Driver contrast sensitivity and reaction times as measured through a salt-covered windshield

BackgroundThe objective of this study was to use contrast sensitivity measurements to determine the effect of windshield salt film on driver vision. This effect simulates road salt spray that dries in place on a vehicle windshield during winter driving conditions.MethodsTen emmetropic subjects were tested to assess contrast sensitivity functions through windshields that were clear compared with the same stimuli as viewed through windshields coated with salt film. Achromatic stimuli were generated by a VisionWorks system and were presented at 4 spatial frequencies (0.5, 3, 10, and 20 cycles per degree).ResultsA significant reduction in contrast sensitivity through the salt film was found at all spatial frequencies. In addition, reaction time to detect the stimuli was also found to be increased significantly at 2 of the 4 spatial frequencies through the saline-covered windshield.ConclusionThe results of this study indicate that windshield salt film reduces the ability to detect high and low contrast objects in a simulated driving environment as well as increases the subjects’ reaction times.