vision and driving-2.27.175c2cabd466efc6790a0a-6728e7c952118b70f16620a9fc754159.r37.… ·...

Vision&Driving‐Elizabeth Green/ADED 3/9/2017

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Vision and DrivingElizabeth Green, OTR/L, CDRS, CAE

Pacific Northwest Driver & Traffic Safety Conference

March 5, 2017Portland OR

Objectives

• The attendee will understand basic visual function and anatomy

• The attendee will learn common visual perceptual functions and how they apply to the task of driving.

• The attendee will gain a better understanding of common visual impairments on the driver’s ability to manage traffic and avoid hazards.

What you need for today’s session

• Grab a partner• 2 pens or pencils or dum-dums (ha!)• 2 pieces of blank paper


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Visual FieldThe visual field is the portion of the viewing area that can be visualized without turning the head, irrespective of acuity.

Normal Visual Field

180 degrees

Visual Fields

References: http://www.utoronto.ca/neuronotes/NeuroExam/cranial_2b.htm

Understanding Low vision,

Randall T. Jose


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Anatomy of the EyeSCLERA –the “white” of the eye

CORNEA–the clear covering over the iris

IRIS–the colored muscular “aperture” surrounding the pupil

Anatomy of the EyeLENS–changes shape to focus light on retina

RETINA–the nerve layer in the back of the eye that senses light and creates neural impulses that travel through the optic nerve to the brain

Anatomy of the EyeMACULA–the portion of the retina that processes sharp, clear, central vision.

FOVEA–the pit or depression within the macula that provides greatest visual acuity

OPTIC NERVE–Carries signals from the retina to the brain


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Cranial Nerves• II – Optic Nerve

• transmits visual information from retina to the brain

• III – Oculomotor Nerve• Controls eye movements

• IV – Trochlear Nerve• Controls eye movements

• VI – Abducens Nerve• Controls eye movements

Extraocular Muscles

Oculomotor skills

Scanning is the ability to search the environment in a coordinated manner to find specific things.

Localization is the ability to find a moving object---and follow it.

Tracking is the ability to follow a line-- of print, a curb, or the dividing line on a roadway

Oculomotor skills

• Smooth pursuits - the ability of the eyes to smoothly follow a moving object.

• Saccades – the purpose of saccades is to move the eyes as quickly as possible, so that the point of interest will be centered on the fovea .

• Eye Alignment - Normal alignment of both eyes allows the brain to fuse the picture from each eye into a single 3-dimensional image.


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Eye Movement Disorders

•Strabismus•Amblyopia•Nystagmus

Binocular Vision Disorders

• Diplopia• Strabismus• Impaired

Stereopsis

Visual Acuity• *NORMAL : 20/20 to 20/50.

• *LOW VISION: worse than 20/70 and with reduced visual fields

• LEGALLY BLINDNESS: 20/200

• PROFOUND BLINDNESS: 20/400 to 20/1000

• NEAR TOTAL BLINDNESS: worse than 20/1000

What are the visual requirements in your state?http://lpp.seniordrivers.org/


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Acuity Loss-refractive errors• Myopia-nearsightedness

• Hyperopia-farsightedness

• Astigmatism-irregular curvature of the cornea or lens

• Presbyopia-decline of lens flexibility (age related)

Visual Field Disorders

• Homonymous Hemianopsia

• Scotoma

• Peripheral Field Loss

• Ptosis

Visual field defects associated with hemianopia. From Polaski and Tatro, 1996.

Deficits in Contrast Sensitivity


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Driver with visual impairmentClinical Vision Assessment

Visual Screening

• Acuity• Contrast Sensitivity• Night Vision, Glare Vision

and Recovery from Glare• Oculomotor Control

• Depth Perception• Color Perception• Visual Field Testing• Visual Scanning• Visual Perceptual Skills

Stereoscopic Vision Testing

• These are self-contained devices, similar to devices used by state DMV for the vision test.

• Enclosed, lighted box with slides to test acuity, color, fusion, phorias, depth perception, contrast, and glare.

• Commercially available testing equipment:

• Stereo Optical Company, Inc.• Keystone View


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Acuity Contrast SensitivityOptec Vision Tester with F.A.C.T slides

• Functional Acuity Contrast Test

FusionLeft Both

Right

Lateral Phoria Test


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Vertical Phoria TestCOLOR PERCEPTION

Depth Perception

• This tests for binocularity or the eyes ability to work together.

• If a client reports having monocular vision, you will not need to test depth perception.

Night Vision, Glare Vision, Glare Recovery

AAA Night Vision Tester APP: Night Glare, by McAtayl LLC


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Oculomotor Skills

• Smooth Pursuits• Saccadic Eye Movements• Shifting Fixation from Near to Far Points

Vision Field Testing

• Confrontation Testing• Goldmann field exam • Automated Perimetery – Computerized Visual

Field Testers• Humphrey Visual Field Analyzer

Visual Scanning

Dynavision 2000

Trail-Making Test, Part B• Tests working memory,

visual processing, visual-spatial skills, divided attention and psychomotor coordination

• Patient connects in alternating order numbers and letters

• Test is scored by time (sec) to complete


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Clock Drawing Test

•INSTRUCTIONS:

• DRAW THE FACE OF A CLOCK• ADD ALL NUMBERS FROM 1-12• DRAW THE HANDS TO SHOW 11:10

Clock Drawing Test• CDT can assess:

• memory• visual perception & visual

spatial skills• selective attention• executive skills

• Draw clock face, numbers, and set time

• Scoring based on 8 components of Freund Scoring Criteria

Picture courtesy of Barbara Freund, PhD Eastern Virginia Medical School

Useful Field of ViewAnother tool which has shown some

correlation to increased crash risk is the Useful Field of View (UFOV), a 15-30 minute computerized test. This test assesses central vision and processing

speed, selective attention, and divided attention.

Functional Vision TestingObserve the client doing functional tasks without revealing that you are evaluating their performance

• Observe how he /she:• fills out forms• Reads • negotiates the environment

• Inside• outside

• finds items in purse or wallet

• Can the client identify objects of different sizes at various distances?

• How does lighting affect performance?

• Difficulty adjusting to indoor and outdoor lighting

• Rain, snow, or clouds, versus a bright and sunny day?


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Ask Vision Related Questions

• Do they have trouble locating things: keys and other small objects, curbs, uneven pavements, clothing, etc.

• What can they read? Medicine labels, newsprint, the medium headlines, or just the big headlines, labels, instructions, bills, cards and letters.

• General observations may give clues: mismatched clothes, misaligned buttons, stains on clothing, and how they interact with the environment, including the therapist.

• Talk to family and friends about how they do completing daily routines.

Visual Deficits and the Driving Evaluation

The following slides are problems that are noted during the driving evaluation and are most

probably related to visual deficits:.

Use of an Eye Check Mirror

• Note the clients ability to use and the frequency of use of:

• the rear view mirror• the side view mirrors• head checks

• Note if the client:• Stares at road scene• Moves eyes randomly and is distracted

by any movement

Visual Deficits and the Driving Evaluation Misjudging Distance or Speed

• Client lacks an understanding of time and or space requirements for an unprotected right or left turn.


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Visual Deficits and the Driving Evaluation Failure to Note Road Conditions and Details

Client fails to note:• Signs

• Pot holes and other debris

• Pedestrians

• Animals

• Items to the sides of the road or in other lanes of the roadway

Visual Deficits and the Driving Evaluation Deficits in Glare Recovery or Contrast Sensitivity

• In varying light or weather conditions the client has difficulty with:

• Seeing lane markings• Traveling in areas from shade to bright sun or vice

versa• Recovering vision when traveling under bridges

(such as underpasses on the highways)

Visual Deficits and the Driving Evaluation Difficulty Maintaining Lane Position

• Client fails to maintain a central lane position.

• Client crosses or drives on the left or right lane markings

• Client hits, swipes or is too near curbs or road dividers.

Visual Deficits and the Driving Evaluation Recognizing and AnticipatingThe ability to recognize and anticipate are related to many visual skills. More specifically it is often related to looking forward. Lead zone, forward scan, looking to the horizon etc. may be problematic due to driving habits or visual deficits.


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Visual Deficits and the Driving Evaluation Difficulty in Shifting the Eyes and Gaze

• Examples include:• from the road to the dash, from the dash to the road,

from the road to the mirrors• Observe how the client completes checks such as:

• Locating instruments-signal gear • Looking from the front of the vehicle to focus on

the dash indicators• Reading the odometer and speedometer• Reading the gear selection

Other Driving Skills That Require Adequate Visual Acuity:• Recognizing traffic light color• ID arrow signals• ID street signs• ID highway informational

signs• ID regulatory signs.

• ID changes in roadway (bends/curves)

• Recognizes and avoids road dividers islands or curbs

• When navigating, notices other roads when trying to search for the intended street.

On the Road-Behind the Wheel

• When errors are observed, the evaluator needs to determine:

• Is there a pattern?• Does the error occur consistently?• Does the error occur during specific lighting conditions?• Do the problems relate to deficits noted on the clinical

assessment?


• Were there instances where the skill was adequate-what were the conditions?

• Was physical driver intervention required by the evaluator/instructor?

• Was verbal cueing required by the evaluator/instructor?


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• Did the driver note the problem and attempt to self correct?

• Did the driver make any accommodation or statement about how they “usually” handle that problem?

• Can they process the information they see quickly enough to make appropriate responses?

Consider this:

A client stops past the stop line (or stop sign) is this due to: A. a driving habit, B. poor observation skills, C. decreased depth perception, D. decreased attention or E. limited strength to push the brake pedal?

Consider this:The client had an episode of loss of lane position lasting for more than 5 seconds. The driver crossed the left lane markings. It occurred on a rural road when traveling from bright sun into a darkly shaded area. The client stated “that wouldn't happen if I had on my good sunglasses”.

What are some considerations for this driver?

Eye Diseases and Disorders Affecting Vision


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Brain Injury and Stroke

The cause of the stroke and area of the brain affected will determine the type of vision impairment.

Stroke or Brain Injury can cause:• Blurred vision • Sensitivity to light, glare sensitivity • Reading difficulties; words appear to move • Comprehension difficulty • Attention and concentration difficulty • Memory difficulty

Brain Injury and Stroke

• Double vision • Aching eyes or headaches with visual tasks • Inability to maintain visual contact • Difficulties with:

1. Ocular pursuits (eye tracking ability) 2. Saccades ( difficulties with shifting gaze quickly from

one point to the other), 3. Accommodative inability ( focusing). 4. Binocular vision (eye alignment)

Visual Spatial Disorder & Visual Neglect

• When certain portions of the brain are damaged, the patient may fail to appreciate space to one side, which is usually to the left.

• Unlike visual field loss, this problem is not a physical loss of sensation, but rather a loss of attention to the area.

• Both neglect and field loss may occur together.

Various Conditions and Vision

Intellectual Disability (aka MR): refractive error, strabismus

Cerebral Palsy: refractive error, strabismus, amblyopia

Down’s Syndrome: refractive error, strabismus, cataracts, blepharitis

Deafness: refractive error, strabismus

Myelomeningocele (type of Spina Bifida): strabismus


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Low Birth Weight: Retinopathy of prematurity, myopia, strabismus

Albinism: Depressed central visual acuity, or low vision, vision is stable and does not deteriorate over time, normal color perception and near normal peripheral visual fields

Congenital Nystagumus: All nystagmus degrades visual acuity by reducing the stability of fixation


Stargardts Disease: form of macular dystrophy, small areas of vision loss or blindspots, difficulty adapting to the dark after sunlight exposure

Fetal Alcohol Syndrome: steep corneal curvature, astigmatism, telecanthus, ptosis

Multiple Sclerosis: optic neuritis, blurring of vision, double vision, delayed blink reflex, nystagmus, decreased acuity and blindness

Other WEB SitesAAAwww.aaa.com

AARPwww.aarp.org

ADED: Assn. Driver Rehabwww.aded.net

Insurance Institute for Highway Safetywww.highwaysafety.org

National Highway Traffic Safety Administrationwww.nhtsa.dot.gov

The USAA Educational Foundationwww.usaaedfoundation.org

US Administration on Agingwww.aoa.gov

Aim High

Keep Your Eyes Moving

Get the Big Picture


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