Publication:

Colour vision deficiency and driving: impact on safety, performance and everyday challenges

Background This study aimed to assess the impact of colour vision deficiency (CVD) on driving performance, challenges and related factors among licensed male drivers.

Methods This prospective observational study recruited drivers with normal and colour vision deficiency. Initial screening used the Ishihara plates, followed by AO-HRR plates to confirm the type of congenital CVD, and the Farnsworth Lantern signal test to assess signal perception. Drivers with best-corrected visual acuity less than 6/12 or acquired CVD were excluded. Detailed eye examinations and occupational/driving histories were also collected.

Results The study included 63 male drivers: 30 with normal colour vision (mean age 41.1±6.6 years) and 33 with congenital CVD (mean age 38.7±8.9 years). Drivers with CVD were eight times more likely to experience difficulties compared to the normal vision group (OR: 7.80, 95% CI: 2.22-27.39, p=0.001), and nearly five times more likely to report difficulties under adverse conditions such as rain, fog, bright sunlight, (OR: 4.79, 95% CI: 1.36-16.87, p=0.015). No statistically significant association was found between CVD and road traffic accidents (RTA) in current study (p=0.07). However, CVD did affect the driving performance and self-reported difficulties.

Conclusions No statistically significant association was found between CVD and RTA in current study; however, it significantly affects driving performance, with protans experiencing delayed signal recognition and deutans experiencing more colour confusions, especially under adverse weather conditions when secondary cues were absent.