DVLA rule changes

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May 16 2012

Lyndon Taylor, optometrist and AOP vision standards adviser, reports on the recent changes to the DVLA visual acuity test

On May 1, 2012 DVLA quietly introduced some changes to the vision standards for drivers in the UK.
The background to the changes goes back to Annex II of a European directive in 1991. This was partially implemented by the UK in the late 90s but left a number of loopholes, particularly around the number plate test. There is now also an Annex III which must be implemented by the end of this year, and I understand that the recent changes have been put in place to make that implementation possible.

Class 1 (cars and light vans) licences
As optometrists are aware, there is a poor correlation between the number plate test and Snellen Visual Acuities(1). Annex II set the EU standard for car drivers at 0.5 or 6/12 Snellen and, while the UK Government has always argued that the number plate test is ‘equivalent’ to this standard, there have always been a few cases where patients with a best binocular visual acuity (VA) of 6/24 have managed to scrape through the number plate test. To remove this anomaly, from May 1, the basic visual acuity standard has been amended to say: ‘The standard for ALL drivers is the ability to read in good daylight (with the aid of glasses or contact lenses, if worn) a registration mark fixed to a motor vehicle and containing characters 79mm high and 50mm wide from 20 meters OR characters 79mm high and 57mm wide from 20.5 metres [NB the former refers to a post-1/9/2001 plate and the latter to an older style plate]’

‘Visual acuity (with the aid of glasses or contact lenses, if worn) must be at least 6/12 with both eyes open ’
The latter condition does not appear to be a part of legislation, but is based on the statement that DVLA would “consider anyone whose eyesight is below any EU minimum standard to be a source of danger when driving.”
Implications for optometrists
While the addition of a Snellen acuity parameter to the vision standards for drivers is to be welcomed, following the Optical, Confederation’s long-term lobbying, the retention of the number plate standard still leaves a degree of uncertainty for optometrists.
We know that a few drivers with visual acuities better than 6/12 will still fail the number plate test. This means that while optometrists can now confidently say that someone who cannot manage 6/12 binocularly will definitely fail the eyesight standards, we still cannot say with certainty that someone with 6/12 or better will pass a number plate test.

Visual fields (all licences)
The standard for the horizontal field remains the same at 120 degrees. Until now, there was no requirement for how this was to be split each side of the centre; in theory, someone with only 20 degrees to the right but 100 degrees to the left could pass. From May 1, an extra condition is added that there must be at least 50 degrees to each side. This does seem to be a sensible change, though it may lead to few existing licences being revoked.

Class 2 (LGV and PCV) licences
This is perhaps the most interesting change, in that from May 1, these drivers’ ‘better eye’ must achieve a VA of 6/7.5 (0.8) Snellen rather than 6/9 previously. Also, there is now a refraction limit of +8.00 dioptres. All other conditions (6/12 worse eye and 3/60 each eye unaided) remain unchanged.
This will not affect very many drivers, but unusually there do not seem to be any ‘grandfather rights’ associated with this change. The existing rights for unaided vision and monocularity for those who first got a licence prior to 1983-1996 remain unchanged. This means that any group 2 driver who can read 6/9 but not 6/7.5 is now probably driving illegally.
Implications for optometrists
This change has the potential to cause major problems in practice. The difference between 6/7.5 and 6/9 is small and many practices do not have a chart with a 6/7.5 line. Practices must also be extremely careful to ensure that their charts are accurately set up before advising patients who are at all borderline. In particular, fixed charts must be very close to 6m (if the chart is at 5m or 7m the error is about the difference between 6/7.5 and 6/9). Computer or projector charts must be set correctly for the testing distance. It would also be unwise to rely on any test chart with a viewing distance of a lot less than 6m, as there is no evidence that VAs will scale accurately from 3-4m, as used in some testing rooms. Practices should consider having at least one Snellen chart available with a 6/7.5 line at 6m viewing distance.
The +8.00 refraction limit does not specify whether it is the sphere power or ‘highest meridian’. The main issue now is with young applicants who can still achieve 3/60, but who will not be able to do so in a few years time. Such patients need careful counselling on the implications for their future employment.
These changes may well affect other groups, such as taxi drivers and holders of the National Private Pilots licence whose standards are tied to the group 2 standard.

These changes were introduced very quietly and do not yet seem to have hit the wider public press. Optometrists will probably be the first point of contact for patients who are concerned about their ability to drive, so we need to be fully familiar with these changes and their implications. DVLA’s ‘At a Glance’ guide to the current medical standards of fitness to drive provides the full current standards (2) and can be downloaded at www.dft.gov.uk/dvla/medical/ataglance
1. Drasdo, N & Haggerty, CM (1980).  A comparison of the British number-plate and Snellen vision tests for car drivers.  Ophthal, physiol, Opt. 1, 39-54.
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