Glaucoma has been shown to impair hazard detection ability and increase crash risk compared to controls. Differences in visual search behavior of the driving scene may explain these differences; however, there has been limited investigation of this issue with inconsistent findings.
Through eye movement tracking of older drivers with glaucoma, we explored their visual search behavior in comparison with controls while performing the DriveSafe, a slide recognition test purported to predict fitness to drive.
Thirty-one drivers with glaucoma (mean age, 71.7 ± 6.3 years; average better-eye mean defect,−3 dB; average worse-eye mean defect,−12 dB) and 25 age-matched controls underwent measurements of their visual acuity, contrast sensitivity, visual fields, and useful field of view (visual processing speeds). Participants' eye movements were recorded while they completed the DriveSafe test, which consists of brief presentations of static, real-world driving scenes containing various road users (pedestrians, bicycles, vehicles). Participants reported the types, positions, and direction of travel of road users in each image; the score was the total number of correctly reported items (maximum, 128).
Drivers with glaucoma had significantly worse DriveSafe scores (P = .03), fixated on road users for shorter durations (P < .001), and exhibited smaller saccades (P = .02) compared with controls. For all participants, longer fixation times on road users (P < .001) was the eye movement measure most strongly associated with better DriveSafe scores; this relationship was not significantly different between groups. Useful field-of-view divided attention was the strongest visual predictor of DriveSafe scores.
Eye movement changes in the glaucoma group may reflect increased difficulty in identifying relevant objects in the visual scene, which may be related to their lower DriveSafe scores. Given the DriveSafe’s potential utility in assessing drivers with visual impairment before on-road testing, further investigations on how DriveSafe performance and eye movement patterns compare to those during on-road driving are warranted.
1School of Optometry and Vision Science and Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland, Australia
2Lions Eye Institute and Centre for Ophthalmology and Visual Science, University of Western Australia, Nedlands, Western Australia, Australia *email@example.com; firstname.lastname@example.org
Submitted: September 5, 2018
Accepted: February 24, 2019
Funding/Support: SL was supported by a School of Optometry Vision Science Scholarship and a Queensland University of Technology Higher Degree Research Student Sponsorship.
Conflict of Interest Disclosure: None of the authors have reported a financial conflict of interest.
Author Contributions and Acknowledgments: Conceptualization: AAB, JMW; Data Curation: SS-YL; Formal Analysis: SS-YL; Funding Acquisition: JMW; Investigation: SS-YL; Methodology: SS-YL, AAB, JMW; Project Administration: SS-YL; Resources: JMW; Supervision: AAB, JMW; Writing – Original Draft: SS-YL; Writing – Review & Editing: SS-YL, AAB, JMW.
The authors would like to thank Mr. Trent Carberry for his assistance with the study and the study participants.