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Medical aspects of fitness to drive – A guide for health practitioners

This guide is to assist health practitioners in assessing the fitness to drive of any individual. It also sets out the responsibilities and obligations of health practitioners.

6. Visual standards

This section covers:

Summary table

The table below summarises the information outlined in this section. However, practitioners should ensure that they are familiar with the guidance outlined in the entire section rather than relying solely on the table.

Visual condition or testClass 1 or class 6 licence and/or a D, F, R, T or W endorsement (see appendix 3)Class 2, 3, 4 or 5 licence and/or a P, V, I or O endorsement
In all circumstances, a visual field of 140° s7 is required.
Visual acuity Minimum combined visual acuity of 6/12. Minimum combined visual acuity of 6/9.
Substandard vision (visual acuity between 6/18 and 6/60 in the worse eye) Generally no driving restrictions if meet the combined visual acuity standard and visual field standard. We recommend that a thorough eye examination of the better eye for pathology is undertaken. Where an individual's vision can be substantially corrected by wearing lenses, this should be recommended as a licence condition. Same as private classes.
Monocular vision (visual acuity in the worse eye of less than 6/60) Generally no driving restrictions once successful adaptation has been achieved. We recommend that a thorough eye examination of the better eye for pathology is undertaken. Generally considered unfit to drive. However, the Agency may grant licences in exceptional circumstances, eg to existing licence holders if there are sound reasons to do so. An eye examination, including the better eye for pathology, should be undertaken by an optometrist or ophthalmologist.
Diplopia Should not drive until the condition has been assessed and satisfactorily treated. Generally considered unfit to drive. In exceptional circumstances, the Agency may consider granting a licence if the application is supported by an optometrist or ophthalmologist report.
Cataracts and aphakia Driving restrictions may be necessary if difficulties with glare intolerance or vision occur. Same as private classes.
Night blindness - retina pigmentosa A licence may be issued subject to only driving within daylight hours. A licence is unlikely to be granted. In exceptional circumstances, the Agency may consider granting a licence if the application is supported by an optometrist or ophthalmologist report.
Disability glare Refer to section 6.9. Same as private classes.
Colour blindness No driving restrictions. Generally no driving restrictions. However, individuals with colour vision problems should be warned of the potential hazards.

Legal obligations on medical practitioners relevant to this section

The law requires:

  • medical practitioners to advise the Agency (via the Chief Medical Adviser) of any individual who poses a danger to public safety by continuing to drive when advised not to (section 18 of the Land Transport Act 1998 - see section 1.4)
  • medical practitioners to consider Medical aspects of fitness to drive when conducting a medical examination to determine if an individual is fit to drive.

Section 18 of the Land Transport Act 1998 also provides that a medical practitioner or registered optometrist who gives notice in good faith under section 18 will not be subject to civil or professional liability because of any disclosure of personal medical information in that notice.

The requirements for visual standards, in terms of visual acuity and visual field, are outlined in the Land Transport (Driver Licensing) Rule 1999. Therefore, any variations from the standards for visual acuity and visual field can only be granted by the Agency.

The Driver Licensing Rule includes two categories of eyesight:

  • 1. Drivers who have vision in both eyes

    Class 1 or class 6, or a D, F, R, T or W endorsement: Have a visual acuity of at least 6/12 using both eyes and at least 6/18 using each eye separately.

    Classes 2-5, or a P, V, I or O endorsement: Have a visual acuity of at least 6/9 using both eyes and at least 6/18 using each eye separately.

    Individuals who have a visual acuity of less than 6/18 but better than 6/60 in one eye and who have a combined visual acuity standard of either 6/12 or 6/9 (depending on licence type) do not meet the standards outlined in the Rule because a visual acuity of at least 6/18 is required in each eye. For these individuals, the Agency may grant an exemption from the Rule. In practical terms, medical practitioners or optometrists should consider the guidance in section 6.4 when issuing an eyesight or medical certificate, and advise their patient that the Agency will consider their application for an exemption. Medical or eyesight certificates should include a note that the certificate must be sent to the Chief Medical Adviser.

  • 2. Drivers who have vision in only one eye

    Class 1 or class 6, or a D, F, R, T or W endorsement: Have a visual acuity of at least 6/12 in one eye.

    Classes 2-5, or a P, V, I or O endorsement: No standard is specified in the Rule for monocular vision. Therefore, the holders of these licence types or endorsements would need to apply for an exemption at the time of application or renewal.

Dealing with individuals who are unfit to drive

Medical practitioners can usually successfully negotiate short-term cessation of driving, such as while awaiting eye surgery, with patients. However, if longer periods are necessary, we recommend that medical practitioners advise their patients both verbally and in writing. We also recommend that the individual be told how soon they might expect to have this situation reviewed. If a practitioner suspects that an individual is continuing to drive against medical advice, they are legally obliged to inform the Agency under section 18 of the Land Transport Act 1998 (see section 1.4).

Introduction

The eyesight standards are the only medical-related standards in this guide that are outlined specifically in the Land Transport (Driver Licensing) Rule 1999. The standards relating to visual acuity and visual field in this section must be met, unless the Agency grants an exemption from the standards outlined in the Rule.

Between 2003 and 2007, a driver's defective vision was considered to have contributed to 72 crashes. As a result of these crashes, four people were killed, 15 people received serious injuries and 79 people received minor injuries. The contribution of vision-related factors is probably significantly underestimated because establishing that a visual condition contributed to a crash poses a number of difficulties. However, studies in the United States of America (American Optometric Association 2000) have shown that the use of vision-related re-licensing policies have shown identifiable safety benefits.

Term of licence

The maximum term for which a licence may be issued is 10 years. In the interest of road safety, progressive conditions may make it prudent to recommend review at shorter intervals. Practitioners may wish to consult with the Chief Medical Adviser or the Medical Review Advisers when recommending shorter-term reviews.

Other factors, such as diminished cognitive ability and restricted movement, when associated with reduced vision may compound the level of risk in driving.

Examples of progressive conditions include:

  • age-related macular degeneration
  • glaucoma
  • diabetic retinopathy
  • high myopia
  • keratoconus.

Licence conditions

Practitioners can recommend to the Agency that an individual have a condition placed on their licence. Below are some examples of licence conditions that the Agency may impose:

  • must wear prescribed lenses
  • occlusion to be worn (in cases of diplopia)
  • external mirrors fitted on both sides
  • daytime driving only
  • requirement for regular medical assessment, eg yearly check by an optometrist or ophthalmologist for individuals with deteriorating eyesight problems.

6.1 Temporary visual impairments

An individual should not drive unless they meet the visual acuity and visual field requirements outlined in this section.

Individuals who suffer sudden deterioration of vision in one eye, or in both, should not drive until the condition has recovered or they have obtained an optometric or medical review of their fitness to drive.

Where mydriatics have been used to dilate the pupils, individuals need to be warned that this may impair acuity and induce glare disability. Recovery is generally within two hours and individuals should be advised accordingly.

6.2 Visual acuity

Marked loss of visual acuity is likely to reduce the ability to drive safely. The complexity of visual tasks required for driving suggests that visual defects may become more important under conditions of reduced lighting and at night.

Testing visual acuity

Each eye is to be tested separately and both tested together. The smallest line read with no more than one error represents the visual acuity.

Visual acuity should be tested using either of the following:

  • the standard Snellen wall chart, or projector and screen - the chart should be well illuminated (a minimum of 500 lux at the surface) and at eye height from the floor. The chart should be viewed from six metres. If this distance is not available directly, a reversed chart may be viewed indirectly through a mirror, so that the total distance from subject to mirror to chart is six metres
  • an equivalent test, such as a screening instrument of a design approved by the Agency.

Advice for practitioners

Testing distance should be at six metres. Practitioners are advised that testing at distances less than six metres advantages all under-corrected myopes and disadvantages hyperopes. The effect of testing at four metres is to enable the under-corrected myope to read one extra Snellen line.

To maintain the integrity of the minimum standards for visual acuity, compensatory lenses (available from some optical suppliers) should be used at testing distances other than six metres. Alternatively, practitioners should use a reversed chart viewed indirectly through a mirror so that the total distance from subject to mirror to chart is six metres.

An examination by an optometrist is recommended when in doubt, eg if there is noticeable narrowing of the lids to improve vision.

If an individual does not meet the visual acuity standards, then they may be able to apply to the Agency for an exemption from the standards, but a supporting medical or optometric assessment would be needed. For higher classes, or individuals with serious visual conditions (such as progressive conditions or conditions that involve pathology in the eye), consideration would require a supportive assessment from a registered optometrist or ophthalmologist.

Medical standards for individuals applying for or renewing a class 1 or class 6 licence and/or a D, F, R, T or W endorsement

The standard of visual acuity required is 6/12 using both eyes together, with or without correcting lenses. When the vision in the worse eye is less than 6/18 but better than 6/60 corrected, the applicant should be classified as having sub-standard vision in one eye (see section 6.4).

Medical standards for individuals applying for or renewing a class 2, 3, 4 or 5 licence and/or a P, V, I or O endorsement

The standard of visual acuity required is 6/9 using both eyes together, with or without correcting lenses. If the worse eye is less than 6/18 but better than 6/60, the applicant is to be classified as having sub-standard vision in one eye (see section 6.4).

6.3 Visual fields

For safe driving, a good visual field is essential to allow a driver to detect other vehicles and pedestrians to the side of the line of vision. The required horizontal field should be tested using either of the following:

  • a visual screening instrument of a design approved by the Agency
  • confrontation, manual perimetry or a suitable programme on an automated perimeter (for confrontation, the use of a wand with an LED or a small white target at the tip - such as Bjerrum Screen targets - is recommended).

Advice for practitioners

Practitioners should ensure that each quadrant is tested. Where abnormality in the visual field is indicated by the initial screening or clinical examination, refer the candidate to a registered optometrist or ophthalmologist for further examination. The Titmus screener does not test fields above or below the horizontal and 45 degrees either side of fixation. It is very important that any scotoma be assessed.

There should be no significant pathological field defect in the binocular field that encroaches within 20 degrees of fixation either above or below the horizontal meridian. This includes homonymous hemianopic, homonymous quadrantanopic and bitemporal hemianopic defects within 20 degrees of fixation. Practitioners are advised that the following conditions may give rise to significant field defects:

  • cerebral lesions
  • glaucoma
  • panretinal photocoagulation
  • retinitis pigmentosa.

Visual field standard for individuals applying for licences of all classes of vehicle with or without endorsements

For all licence classes, the minimum standard is a binocular horizontal field of 140 degrees. There should be no significant pathological field defect encroaching within 20 degrees of the point of fixation.

6.4 Visual acuity in the worse eye less than 6/18 but better than 6/60

For all classes and endorsement types, individuals must meet the visual acuity (see section 6.2) and visual field (see section 6.3) standards. It is important that an individual's better eye is free of pathology that affects fitness to drive.

Medical standards for individuals applying for or renewing a class 1 or class 6 licence and/or a D, F, R, T or W endorsement

A medical or optometric examination of the eyes should be undertaken.

Medical standards for individuals applying for or renewing a class 2, 3, 4 or 5 licence and/or a P, V, I or O endorsement

A thorough examination is required, and, where appropriate, individuals should be referred to an optometrist or ophthalmologist for examination to ensure that adequate checks of the better eye for pathology are undertaken.

6.5 Monocular vision

For all classes and endorsement types, individuals must meet the combined visual acuity (see section 6.2) and visual field (see section 6.3) standards. It is important that an individual's better eye is free of pathology that affects fitness to drive. Here, the definition of monocular vision used is where an individual has a visual acuity in their worse eye of less than 6/60 or has vision in only one eye.

Medical standards for individuals applying for or renewing a class 1 or class 6 licence and/or a D, F, R, T or W endorsement

The Agency will probably impose a licence condition that any vehicle the individual drives should be fitted with external rear-view mirrors on both sides. Practitioners should recommend this condition when assessing fitness to drive.

Because adaptation to the loss of vision in one eye can vary between individuals, where doubt exists, a practical driving test should be carried out before allowing an individual to return to driving.

Medical standards for individuals applying for or renewing a class 2, 3, 4 or 5 licence and/or a P, V, I or O endorsement

Individuals with monocular vision are generally considered unfit to drive. The Agency may allow exceptions, eg current monocular vision commercial drivers applying for their licence to be renewed. A supporting opinion from an optometrist or ophthalmologist, including an assessment of the health of the good eye, should accompany any requests. The opinion should confirm that the individual's vision meets the combined visual acuity and visual field standards.

The Agency is likely to impose a licence condition that any vehicle the individual drives should be fitted with external rear-view mirrors on both sides.

Because adaptation to the loss of vision in one eye can vary between individuals, where doubt exists, a practical driving test should be carried out before allowing an individual to return to driving.

6.6 Diplopia (double vision)

Diplopia in the primary position represents a hazard to safe driving. An individual who experiences the sudden onset of diplopia (that is considered to be more than transient) should not drive until the condition has been assessed and satisfactorily treated.

All individuals with diplopia should have a vision assessment undertaken by an optometrist or ophthalmologist.

Medical standards for individuals applying for or renewing a class 1 or class 6 licence and/or a D, F, R, T or W endorsement

An individual who experiences diplopia (double vision) may drive provided that:

  • the diplopia can be remedied by the use of prisms or occlusion and the individual can meet the visual acuity (see section 6.2) and visual field (see section 6.3) standards, and
  • the individual has adapted to the condition.

Individuals with diplopia that occurs only in a very limited direction of gaze may be fit to drive.

Advice for practitioners

Practitioners may also determine that, in some individuals, the presence of some forms of diplopia is consistent with safe driving, eg where compensated by head posture.

Medical standards for individuals applying for or renewing a class 2, 3, 4 or 5 licence and/or a P, V, I or O endorsement

Individuals should not drive with diplopia. The Agency may consider issuing a licence subject to a favourable assessment by an optometrist or ophthalmologist. If diplopia is resolved, the Agency may issue a licence.

6.7 Night blindness

Individuals who may have reduced vision in dim light, eg use of miotics, those with cataracts, retinitis pigmentosa and other inherited retinal disorders, and those with diabetic retinopathy treated with panretinal photocoagulation, should be referred to their optometrist or ophthalmologist for assessment of fitness to drive.

Medical standards for individuals applying for or renewing a class 1 or class 6 licence and/or a D, F, R, T or W endorsement

Individuals may be considered for a licence with the condition that driving be restricted to daylight hours only.

Medical standards for individuals applying for or renewing a class 2, 3, 4 or 5 licence and/or a P, V, I or O endorsement

Individuals are generally considered unfit to drive. The Agency may consider issuing a licence subject to a favourable assessment by an optometrist or ophthalmologist. The Agency would probably impose a licence condition to restrict driving to daytime hours only.

6.8 Cataracts and aphakia

Cataracts are common, and prevalence increases with age, reducing acuity and sometimes causing increasing problems due to glare. A licence condition of daytime driving only may be recommended on the advice of an optometrist or ophthalmologist.

6.9 Glare disability

Practitioners should note that glare may be disabling in some instances, eg where a cataract is present, following some refractive surgical procedures and for some contact lens wearers. In such cases, practitioners should take appropriate action, which may include recommending the condition of daytime driving only.

6.10 Colour vision

There is no colour vision requirement in determining fitness to drive.

Advice for practitioners

Practitioners should advise individuals of the impact of colour vision on driving. Defective colour vision is mainly inherited and occurs in 8 percent of men and 0.2 percent of women. Of men, 6 percent have a green perception difficulty (duetan defect) and 2 percent have a red perception difficulty (protan defect). Less than half of 1 percent have a severe red perception difficulty (protanopia). Some studies indicate that individuals with a protan defect have a reduced visual distance for detecting vehicle tail lights and red traffic signal lights, and may have an increased nose-to-tail collision rate.

 

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