Even moderate visual impairments degrade drivers’ ability to see pedestrians at night

Wood, Joanne M., Tyrrell, Richard A., Chaparro, Alex, Marszalek, Ralph P., Carberry, Trent P., & Chu, Byoung Sun (2012) Even moderate visual impairments degrade drivers’ ability to see pedestrians at night. Investigative Ophthalmology and Visual Science.

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Purpose: To determine the effect of moderate levels of refractive blur and simulated cataracts on nighttime pedestrian conspicuity in the presence and absence of headlamp glare.

Methods: The ability to recognize pedestrians at night was measured in 28 young adults (M=27.6 years) under three visual conditions: normal vision, refractive blur and simulated cataracts; mean acuity was 20/40 or better in all conditions. Pedestrian recognition distances were recorded while participants drove an instrumented vehicle along a closed road course at night. Pedestrians wore one of three clothing conditions and oncoming headlamps were present for 16 participants and absent for 12 participants.

Results: Simulated visual impairment and glare significantly reduced the frequency with which drivers recognized pedestrians and the distance at which the drivers first recognized them. Simulated cataracts were significantly more disruptive than blur even though photopic visual acuity levels were matched. With normal vision, drivers responded to pedestrians at 3.6x and 5.5x longer distances on average than for the blur or cataract conditions, respectively. Even in the presence of visual impairment and glare, pedestrians were recognized more often and at longer distances when they wore a “biological motion” reflective clothing configuration than when they wore a reflective vest or black clothing.

Conclusions: Drivers’ ability to recognize pedestrians at night is degraded by common visual impairments even when the drivers’ mean visual acuity meets licensing requirements. To maximize drivers’ ability to see pedestrians, drivers should wear their optimum optical correction, and cataract surgery should be performed early enough to avoid potentially dangerous reductions in visual performance.

Impact and interest:

28 citations in Scopus
25 citations in Web of Science®
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ID Code: 50056
Item Type: Journal Article
Refereed: Yes
Additional Information: published ahead of print March 16, 2012,
Additional URLs:
Keywords: visual impairment , uncorrected refractive error , cataract
DOI: 10.1167/iovs.11-9083
ISSN: 0146-0404
Subjects: Australian and New Zealand Standard Research Classification > MEDICAL AND HEALTH SCIENCES (110000) > OPTOMETRY AND OPHTHALMOLOGY (111300)
Divisions: Current > Institutes > Institute of Health and Biomedical Innovation
Copyright Owner: Copyright 2012 by The Association for Research in Vision and Ophthalmology, Inc.
Deposited On: 02 May 2012 04:48
Last Modified: 02 Nov 2012 07:21

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