Glaucoma patients with moderate-to-severe visual field loss may have greater difficulty seeing in the dark, leading them to hang up their car keys for good, a new study in the Journal of Glaucoma reports.

Researchers from the University of Toronto enrolled 99 individuals with glaucoma, including 19% who had given up driving. The study found patients with moderate-to-severe glaucoma, when compared with those with a milder condition, showed a significantly higher percentage of driving cessation—33% vs. 8%. Of the moderate-to-severe group, investigators found 27% reported a presence of glare versus 6% who had a less accelerated type of glaucoma. Additionally, the subjects with moderate-to-severe glaucoma had more difficulty with dark adaptation, representing 31% compared to 10% in the mild group.

Another study highlight: individuals who experienced difficulty with dark adaptation were about four times more likely to have issues driving at night or in poor driving conditions.

Based on their findings, researchers noted the importance of incorporating the assessment of glare and dark adaptation when evaluating and counseling patients with glaucoma about their fitness to drive.

Tam ALC, Trope GE, Buys YM, et al. Self-perceived impact of glaucomatous visual field loss and visual disabilities on driving difficulty and cessation. J Glaucoma. September 4, 2018 [E-pub, ahead of print].