A recent survey by the Driver and Vehicle Licencing Agency (DVLA) found that less than half of UK drivers knew they were required to be able to read a number plate from a distance of 20 metres in order to drive safely.
The vision test to read a number plate is quick and simple, and the DVLA provides some helpful estimates for the distance required for the test. However, the question remains whether this test is a fair assessment of a driver’s vision for safe driving.
Recent reports suggest that the DVSA is considering tightening UK driving regulations when it comes to the eyesight test.
It’s important to note that factors such as lighting, time of day, weather, age, color and cleanliness of the number plate, and letter size and spacing can all affect the ease of reading a number plate. Vision is typically assessed and reported as a fraction, with 6/6, 6/9, or 6/12 being common measurements in the UK.
While the Snellen test developed in the 1860s has been widely used, the more recent LogMAR test has become popular for its uniform letter spacing. Despite this, UK driving regulations still primarily rely on the Snellen test.
Furthermore, in the UK, the requirement to read a number plate from a distance of 20 metres is just one aspect of the visual test. A full visual field and at least 6/12 Snellen vision are also necessary. However, crowding, a phenomenon that affects some individuals’ ability to see all the letters on a number plate, is not accounted for in the current test.
According to recent studies, other factors such as glare sensitivity, visual field loss, and the useful field of view play significant roles in predicting driving accidents. This raises the question of whether the current visual acuity test is the best predictor of driving performance.
With an aging population and a significant increase in older drivers in the UK, there is a need to further evaluate the effectiveness of the current vision test for driving. Rather than solely relying on the 20m number plate test, it may be necessary to consider more comprehensive and reliable exams to ensure that drivers meet the necessary visual requirements for safe driving.