Driving with Binocular Visual Field Loss? A Study on a Supervised On-Road Parcours with Simultaneous Eye and Head Tracking

Abstract

Post-chiasmal visual pathway lesions and glaucomatous optic neuropathy cause binocular visual field defects (VFDs) that may critically interfere with quality of life and driving licensure. The aims of this study were (i) to assess the on-road driving performance of patients suffering from binocular visual field loss using a dual-brake vehicle, and (ii) to investigate the related compensatory mechanisms. A driving instructor, blinded to the participants' diagnosis, rated the driving performance (passed/failed) of ten patients with homonymous visual field defects (HP), including four patients with right (HR) and six patients with left homonymous visual field defects (HL), ten glaucoma patients (GP), and twenty age and gender-related ophthalmologically healthy control subjects (C) during a 40-minute driving task on a pre-specified public on-road parcours. In order to investigate the subjects' visual exploration ability, eye movements were recorded by means of a mobile eye tracker. Two additional cameras were used to monitor the driving scene and record head and shoulder movements. Thus this study is novel as a quantitative assessment of eye movements and an additional evaluation of head and shoulder was performed. Six out of ten HP and four out of ten GP were rated as fit to drive by the driving instructor, despite their binocular visual field loss. Three out of 20 control subjects failed the on-road assessment. The extent of the visual field defect was of minor importance with regard to the driving performance. The site of the homonymous visual field defect (HVFD) critically interfered with the driving ability: all failed HP subjects suffered from left homonymous visual field loss (HL) due to right hemispheric lesions. Patients who failed the driving assessment had mainly difficulties with lane keeping and gap judgment ability. Patients who passed the test displayed different exploration patterns than those who failed. Patients who passed focused longer on the central area of the visual field than patients who failed the test. In addition, patients who passed the test performed more glances towards the area of their visual field defect. In conclusion, our findings support the hypothesis that the extent of visual field per se cannot predict driving fitness, because some patients with HVFDs and advanced glaucoma can compensate for their deficit by effective visual scanning. Head movements appeared to be superior to eye and shoulder movements in predicting the outcome of the driving test under the present study scenario.

Compensatory eye and head movements of patients with homonymous hemianopia in the naturalistic setting of a driving simulation

“…Importantly, the observed differences in detection performance between the HP and LP group could not be explained by age, sex, handedness, video game experience, holding of a driver's license, years of driving experience, time between brain lesion and examination, or side and extent of the homonymous visual field defect, since we did not find significant differences for any of these variables between the groups. The little relevance of the extent of a visual field defect for driving performance has previously been demonstrated [8,14,27]. Despite obvious differences in the detection rate, both patient groups exhibited significantly longer reaction times to obstacles presented in their blind field compared to the Co group's reaction times to obstacles presented in the right hemifield.…”

“…Surely, though, as opposed to actual driving, participants in our study did not have to perform such driving tasks as merging into floating traffic, requiring additional head movements to check for other traffic at the side and back of one's own vehicle. Reconciling divergent evidence for the importance of either eye or head movement in compensatory visual search behavior of patients with HH, Kasneci and colleagues [27], employing quantitative analyses of both eye and head movements in an onroad test, found that both increased eye and head movements into the blind hemifield contributed to successfully passing a driving test.…”

Impact of superior and inferior visual field loss on hazard detection in a computer-based driving test

“…Future studies may wish to consider whether these participants are using certain strategies to help improve their vigilance when detecting hazards or driving. Some patients may compensate for their visual deficit by using more effective scanning strategies when driving,25 a finding that has also been reported when considering other visual tasks 26 27. We, therefore, plan to investigate whether compensatory eye movement changes may have helped some participants to overcome hazard perception impairment.…”

SubsMatch 2.0: Scanpath comparison and classification based on subsequence frequencies

“…Details on data collection can be found in Kasneci et al (2014a), Kübler et al (2015a), and Kübler et al (2015b). Aim of these studies was to investigate the relationship between binocular visual field defects, eye movements, and driving performance.…”