visual requirements for driving Flashcards
what is it a criminal offence for a driving licence holder or applicant to do
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
by law when is awareness of a criminal offence normally regarded
regarded in law as starting 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
what type of vehicles is group 1 drivers allowed to drive
ordinary family cars and light vans
what is the reading of number plate standards for group 1 drivers and what year of number plates does this refer to
- 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 metres (just under 66 feet) - this refers to a post 1st September 2001 number plate
what new addition was made to the rules of reading a number plate, from when did this rule apply and why
- In addition, 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.
- from May 2012
- Brings the UK more in line with the EU standard which is 6/12 (or 0.5 decimal which is the notation Europe tends to use instead of snellen)
what is there no precise snellen equivalent to and what implications can this have when testing
- to the number plate standard
- The normal number plate test found on many test charts is NOT equivalent and should not be relied upon
what did Latham et al (2014) find about the visual acuity standards related to group 1 drivers
- With a binocular VA of 6/12 not all participants could pass the number plate test (as artificial light in the test room is not the same as daylight)
- In addition, some participants passed the number plate test but had VA below 6/12 (approx. 14-15%)
what did the findings of Latham et al (2014) suggest in order 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 (i.e. all 5 letters on every line of the LogMAR)
- Drivers with 6/7.5 (+0.10 logMAR) 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 (+0.12—+0.30 logMAR) should be advised to check their ability to read a number-plate, as some may not be able to.
what did the AOP advise about how optometrists should respond if a patient asks if they’re fit to drive
- optometrists should not provide certificates of ability to pass the “number plate test” based on consulting room tests
- Statutory law and the law of tort make it unwise to advise on ability to pass “number plate test” based on Snellen VA alone
- If it is only acuity that is in question (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
what should a patient do if they’re in doubt about whether they meet the visual requirements as a group 1 driver from their test results at the opticians
the patient should report to the Licensing Centre who will arrange for the test to be accurately carried out at a Driving Test Centre
if a patient’s unaided vision is worse than 6/12, whose responsibility is it for the DVLA to know of this and what must the optometrist do on their side
- It is the patient’s responsibility to inform the DVLA if they are below the required visual standards for driving
- Explain that the patient’s insurance may be affected if they do not wear their glasses
- Annotate the record card with advice given to the patient
what must you as an optometrist do if a patient refuses to wear their distance glasses in order to meet the visual requirements for group 1 drivers and refuses to take your advice
- note this on the record card – ideally get patient to sign this
- If the patient is “…clearly visually dangerous”, and is continuing to drive despite your professional advice, consult the legal department of the AOP before going straight to the DVLA as this can breach patient confidentiality
which types of vehicles are group 2 licence holders allowed to drive
- LGV = large goods vehicles (lorries)
- PCV = passenger carrying vehicles (buses)
Must pass the number plate test
what 3 changes wee made from march 2013 in regards to group 2 licence holders and their visual requirements
- 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 equal to or less than +8.00D (due to aberrations in high positive lenses) and there’s no specific limit for the corrective power of contact lenses
why were more stringent va’s for group 2 drivers required
as they have more responsibilities
why is the spectacle corrective power of no more than +8.00D for group 2 drivers required and what exceptions are there
due to the aberrations found in high +ve spectacle lenses
however they can use contact lenses that are > +8.00D in power
give 6 suggestions as to why the visual requirement rules for group 2 drivers does not help optometrists
- 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 (as they can accommodate through the lens as they get older)
what is there no statutory requirement in UK legislation of for group 1 drivers and what applies to them instead
- for fields of vision
- but the Second EC (european) Directive applies
what UK rules are there for european drivers who want to drive in the UK
- if they come to the UK, they can drive for up to one year without a UK licence
- they are allowed to use bioptic telescopes when driving, even though it is not a UK rule
when will a visual field standard usually be applied to a driver
when there is evidence that a defect exists
what are the standards/rules for safe driving defined as, (which apples to a patient who has a existing visual field defect)
- The minimum field of vision for safe driving is defined as a field of vision of at least 120º on the horizontal measured by the Goldmann perimeter using the III4e settings (or equivalent perimetry).
- In addition there should be no significant defect in the binocular field which encroaches within 20º of fixation above or below the meridian.
what is the minimum field of vision required in the horizontal meridian and what must this specifically be measured by
120º
the Goldmann perimeter using the III4e settings (or equivalent perimetry).
what is the minimum field of vision required binocularly in the vertical meridian
no significant defect in the binocular field which encroaches within 20º of fixation above or below the meridian
By these means homonymous or bitemporal defects which come close to fixation, whether hemaniopic or quadrantopic, are not accepted as safe for driving.”
a driver cannot have any __________ in the ___________ _____ degrees of visual field all ___________
a driver cannot have any defects in the central 20 degrees of visual field all around
what rule about horizontal visual field requirements has been changed and since when
- a minimum of at least 50 degrees visual field in the outer half of the visual field both sides must be present
- a new rule from 2012
what type of visual field test is the group 1 licensing decisions currently based on
the outcome of the binocular Esterman test
what visual field machine uses the binocular Esterman test carried out on group 1 license holders
the Humphrey Field Analyser (HFA)
not allowed on the Henson
how are the stimuli presented with the Esterman test and what results regard the test results as invalid
- a bright stimulus (10dB) which uses supra threshold at each of 120 locations within the visual field
- If more than 20% false positives then the test is invalid
at what distance is the Esterman test carried out and how long does it take
- Test carried out at 1/3rd metre
- 4 to 5 minutes for the test
list 4 disadvantages of the Esteman test
- Stimuli arranged in a pattern that was designed to predict a person’s mobility (walking) performance
- 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) (as only 10DB higher/supra threshold)
- Fusion difficulties
explain how the Esterman test does not actually measure points in the VF that are most important
Out of the 120 points tested:
- only 34 locations tested within the central 20 degrees
- no locations within the central 7.5 degrees
- and a predominance of these central locations falling in the lower half of the visual field (22 versus 12)
which part of the visual field is the density of the Esterman targets the most dense and what implications does this have
The density of targets is higher within the central 20º and in the lower hemifield.
Therefore the sensitivity to detect paracentral scotomata is lowest in the upper visual field (where the dashboard tends to be).
Unfortunately, this area is particularly relevant when driving!
how many % of the Esterman stimuli fall within the keys parts of the field for a driver
only 25%
what does the DVLA guidance regard as acceptable on Esterman tests with defects affecting central 20 degrees only for group 1 license holders
the following are generally regarded as acceptable central loss:
- Scattered single missed points
- A single cluster of up to 3 contiguous points
so they’re allowed some missed points in their central VF
what does the DVLA guidance regard as unacceptable on Esterman tests with defects affecting central 20 degrees only for group 1 license holders
(i. e. significant) central loss:
- A cluster of 4 or more contiguous points that is either - wholly or partly within the central 20 degree area
- 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
explain the exceptional cases for issuing a licence to drivers who previously have held a licence which was lost by failing the visual field rules
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 field loss condition
and there is no other progressive condition that is likely to affect the visual fields
- In addition there must be
Clinical confirmation of full functional adaptation from an ophthalmologist
what must the applicant do if their re-application for a previously failed Esterman test that is now an exceptional case do
Carry out a satisfactory practical driving assessment
explain the exceptional cases for issuing a PROVISIONAL driving licence to drivers with a static field defect that prevents them driving (2009)
- 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 (e.g. if got since a child)
There are no other relevant medical conditions - Once an instructor says driver is competent an on-road “assessment” will be arranged by DVLA (not a “test”), only to prove to the driving instructor
- 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
what three conditions must be met if a patient with a static field defect that prevents them from driving should be considered a 3 year provisional licence (with dual controlled cars only)
provided the:
- Condition is non-progressive
- Applicant has fully adapted to the field defect (e.g. if got since a child)
- There are no other relevant medical conditions
what 2 findings will be disregarded when assessing the width of the PERIPHERAL field
- 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
why is 45 L and 75 R Fail results of an Esterman VF test a fail
because even though the points still add up to 120 degrees horizontally, from May 2012 the rules stated that horizontal field must be at least 50° in each direction
what is the visual field requirements of group 2 license holders
- 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
if they do not meet these requirements, there is no exceptions, they are not allowed to drive
what must group 1 drives cease driving on diagnosis of
of soon after getting diplopia
when can group 1 drivers resume driving after being diagnosed with diplopia
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
what exception does a group 1 driver who has diplopia have
a stable uncorrected diplopia of 6 months’ duration or more may be compatible with driving if there is consultant (ophthalmologist) support indicating satisfactory functional adaptation (i.e. px who understands which is real image)
what are the regulations for group 2 drivers and diplopia
Permanent refusal or revocation if insuperable diplopia. Patching is not acceptable
what are the regulations on colour vision with group 1 and 2 drivers
Defective colour vision is no bar to driving
what are the rules and regulations of group 1 monocular drivers
- Must inform DVLA if complete loss of an eye
- 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)
what are the rules and regulations of group 2 monocular drivers
if they have 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 licence.
what type of licence holders does the rules of monocular drivers regard
people who have had their license and not provisional license holders
state 2 rules and regulations on vision under adverse lighting conditions and state which groups of licence holders this applies to
- 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. (however there is no test in the clinic to test 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.
- this applies to both groups 1 and 2
list 4 rules and regulations regarding blepharospasm (constant twitching of the eye) and which groups of license holders does this apply to
- 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.
- this applies to both groups 1 and 2
list the 4 rules and regulations regarding frames and lenses to drivers
- 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 photochromic lenses when entering tunnels and roads shaded by trees - Patients with borderline acuities (6/9 or 6/12) should be advised not to drive vehicles with tinted windscreens or be prescribed tints
- Muscle imbalance must be corrected unless well tolerated
what are the 3 pieces of advise that should be given to patients in regards to frames and lenses
- the limitations of high power lenses
- the dangers of wearing tinted lenses at dusk or at night (which affects ability to drive)
- the dangers of photochromic lenses when entering tunnels and roads shaded by trees
what can cause reduced visual fields in patients with diabetic retinopathy and what action is taken place to make sure this patient is safe to drive
- Laser treatment to both eyes (pan retinal photocoagulation) can cause reduced visual fields as killing the vessels also kills that part of the retina
- DVLA will investigate fields in cases where the laser treatment has been carried out on both eyes
from what age and how frequently does a driving license need to be renewed
at age 70 years and every 3 years after that
