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Abstract
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Vision is generally considered to be the most important sensory ability for safe driving. The legislation of most countries globally imposes visual assessment for all candidates for a driving licence. In high-income countries, specific regulations that are inspired by apparently objective and frequently updated criteria are developed and implemented to guide the assessment of fitness to drive as a holistic and legal concept. However, the proportion of drivers in many low-income and middle-income countries (LMICs), including those drivers involved in transportation of the public in large numbers, who are still able to secure a driving licence without ever having their vision assessed might seem shocking and reveals challenges in law implementation. Paradoxically, it is observed that these shortcomings do not necessarily translate into a higher proportion of drivers with visual defects and the methods to assess visual function of drivers needs to be revisited.
Several studies have attempted to estimate the proportion of drivers with visual defects in all settings and some often attempt to associate the presence of such defects with the risk of occurrence of road traffic crashes. The Article by Prabhath Piyasena and colleagues in The Lancet Global Health is an interesting overview of the problem, specifically in LMICs, with a focus on the prevalence of visual defects, adherence to visual parameters included in driving licensure requirements, and the possible association with the risk of poor driving outcomes.
The systematic review and meta-analysis of 15 394 participants (mean age 39·3 years [SD 9·65]; 1167 [7·6%] of 15 279 female) found that the prevalence of vision impairment among road users ranged from 1·2% to 26·4%, colour vision defects from 0·5% to 17·1%, and visual field defects from 2·0% to 37·3%. The meta-analysis revealed a 46% greater risk of having a road traffic crash among those with central acuity visual impairment (risk ratio [RR] 1·46 [95% CI 1·20-1·78]; p=0·0002) and a greater risk among those with colour vision defects (RR 1·36 [1·01-1·82]; p=0·041) or defects of the visual field (RR 1·36 [1·25-1·48]; p<0·0001). It also shows a poor adherence to licensure requirements. Assessment of vision as a component of fitness to drive is historically based on perceptual parameters ranging from the most basic--ie, visual acuity, colour vision, and visual fields--to more specific ones such as stereopsis (the ability to appreciate depth), contrast sensitivity, and peripheral vision. Such parameters play an important role in safe driving...
Language: en |