Drivers - Its National Glaucoma Awareness Week

Most of the sensory input to the brain required for driving is visual. However surprisingly, there is little evidence that defects of vision alone cause many road accidents. Nevertheless adequate standards of vision do need to be set for drivers on today’s busy roads.

These standards are set down by statutory requirement, and following guidance from the Secretary of State for Transport’s Honorary Advisory Panel for Vision and Driving. They are applied by the Driver and Vehicle Licensing Agency (DVLA) which is an executive agency of the Department for Transport.

The minimum visual standards for driving depend on the type of license. These were laid down by the European Community in 1983 and were incorporated Into UK law in 1997. They are required by the DVLA under the Road Traffic Act.

The requirements for car drivers are:
Standard 1: The driver should be able to read a standard car number plate at 20.5 metres with or without glasses or contact lenses. This is usually considered to be equivalent to a visual acuity of 6/10 (i.e. between 6/12 and 6/9 - Snellen acuity). This standard refers to the clarity of sight (central vision), i.e. how well an individual can see details with or without spectacles.

Standard 2: The driver should have a binocular (monocular if appropriate) horizontal field of vision of 120 degrees minimum and no significant field defect in the binocular field within 20 degrees of fixation either above or below the horizontal meridian.This standard refers to the degree of loss of vision away from the centre.

Higher standards apply for those holding a bus (PCV) or lorry (LGV) licence.

Glaucoma damages the off centre parts of the field of vision first and does not affect the central detailed vision until the late stages of the condition. This off centre damage can go unnoticed for some time, partly because we use our central vision most of the time and partly because, if the damage is Driving and glaucoma in different areas of the visual field in each eye, one eye will fill in for the other.

The danger comes, especially in driving, when the damaged areas in each eye overlap: instead of an accurate combined visual picture, the brain will insert the missing parts from memory and the driver will have no idea that this is happening, this may give a dangerously inaccurate picture.

Ocular hypertension (raised pressure without field loss) does not need to be reported, as ocular hypertension suggests that the visual fields are normal.

If glaucoma is diagnosed in one eye and the other eye has normal vision, it is not necessary to inform the DVLA. Anyone suffering from glaucoma (with visual field defects) in both eyes should, inform the DVLA (Drivers Medical Branch, Swansea, SA99 1TU). The DVLA will require further details about the vision and may arrange for a field of vision test to be carried out at an approved centre. The test will be performed with both eyes open and will be slightly different from the test usually performed by optometrists or hospital eye departments to assess glaucoma.

Ensure that the visual acuity and visual field tests performed are indeed binocular (measured with both eyes open) and that the appropriate glasses or lenses are worn if required, as this will give a more accurate result than the combined results of each eye taken separately.

If the results of the visual test mean that you do not meet the required standard, it is possible to seek a second opinion at your own expense, and submit this to the DVLA for their consideration.

If you were to receive a form from the DVLA withholding or revoking your driving licence, this would include the information regarding your rights to appeal. Appeal can be made to the Magistrates Court of England or Wales or a Sheriff Court in Scotland. Before going ahead with an appeal, do not hesitate to discuss the matter with your eye specialist or GP to confirm whether or not the DVLA have a valid case, because if you were to lose your appeal you may have to bear the costs involved. If a decision is made to go ahead with the appeal, the form should be signed and returned.

It would then be passed to the DVLA Legal Department who would take up the case and advise you of the procedure. It is usual for the official at the DVLA who signed the original revocation, to complete a statement and possibly attend court to support it. Whether or not an appeal against the decision is made, or a driver’s license is granted or revoked, we would advise you to inform your GP and your insurance company. Insurance cover may become void if an individual fails to meet the medical requirements.

For more information, see dvla.gov.uk/drivers.aspx