Visual standards for driving

Question 1

How important is it to notify DVLA when you notice an eye condition that could put you in danger:

Answer 1

*“It is a criminal offence for a driving license holder or applicant to fail to notify the Drivers Medical Branch, Driver and Vehicle Licensing Centre, Swansea, immediately they become aware of any eyesight condition which is likely to cause them to be a source of danger to the public when driving.”
*Failure to notify can also have serious motor insurance implications.
*Let dvla know as soon as you think something is wrong with your vision

Question 2

When should you notify DVLA if you notice an eye condition that could put you in danger:

Answer 2

As soon as the person has knowledge that a danger exists and this includes when they have received professional advice that their condition represents an immediate or potential danger when driving

Question 3

What are drivers asked in terms of vision:

Answer 3

Whether they meet the standard for driving and if need to wear corrective glasses or contact lenses to achieve this standard

Question 4

What is shown on drivers licence in terms of vision:

Answer 4

*Drivers who have a refractive correction have it indicated on back of driving licence
*This means the person needs to wear glasses for driving

Question 5

What is the standard for group 1 drivers:

Answer 5

• 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 metres (just under 66 feet )
  AND
• The visual acuity (with the aid of glasses or contact lenses if worn) must be at least 6/12 (0.5 decimal) with both eyes open, or in the only eye if monocular.”

Question 6

What does group 1 consist of:

Answer 6

Ordinary family cars and light vans

Question 7

How reliable is number plate test found on test charts:

Answer 7

• There is no precise Snellen equivalent to the number plate standard
• In terms of visual angle it is equivalent to 6/15 BUT…
• Drasdo and Haggerty found that applying a standard of 6/9-2 (6/10) resulted in a mathematical equivalent to this (i.e. this standard failed the same proportion of people, but not necessarily the same individuals).
• The normal number plate test found on many test charts is NOT equivalent and should not be relied upon.”
• SO Just because someone can read the number from 20m, doesn’t mean they can read 6/12 and vice versa

Question 8

Advice to patients on whether they can pass the number plate test based on Snellen VA

Answer 8

• Latham et al(2014) found that with a binocular VA of 6/12 not all participants could pass the number plate test
• And some participants passed the number plate test but had VA below 6/12 (approx. 14-15%)

They suggest the following
 To best predict drivers’ ability to read a number-plate, vision should be assessed using a logMAR letter chart or a Snellen chart scored by full line
 Drivers with 6/7.5 or better vision can be advised that they meet the driving standard. If no 6/7.5 line on the chart then driver should be able to read 6/6.
 Drivers with acuity between 6/9 and 6/12 should be advised to check their ability to read a number-plate, as some may not be able to.

Question 9

Whats different about using number plate test and driving:

Answer 9

Conditions in test room are different – artificial lighting in room compared to outside lighting and weather conditions different

Question 10

How should optometrists respond if a patient asks if they are fit to drive:

Answer 10

• Optoms should not provide certificates of ability to pass the “number plate test” based on consulting room tests
• It is unwise to pass “number plate test” based on Snellen VA alone
  If it is only based on acuity (i.e. not fields or diplopia etc) it is best to advise the patient to satisfy themselves that they can pass the “number plate test”
• If in doubt the patient should report to the Licensing Centre who will arrange for the test to be accurately carried out at a Driving Test Centre

Question 11

Rule for driving and vision:

Answer 11

Drivers should prove that their vision meets standard for driving every 10 years

Question 12

Example of whether px is fit to drive:

Answer 12

Hyperopic Presbyope:
- Unaided Vision R 6/24 L 6/24 Binoc 6/24 +1
- Wears N/V specs only
- Rx: R+2.00DS6/5L+2.00DS6/5
- Add +2.00D R & L = N5
- Without distance glasses, this patient would probably not pass the Number Plate Test and does not achieve 6/12
- Advise the patient of the legal requirements for driving

Question 13

What does group 2 (Class 2) drivers involve:

Answer 13

• LGV = large goods vehicles (lorries) AND
• PCV = passenger carrying vehicles (buses)

Question 14

Criteria for group 2 drives:

Answer 14

• Must pass the number plate test
• Must achieve at least 6/7.5 VA in the better eye [was 6/9 previously]
• Must achieve at least 6/60 VA in the worse eye [was 6/12 previously]
• “Must have a corrective power of < or = +8.00D” There’s no specific limit for the corrective power of contact lenses.

Question 15

Do the new standards for Group 2 help optometrists – why:

Answer 15

• No!
   The difference in VA between 6/7.5 and 6/9 is very small
  Not every Snellen chart has a 6/7.5 line
  Test chart must be positioned accurately at 6m
  Charts at shorter distances than 6m and scaled to 6m must be accurately scaled
  +8.00D refraction limit does not specify whether it is the mean sphere power or “highest powered meridian”
  Hyperopes often become more hyperopic as they get older, so may start off less than +8.00D before crossing the +8.00D boundary
   Calling px back on different day under same conditions could result in up to a line difference in va from what they read day before = va very variable

Question 16

Rule of visual fields and driving:

Answer 16

• There is no statutory requirement in UK legislation for fields of vision for Group 1 drivers but the Second EC Directive applies.
  *So difficult to tell if px is okay to drive or not
  *Doesn’t say if with the correction or without
  *How the EC directive requirements are interpreted are country dependent – most say with standard or habitual rx

Question 17

Criteria for driving and visual fields:

Answer 17

The following standard is usually applied when there is evidence that a defect exists.
-The minimum field of vision for safe driving is defined as a field of vision of at least 120 degrees on the horizontal measured by the Goldmann perimeter using the III4e settings (or equivalent perimetry).
-And there should be no significant defect in the binocular field which encroaches within 20 degrees of fixation above or below the meridian = circle of radius 20 degrees

Question 18

Which visual field defects are not accepted as safe for driving:

Answer 18

Homonymous or bitemporal defects which come close to fixation, whether hemaniopic or quadrantopic,

Question 19

What is the estermann test and procedure of it:

Answer 19

• Esterman test presents a bright stimulus (10dB) at each of 120 locations within the visual field
• If more than 20% false positives then the test is invalid
• Test carried out at 1/3rd metre
• 4 to 5 minutes for the test

Question 20

Disadvantages of estermann test:

Answer 20

-Stimuli arranged in a pattern that was designed to predict a person’s mobility (walking) performance…..
oThe density of targets is higher within the central 20 degrees and in the lower hemifield. Therefore the sensitivity to detect paracentral scotomata is lowest in the upper visual field. Unfortunately, this area is particularly relevant when driving!
-Number of locations tested within the most functionally-relevant area of a driver’s visual field is very limited,
-Only 34 locations tested within the central ±20°, no locations within the central ±7.5°, and a predominance of these central locations falling in the lower half of the visual field (22 versus 12)
-Can only detect the densest of scotoma(ta)
-Fusion difficulties
-Only about 25% of the Esterman points tested fall within the key parts of the field for driving.

Question 21

DVLA guidance for esterman tests with defects affecting central 20° only:

Answer 21

For GROUP 1 licensing purposes, pending the following are generally regarded as acceptable central loss:
Scattered single missed points
 A single cluster of up to 3 contiguous points

Question 22

DVLA guidance for esterman tests with defects affecting central 20° wholly or partly:

Answer 22

For GROUP 1 licensing purposes the following are generally regarded as unacceptable (i.e. significant) central loss:
 A cluster of 4 or more continuous points that is either wholly or partly within the central 20 degree area

• Unacceptable central loss:
  Loss consisting of both a single cluster of 3 contiguous missed points up to and including 20° from fixation, and any additional separate missed point(s) within the central 20° area
  Central loss of any size that is an extension of a hemianopia or quadrantanopia

Question 23

Example of esterman fail:

Answer 23

A cluster of more than 3 contiguous missed points in the central 20 degrees.

Question 24

Exceptional cases for issuing a licence to drivers who previously have held a licence which was lost by failing the visual field rules:

Answer 24

• They can reapply for a licence if the defect:
  
  • Has been present for at least 12 months
  • Is caused by an isolated event or a non-progressive condition
    and there is no other progressive condition that is likely to affect the visual fields
• And there must be clinical confirmation of full functional adaptation
• If the re-application is accepted then the applicant must carry out a satisfactory practical driving assessment

Question 25

Exceptional cases for issuing a provisional driving licence to drivers with a static field defect that prevents them driving (2009):

Answer 25

A 3-year provisional licence (dual controlled cars only) will be issued provided
 Condition is non-progressive
 Applicant has fully adapted to the field defect
 There are no other relevant medical conditions
- Once an instructor says driver is competent an on-road “assessment” will be arranged by DVLA
- If assessment is “favourable” (field defect is not affecting driver’s ability to drive safely) an unrestricted provisional licence will be issued in the normal way

Question 26

What is disregarded when assessing the width of the field:

Answer 26

• A cluster of up to three missed points lying on or across the horizontal meridian
• A vertical defect of only a single point width but of any length, which touches or cuts through the horizontal meridian

Question 27

Group 2 drivers: Visual fields and driving criteria

Answer 27

-The horizontal visual field should be at least 160 degrees
-The extension should be at least 70 degrees left and right and 30 degrees up and down.
-No defects should be present within a radius of the central 30 degrees.

Question 28

Diplopia driving criteria:

Answer 28

• Grp 1: Cease driving on diagnosis. Resume driving on confirmation to the Licensing Authority that the diplopia is controlled by glasses or by a patch which the licence holder undertakes to wear while driving.
• Grp 1: Exceptionally a stable uncorrected diplopia of 6 months’ duration or more may be compatible with driving if there is consultant support indicating satisfactory functional adaptation.
• Grp 2: Permanent refusal or revocation if insuperable diplopia. Patching is not acceptable

Question 29

Colour vision and driving criteria:

Answer 29

• Group 1 and 2 = defective colour vision is no bar to driving
• Cause can still see colour but not same brightness as everyone

Question 30

Monocular drivers criteria i.e complete loss of vision in one eye:

Answer 30

• Grp 1: Must inform DVLA if complete loss of an eye
• Grp 1: Recent loss of an eye may require a period off driving for adaptation, but then driving can be resumed (as long as the driver can satisfy the VA, number plate and visual field requirements with their remaining eye)
• Grp 2: Complete loss of vision in one eye or corrected acuity of less than 3/60 (Snellen decimal 0.05) in one eye. Applicants are barred in law from holding a Group 2 license.

Question 31

Which conditions effecting lighting can prevent drivign (Grp 1&2):

Answer 31

• Patients with cataract, and those who have had refractive surgery may be unable to meet the required standards under conditions of poor light or glare.
• A history of inability to see effectively when driving at night with headlights either due to a night vision defect such as retinitis pigmentosa may stop the person being issued a driving licence.

Question 32

Criteria for blepharospasm and driving:

Answer 32

• Grp 1 & 2 – must not drive and inform DVLA
• Consultant opinion required.
• If mild, driving can be allowed subject to satisfactory medical reports.
• Control of mild blepharospasm with botulinum toxin may be acceptable provided that treatment does not produce debarring side effects such as uncontrollable diplopia.
• DVLA should be informed of any change or deterioration in condition.
• Driving is not normally permitted if condition severe, and affecting vision, even if treated.
• Cause its uncontrolled movement or twitching of lids

Question 33

Frame and lenses for driving:

Answer 33

• Care should be taken in frame selection not to obscure lateral vision
• Advice should be given on:
  The limitations of high power lenses
  The dangers of wearing tinted lenses at dusk or at night
  The dangers of transition lenses when entering tunnels and roads shaded by trees
• Patients with borderline acuities should be advised not to drive vehicles with tinted windscreens or be prescribed tints
• Muscle imbalance must be corrected unless well tolerated

Question 34

Diabetic retinopathy and driving:

Answer 34

• Laser treatment to both eyes (pan retinal photocoagulation) can cause reduced visual fields
• DVLA will investigate fields in cases where the laser treatment has been carried out on both eyes

Question 35

What is the leading cause of visual field loss in 2% population:

Answer 35

POAG

20% of people with glaucoma still exhibit progressive visual field loss.
50% diagnosis rate so so 50% don’t know they have glauocoma