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Leaflet: Vision and Driving in Your Car


As a driver you have a duty to inform the DVLA Drivers Medical Branch, Swansea, SA99 1TU at once if:

• You have any physical or mental disability which affects your fitness as a driver or which might do so in the future.

• You may come to know in the future that you have such a disability or condition.

If you are informing the DVLA please write to them at the address above giving your driving licence number or full name and date of birth and tell them what the medical condition is in as much detail as possible. The medical rules are explained in leaflet D100 (available from post offices).

Car number plate test

There is a minimum legal eyesight standard which must be satisfied at all times when you drive. The standard is the ability to read a number plate at 20.5m (67 feet). If you need glasses or contact lenses to do this, you must wear them everytime you drive.

More stringent rules apply to drivers of medium sizes vehicles, large goods vehicles, minibuses and buses. If you drive one of these vehicles please check with the hospital optometrist who will explain the level of vision you are required.

The number plate test is an absolute standard in law and is not open to interpretation.

Visual field defects

An adequate field of vision (how far you can see to the side when looking straight ahead) is necessary for driving. It is recognised however, that people with one eye can drive a car safely so long as they are well adapted to using only one eye.

A field of vision 120 degrees wide and 20 degrees above and blow fixation is required to drive.

A special test is required for this and is only undertaken when there is a possibility of the visual field being affected. Fewer than 1% of drivers would fail this test.

If both eyes are affected with glaucoma, cataract, have received laser treatement for diabetic eye disease, have problems adapting to low light levels, or you have migraines, or have had a stroke, you should inform the DVLA; they will make arrangements for you to have a visual field examination if their medical adviser feels it to be necessary. This is not exhaustive—if you feel you have a problem it is your responsibility to inform the DVLA.

Double vision

If you have double vision (the medical term is diplopia), you should not drive until the DVLA have investigated your case. It is acceptable for you to wear an eye-patch to stop the double vision but, like monocular drivers, you need to be properly adapted to this before driving.

If your double vision is not constant you should seek advice from an optometrist, eye doctor, or orthopist, to see if it can be treated or corrected in any way. Even though the double vision is not present all the time you should not drive.


If you have cataracts, corneal problems or have had refractive surgery to correct your vision, glare may be a problem. In the first instance you should check your ability to read a number plate at 20.5m (67 feet). If you fail the number plate test you must inform the DVLA.

The Highway Code specifies that tinted glasses should not be worn for driving at night unless prescribed for specific condition.

Colour vision

There is no evidence of a link between colour vision defects and road traffic accidents. If you are severely red colour blind (the medical term is protanopia) single red light marking hazards could be a problem. You do not have to inform the DVLA if you have defective colour vision.


Your insurer may invalidate your insurance if you fail to comply with the current legal requirements for driving.

Any questions?

Please ask your GP, eye doctor, optometrist, or orthoptist. They can advise you.

If at any time you are concerned do not hesitate to contact the hospital.


Visit the Minor Injuries Unit webpage for more information about this service.

Date of creation: April 2019
Date of review: April 2021
URN: 121