Asian Journal of Research and Reports in Ophthalmology

Aim: The aim of the study was to assess the pattern of visual function (visual acuity, contrast sensitivity, colour vision, stereoacuity and visual field) and its association with risk of RTA among CVDs in Gwagwalada, FCT-Abuja.

Study Design: Community base cross sectional study.

Place and Duration of Study: Four major motor parks within Gwagwalada, Abuja, Nigeria. This study lasted for 4 months.

Materials and Methods: Commercial Vehicle Drivers (CVDs) with minimum of one-year driving experience, who were aged 18 years and above and consented to participate in the study were recruited. An interviewer administered questionnaire was used to obtain information on RTA count and years of driving from which RTA rate (crashes per person years of driving) was determined. Visual acuity status was assessed based on WHO and FRSC definitions using a smartphone Peek Acuity application. Contrast sensitivity and colour vision were assessed using Pelli-Robson chart and Ishihara chart respectively while Stereoacuity and visual fields were assessed using Titmus Stereo chart and Confrontation perimetry, respectively. Multiple visual functions were assessed to provide a comprehensive evaluation beyond visual acuity alone. Descriptive and inferential statistics, were carried out using the SPSS version 25. The level of statistical significance was set at p < 0.05.

Result: A total of 188 male CVDs, were enrolled, with majority (66%) of them being in the 41 to 60 years age group. 57.4% of the drivers were involved in at-fault RTA. Majority (58%) of CVDs had at least one form of visual function impairment and stereoacuity accounted for the highest abnormality (47.3%). Visual impairment prevalence, based on WHO and FRSC definitions, were 18.1% and 21.8%, respectively. Abnormal visual acuity, based on FRSC definition, showed 12.5 times higher likelihood of RTA per year of driving (CI: 1.1 - 147.5, p=0.045) while abnormal stereoacuity revealed 2.4 times higher likelihood of RTA per year of driving (CI: 1.2 - 4.8, p=0.016). Drivers aged 18-40 years showed 2.6 times higher likelihood of RTA per year of driving (CI: 1.1 - 6.0, p=0.026).

Conclusion: This study found that abnormal stereoacuity and visual acuity based on FRSC visual standard for driving were significantly associated with increased risks of RTAs. These findings should guide driving regulations and eyecare policies for drivers in Nigeria. it is also recommended that enforcement of pre-license vision testing regulations for drivers should be strengthened and made mandatory to improve Public safety.