Visual functions and their association with road traffic accidents among vehicle drivers in Gauteng

Background: South Africa has a high mortality rate because of road traffic accidents (RTAs) compared to other countries. Aim: To determine the visual functions and their association with the occurrence of RTAs among vehicle drivers in the Gauteng province of South Africa. Setting: Eight driver's license testing centres (DLTCs) in the Gauteng province. Methods: A cross-sectional study involving a multi-stage random sampling approach was conducted. Data collected using the questionnaire included participants' demographic details. Ocular health examination included the measurement of visual acuity (VA), refractive errors, visual fields, colour vision, stereopsis, contrast and glare sensitivity. Results: A total of 579 motor vehicle drivers were enrolled in this study. Drivers who reported daily alcohol consumption had a higher risk of being involved in RTAs (odds ratio [OR] = 1.8, 95% confidence interval [95%CI] = 1.09-2.99, P = 0.02). Visual acuity (OR = 1.43, 95%CI = 0.99-2.06, P = 0.05), refractive errors (P = 0.03, chi(2) = 61.57), abnormal contrast sensitivity (OR = 0.53, 95%CI = 0.31-0.93, P = 0.03) and deutan colour vision defects (P = 0.002, chi(2) = 31.42) were significantly associated with RTAs. Visual field defects (OR = 0.98, 95%CI = 0.97-1.00, P = 0.09), stereopsis anomaly (OR = 1.00, 95%CI = 0.99-1.00, P = 0.35) and abnormal glare sensitivity (OR = 1.00, 95%CI = 0.99-1.01, P = 0.32) were not significantly associated with the occurrence of RTAs. Conclusion: These results suggest reviewing the visual requirements for obtaining a driver's license by incorporating colour vision and contrast sensitivity assessment. Contribution: The study addresses a gap in the country's current vision testing standards for driving.