Auditory Reminder Cues to Promote Proactive Scanning on Approach to Intersections in Drivers With Homonymous Hemianopia: Driving With Hemianopia, IX

Question  Do auditory reminder cues promote proactive scanning (making an early large scan to the blind side) by individuals with homonymous hemianopia when approaching intersections in a driving simulator?

Findings  In this post hoc analysis of data from 14 individuals with homonymous hemianopia who had participated in a cross-sectional study, the percentage of intersections at which an early large scan was made was higher in drives with vs without reminders (65% vs 45%). Responses to hazards were approximately 2 seconds faster when an early large scan was made.

Meaning  In this study, the auditory reminder cues promoted proactive scanning and faster responses to hazards.

Importance  Individuals with homonymous hemianopia (HH) are permitted to drive in some jurisdictions. They could compensate for their hemifield vision loss by scanning toward the blind side. However, some drivers with HH do not scan adequately well to the blind side when approaching an intersection, resulting in delayed responses to hazards.

Objective  To evaluate whether auditory reminder cues promoted proactive scanning on approach to intersections.

Design, Setting, and Participants  This cross-sectional, single-visit driving simulator study was conducted from October 2018 to May 2019 at a vision rehabilitation research laboratory. A volunteer sample of individuals with HH without visual neglect are included in this analysis. This post hoc analysis was completed in July and August 2020.

Main Outcomes and Measures  Participants completed drives with and without scanning reminder cues (a single tone from a speaker on the blind side). Scanning was quantified by the percentage of intersections at which an early large scan was made (a scan with a head movement of at least 20° made before 30 m from the intersection). Responses to motorcycle hazards at intersections were quantified by the time to the first fixation and the time to the horn-press response.

Results  Sixteen individuals were recruited and completed the study. Two were subsequently excluded from analyses. Thus, data from 14 participants (median [IQR] age, 54 [36-66] years; 13 men [93%]) were included. Stroke was the primary cause of the HH (10 participants [71%]). Six (43%) had right-sided HH. Participants were more likely to make an early large scan to the blind side in drives with vs without cues (65% vs 45%; difference, 20% [95% CI, 5%-37%]; P < .001). When participants made an early large scan to the blind side, they were faster to make their first fixation on blind-side motorcycles (mean [SD], 1.77 [1.34] vs 3.88 [1.17] seconds; difference, −2.11 [95% CI, −2.46 to −1.75] seconds; P < .001) and faster to press the horn (mean [SD], 2.54 [1.19] vs 4.54 [1.37] seconds; difference, −2.00 [95% CI, −2.38 to −1.62] seconds; P < .001) than when they did not make an early scan.

Conclusions and Relevance  This post hoc analysis suggests that auditory reminder cues may promote proactive scanning, which may be associated with faster responses to hazards. This hypothesis should be considered in future prospective studies.