Rapid campimetry - a novel robust kinetic approach for visual field screening in glaucoma

Abstract

Purpose: To investigate the robustness and variability of a novel kinetic visual field (VF) screening method termed rapid campimetry (RC).

Methods: In RC visual field (VF) screening is enabled via kinetic-based testing on any computer (10°/4.7 s at 40-cm viewing distance) and high contrast in a dark room (1 cd/cm²). In experiment (1): 30 participants [20 healthy participants (HC), 5 glaucoma patients (GLA) and 5 patients with cataract (CAT)] were included to test the intra-session variability (fatigue effect) and the following effects on RC: room illumination (140 cd/m²), ±3 D refractive errors, media opacity. In experiment (2): Inter-session variability (1-3 weeks apart) was assessed in 10 HC and 10 GLA. Since RC detects absolute scotomas, the outcome measure was the size of physiological (blindspot) and pathological (glaucoma) scotomas in degrees. A repeated measures ANOVA was employed in experiment 1 and intraclass correlation (ICC) in experiment 2.

Results: Neither the size of the blindspot nor the VF defects differed significantly between the different testing conditions. For intra-session variability, the average bias of blindspot size was -0.6 ± 2.5°, limits of agreement (LOA), in comparison to 0.3 ± 1.5° for VF defects, both with ICC of 0.86 and 0.93, respectively. For the inter-session repeatability, the average bias and LOA for blindspot size was 0.2 ± 3.85° in comparison 1.6 ± 3.1° for VF defects, both with ICC of 0.87 and 0.91, respectively.

Conclusion: RC was robust to suboptimal testing VF conditions and showed good-to-excellent reliability between VF testing visits holding high potential for teleophthalmology.

Keywords: confounding VF factors; glaucoma; rapid campimetry; teleophthalmology; visual field.

FIGURE 1

Illustration of trajectory of the test point. The test point trajectories are indicated for campimetry testing of the right eye as a dashed line (not shown during testing). The red circle denotes the start position of test spot which subsequently travels along the dashed line; the blindspot is indicated as a black disk not shown during testing. Participants are instructed to fixate the central cross during testing.

FIGURE 2

Comparison of blindspot and glaucoma-induced VF-defect size in different conditions using RM-ANOVA: (A) the size of blind spot differences across groups and conditions and (B) the size of visual field (VF) defect in glaucoma group. For abbreviations see Table 1.

FIGURE 3

Intrasession and intersession variability of the standard rapid campimetry tests (T_ST): Subplot (i) on the same day and subplot (ii) on different days, 1–3 weeks apart. (A,B) Correlation plots for blindspot’s size. Bland-Altman plots for (C,D) blindspot’s size reproducibility and (E,F) VF defects’ size reproducibility.