Performance-based visual field testing for drivers with glaucoma: A pilot study

Objective: Conventional visual field (VF) tests are limited in predicting on-road driving performance of individuals with glaucoma. We developed a new performance-based VF test in a driving simulator for individuals with glaucoma. The aim was to evaluate the psychometric properties of the newly developed test. Methods: In this pilot study, 17 drivers with glaucoma aged 65.24 ± 9.69 and 13 control drivers aged 61.27 ± 11.45 completed the performance-based VF task. Construct validity was determined by comparing performance on the new task with results on conventional visual and perimetry tests including Humphrey Visual Field Analyzer, Keystone Vision Screener, and Useful Field of View (UFOV). Concurrent validity was evaluated by comparing performance on the new task with on-road driving performance, scored using the Test Ride for Investigating Practical fitness-to-drive (TRIP). Ten individuals (7 with glaucoma and 3 controls) participated in the test–retest reliability assessment. Results: Drivers with glaucoma identified fewer symbols (P = .047) and took longer to respond to the symbols (P = .048) compared to controls. In the glaucoma group, correct responses on the performance-based VF test correlated strongly (r = −0.51, P = .046) with UFOV divided attention. Both glaucoma and control groups achieved submaximal to maximal scores on the TRIP (median [Q1–Q3], glaucoma: 193 [191–196]; controls: 196 [195–196]; P = .16). No strong correlations were found between scores on the performance-based VF test and on-road driving performance in glaucoma. The intraclass correlation coefficients ranged between 0.77 for response time and 0.92 for correct responses, indicating good to excellent test–retest reliability. Conclusions: We established the construct validity and test–retest reliability of the performance-based VF test. Future studies should include a larger sample with more severe driving difficulties to demonstrate the concurrent validity between performance-based VF testing and on-road driving performance in glaucoma.