Regular testing of drivers is important

Several different approaches to measure vision in order to improve road safety have been identified around the world. A trend seen in the literature performed by researchers at VTI (The Swedish National Road and Transport Research Institute) is that traditional vision tests increasingly are supplemented by cognitive tests.

Both visual impairments and cognitive impairments may develop gradually and it can take a long period of time for them to become discernable. As a consequence, affected persons seldom perceive that their driving skill have deteriorated.

– This is a central question to address and an important reason to advocate regular testing of drivers, says Birgitta Thorslund, researcher at VTI.

Birgitta Thorslund will be presenting the research results about vision May 18th at the international conference RS5C (Road Safety on Five Continents) at the Windsor Flórida Hotel in Rio de Janeiro, Brazil.

Visual acuity is a measure of the eye’s resolution power and is dependent on several components such as the optical system, the receptors on the retina and the brain. Several diseases, such as cataracts, may affect visual acuity and impair driving performance due to late detection of pedestrians and other risk factors. Numerous studies have demonstrated that the traditional tests of visual acuity, on their own, are not appropriate to identify unsafe drivers. According to several sources, testing of visual acuity used for screening should be accompanied by further tests such as contrast sensitivity, visual field, and tests of cognitive abilities.

The main purpose of the present study was to investigate visual capabilities important for safe driving. The study answered questions about the visual capabilities essential for safe driving; which tests are available and how are they used? As well as existing evidence for these tests.
– Contrast vision, color vision, diplopia and adaptation are important subjects that we need to take into account in this kind of research, says Birgitta Thorslund.

Many studies carried out traditional tests of visual acuity, however according to the results of this review, no one has found a strong correlation with road safety. The fact that visual acuity is essential for safe driving is rarely doubted, but tests for visual acuity are considered inadequate. It is often suggested to be accompanied by a test for contrast sensitivity. VTI share this view and find it reasonable given that visual acuity is measured under very optimal conditions rarely seen in traffic.

The results suggest a combination of different tests according to individual conditions for a fair assessment of the driving ability.

Facts
VTI, Swedish National Road and Transport Research Institute is an independent, internationally established research institute which is engaged in the transport sector. Our core competence is in the fields of safety, economy, environment, traffic and transport analysis, public transport, behavior and the man-vehicle-transport system interaction, and in road design, operation and maintenance. VTI is a world leader in several areas, for instance in simulator technology.

RS5C
Road Safety on Five Continents (RS5C) is an international conference aiming at increasing road safety globally by providing a platform for this essential knowledge exchange and helping the participating countries to find a good balance between road safety and mobility. RS5C is organized by VTI in close cooperation with The Brazilian National Association for Transportation Research and Education (ANPET).

Contact
Birgitta Thorslund, researcher, VTI, Sweden, +46 13 20 41 55