Abstract
Purpose :
Night-time driving is more dangerous than in the day, with elevated crash rates, particularly for those involving pedestrians and other vulnerable road users. The aim of these studies was to develop a Night-time Hazard Visibility Test (NHVT) and explore the impact of optical blur and simulated cataracts on NHVT performance.
Methods :
A novel computer-based Night-time Hazard Visibility Test (NHVT) was developed using 50 video clips of real-world night-time roads taken from the driver’s perspective, which included a range of hazards (pedestrians, bicyclists, motor cyclists and other motor vehicles). Participants responded when they first recognized potential hazards in each video that would require them to take evasive action to avoid a collision. Videos were split into 2 sets of 25, balanced for road hazards. Raw response times were converted to z scores relative to the whole sample within each study; a more positive score represented longer (delayed) response times. In Study 1, 16 young visually normal drivers (M=22.3 ± 2.2 yrs) completed the NHVT using their best-correction and with optical blur (+1.00 DS). In Study 2, an additional 16 young visually normal drivers (M=21.1 ± 1.2 yrs) completed the NVHT using their best-correction and with simulated cataracts (diffusion filter). In both studies, the order of visual conditions and NHVT video sets were counterbalanced.
Results :
Both studies showed significant delays in NHVT response times in the presence of simulated vision impairment relative to best-corrected vision. In Study 1, blur significantly reduced photopic visual acuity (VA) (0.09 vs -0.21 logMAR; p<0.001) and delayed response times (1.07 vs 0.21 z score; p<0.001) compared to best-corrected vision, predominantly for low contrast pedestrians. In Study 2, simulated cataracts also significantly reduced photopic VA (0.01 vs -0.16 logMAR; p<0.001) and delayed response times (0.83 vs 0.42 z score; p<0.001).
Conclusions :
This novel NHVT was sensitive to low levels of blur and simulated cataracts, highlighting the impact of these conditions on the ability to promptly detect potential hazards in the night-time driving enviornment. These findings demonstrate the potential for the NHVT to assess visual performance for night driving. Future work will refine the videos and explore this test in other populations, particularly in drivers using current and emerging optical corrections and in those with ocular disease.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.