The effects of visual field loss from glaucoma on performance in a driving simulator

BACKGROUND: To examine the effects of different stages of visual field loss (VFL) from advanced glaucoma on performance in a driving simulator. METHODS: Data on performance and safety from a traffic simulator test for 104 participants with withdrawn driver's licences due to visual field loss from advanced glaucoma were compared with data from 83 individuals without visual deficits in a cross-sectional study. Individuals with glaucoma that regained their driving licences after a successful simulator test were then followed in a national accident database. RESULTS: Glaucoma participants passed the test in 71% (95% confidence interval 61-79%) of the cases. Younger participants were more successful than older. No significant differences on safety or performance measures were detected between glaucoma- and normally sighted participants. Compared with passed glaucoma participants, failed glaucoma participants had more collisions, more critical failed to give way events, longer time headways, and longer reaction times. This group had also a higher extent of central visual field loss. None of the participants with a regained licence were involved in a motor vehicle accident during the 2 to 4 year follow-up after the simulator test. CONCLUSION: Severity of glaucoma predicts driver safety on a group level. However, even individuals with severe visual field loss from glaucoma might drive safely, which highlights the need for individual assessments for licencing purposes.