The effect of pupil dilation with tropicamide on vision and driving simulator performance

Purpose To assess the effect of pupil dilation on vision and driving abilit y. Methods A series of tests on various parameters of visual function and driv ing simulator performance were performed on 12 healthy drivers, before and after pupil dilation using guttae tropicamide 1%. A driving simulator (Tran sport Research Laboratory) was used to measure reaction time (RT), speed ma intenance and steering accuracy. Tests of basic visual function included hi gh- and low-contrast visual acuity (HCVA and LCVA), Pelli-Robson contrast t hreshold (CT) and Goldmann perimetry (FIELDS). Useful Field of View (UFOV - a test of visual attention) was also undertaken. The mean differences in t he pre- and post-dilatation measurements were tested for statistical signif icance at the 95% level using one-tail paired t-tests. Results Pupillary dilation resulted in a statistically significant deterior ation in CT and HCVA only. Five of 12 drivels also exhibited deterioration in LCVA, CT and RT. Little evidence emerged for deterioration in FIELDS and UFOV. Also, 7 of 12 drivers appeared to adjust their driving behaviour by reducing their speed on the driving simulator, leading to improved steering accuracy. Conclusions Pupillary dilation may lead to a decrease in vision and dayligh t driving performance in young people. A larger study, including a broader spectrum of subjects, is warranted before guidelines can be recommended.