Eye tests 'let unsafe drivers stay on road'

Guidelines to assess whether a person's eyesight is good enough to drive are unreliable and do not predict whether someone is legally safe to be on the road, researchers have found.

Guidelines to assess whether a person's eyesight is good enough to drive are unreliable and do not predict whether someone is legally safe to be on the road, researchers have found.

A study published in the British Medical Journal today shows that opticians, ophthalmologists and doctors are giving drivers conflicting advice and in many cases are saying that people are safe to drive when they are not.

The legal visual standard required for driving a car or motorbike is to be able to read a number plate at 20.5 metres. The Driver and Vehicle Licensing Agency suggests this corresponds to a score of between 6/9 and 6/12 on a standard visual test used by health professionals, known as the Snellen chart. Perfect sight, which in the United States is called 20:20 vision, corresponds to 6/15 on the Snellen chart.

Researchers from the Royal Hallamshire Hospital, Sheffield, tested whether 100 participants could read a number plate at 20.5 metres. Those who took part, all wearing their usual glasses, had either 6/9 vision or 6/12 vision.

The findings showed that just over one-quarter, 26 per cent, of those with 6/9 vision failed and two-thirds with the poorer 6/12 score failed.

The researchers sent questionnaires to 100 GPs, 100 opticians and 100 ophthalmologists, asking them what advice they would give to patients who were seeking to ensure their vision was good enough to drive.

The advice given was found to be inconsistent. Three-quarters of family doctors advising patients with 6/9 vision said they could drive, 13 per cent said they should not drive, and 11 per cent were unsure.

Of the GPs advising patients with 6/12 vision, 21 per cent said they could drive, 54 per cent said they should not drive, and 25 per cent were unsure. Dr Zanna Currie, who led the research, said it could not be assumed that a driver with 6/9 vision would meet the standard for driving or that those with 6/12 vision should not drive. She said that all drivers with 6/9 vision or less should be encouraged to self assess their vision by trying to read a number plate at 20.5 metres.

"The practicalities of measuring the distance and self assessing can be off-putting for some. If those testing vision could provide a way for people to self assess, by mounting a number plate at the correct distance outside the practice, this would provide a useful public service. Snellen is a poor predictor of an individual's ability to meet the required visual standard for driving."

William Westlake, an eye specialist from The Lions Eye Institute in Western Australia, said more sophisticated tests were required to help to determine the driving ability of people who do not meet the current standards and, when appropriate, allow them to retain their licences. "The DVLA should monitor and audit the results of the current visual requirements," he said.

A spokesman for the DVLA said it would not change its guidance to health professionals. "This guide is purely for guidance for the medical profession and is not intended to be prescriptive."