1. “But I only drive to the shops…”
Mr Javeed Khan
Consultant Ophthalmologist
St Mary’s Hospital
Isle of Wight

2. Driving standards What is the evidence
Driving standards What is the evidence? Age and Driving Monocular drivers Dilated pupils

4. Do these patients need to notify DVLA?
45 year old with ocular hypertension
68 year old bilateral glaucomatous field loss
75 year old with glaucoma, field defects in one eye only
Lorry driver on Latanoprost, mild field loss in one eye
Lorry driver with colour blindness
42 year old with night blindness

5. Driving is a demanding activity
PERCEPTION Central Fixation Peripheral Scanning INTERPRETATION Reaction Time DECISION ACTION Motoring Ability

6. Is Poor Visual acuity a contributory factor in road accidents?
Since 2005 official accident reports have included ‘contributory factors’
Less than 2% of accidents occur due to vehicle defects
Most are due to ‘Human Factors’

7. Is poor visual acuity a contributory factor in road accidents?
From 2005 – 2009 nearly 700,000 accidents on UK roads
0.4 % of fatal accidents and 0.2 % of all accidents due to ‘defective/uncorrected eyesight’
Since 2005 official accident reports have included ‘contributory factors’
Less than 2% of accidents occur due to vehicle defects
Most are due to ‘Human Factors’

8. How important is poor vision as a contributory factor in road accidents?
From 2005 – 2009 nearly 700,000 accidents on UK roads
0.4 % of fatal accidents and 0.2 % of all accidents due to ‘defective/uncorrected eyesight’
Mobile phone use 0.2 % of all accidents
Since 2005 official accident reports have included ‘contributory factors’
Less than 2% of accidents occur due to vehicle defects
Most are due to ‘Human Factors’

9. How important is poor vision as a contributory factor in road accidents?
From 2005 – 2009 nearly 700,000 accidents on UK roads
0.4 % of fatal accidents and 0.2 % of all accidents due to ‘defective/uncorrected eyesight’
Mobile phone use 0.2 % of all accidents
‘Failed to look properly’ 20% of fatal and 35% of all accidents
Vision affected by sun/headlights/dirty windscreen 3.5%
Since 2005 official accident reports have included ‘contributory factors’
Less than 2% of accidents occur due to vehicle defects
Most are due to ‘Human Factors’

10. VISUAL STANDARDS FOR DRIVING
With both eyes open and with the aid of glasses or contact lenses if worn:
Can read number plate at 20 metres in
good daylight
Snellen visual acuity 6/12 or better
Snellen visual acuity since 2012

11. Group 2 (Lorry, Bus) Snellen visual acuity: Better eye 6/7.5
Before 2012: Worse eye to be at least 6/9
Now 6/60 acceptable in worse eye
No minimum uncorrected visual acuity
But glasses no more than + 8 dioptres

13. Case
Lorry driver develops posterior sub-capsular cataract in left eye, Right eye pseudophakic
VA:
Right eye: 6/6 unaided
Left eye: 6/36 unaided no improvement
Both eyes open: 6/6
Patient doesn’t complain of glare, has full fields
Can he continue to drive his lorry while waiting for cataract surgery? Yes, as long as no other visual impairment

14. Evidence for visual acuity standard: Why 6/12 on Snellen?
In 1937 standard introduced:
Number plate at 75 feet (23 metres)
Equal to stopping distance at 30 mph

15. Evidence for visual acuity standard
As number plate sizes changed distance changed:
20.5 metres pre-2001
20 metres Current

16. Evidence for visual acuity standard: Why 6/12 on Snellen?
Drasdo and Haggerty 1983:
Approximates to 6/9-2 or 6/10 based on their statistical model
Charman 1997:
Calculated Snellen equivalent as 6/15 based on angular subtense (13.4 minutes of arc)
Current standard 6/12

17. How reliable is the Snellen standard in predicting number plate test results?
Currie et al BJO 2000
100 patients with vision 6/9 or 6/12
Ability to read number plate tested
26 % of 6/9 FAILED and 34% of 6/12 PASSED

19. Number plate difficulty
T174ILE
P610VOH
M528CBY
T174ILE
P610VOH
M528CBY
Kiel et al 2003
McMonnies 1999 (Chart construction and letter legibility)

20. Does poor visual acuity cause accidents?
Since 2005 official accident reports have included ‘contributory factors’
Less than 2% of accidents occur due to vehicle defects
Most are due to ‘Human Factors’

21. Is there a link between poor visual acuity and accidents?
The evidence is WEAK from studies of accidents Greater likelihood of involvement in more than 1 accident if VA poor (Hofstetter et al 1976) Weak correlation between driving and VA (Burg et al 1976)

22. Is there a link between poor visual acuity and accidents?
Studies of accidents:
Studies not big enough to pick up statistical difference
Motor accidents are rare
Owens et al: not likely to fall victim to fatal accident if drive for 3738 years
Extremes of vision in drivers is rare
People exhibit adaptive behaviour
Confounding variable e.g. glare from cataract

23. Is there a link between poor visual acuity and accidents?
Studies on closed road circuits:
Poor acuity affected sign recognition and hazard avoidance
Increased time to complete circuit
But
No impact on manoeuvring ability or maintaining lane position
Studies on simulators
In different conditions: support the findings from closed circuit studies

24. Is there a link between poor visual acuity and accidents?
Effect of Legislation:
In Florida mandatory rescreening introduced for over 80s
Those that failed were given an opportunity to correct vision (glasses, cataract surgery etc.)
Most were able to go back to driving after correction
After 3 years:
Accident fatality rates in over 80s fell by 17%

25. Case Patient has cataracts VA: Right eye: 6/18, Left eye: 6/24
Both eyes open: 6/12-3
Patient can read number plate in good light at 20 metres
What must the patient do?
Stop driving
Offer to surrender license to DVLA
Apply for restoration after successful cataract surgery

26. Is there a link between visual field loss and accidents?
Since 2005 official accident reports have included ‘contributory factors’
Less than 2% of accidents occur due to vehicle defects
Most are due to ‘Human Factors’

28. Evidence for Visual Fields and accidents
People with visual field defects have DOUBLE the number of accidents/traffic violations
Half of the people with field loss were unaware of problems with peripheral vision
Johnson and Keltner (1983) in a study of 10,000 drivers

29. Evidence for Visual Fields and accidents
Visual field size best predictor of real-world and simulator crashes and driving performance
Especially defects within 100 degrees
But actual cut-off value for standards is unclear

31. VISUAL FIELDS Tested with:
Target equivalent to white, Goldmann III4e settings
Esterman binocular field (sometimes Monocular fields exceptionally Goldmann)
False positive no more than 20%

32. Esterman Binocular Field
120 points Suprathreshold 10dB

33. Esterman Binocular Field
350
Horizontally +/- 75 degrees Superior 35 degrees Inferior 55 degrees
550

34. Esterman Central +/- 20 degrees
Sparse 12 points above and 22 below fixation

35. VISUAL FIELDS STANDARDS:
Field of at least 120 degrees on the horizontal
Minimum 50 degrees to left and right

36. 750
450
600
600
500
700

37. VISUAL FIELDS STANDARDS:
No significant defect in central 20 degrees of fixation above and below horizontal

39. Central defects Allowed Scattered single missed points
Single cluster of up to 3 adjoining points

42. Central defects Not Allowed
Cluster of 4 even partly within central 20 degrees
Cluster of 3 and additional single
Central extension of hemianopia/quadrantonopia greater than 3 points

46. Peripheral defects
Allowed
Cluster of 3 on or across horizontal

48. Limit of field measured at this point (750)

49. Peripheral defects Allowed
Cluster of 3 on or across horizontal
Vertical defect of any length but single point width cutting across horizontal

50. Limit of field measured at this point (500)

51. Pass? Limit of field measured at this point (500)

52. Limit of field measured at this point (750)

58. Case
Patient must: Stop Driving Notify DVLA DVLA will arrange Esterman, license may be revoked After 12 months: May re-apply as an exceptional case if: Non-progressive, no other ocular pathology or impairment And Full functional adaptation Satisfactory practical driving assessment

59. Problems with Esterman fields

61. ‘Only 25% of measured points fall within the most functionally relevant area’ Rauscher et al, UK department of transport 2007

62. Esterman field problems
Too many inferior points
Many points on right side periphery irrelevant for RHD cars

64. Superior v Inferior field defect simulation
Hazard perception test score: Significantly worse with superior defect than with inferior
Crabb et al in a study of 30 UK drivers

65. Esterman field problems
Stimulus too bright in centre
No points tested in central 7.5 degrees

66. Esterman field problems
Difficulty with fixation monitoring
Too lenient?
Alternatives in the future:
Humphrey fields integration
Traffic algorithm

67. Other relevant tests for visual function
Contrast Sensitivity
Glare Sensitivity
Useful Field of View (UFOV)

68. Other relevant tests for visual function
Contrast Sensitivity
Grey letters against white background
Simulates night driving ( e.g. ‘detecting dark coated pedestrian at night’)
Stronger correlation with crashes than visual acuity
Martoletti et al 1998, Dunne et al 1998 TWICE the risk

69. Other relevant tests for visual function
Contrast Sensitivity
Pelli Robson
But no normative database
across centres
No accepted cut-off values

70. Other relevant tests for visual function
Glare Sensitivity
Sensitivity to glaring light sources (setting sun, headlights)
Increased relative risk of accidents (von Hebenstreit 1995, Lachenmayr 1998)
But no established methods (Straylight measurement being developed) or adequate cut-off values

71. Other relevant tests for visual function
Useful Field of View (UFOV)
Tests ability to perform simultaneous detection tasks
Combines visual task with neuro-psychological task of attention
Predicts fitness to drive

72. Identify Central target Localize additional target With Distractors

74. Problems with UFOV
May be difficult to interpret Expensive Performance may improve with practice

75. Age and Driving

76. Driving and the older driver
Decline in sensory, cognitive and motor function
Increased reaction time
Reduced motoring ability
Reduction in Contrast sensitivity
Difficulty seeing road signs
Visual acuity, Visual field sensitivity and stereoacuity
Problems at intersections
Increased glare sensitivity
Difficulty seeing road markings
Increased cataract, AMD and glaucoma
Personality: Increased hesitancy

77. Useful Tests in older drivers

78. Coping with reduced functions
Self-imposed limits
Advantage of experience: Diminishes with increasing impairment due to age

79. Advantage of experience: Age group 40-60
Compensates for impairments but at the cost of increased stress

80. Accidents by age

81. Accidents by age Older drivers more likely to have:
Multi vehicle accidents
Fatal accidents
Accidents in inner city roads not on country roads
Accidents at junctions and intersections
Failure to give way
Right turns

82. If standards met but driver unsure
Self-regulation
Family and friends
Driving assessed in a confidential and objective test from Royal Society for the Prevention of Accidents (RoSPA)

83. Who needs to inform DVLA: (Failure to inform: £1000 fine and possible prosecution if accident)
STOP DRIVING:
Any condition if fail to meet visual standards
Bilateral field defects
e.g. hemianopia, quadrantonopia, glaucomatous
Diplopia

84. Who needs to inform DVLA: (Failure to inform: £1000 fine and possible prosecution if accident)
Bilateral conditions even if standards achieved
Glaucoma, Diabetic retinopathy, AMD, BRVO, cataract
If both eyes affected
Inform DVLA if:
Laser in both eyes
Vision problems in both eyes

85. Do these patients need to notify DVLA?
45 year old with ocular hypertension No
68 year old bilateral glaucomatous field loss Yes
75 year old with glaucoma, field defects in one eye only No
Lorry driver on Latanoprost, mild field loss in one eye Yes
Lorry driver with colour blindness No
42 year old with night blindness Yes

86. Who needs to inform DVLA: (Failure to inform: £1000 fine and possible prosecution if accident)
Blepharospasm: cannot drive if severe
Night blindness: considered on individual basis
Nystagmus
Optic Neuritis/atrophy
Tunnel Vision

87. DIPLOPIA Cease driving at diagnosis Inform DVLA
Resume driving after confirming to DVLA that diplopia controlled with glasses/patch
If patch must satisfy conditions for monocularity
Exception:
Stable diplopia of 6 months or more: uncorrected
If consultant support indicating satisfactory functional adaptation

88. QUAD BIKES

89. Anyone got a spanner?

90. Mobility Scooters Class 3 can be driven on roads maximum speed 8 mph
Recommended that should be
able to read number plate at
12.3 metres (40 feet)

91. Monocular Drivers
Limited peripheral vision nasally degree deficit
Saccades and head rotation to compensate
Physiological blind spot: 2 metres size at 20 metres distance
Effect diminished by Ocular re-fixation (average 3 times/second) and
Head movements BUT
Small objects may remain unseen for longer
Lack of stereopsis
Uncertain relationship with crash rates
Risk of one eye temporarily losing sight due to FB, watery eye

92. Are monocular drivers unsafe?
Accidents
Johnson and Keltner: Same crash rates
Closed-course study of driving performance
Woods et al: Driving no worse
Simulator studies
McKnight et al: No significant safety issues
However
Liesmaa: more dangerous behaviour at junctions and while overtaking

93. Monocular drivers: Formula One (eye) or Two

94. Case 5 Patient diagnosed with choroidal melanoma Right eye enucleated
Left eye: VA: 6/6, Full fields
Patient can read number plate in good light at 20 metres
How does this affect driving?
Must adapt
Inform insurers?
Does the patient need to notify DVLA? No need

95. DVLA requirements for monocular drivers
Visual Acuity Snellen 6/12
Number plate at 20 metres
Same standard for visual fields
Can drive when ADAPTED to the condition
NO need to notify DVLA

96. Dilated Pupils Cycloplegia Spherical Aberrations: Glare, dazzle
Reduced distance VA
in high hypermetropes
Spherical Aberrations:
9 times increased aberration
Glare, dazzle

97. Study of daytime driving in dilated patients on closed circuit: 1% Tropicamide
Vision measures
Visual Acuity reduced: average 2 letters maximum 1 line
Contrast Sensitivity worse: average 1 letter maximum 4 letters
Glare sensitivity worse: average 4 letters
Driving measures
Significantly worse for: potholes, road debris, speed bumps, pedestrians, other vehicles
No problems with: Road signs, traffic cones, gap perception

98. Dilated Pupils Potamitis et al on driving simulator studies:
Reduced High Contrast Visual Acuity
Reduced Contrast Sensitivity
BUT Driving not impaired
But remember: they used driving simulator, no glare, young patients, no ocular disease
Likely to be worse in older people, at night, foggy conditions, with cataract/AMD
Insurance Implications?

99. Electric cycle:

100. Segway

102. QUESTIONS?

103. Fields for class 2 drivers

104. Action to be taken if patient ignores your advice and continues driving
Explain to patient:
1. Their eye condition may affect ability to drive
2. They have a legal duty to inform DVLA
If patient refuses to accept advice:
Suggest second opinion, help to arrange and advise to STOP driving until then
If continues to drive:
Reasonable effort to persuade them to stop
Discuss with relatives/carers/friends with patients permission
If all fails:
Inform patient that you intend to write to DVLA
Inform DVLA confidentially on ‘Doctor Notification’ form
Let patient know you have informed DVLA

105. AREDS 2

106. AREDS 2: BACKGROUND
AREDS 1 showed 25% reduction in risk of advanced AMD
AREDS 1 formula had
Carotenoid: beta carotene
Anti-oxidants: Vitamins C and E
Minerals: Zinc and copper
But:
Concern about risk of beta carotene in smokers
Side effects of zinc at high doses
No lutein, zeaxanthin, omega 3 FA

107. AREDS 2: OBJECTIVES dietary xanthophylls (lutein and zeaxanthin)
Effects of high supplemental doses of:
dietary xanthophylls (lutein and zeaxanthin)
and omega -3 fatty acids on
the development of advanced AMD
cataract and
moderate vision loss (the loss of 15 or more letters).
Effects on the development and progression of AMD of:
eliminating beta-carotene in the original AREDS formulation
reducing zinc in the original AREDS formulation

108. AREDS 2: RESULTS Omega 3 Fatty Acids
No benefit over AREDS original

109. AREDS 2: RESULTS Lutein and Zeaxanthin
No benefit over AREDS original
But:
If beta-carotene removed and replaced with Lutein + Zeaxanthin
Further 18% risk reduction
Also:
If low dietary Lutein and Zeaxanthin
25% risk reduction with supplement

110. AREDS 2: RESULTS Beta-Carotene
Removing beta-carotene did not compromise efficacy of formula
Better without beta-carotene if Lutein and Zeaxanthin added
Increased risk of lung cancer even in FORMER smokers

111. AREDS 2: RESULTS Zinc
Reducing zinc did not compromise efficacy of formula
But no certainty about what is the best dose

112. AREDS 2: Implications for clinical practice
Drop beta-carotene
Add Lutein and Zeaxanthin
No need for omega 3
Reduce zinc to 25 mg
Keep the rest as before
Same formulation for all (smokers included)

113. Vitamin C: 500 mg
Vitamin E: 400 IU
Lutein: 10 mg
Zeaxanthin: 2 mg
Zinc: 25 mg
Copper: 2mg

114. Serous PED: CSR

115. Serous PED: AMD

116. Vitelliform

117. Haemorrhagic PED