Purpose:
To describe the visual field of normal subjects using Humphrey perimetry with size V stimuli and to compare size V thresholds and retest variability with perimetry using size III stimuli.
Methods:
We tested one eye of 58 normal subjects with the Humphrey full threshold algorithm using size V stimuli and with SITA standard using size III stimuli. The patients were retested 1–4 weeks later. We compared the mean scores, concentric zones, and point–wise sensitivities between the sizes and their retest variability within sizes. A two–factor, repeated ANOVA was performed with the dependent variable as sensitivity (dB) at each location.
Results:
The sensitivities were on average 3.93 dB higher for size V and were different for the two tests (p < 0.001). The sensitivity of size V ranged from 0.61 dB more at the fovea to 4.30 dB in the periphery. The mean difference on retest across test locations was 1.58 dB ± 0.39 for size III and 1.42 dB ± 0.37 for size V. The difference in variability between size III and size V increased with eccentricity (interaction was significant: p<.001), with size III having slightly higher variability (Figure).
Conclusions:
The retest variability in normal subjects is slightly less for size V full threshold testing compared with size III SITA standard results and increases with eccentricity.
Keywords: perimetry • visual fields