Assessment of visual functions in night drivers.

Abstract

PURPOSE: To check the visual functions (visual acuity, visual fields, colour vision, contrast sensitivity and glare sensitivity) in people who routinely drive vehicles at night, and draw recommendation for safe driving.

METHOD: A cross-sectional study was conducted among people who routinely drove vehicles at night. According to personal complaints and taking full ocular and driving history, data of 55 night drivers was recorded by self-designed proforma. Visual acuity was recorded on Snellen chart, visual field by Confrontation method, color vision by Ishihara chart and contrast sensitivity with LEA number chart. Stereopsis, dominant eye determination and ocular mobility were also assessed.

RESULTS: The result deducted from the questionnaire and proforma showed that among 55 male respondents 67% belong to young age group (31-50years) 58% have 20-25 years and 42% have driving experience in-between 5-20 years. 65% have 5-7 hours of night driving. 13% have abnormal visual acuity, 33% with some grade of color vision deficiency and 9% with constricted visual field. 8% had abnormal stereopsis and 18% drivers have sub-normal contrast sensitivity.

CONCLUSION: It is concluded from our survey that visual functions are strongly associated with potential skill of driving. Along with visual acuity, visual field, color vision, contrast sensitivity, and stereopsis affect the driving abilities especially at night. As by license agencies of Pakistan only visual acuity is considered as standard, but the other visual function such as visual field, color vision and stereopsis should also be evaluated to acquire a driving license. All of visual functions are equally contributors for safe driving and their assessment is imperative to avoid road traffic accidents.