); Δ
ave = 0.29 × gradient + 2.6 (day 2, measurement 2). As shown in
Figure 8, Δ
SFmap increases as the gradient of the plane becomes steeper. Thus, a large discrepancy is still observed even when the anatomical and functional relationship in
Equation 1 was incorporated.
Table 2 shows ICCs and CVs of the cubic volume associated with the 24-2 VF grid and the 24-2E VF grid. ICCs were high with both patterns; however, bootstrapping suggested that the ICC associated with the 24-2E VF grid was significantly greater than that associated with the 24-2 VF grid (percentile bootstrap test,
P = 0.02). The median of CVs associated with the 24-2E VF grid was 11.2%, which was significantly lower than that observed with the 24-2 VF grid (13.1%,
P = 0.0057, Wilcoxon signed-rank test).