Exposure to green laser decreases driving performance

Abstract

Purpose: To determine the impact of 532 nm laser exposure on vision and thereby driving performance.

Methods: Ten non-professional drivers aged [24;50] yrs drove a test track through gates of 4 plastic cones with randomly placed openings, allowing free passage. A 532 nm laser beam, 45 mrad divergence, was directed against the advancing test driver every second test drive. Irradiance increased from 2 W·m^-2 at the entrance of the test track to 5 W·m^-2 at the last gate (MPE = 10 W·m²). The spatial distribution and the irradiance of the beam was verified before and after each test drive. Driving speed was 25 km·hr^-1 at the entrance gate and then at the drivers choice. For each driver, the background illuminance varied from daylight to darkness, [1000-0.01 lux]. Altogether, 32 test drives per driver were analyzed. The significance level was set to 0.05.

Results: None of the subjects recruited had any ophthalmological disorder before or after test driving.<br /> A driver perceives less driving certainty with laser exposure than without as indicated by Wilcoxon’s paired sample test.<br /> An analyses of variance supported that laser exposure increases driving time and indicated an interaction between laser exposure and background illumination.<br /> A chi² analysis indicated that laser exposure is associated with more wrong choices of gate and more hits of cones than driving without laser exposure. A descriptive analysis indicated more wrong choice of gate and more hit cones with less background luminance.<br /> Sun visor folded down when exposed to laser was advantageous on driving time, number of wrong gates chosen per driver, and accumulated number of cones hit as indicated by paired t-test and chi² analysis.

Conclusions: Exposure to 532 nm laser light while driving below 25 km·h^-1 in dark conditions decreases perceived safe driving speed, causes wrong decision of road geometry, increases risk of mispositioning the vehicle, and decreases the subjective perception of controlled driving. Sun visor folded down during green laser exposure improves the driving performance and the perception of driving certainty.