Impairment of depth perception and risk factors among commercial motor-vehicle drivers

Introduction

Depth perception, referred to as stereopsis is the ability of the eyes to fuse two somewhat different images created by stimulating two distinct retina areas to produce binocular single vision. Impairment of depth perception is a suggested risk factor in road traffic injuries and deaths globally. This study aimed to determine the prevalence of impaired depth perception and associated risk factors among commercial motor-vehicle drivers in Benin City, Edo State, Nigeria.

Methods

A cross-sectional study of 341 commercial motor-vehicle drivers aged ≥ 20 years in Benin City Metropolis using a purposive sampling technique. Socio-demographic data were collected using a self-administered questionnaires. Depth Perception was assessed using TNO Random Dot Stereogram Chart. Data was analyzed using IBM-SPSS version 29.0. Statistical significance was considered at p < 0.05.

Results

A total of 326 (95.6%) males and 15 (4.4%) females participated in this study. The overall prevalence of impaired gross and fine depth perception were 18.8% and 83.9% respectively. While 19.0% of males and 13.3% of females had impaired gross depth perception, 85.8% of males and 40.0% of females had impaired fine depth perception. Impaired depth perception increases with increase in age, years of driving experience and hours driven per day.

Conclusion

The high prevalence of impaired depth perception in this study could promote occurrence of road traffic accidents due to inability to make precise judgment especially at near and intermediate distances. Routine depth perception assessment of drivers is recommended prior to issuance of driver’s license and relicensing.