Glare susceptibility test results correlate with temporal safety margin when executing turns across approaching vehicles in simulated low-sun conditions

Ophthalmic Physiol Opt. 2007 Sep;27(5):440-50. doi: 10.1111/j.1475-1313.2007.00503.x.


The purpose of this study was to compare the results of a laboratory glare susceptibility test with the execution of turns at an intersection (turns that required the driver to cross a lane containing approaching traffic). We measured glare susceptibility by means of low and high-contrast letter charts with and without a glare source. Driving performance in the absence and presence of simulated low sun was assessed using a simulator. In particular, we measured the difference between the time taken to complete a turn across the path of an approaching vehicle and the time to collision (TTC) with the approaching vehicle (the safety margin). The presence of glare resulted in a significant reduction in the safety margin used by drivers (by 0.65 s on average) and the mean number of collisions was significantly higher in the glare conditions than in the non-glare conditions. The effect of glare was larger for low-contrast than for high-contrast oncoming vehicles. Older drivers (45-60 years) had a significantly greater reduction in safety margin than younger drivers (19-29 years), though there was a large inter-individual variability in both age groups. We suggest that the reduction in retinal image contrast caused by low-sun caused drivers to overestimate the TTC with approaching vehicles.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Accidents, Traffic / prevention & control*
  • Adult
  • Automobile Driving*
  • Cataract / physiopathology
  • Contrast Sensitivity
  • Glare*
  • Humans
  • Judgment*
  • Light
  • Middle Aged
  • Regression Analysis
  • Vision Disorders / diagnosis*
  • Vision Tests
  • Visual Acuity