Abstract
Purpose :
The mechanisms underlying the elevated crash rates of older drivers with visual impairment are poorly understood. While a key driving skill involves timely detection of hazards, the hazard detection ability of drivers with visual impairment and the visual predictors of this performance have been largely unexplored.
Methods :
Participants included older drivers 65+ years with a range of ocular diseases including cataracts, age-related maculopathy and glaucoma resulting in reduced visual function (n=158; M=72.2±5.5 yrs) and a group of visually normal drivers (n=108; M=75.6±6.3 yrs). Visual performance was assessed using standard clinical measures (visual acuity, contrast sensitivity, visual fields) as well as non-standard measures (useful field of view and motion sensitivity). Participants also completed a computerized Hazard Perception Test (HPT), which has been related to crash risk in older drivers and comprises a series of real-world traffic videos recorded from the driver’s perspective. Participants responded to road hazards appearing in the videos and hazard response times were recorded.
Results :
Participants with visual impairment had significantly worse visual performance on both standard clinical and non-standard measures (p<0.01) than the controls. They also exhibited an average of 0.42s delay in hazard response time (p=0.034) compared to the controls. Of the standard vision measures, visual acuity was the strongest predictor of hazard response times (standardized beta =0.273; p<0.001), while of the non-standard measures, motion sensitivity was the strongest predictor of hazard response times (standardized beta =0.317; p<0.001), even when adjusted for age. In a subgroup analysis, these associations were stronger in the visually impaired group.
Conclusions :
Older drivers with visual impairment exhibited delayed hazard response times compared to controls with normal vision and this was most strongly associated with decreased motion sensitivity. These findings have implications for assessing driving safety in older adults with visual impairment, given that the HPT has been shown to be associated with driving safety in older adults.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.