Effect of Exposure to Computer Simulated Visual Field Test on Variability of Test Results

Abstract

Purpose: To evaluate the efficacy of a computer simulated visual field test in reducing visual field variability and improving visual field test reliability indexes in perimetric novices

Methods: This randomized controlled trial enrolled patients newly referred to a glaucoma clinic for visual field (VF) testing and evaluation. Eligibility criteria included age 18 years or greater and no more than 1 previous VF test examination during the past 4 years. Patients were randomized to intervention or control groups. The intervention group received computer simulated visual field tests (CSVF) before completing a 24-2 Sita Standard VF test (Humphrey Field Analyzer II, Carl Zeiss Meditec, Dublin, CA) in 2 separate sessions 1-2 weeks apart, while control subjects completed two 24-2 Sita Standard VF tests without any prior preparation. Right eyes were tested first in both standard and computer-simulated VFs. The main study outcome was absolute difference in mean deviation of the first and second Sita Standard VF exam. Secondary outcomes included false positive responses, false negative responses and proportion of unreliable exams. Analyses were conducted separately for right and left eyes.

Results: Sixty-two patients completed study procedures, including 31 randomized to standard therapy and 31 randomized to the intervention. Mean age (sd) was 69 (10) years and 71% of the participants were female. Absolute difference between first and second VF MD (sd) for right eyes was 2.3 (3.1) dB in the control group and 1.4 (2.0) dB in the intervention group (p=0.17). For left eyes the effect of training went in the opposite direction, with an absolute first to second VF MD difference of 1.9 (2.3) dB and 2.4 (3.0) dB in the control and intervention group respectively. (p=0.44)

Conclusions: Computer simulated visual field training did not achieve a statistically significant effect on the variability of an initial set of 2 visual fields obtained shortly after glaucoma or glaucoma suspect diagnosis. However, we observed a trend towards a positive effect in right eyes that were tested first, suggesting that further refinement may be able to increase the accuracy of VF results. Future methods may also need to minimize fatigue, which may explain the observed trend towards a greater variability in left eye testing.

Keywords: 758 visual fields • 466 clinical (human) or epidemiologic studies: treatment/prevention assessment/controlled clinical trials • 584 low vision