Abstract
Glaucoma is an optic neuropathy that impairs peripheral vision, increasing motor vehicle crash risk. Mechanisms underlying impaired driving in glaucoma demand further study. Here, we developed a novel driving simulator visual field (DSVF) task to study how glaucomatous visual field (VF) loss affects driving under naturalistic conditions. DSVF was completed in a dynamic panoramic driving simulator with 290-degree forward field of view. Stimulus size and retinal positions mirrored standard clinical perimetry (Humphrey Visual Field; HVF), facilitating cross-platform comparisons. We calculated global visual field index (VFI) to estimate proportion of VF unimpaired, similar to HVF (Bengtsson, 2008). We studied 13 glaucoma patients with VF impairment (VFI: 24-88% worse eye) and 10 comparisons without VF impairment (VFI: 99-100%). In Experiment 1, participants completed monocular DSVFs against a gray background while maintaining stable fixation. DSVF VFIs demonstrated high test-retest reliability (r>.98) and correctly mapped VF blind spots. VFI estimates between DSVF and HVF platforms correlated for left (r=.87) and right eye (r=.87) VFs. In Experiment 2, participants completed binocular DSVFs without fixation against a naturalistic background during three cognitive load conditions: (1) stationary; (2) simulated driving; (3) simulated driving while concurrently performing an auditory task (PASAT). Baseline binocular DSVF performance was also measured using a gray background to evaluate cognitive load effects. Consistent with previous studies (Park & Reed, 2015; Wall et al., 2004), we found load-dependent VFI reductions. Furthermore, VFI reductions were greater in glaucoma patients than controls during simulated driving (p< .05; Cohen's d=.98). In summary, DSVFs are a valid measure of VF loss when compared to standard clinical perimetry, and demonstrate load-dependent VF impairments during driving simulation. Importantly, glaucoma patients experienced greater VF impairment than controls during driving simulation. These results suggest attention impairments may affect safety critical tasks such as visual search in the periphery in glaucoma.
Meeting abstract presented at VSS 2018