Abstract
The purpose of this study is to describe the visual field morphology and the repeatability of normal participants using Humphrey perimetry with stimulus sizes III, V and VI. We tested one eye of 60 ocular healthy participants with the Humphrey perimeter using sizes III (0.43°) SITA Standard, V Full Threshold (1.72°) and VI Full Threshold (3.44°) stimuli. The patients were retested 1-4 weeks later. We compared the mean scores, eccentricity zones, and point-wise sensitivities among the sizes and their retest variability. Repeated measures ANOVA on Ranks was performed with the dependent variable as sensitivity (dB) of average sensitivity of each eccentric zone. The mean sensitivities (average of the two visits) were sizes III: 30.16 ± 1.1, V: 34.4 ± 1.0 and VI 36.0 ± 1.0 (p < 0.001 with all Tukey post hoc paired comparisons significant). Significant differences between the groups were also present for each eccentric zone except 0° for size V vs. size VI. The mean difference on retest across test locations was 0.26 dB for size III, 0.26 dB for size V, and 0.27 dB for size VI indicating minimal learning effect. The difference in variability between sizes III, V and size VI increased with eccentricity, with size III increasing more than the larger stimulus sizes but statistical significance for this difference was not reached. In this investigation, we found with increasing stimulus size, the visual field morphology flattens, and the retest variability becomes slightly less for stimulus sizes V and VI full threshold testing compared with size III SITA standard results.