Vision and Driving What is Vision Seeing Your Way to Better Client Outcomes The primary sense that we use to acquire information about our environment. Includes Beth Rolland, OTR, CDRS Eye movement Acuity Perception
Vision Facts Vision Facts
90% of the information we gather Eye is the only organ in the body comes from the visual system. innervated by both the central and Vision allows us to be anticipatory autonomic nervous systems Central – voluntary movements The visual system is the fastest and (pursuits, saccades, lid opening/closing) most complicated of all sensory systems. Autonomic – involuntary control (pupil constriction and dilation) 50% of all neurologic insults cause visual deficits.
Vision Facts
The visual system provides the highest level of sensory information processing in the human body and is the most highly integrated of all systems. Anatomy of the It is estimated that 65% of all nerve fiber interactions with the brain have Eye something to do with the visual An Overview information processing system.
1 Anatomy of the Eye Eye Structure & Function
Eye parts resemble a camera Sclera - white outer protective coat; the "white of the eye". Cornea - transparent, curved structure in front Iris - colored part seen through the cornea. Pupil - black part in the middle of the iris. Constricts or dilates according to the amount of light passing through. Lens - transparent disc (with both sides being convex) immediately behind the iris and pupil.
Eye Structure & Function Eye Structure & Function
Rods - more numerous, mostly at outer edge Aqueous humour - transparent fluid respond to low levels of light, peripheral (water consistency) circulates behind cornea and in front of the lens. movement. Vitreous humour – fills the eyeball Cones - far fewer, concentrated in center between lens and retina (like transparent respond to color and details. jelly). Macula - small center of the retina Retina - light-sensitive layer of millions of nerve cells lining back of the eyeball. responsible for central vision—ie: reading. Rod cells – tall, thin Retinal pigment epithelium – dark layer of cells at Cone cells - rounder back of retina Provide oxygen & nutrients to rods/cones.
Eye Structure & Function Eye Structure & Function
Choroid - large network of blood vessels (behind Retina – the retina) located at the back of the eye and connected transport oxygen & nutrients to retinal pigment to the brain. cells. made up of many millions of light-sensitive cells Optic disc - small yellow oval structure in retina known as photoreceptor cells which transmit nerve cell connections travel from all the rods electrical impulses to the brain to enable sight. and cones. Optic nerve and beyond - "cord" of nerve cell connections that passes from eyeball to destinations throughout brain.
2 Cranial Nerves Cranial Nerve II (cont.)
Cranial Nerve II (Optic Nerve) The optic nerve has only a special sensory component Originates at the Retina Visual information enters the eye in the Connected to the specialized receptors form of photons of light in the retina—the rods and cones. Light is converted to electrical signals in the photoreceptors (rods and cones) Exits the back of the eye in the orbit located in the retina Where the optic nerve tract begins. Signals travel optic nerves, chiasm, and tract lateral geniculate nucleus (thalamus) occipital lobe (visual centers)
Cranial Nerves Cranial Nerve III (cont.)
Cranial Nerve III (Oculamotor Medial Rectus: Nerve) the ocular muscle whose contraction turns the eyeball medially Raises eyelid and controls pupils These muscles are an integral part Drooping eyelid = ptosis Controls several key eye muscles. of how well and how smoothly your These muscles include the following: eyes move. Superior Rectus: the ocular muscle whose contraction turns the eyeball upward and medially Inferior Rectus: the ocular muscle whose contraction turns the eyeball down and medially
Cranial Nerves Cranial Nerves
Cranial Nerve IV (Trochlear Nerve) Purely motor nerve supplying one muscle: Cranial Nerve VI (Abducens Nerve) Superior oblique: Intorsion- inward rotation of upper part of Lateral Rectus: eye about an axis or a fixed point. Pulls the eye away from the nose Secondary movement-moves eye out and down. Damage to this nerve will result in the Damage results in eye slightly affected eye turning inward (cross elevated in primary gaze position eye) (straight ahead gaze) Intermittent double vision in lateral gaze Effect of esotropia is greater at distance Reading ok, driving a problem
3 Cranial Nerve Summary
Nerve Nerve supplies Function Clinical observations
CNIII- oculomotor Upper eyelid Eyelid movement Ptosis SR, IR, MR, IO Eyeball movement-up, Exotropia (down&out) Ciliary Muscle down, and medially Diplopia at near Sphincter of Iris Pupil constriction No pupil accomodation CNIV-trochlear Superior obique Eyeball movement- down Hypertropia/phoria and out Vertical diplopia Lateral tilt of head
CNVI- abducens Lateral rectus Eyeball movement Esotropia/phoria outwards Diplopia at distance
Eye Anatomy Videos
Dr. Tim Root https://timroot.com/anatomy-of-the-eye- video/ Anatomy video Neuro-anatomy Functional Vision
Hierarchy of Visual Oculamotor Control Adaptation
Oculamotor Control (pursuits, Visual Fixation - ability to find target and saccades) hold eyes on it Visual Attention Pursuits – ability to follow a moving target (without head movement) Visual Scanning Saccades – rapid eye movements in any Pattern Recognition direction (without head movement) Visual Memory Visuo-Cognition (perception) Implication for driving: if you can’t see it, you can’t respond to it!; objects are moving in driving Adaptation (thought, reasoning) environment – pedestrians, bicycles, cars
4 Visual Attention Visual Scanning
Cognitive component Ability to pick out relevant information in an environment and suppress irrelevant Visual Scanning – ability to find things in information the environment Sustained attention – maintain over time Peripheral Vision – what can be seen on Shifting attention – change focus from one thing to the side without head or eye movement another rapidly Not clear, but brain fills in and seems clear Divided attention – attend to multiple factors at Alerts to movement – prompts saccade or head once (ie: hazards on both right and left side) turn to use central vision for more information
Implication for driving: if you are not paying attention, Implication for driving: hazards come from all you will miss things fields; inadequate scan will miss things
Visual Fields – Peripheral Pattern Recognition Vision Norms: . Cognitive process that matches information 65 degrees upward from a stimulus with information retrieved 70 degrees downward from memory 60 degrees nasally 90-110 degrees temporally . Allows anticipatory awareness
Implication for driving: if you don’t anticipate, you will respond late
Visual Memory Visuo-Cognition (perception)
Ability to process and interpret meaning from Recollected information about what visual information gained through eye sight one has seen. visual discrimination Mental storage of information visual figure ground – distinguishing object from background Ability to retrieve stored information visual closure – “seeing” the whole from a part visual memory – recalling what you saw visual form constancy – recognizing objects when they are Implication for driving: deficit may lead to turned around difficulty finding your way, finding your visual spatial relationships – where one thing is in relation to car in a lot, remembering what was on the another left when you scan right visual-motor integration – eye/hand coordination
Implication for driving: . Poor lane position . Unsure where they are relative to parked cars, lanes . Unable to coordinate steering movements quickly enough to maintain straight path Other Crucial . Improperly placed turns . Unsure where to start turn – especially lefts Vision Skills . Unsure where curve starts for rights . Poor sign recognition (ie: branch over stop sign) . Difficulty driving at night (poor contrast)
Visual Acuity Visual Acuity
Ability to focus either near or far Includes Contrast Sensitivity Expressed as a fraction Ability to see objects of decreasing contrast rather than size High contrast: black on white, etc. Numerator: testing distance at which stimulus is recognized Low Contrast: grey on white; white on white, etc. Denominator: distance at which letter being viewed could be recognized by a person with normal visual acuity (20/20) Contrast Sensitivity has been linked to crash risk Implication for driving: difficulty driving at night, Implication for driving: state laws for minimum; dusk or dawn; difficulty seeing items against same inability to read signs or see road details color background (green car with green bushes)
Contrast Sensitivity Binocular Vision
Combining images from each eye into single image. Images must fall precisely on corresponding positions on each retina or double vision will occur. Muscles work together to position eyes properly to focus light on center of each eye, providing clear vision.
6 Binocular and Stereoscopic Binocular Vision Vision Focusing near - eyes move closer together (convergence) Focusing far - the eyes move further apart (divergence) Misalignment of eyes – double vision Double vision usually either near OR far Muscle weakness pulls eye opposite May be in one gaze (ie: far left gaze) May be constant
Implication for driving: blurry vision, motion sickness, inability to accurately judge space
Stereoscopic Vision Binocular and Stereoscopic Vision Depth Perception Slight difference in angles of images received in each eye gives People think and learn best in three images depth Loss or suppression of one eye affects depth dimensions. Do use other cues When scanning text quickly, we can absorb 100 Light, shade, shadows, color and relative letters per second - the computer equivalent of 100 sizes of objects contribute to depth bits per second. Cognitive component - learn the signs When glancing at a three-dimensional object, we can that enable them to perceive depth. see the equivalent of 1 billion bits per second.
Implication for driving: difficulty judging space and speed Implication for driving: good binocular vision lets you see faster and react faster on the road
Visual History
Patient complaints (diplopia, blurred vision, dizziness, headaches, eye fatigue, balance difficulties) Optical History (cataracts, glaucoma, diabetes, macular Vision Screen degeneration, surgery)
7 Evaluating Far Acuity Evaluating Far Acuity
*Must pass state standard for vision in state they hold license Test each eye separately and then Options: together (Optec tests separately with both eyes working) Optec Vision Tester – quick and easy; also tests contrast sensitivity, alignment, depth, Many states have requirements that color, road sign recognition both eyes pass the standard Snellen or Lea Chart – cheap and easy Testing separately lets you know which eye has an issue
Visual Acuity Evaluating Far Acuity
Optec Procedure Equipment Client wears corrective lenses for distance Select appropriate assessment tool (Optec, Snellen chart/ Lea symbols) Begin at 20/40 line Left eye sees left column; right eye sees right column; both eyes see middle column If client does not start with left column, turn off right eye and have them try again If client does not read right column, turn off left eye
Evaluating Far Acuity Evaluating Far Acuity
Snellen Chart (or Lea Chart) Procedure Optec Stand 10 or 20 feet away (based on chart) Instruct client to read down to last line Client wears corrective lenses for distance they can make out Test monocularly then binocularly Far acuity is last line where 3 out of 4 letters in the column are identified Begin at 20/40 line (or line required by state of correctly license) If the client has aphasia, try giving If patient has difficulty, isolate lines them a piece of paper and pencil to write the letters
8 Evaluating Far Acuity Evaluating Far Acuity
. A large discrepancy between eyes can lead to Snellen Chart suppression and will affect depth Use Lea symbols if client has aphasia . Two line discrepancy – refer to a vision specialist . Far acuity is last line where 75% or Older patients often have cataracts, which affect more of letters are identified acuity correctly . May not meet state standard for vision
Evaluating Far Acuity Evaluating Contrast Sensitivity . Some folks have trouble with Optec . If not meeting standard in Optec, try Snellen Optec 5000 – contrast slides . **In most cases, it is not legal to take a client on the road if vision does not meet state minimum Day and night testing . If below state standard, refer to eye doctor Can also test glare . May have to wait for cataract surgery prior to BTW Contrast Sensitivity Chart
Contrast Sensitivity-Optec Contrast Sensitivity Charts
Pelli Robson Chart
Hamilton-Veale Chart
9 Evaluating Pursuits Evaluating Pursuits
Equipment – colored target, eye patch Look for: choppy movement, inability to move the eye through entire range of motion, nystagmus Procedure: (slow beating motion), excessive head movement Patch one eye Refer to eye doctor if deficits are significant Test without glasses Nystagmus – often in extreme side gaze; can be in Have client hold head still and follow target as primary gaze you move it. Will blur image on that side Hold target 16” from patient and move in the Can appear like double vision form of “H”, “X” and “O” Client will have to be taught to turn head to that side rather than relying only on saccades
Evaluating Saccades Evaluating Saccades
Equipment: two different colored targets; Look for: choppy movement, overshooting, eye patch undershooting, nystagmus, searching for target, inability to disassociate head and eye movements Procedure: Searching for target may mean field cut or Patch one eye inattention on that side Test without glasses May benefit from visual exercise program Have patient hold head still and look back and Refer to eye doctor with overshooting, forth between the targets on your command undershooting, significant deficit, searching for Hold targets 16” from patient, 12” apart target on return (suspect neglect) Test in upward, horizontal and downward gaze
Evaluating Visual Fields Evaluating Visual Fields
Optec has visual field test Will only test horizontal field Double simultaneous stimuli Will not test superior or inferior field cuts Will detect field cuts in planes other If you suspect a field cut, don’t rely only on Optec than horizontal Easy for client to cheat! Obvious when cheating! They will move eyes to search for targets Use with known or suspected field cut Clients don’t always understand directions Use with clients who have difficulty Mix up right, left and both with Optec
10 Evaluating Visual Fields Evaluating Visual Fields
Optec procedure: Double simultaneous stimuli procedure: Test without glasses (ear piece often obscures Patch one eye, sit opposite client and instruct target) them to look at your nose at all times Instruct client to look straight ahead Start with arms in horizontal plane and Emphasize that targets will not be in the picture, but determine end ranges of fields will be well to the side Instruct client to identify right left or both Randomly choose targets right, left or both fingers moving Check each target several times Start with single stimulus then move to simultaneous stimulus Repeat procedure for vertical and diagonal Look for targets missed repeatedly, targets seen planes when singular but missed when double (suspect inattention/neglect), delay in responding Repeat binocular (inattention more obvious)
Evaluating Visual Fields Clinical Correlations
1. Macula Norms: 2. Optic Nerve 60-65 degrees upward 3. Optic Chiasm 70-75 degrees downward 4. Optic Tract 60 degrees nasally 5. Lateral Geniculate 90-100 degrees temporally 6. Optic Radiation 7. Visual Association 8. Primary Visual Area
Visual Field Loss Visual Field Loss
Homonymous field loss – both eyes Hemianopsia – half of field; severe loss Many states will not allow driving with HH Quadranopsia – one quarter of field Temporal lobe – usually upper field Parietal love – usually lower field Easier to compensate for upper field loss Location of infarct will dictate field loss Infarcts further back will cause greater loss and be more permanent More likely to be in one eye if further forward • Right Homonomous Hemianopsia
11 Visual Field Loss Visual Field Loss
• Binasal Hemianopsia • Bitemporal Hemianopsia
Visual Field Loss Visual Field Inattention/Neglect
Can be with field loss or without Three types (may have one or all) Personal space – dressing, shaving, washing face Peripersonal space – arm’s reach, desk activities Will show up with cancellation tests, field testing, clock drawing, Rey Osterreith figure copy Extrapersonal space – beyond arm’s reach • Quadrantopsia Difficult to test in office More dangerous for driving May veer to one side when walking; miss doorway to office,
Evaluating Evaluating Inattention/Neglect Inattention/Neglect Look for patterns: Clock drawing Poor saccade to one side (searching on return) Ask client to draw a clock with all the numbers on it, and the time reading “10 minutes past 11” Difficulty with field testing (maybe just unpredictable) Look for: Odd clock drawing spacing – even, or more on one side? (inattention) Leaving out details on one side of Rey Osterreith copy Hand placement (abstract skills) Taking longer to find targets on one side of Trails A or B Rey Osterreith copy Ignoring small peripheral shapes on Visual Form Discrimination Test Have client copy the picture Look for missing details on one side
12 Clock Drawing Test Rey Osterreith Figure Copy
Rey Osterrieth Errors Evaluating Convergence
Procedure Client wears reading glasses if applicable Hold a pencil 16” in front of client’s nose Slowly move pencil toward client’s nose Client tells you when pencil doubles OR – note when one eye stops coming in toward the nose Normal is 2”-4” from nose
Evaluating Alignment Evaluating Alignment
. Optec – simple, quick . Corneal Reflex Procedure . Use slide with musical notes and arrow Hold pen light 16” from bridge of nose . Ask client if they see both notes and an arrow Client looks at light pointing down from the top of the slide Observe reflection in both pupils . Have them identify to which number note the Look for symmetry of reflection arrow is pointing Medial reflection indicates exophoria Lateral reflection indicates esophoria . Normal range – between 4 and 12 **Do not perform if seizure precautions!**
13 Evaluating Alignment Evaluating Visual Scanning
. Maddox Rod Procedure . Paper & Pencil Scan sheets Test each eye separately . C & E Cancellation Sheet Hold rod so lines on rod are oriented horizontally . Trails A Stand 10 feet from client Hold penlight behind card and direct light through . Mesclun Scans the hole in the center . Star Cancellations Client indicates which number the vertical line passes through. This represents horizontal . Disadvantage: small space – mostly focal vision alignment Repeat with lines on rod oriented vertically for vertical alignment **Inability to see line may be a suppression**
Evaluating Visual Scanning Dynavision
. Dynavision or Wayne Sacadic Fixator . Advantage: bigger space; uses periphery . Disadvantage: cost, size . If your clinic has one, great test to add . Norms . Grossly looking for one target per second (60 targets/minute)
Neuro-optometrists
Specialize in functional vision What do I do if I Evaluate more than acuity and eye health Use interventions such as prism lenses find a vision Refer clients for therapy (or treat in their offices) deficit?? Find one and get to know them! Source of referrals as well as help for your clients
14 Neuro-optometrists Neuro-optometrists
NORA Put off Behind the Wheel evaluation if deficits are significant and have not Neuro-optometric Rehab Assoc. been addressed https://nora.cc Both neurological and congenital diagnoses Search feature to find a provider may make it to you before a good functional evaluation Courses in evaluation and treating vision dysfunction If training in the car and noticing poor tracking, trouble with curves/turns, take a step back and send for vision therapy
Vision Therapy Vision Exercise Program
OT clinic with a vision rehab program Deficits in Pursuits/Saccades Neurological Outpatient Rehab site Thumb Rotations - pursuits Often covered by insurance Hart Charts - saccades Eyecanlearn.com Neuro-optometrist with in-office program Tracking – Pursuits/Saccades Often out of pocket expense Program for kids, but good for adults also Brock String – eye pointing, accomodation
Skills that Decline as we Age Vision Deficits Common in Older Drivers Acuity Contrast sensitivity Spatial skills Peripheral fields Awareness – particularly of the periphery, and of multiple targets Visual processing speed Anticipatory decision making Visual/Physical reaction – “reflexes”
15 Vision Deficits Useful field of view
Visual area over which information can be extracted at a brief glance without eye or Visual Acuity head movements. Static – ability to focus on a target State standards differ Correlated to crash risk in older drivers Road signs designed for 20/40 UFOV decreases with age NJ does not retest after initial licensing (!) decreases in visual processing speed Dynamic – distinguishing details of objects in motion reduced attentional resources less ability to ignore distracting information. 40% of 90 year olds have a UFOV of less than 20 degrees (tunnel vision)
Visual Diseases/Disorders Visual Diseases/Disorders (cont.) Macular Degeneration Cataracts Loss of central vision; periphery intact Clouding of the lens--loss of acuity/hazy vision Very dangerous for driving as it worsens Scotoma Poor night vision Loss of a spot of vision (macular degeneration, optic Diabetic Retinopathy neuritis, surgery, etc.) Can sometimes learn to move head and adjust spot Leakage and other damage to blood vessels of to a place it does not interfere the retina Glaucoma Retinal scars; blind spots from laser treatments Increased fluid pressure-damages optic nerve Loss of peripheral vision Poor night vision
Visual Diseases/Disorders Macular Degeneration (cont.)
Low Vision Significantly decreased acuity Bioptic Lenses—some states allow Require significant training
Outside the car
Inside the car
16 Scotoma 20/200 Acuity
Glaucoma
Vision Deficits Common after Stroke/TBI
Ocular-motor deficits Cranial Nerve III Damage
Pursuits, saccades Cranial nerve damage III drooping eyelid; may impair peripheral vision Eye postures down and out IV – Difficulty with downgaze Head tilt to opposite side VI eye won’t move out (“cross eye”) **big effect on driving Decreased ability to scan for hazards Nystagmus—abnormal oscillations of eye(s)
17 Cranial Nerve VI Damage Poor Alignment
. Strabismus (tropia) – unable to voluntarily align eyes to look at an object; constant . “Cross Eyed” – one eye deviates medially . “Wall Eyed” – one eye deviates laterally . Corrected surgically . Phoria – misalignment that fluctuates; more apparent with fatigue . May be alternating – either eye different times
Alignment Deficits
Suppression Brain ignores image from one eye Common when there is double vision Loss of depth perception New? Or longstanding? Fusion deficits Not using both eyes together as a team Loss of depth perception New? Or longstanding?
Visual Field Loss Visual Field Loss
Homonymous field loss – both eyes Hemianopsia – half of field; severe loss Many states will not allow driving with HH Quadranopsia – one quarter of field Temporal lobe – usually upper field Parietal love – usually lower field Easier to compensate for upper field loss Location of infarct will dictate field loss Infarcts further back will cause greater loss and be more permanent More likely to be in one eye if further forward • Right Homonomous Hemianopsia
18 Visual Field Loss Visual Field Loss
• Binasal Hemianopsia • Bitemporal Hemianopsia
Visual Field Loss Vision Deficits (cont.)
Peripheral Deficits Visual Field Cuts One eye only – easier to compensate Homonymous – most states won’t allow driving (NJ & NY do, PA does not) Normal binocular field=180 deg. side to side Effect of vehicle speed on Visual Field 200 deg field at 20 mph=104 degrees 200 deg field at 40 mph=70 degrees • Quadrantopsia Normal VF at 60 mph=40 degrees Field deficit will worsen as speed increases Peripheral vision is not clear—alerts to motion
Visual Attention Deficits Impaired Visual Processing
Inattention/Neglect (neurological dx) Combines visual and cognitive systems Field is either normal or decreased Slow Processing common in: Unfit for driving if extrapersonal—needs to resolve first Neurological dx – CVA, PD, MS, TBI Unable to compensate Decreased divided attention General aging population Field can be either normal or decreased Compounded by: Work in clinic first Low illumination Common in neurological dx, but also prevalent in the well elderly Stress Illness Fatigue Sensory overload
19 Spatial Skills Deficits Spatial Skills Deficits (cont.) Figure Ground
Differentiating foreground from background Topographical Disorientation Form Constancy Relationships of places to one another Attending to subtle variations in form Finding your way in space Perceiving the whole object when you only see a piece of it Spatial Relations Position in Space Position of objects in relation to each other Up/down, front/behind, left/right Interpreting speeds of movement
Spatial Skills Deficits (cont.) Implications for Driving Time and space management (stopping too late or too soon at intersections) Parking difficulties (esp. backing) Not seeing signs, confusing arrows Vision Deficits Common Interpretation of the unexpected with Congenital Diagnoses (construction, car breakdowns) Maneuvering difficulties—position on road Getting lost in familiar surroundings Lane selection
Vision Deficits Cerebral Palsy
Congenital Diagnoses that often present Common Deficits with vision deficits Strabismus or Phoria Cerebral Palsy Poor Binocular vision Spina Bifida Absent depth perception Learning Disabilities Poor visual/spatial skills ADHD/Asperger’s Slow scanning Retinitis Pigmentosa Difficulty multi-tasking Albinism Often have difficulty with lane position, turns and curves Often see detail at expense of big picture
20 Spina Bifida ADHD/Asperger’s
Common deficits Common deficits Weak eye muscles – strabismus Difficulty with visual multi-tasking Poor scanning skills Difficulty disassociating head & eye movements Inefficient visual scanning – or looking for the wrong things Often see detail at expense of big picture Watch Rey Osterreith drawing
Retinitis Pigmentosa Ocular Albinism
Common deficits Common deficits Unable to see the color red Reduced pigment in eye – crucial for vision Very poor contrast sensitivity (see brake lights Low vision better in the dark) Poor depth perception Low vision – often referred with bioptic lenses Nystagmus Decreased peripheral vision Strabismus Poor night vision Photophobia Abnormalities in optic nerve – affects connection to the brain
Bioptic Lenses
For drivers whose acuity cannot be corrected to the state minimum Carrier lens plus telescopic lens Driver uses carrier lens 95% of time Uses telescopic lens to read signs Legal in 37 states, including NY, NJ, PA Driving with Low Vision Requires significant training OUTSIDE the car prior to any driving Requires a driving specialist with special training
21 Driving with Vision Deficits
Driving with Homonymous Hemianopia Driving with HH (HH) Homonymous hemianopias (HH) Approx. 40% of post-chiasmal lesions HH Research 22 states and many countries do not allow driving (2009) No study has looked at actual crash rates Disqualified by arc of vision requirement Prognosis may be better with macular sparing Some allow after special evaluation Monocular Sector Prisms Lower accuracy in seeing pedestrians in simulator and Can increase arc of vision enough to qualify traffic/pedestrians in on-road study (Bowers I) No research yet to determine if they increase safety (Elgin) Widely differing abilities to compensate (miss rates Recommend training prior to evaluation on-road from 0-100% ) Greater incidence of positioning errors (over lane line Bowers II) Age is the best predictor of blind-side miss rates
Driving with HH Evaluation – Field Cuts
HH research (cont.) Tips for Evaluators
. Most detection errors occurred at intersections (Bowers pilot) Know the law in your state for peripheral fields
. Scan magnitude was not large enough (especially to right side Bowers IV) Clients with significant field loss may be able to drive safely . No peripheral vision cue how far to scan Question client about navigation in crowded places – malls, . Missing pedestrians, etc. on sidewalk supermarkets, etc. Do they run into things?
. Judgment on fitness to drive cannot be based solely on visual field size (Gera) Send to an OT vision specialist to learn scanning strategies and improve speed and accuracy outside the car first . Longer time not driving adversely affects outcome (Gera) less expensive (often covered by insurance) . Better prognosis with good contrast sensitivity and faster processing speed (Elgin) safer . Research shows that many people with HH are driving AMA
22 Evaluation – Field Cuts Training Techniques-Field Cuts Tips for Evaluators Look closely at the following maneuvers during BTW: Teach compensation techniques lane position – middle line, shoulder line, lane choice Look as far down the road as possible intersection hazard detection – are they scanning far enough to see the sidewalk on both sides? Turn head when approaching targets identified steering stability – do they hold a straight line? Children playing, cars at intersections, people getting into cars in driveways, bicycles, pedestrians One drive is not enough to make decision Routes should include a variety of traffic scenarios Keep eyes moving constantly Choose routes that challenge client from the blind side Turn head and be especially vigilant at Choose areas with pedestrians intersections Insist on 8-10 drives with different traffic and times of day Be sure to scan far enough – all the way to sidewalk to look for pedestrians Familiar roads will be safer – but there can be changes, detours, surprises
Training Techniques-Field Training Techniques-Field Cuts Cuts
Teach compensation techniques Teach compensation techniques Use mirrors more frequently Choose lane wisely Scan for aggressive drivers coming from Driving in lane corresponding with field cut behind, tailgaters, traffic in lane on vision loss will eliminate cars cutting you off from that side lane Vigilently check the side mirror on side of loss Staying in the right lane will avoid difficulty of lane change to the left and vise versa – but Beware of parking lots!! eventually left lane drivers may have to lane Uncontrolled air space – look for backup change right to exit lights, pedestrians, doors opening, cars cutting Plan lane changes far in advance – don’t try to across spaces, cars at ends of rows cut over at the last second
Training Techniques-Field Training Techniques-Field Cuts Cuts
Teach compensation techniques Suggest technology If client can purchase a new vehicle, suggest the With right side loss, beware of parking following options: lot entrances/exits, driveways, kids Blindspot detection playing in yards Lane position detection Back-up camera – looking over shoulder will be harder With left side loss, be wary of car in with field cut left lane directly next to you Intelligent cruise control Address position of side mirrors to reduce blindspot Suggest spot mirrors on both sides Suggest panel rearview mirror
23 Training Techniques-Field Training Techniques- Cuts Turns/curves/lane position Teach client to look ahead, as far around Teach compensation techniques the curve/turn as possible With right side loss, beware of parking Look for yellow line ahead lot entrances/exits, driveways, kids playing in yards Try to keep same distance from yellow line With left side loss, be wary of car in Use landmarks left lane directly next to you There is almost always a manhole where you need to start a left turn Use a magnet on the hood of the car to line up with the yellow line
Training Techniques- Training Techniques- New Drivers New Drivers
Teach hierarchy of scanning Teach eyes up and out Most important to least important (ie: Look far down the road brake lights ahead vs. car in its lane Use saccadic eye movements approaching from ahead constantly Teach first as passenger – parent/you. Emphasize hazards Identify one thing, then two, etc. Bicycles, motorcycles, pedestrians, Commentary driving runners, car approaching over center line
Techniques-Driving at Night Techniques-Driving in Bad Weather More difficult with: glaucoma, More difficult with: glaucoma, cataracts, photosensivity, poor cataracts, poor contrast sensitivity contrast sensitivity Techniques Techniques Keep windshield clean Don’t look at headlights – look to Windshield wipers fully functioning side of road Slow speed Drive new routes first in daylight Leave greater following distance Use yellow lenses to cut glare
24 Techniques-Lane Techniques-Vision/Vestibular Position Difficulty Dysfunction Common after Concussion Teach client to use center (yellow line) as guide Dizziness with head turns Uncomfortable with motion in the Right side of road expands and periphery contracts May feel movement that is not Use a magnet to line up with center there line Difficulty judging space May need vision therapy Convergence and Accomodation Visual midline off deficits
Techniques-Vision/Vestibular Vision Resources Dysfunction Strategies NORA – www.nora.cc Move eyes first, then head to scan Neuro-optometric Rehab Move more slowly Association – locate a neuro- Expanded rearview mirrors, spot optometrist mirrors Bernell – www.bernell.com Vision therapy Source for vision testing and Very effective for convergence training products Slower roads, familiar routes at first
Questions References
Alberti CF, Peli E, Bowers AR. Driving with hemianopia: II. Detection of stationary and approaching pedestrians in a simulator. Invest Ophthalmol Vis Sci. 2013;55:369-374 Bowers AR, Ananyev E, Mandel AJ, Goldstein RB, Peli E. Driving with hemianopia: IV. Head Scanning and Detection at Intersections in a simulator. Invest Ophthalmol Vis Sci. 2014;55:1540-1548 Bowers AR, Mandel AJ, Goldstein RB, Peli E. Driving with hemianopia: III. Detection performance in a simulator. Invest Ophthalmol Vis Sci. 2009;50:5137-5147 Bowers AR, Mandel AJ, Goldstein RB, Peli E. Driving with hemianopia: I. Detection performance in a simulator. Invest Ophthalmol Vis Sci. 2009;50:5137-5147 Bowers AR, Tant M, Peli E. A pilot evaluation of on-road detection performance by drivers with hemianopia using oblique peripheral prisms. Stroke Res Treat. 2012; 2012:176806 de Haan GA, Melis-Dankers BJM, Brouwer WH, Bredwoud RA, Tucha O, Heutink, J. Car driving performance in hemianopia: in On-Road Driving Study. Assoc. for Research in Vision and Ophth. 2014:14-14042
25 References References
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