Eye Training

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DRIVING AND VISION

• BY
• VONNIE VISION EYECARE CONSULTANTS

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PRESENTER

• DR MRS YVONNE MEGBELE
• OD, MSc Occupational Health
• OCCUPATIONAL VISION CONSULTANT

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KEY POINTS

• Facts about driving and vision
• Various parameters of visual functions and how it
  relates to driving performance.
• Common eye conditions that impair visual
  functions
• How to minimize glare.
• Aging and driving.
• Tips on night driving
• Alcohol and driving

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Facts about driving and vision

• Vision is the most important source of
  information during driving.
• It is estimated that up to 90 of information
  received is visual.
• Researchers have established a relationship
  between accident occurrence and defective vision.
• Statistics show that one driver in 14 has a
  vision defect that may affect driving.
• Driving safely does not depend so much on what is
  seen, but rather on how quickly or adequately
  drivers respond to what is seen.

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The act of driving involves

• Perception- Central (fixation)
• -Peripheral( scanning)
• Interpretation
• Decision(reaction time)
• Action(motor abilities)

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Driving safely thus depends on

• External factors
• Visual characteristics of the obstacle(size,
  colour, contrast)
• State of the vehicle(wind shield, rear view
  mirror)
• Irrelevant information(publicity along the road)
• Reduced visibility(night, fog, rain)
• Condition of the road
• Driver related factors
• Visual performance(visual acuity, visual field,
  contrast sensitivity
• Age
• Experience
• Risk assessment
• Motivation
• Divided attention(use of cell phone, talking ,
  anxiety, fatigue alcohol and drugs)

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VISUAL FUNCTIONS

• Central Vision/Visual Acuity
• Peripheral Vision
• Night Vision
• Glare Resistance and Glare Recovery
• Judgment of Distance
• Eye Movements
• Visual Perception
• Colour vision

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Central vision/visual acuity

• Used to discern details
• Identify what the driver is looking at

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Impaired central vision

• When impaired, it results in the driver failing
  to read signs and/or recognize hazards in a
  timely manner.

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Peripheral vision

• Used in part to detect information that may be
  important for safe driving. E.g road signs,
  appearances of hazards and changes in the flow of
  traffic.
• When the driver looks in the rear view mirror.
• used to monitor traffic in front of the vehicle.
• Used In keeping the vehicle centred in the lane
• used to monitor the lane boundaries.

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Impaired peripheral vision

• Results in the driver failing to react to a
  hazard coming from his far left or far right.
• Failing to heed a stop light suspended over an
  intersection.
• Weaving while negotiating a curve,
• Driving too close to parked cars.

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Night vision

• Required to see under low illumination.
• To see low contrast objects.

• Required to see under low illumination.
• Required to see low contrast objects

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Impaired night vision

• The driver at night failing to react to hazards
  located directly in front of the vehicle.
• Tailgating
• Failing to steer when necessary because the
  driver is unable to see low contrast features of
  the roadway such as its edges and irregularities
  in the road surface.

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Glare resistance and Glare recovery

• Glare is the disruption of vision due to a
  veiling luminance (such as the light from the
  headlights of oncoming traffic at night) being
  superimposed on the visual image (such as the
  outline of the car ahead of you).
• Glare resistance is the extent to which the
  driver can still see critical objects and events
  while facing a steady source of glare such as the
  setting sun or the light from the headlights on a
  steady stream of oncoming traffic at night.
• Glare recovery is the rapidity with which the
  driver's vision functioning returns to what it
  was before the glare was encountered.

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Impaired glare resistance and glare recovery

• Result in the driver being blinded by a glare
  source and consequently missing curves in the
  road.
• Striking unobserved pedestrians.
• Crashing into the rear of slow-moving, stalled,
  or stopped vehicles.

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Judgement of distance

• Required for packing a vehicle.
• Locating children around cars, buses etc.
• Of little benefit in high speed driving because
  it is inoperative beyond 500m

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Impaired judgement of distance

• result in the driver stopping too short of the
  limit line or inside the intersection.
• turning too wide or too short.
• failing to maintain speed and/or following
  distance appropriate for prevailing driving
  conditions.

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Eye movement

• Required for focusing objects for detailed
  viewing after scanning with peripheral vision.

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Impaired eye movement

• results in visual scanning deficiencies.
• There could also be a tendency to look at a
  specific object too long or continuously look
  straight ahead.
• Consequently, the driver may fail to react to
  hazards and heed traffic signs and signals.
• Changing lanes could be especially hazardous if
  the driver spends an excessive amount of time
  looking to the rear of the vehicle.

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Visual perception

• Processing of incoming visual information.

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Impaired visual perception

• result in difficulties with performing several
  visual tasks at the same time.
• The driver may have impaired ability to
• switch attention to important events without
  interference from distracters or clutter in the
  visual environment,
• distinguish foreground from background,
• determine the position of other vehicles, signs,
  and pedestrians relative to self and to each
  other.
• Consequently, the driver may brake and/or stop
  unexpectedly, maintain inordinately long
  following distance (to keep from having to react
  quickly), fail to react to hazards, and/or fail
  to heed traffic signs and signals

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COMMON EYE CONDITIONS

• THAT IMPAIR VISUAL FUNCTIONS

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MYOPIA

• Blur distant vision

• Problems with reading road signs and street
  names.
• Difficulty in night driving.

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Astigmatism

• Blur distant vision and headaches

• Difficulty reading street names and signs.
• Eyes feel tired.

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CATARACT

• Cloudy/hazy vision, glare and change in colour
  perception.

• Difficulties in night driving, poor weather or in
  bright sunlight.

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GLAUCOMA

• No symptoms at the early stage.
• haloes around light.
• Glare /difficulties driving at night
• Difficulties maintaining lane position.

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Macular Degeneration

• Problems seeing detail,
• vision blurred in centre, or
• distorted vision

• Problems with night
• driving or seeing road signs
• or recovery from bright
• light

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RETINOPATHY

• Problems often reported
• with night driving.

• Variable or blurred vision
• Can be without symptoms.

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HOW TO REDUCE GLARE
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• Clean the windshield, windows, and glass surfaces.

• Clean the car's headlights.

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• Adjust the car mirrors properly.

• Have your vision checked regularly.

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• Flip the rear view mirror

• Avoid looking directly at the headlights of
  oncoming traffic.

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• Take frequent breaks if you're driving at night
  for long periods of time

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AGING AND DRIVING
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FACTS

• Age affects the reaction process of driving which
  includes sensing, deciding and acting.
• Age-related decline in vision, cognition and
  motor functions makes older drivers vulnerable to
  crashes in complex situation that require good
  visual perception, attention and rapid response.
• The ability to select relevant visual stimulus
  from an environment full of other distracting
  stimulus is impaired with age.
• Elderly drivers are more prone to accidents that
  involve failing to give right of way,
  intersection collisions, improper turning or
  ignoring stop signs which are all related to
  peripheral and visual field problems.

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Why is aging and driving a problem?

• The pupil shrink and dont dilate as much in the
  dark as we age, reducing the amount of light
  entering the eyes
• The aging cornea and lens in the eye becomes less
  clear as we age, causing light to scatter inside
  the eye, which increases glare and reduces
  contrast sensitivity.
• Advancing years decreases our ability to see
  stationary and moving objects, including cars or
  pedestrians that might cross the road in front of
  us. Our ability to resist glare and see
  reflective road signs and marking also decreases
  with age.
• Many peoples eye have optical imperfections
  called higher order aberrations that cant be
  corrected with eyeglasses and contact lenses.
  These aberrations increase with age and reduce
  vision, especially when the pupil dilates at
  night.
• Age related macular degenerations, glaucoma,
  diabetic retinopathy or cataract affects 33 of
  all people age 40 years and older.

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Tips for maintaining healthy eyes, clear vision
and good driving record.

• Have your eyes examined annually.
• Consider wearing special glasses. E.g.
  anti-reflection coated lenses for glare and wave
  front diagnostic technology to reduce haloes,
  star bursts and other distracting aberrations..
• Reduce your speed when driving at night.
• Seek the best care for age-related diseases.

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Expert advise for driving safely.

• Minimize the risk of driving at night.
• Plan for extra driving time.
• Avoid driving when you are fatigued.
• Always drive defensively- at least2 car lengths.
• Keep your windows clear.
• Keep your car in good repair.
• Use additional rear view mirrors.
• Renew skills with a driving class.

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Night driving tips for older drivers.

• Avoid tinted windscreen or spectacle.
• Dont use cell phones while driving.
• Avoid driving on unfamiliar streets at night.
• Avoid routes with poor lighting, irregular twist
  and poor signage.
• Be extra cautious when approaching intersections.
• Assess your driving ability based on reactions
  from others.

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ALCOHOL AND DRIVING

• It impairs mental efficiency.
• Acts as an anaesthetics.
• Slows the response to a hazardous situation.
• Can cause diplopia(double vision).
• Can cause blurry vision.

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TIPS ON NIGHT DRIVING

• Take your time.
• Allow your eyes the chance to adjust to the
  darkness before you start driving.
• Minimize glare by looking to the bottom right of
  the road to avoid approaching headlights. Use the
  light setting on your rear view mirror to deflect
  the glare from vehicles behind you.
• Keep it dark. Turn off all interior lights.
• Slow down. Reduce your speed to give yourself
  longer time to react to obstacles.
• Tune it up. Keep car in good shape, clean
  headlamps, tallying lights and signal lights.

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YOUR VISION IS YOUR JOB