Evidence Based Visual Assessment for Driving

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Evidence Based Visual Assessment for Driving

• Kevin E. Houston, O.D., F.A.A.O.
• Indiana University School of Optometry
• Low Vision Rehabilitation Services

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Outline

• Literature Review
• Risk Factors
• Age
• Visual Acuity
• Visual Field
• Contrast Sensitivity
• Cognitive Deficits Trail-Making Test
• Indiana Vision Requirements, BMV
• Driver Rehabilitation

3
Literature Review

• SEE Study, VI in MVC
• Salisbury Eye Evaluation Study, Salisbury
  Maryland.
• September 1993-1995
• 1801 drivers with valid license, 65-84
• First study to look at multiple measures of
  visual function VA, CS,Glare, Stereo, HVF, UFOV
• Potential Problems
• Only 3.2 had Bino VA worse than 20/40
• State minimum VF 110

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Salisbury Maryland
5
Literature Review

• Visual Risk Factors for Crash Involvement in
  Cataract Study, Owsley et al.
• 274 Alabama drivers with cataract in 1 or both
  eyes
• 75 drivers had better eye BVA 20/35-20/50
• 46 driver had better eye BVA worse than 20/50
  (state minimum 20/60)
• 39 drivers had 46 at-fault accidents in a 5 year
  review
• 33 had 1, 5 had 2, 1 had 3
• Contrast sensitivity was related to crash
  involvement
• VA and glare was not related to crash involvement
• Potential Confounders
• VA is only a non-factor to 20/60 (state
  regulates)

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Literature Review

• Induced Blur Study (Lighthouse and Queensland
  Tech) Kent Higgins, Joanne Wood, and Alan Tait
  
• 24 young drivers with normal vision
• Blur induced of 20/40, 20/100, and 20/200
• Performance measures
• Total Driving Time
• Sign Recognition
• Hazard Avoidance (foam speed bumps)
• Gap Clearance
• Maneuvering
• Potential Confounders
• Did not look at risk of turning in front of
  traffic

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Gap Clearance Failure
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Maneuvering Failure
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Risk Factor 1 Age

• Drivers aged 75 and above have a 37 higher crash
  rate than all drivers (Cerelli, 1995).
• Fell (1976) 60 of crashes of older drivers due
  to cognitive mistakes compared to 50 of younger
  drivers crashes
• Indiana no longer requires renewal every 3yr at
  age 75

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Cognitive Malfunction
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Risk Factor 2 Visual Acuity

• People with 20/50 had no more accidents that
  those with 20/40. Motorists with the minimum VA
  requirement in Canada of 20/50 had similar
  accident rates to motorists with better than
  20/40 in a sample of 1400 people who had
  accidents. Gresset JA, Meyer FM. Risk of
  accidents among elderly car drivers with visual
  acuity equal to 6/12 or 6/15 and lack of
  binocular vision.Ophthalmic Physiol Opt. 1994
  Jan14(1)33-7.
• Induced blur in 24 participants worse than 20/40
  decreased driving performance Higgins KE, Wood
  J, Tait A. Vision and driving selective effect
  of optical blur on different driving tasks. Hum
  Factors. 1998 Jun40(2)224-32
• SEE study participants with VA worse than 20/40
  were twice as likely not to drive. State laws
  and self-regulation reduces the risk of crash
  involvement.
• Studies undertaken in some states have resulted
  in the acceptance of monocular visual acuity up
  to and including 20/70. American Academy of
  Ophthalmology. Policy statement vision
  requirements for driving. Approved by Board of
  Trustees, October 2001. Available at
  http//www.aao.org/education/statements/loader.cfm
  ?url/commonspot/security/getfile.cfmPageID1208

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Risk Factor 2 Visual Acuity
As VA or Visual Field decreases there is an
initial decrease in at- fault MVC??? The patient
is compensating by driving slower and in familiar
areas only. At a certain point, accident rates
start to go back up when the patient can no
longer compensate.
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Risk Factor Visual Field

• Johnson and Keltner, 10,000 Ca drivers records
• Accident/Conviction rates more than twice as high
  with binocular VF impairment
• Did not specify defect

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Risk Factor Visual Field

• SEE study Visual Field Predicts Crash Rates
• When gt 10 points missed in the inferior binocular
  field
• HVF FF-81, a 60 degree monocular test with target
  intensity of 24dB
• Number of points missed for each eye counted

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Risk Factor Visual Field

• SEE study cont.
• Visual fields for the 2 eyes combined for a
  binocular field, 96pts
• gt10/22 points missed in the binocular inferior
  field or gt20/96 points missed on the whole
  binocular field translated to increased risk

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Risk Factor Visual Field, Hemianopsia

• On the FF-81, hemianopic patients automatically
  miss 11/22 points in the binocular inferior field
  and 48/96 points on the whole binocular field
• Kasten et. al Only 57 of patients with VI from
  Hemianopsia were informed that their driving
  skills may be impaired
• 65 still held a driver's license and one-third
  were still driving
• BMV Form 50190 Request for Special/Courtesy
  Test Affidavit. http//www.in.gov/icpr/webfile/for
  msdiv/50190.pdf

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Risk Factor Reduced Contrast Sensitivity

• Cutoffs
• 2.0 is normal
• 1.5 is consistent with visual impairment
• 274 patients involved in a crash were 8 times
  more likely to have a Pelli Robson score of 1.25
  or less in the worse eye, and 6 times more likely
  to have 1.25 or less in both eyes. Owsley C,
  Stalvey BT, Wells J, Sloane ME, McGwin G Jr.
  Visual risk factors for crash involvement in
  older drivers with cataract. Arch Ophthalmol.
  2001 Jun119(6)881-7.
• SEE study Drivers able to compensate to 1.6,
  then crash rates start to increase.

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Risk Factor Reduced Contrast Sensitivity

• Associated With
• Poor Driving Performance Wood JM, Troutbeck R.
  Elderly drivers and simulated visual impairment.
  Optom Vis Sci. 1995 Feb72(2)115-24.
• Prior Crash Involvement Owsley C, Stalvey BT,
  Wells J, Sloane ME, McGwin G Jr. Visual risk
  factors for crash involvement in older drivers
  with cataract. Arch Ophthalmol. 2001
  Jun119(6)881-7.
• SEE study CS possibly weakly associated

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Trail-Making Test Part B

• Starting with 1, draw a line to A, then to 2,
  then to B, and so on
• Once time starts it doesnt stop
• Examiner corrects mistakes as they happen
• A time for completion of greater than 180 seconds
  signals a need for intervention

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Risk Factor Cognitive Deficits

• Trail-Making Test Part-B
• Classic test of visuo-motor and attentional
  skills
• Developed by U.S. Army Pyschologists in 1944
• Probes Motor Speed and Attention
• These skills are important for safe driving
  (Colsher and Wallace, 1993 Shinar, 1993).

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Trail Making Test Part B

• 1,700 drivers 65 and older
• TMT-B strongly associated with recent crash
  involvement
• 105 drivers 65-88yo
• On-road driving performance significantly
  correlated with TMT-B performance (correlation
  coefficient -0.42)
• 2,508 drivers aged 55 and older, Maryland Older
  Driver Study
• Significant correlation TMT-B performance and
  future at-fault crash (odds ratio 2.21)

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Evidence Based Evaluation

• Best Corrected Snellen Acuity OD, OS
• Mars-Perceptrix or Peli Robson Contrast
  Sensitivity OU
• Brightness Acuity Testing OD, OS
• Humphery Full-Field 81-pt OD, OS
• Combine as binocular field for risk assessment
• Trail-making test part-B

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Indiana Vision Requirements, BMV

• Restriction Codes for Vision
• A Glasses or contact lenses
• B Outside rearview mirrors
• C Daylight driving only
• Visual Field 55 or greater
• 20/40 or better ea. eye s/Rx, no glasses
  restriction
• 20/40 or better best eye, worse eye 20/50 or
  worse, AB restriction
• 20/50 better eye, worse eye 20/70 or worse, ABC
  restriction
• 20/70 BCVA better eye, other eye must also be
  20/70, ABC restriction
• Proof of normal visual field must be submitted

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Indiana Vision Requirements, BMV

• If your patient fails the vision screening at the
  BMV, a Certificate of Vision form is given to the
  patient to be completed by a Low Vision
  Specialist
• BMV sends a letter to your patient stating the
  restrictions, which must be brought to the BMV
  branch to get the license.
• If the vision falls outside the limits, the case
  is sent to the medical advisory board (IDLMAB)
• The board may place specific restrictions or deny
  a license

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Indiana Vision Requirements, BMV

• Waiver of vision requirement is available with
  medical board review
• 20/80 one eye or both eyes together are good
  candidates
• Proof of horizontal binocular field gt120 degrees
• Medical board will recommend on-the-road
  evaluation
• Examining doctor should fill out the Certificate
  of Vision form

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Example

• Patient has BCVA of 20/30 OD, NLP OS.
• Patient has BCVA of 20/50 OD, NLP OS.
• Patient has BCVA of 20/70 OD, 20/70-1 OS.
• Patient has visual field of 35 degrees and acuity
  of 20/20 OD, OS
• Patient has hemianopsia and acuity 20/50 OD,
  20/70 OS

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Case Study

• Your patient with a history of diabetic
  retinopathy has had 2 car accidents in the last
  year.
• She wants to know if her vision is to blame.
  What tests would you run to determine
• If she meets the state requirements for
  licensure?
• If her vision is good enough for safe driving?

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Case Example State Requirements

• Best Corrected Snellen Visual Acuity
• OD 20/30
• OS 20/30-2
• Visual Field, Full Field 81pt
• Missed 40 points
• Left Homonymous Hemianopsia
• Macular splitting

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Visual Field Interpretation

• Field is 60

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Case Study

• Visual Acuity MEETS state minimum requirements
  for day and night driving.
• Does visual field meet state minimum requirement
  of 55 ?
• Yes, this patient would be issued an unrestricted
  license
• Should ANY patients with hemianopsia drive?
• Intuitively we might say no
• It is very helpful to be able to cite evidence
  when talking to the patient
• Extra testing needed to further determine

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Driving with Hemianopsia

• In study of 30 patients with homonymous defects,
  Wood et. Al 2009 found some drivers with
  hemianopia or quadrantanopia are fit to drive
  compared with age-matched control drivers.
  (Joanne M. Wood, Gerald McGwin, Jr, Jennifer
  Elgin, Michael S. Vaphiades, Ronald A. Braswell,
  Dawn K. DeCarlo, Lanning B. Kline, G. Christine
  Meek, Karen Searcey, and Cynthia Owsley On-Road
  Driving Performance by Persons with Hemianopia
  and Quadrantanopia Invest. Ophthalmol. Vis. Sci.
  2009 50 577-585.)
• So we cant say patient isnt fit to drive JUST
  because of hemianopsia

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Case Study Evidence Based Assessment Continued

• Glare Acuity
• Turn lights on and shine penlight from the
  temporal side
• OD 20/60-1
• OS 20/70-2
• Interpretation?

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Glare Acuity Interpretation

• Greater than 2 lines difference is significant
• Change is approximately 2 lines
• Borderline

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Case Study Contrast Sensitivity

• Tested binocularly
• BCVA for reading distance
• Ceiling/miss 2 in a row
• Scored in Log Units
• This Patient CSF 1.4
• Interpretation?

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CSF Interpretation

• 2.0-1.6 is normal
• At scores lower than 1.6, crash rates start to
  increase (SEE study)
• Binocular scores of 1.25 or less are 6 times more
  likely to have a crash (Owsley et. Al)
• So this patient is at increased risk based on CSF
  of 1.4.

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Assessment Trailmaking

• Timed test
• Tested binocularly
• Patient told to connect 1 to A, A to 2, 2 to B
  and so on.
• Should not lift pencil from the page.
• Examiner should stop patient and have them
  correct mistakes as they go.
• This patient completed test in 150 seconds
• Interpretation?

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Trails Interpretation

• Times over 180 seconds translate to increased
  risk.
• Strongly correlated to future at-fault crashes in
  a study of 2,500 drivers (Maryland Older Driver
  Study).
• Patient borderline at 150 seconds

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Retinal Photos
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Case Study Summary

• Evidence Based Driving Assessment
• BCVA 20/30 OD, 20/30-2 OS
• Contrast Sensitivity 1.4
• FF-81 40 points missed
• macular splitting
• High Glare Sensitivity 20/60-1 OD, 20/70-2 OS
• TMT-B 150 seconds
• 4 risk factors and 1 borderline

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Assessment/Plan

• Does this patient meet the vision standards set
  by the Indiana BMV? -gt Yes
• Would you classify this patient as high,
  moderate, or low risk for future at-fault crash?
  -gt High Risk
• How would you proceed?

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Plan

• Discuss risk factors and research with patient.
• Recommend not driving
• Your vision is not good enough for safe driving
• My job is to do what is in your best interest
  and to protect other motorists

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Other Considerations

• CDRS (Certified Driving Rehab Specialist).
• Can Evaluate patient on-road
• Can modify vehicle with mirrors
• Can do training
• Low Vision aids
• Use of Expansion prisms such as EP and Gottlieb
  VFAS are not well studied for impact on driving
• Most states require written permission from MAB
  to use device.
• Bioptic Glasses

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Driving Rehab
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Other Considerations Bioptic Driving

• 20/200 Best Glasses and 20/40 through the Bioptic
• The maximum magnification is 4x
• The visual field requirement is 120 degrees
• No other physical impairments that interfere with
  driving
• Szlyk JP, Seiple W, Laderman DJ, Kelsch R,
  Stelmack J, McMahon T. Measuring the
  effectiveness of bioptic telescopes for persons
  with central vision loss. J Rehabil Res Dev. 2000
  Jan-Feb37(1)101-8.

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Bioptic Driving

• Must complete the training and pass the driving
  test
• Must continue to have vision checked annually and
  a report sent to the Bureau of Motor Vehicles
• The license must be renewed every four years.

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When it is Time to Stop Driving

• Amtrack [phone], or (800) USA-RAIL,
  www.amtrak.com Offers discounts
• Greyhound(800) 752-4841 Provide an assistant
  jpierso_at_greyhound.com
• IndyGo Open Door(317) 917-8747 info_at_indygo.net
  www.indygo.net
• Indianapolis Yellow Cab Discount tickets for
  patients over 60 or wheelchair
• Indianapolis Senior Center Transportation
  317-263-6279 www.seniortransportation.org

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Summary

• Predicting driving safety is related to cognitive
  skills, visual field, contrast sensitivity,
  glare, and visual acuity
• Visual acuity alone is a poor predictor of crash
  risk.
• In Indiana, ODs are not required to report
  unsafe drivers. However, protecting the
  patients health is traditionally considered the
  physicians primary responsibility and may create
  vulnerability in a legal case.

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Future Research Needed

• Prospective study on central scotoma and risk for
  at-fault crash involvement
• Simulation studies on visual acuity
• Prospective study on Hemianopsia and risk for
  at-fault crash involvement
• Prospective study on bioptic drivers and risk for
  at-fault crash involvement

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Drive Safely!
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References and Resources

• AMAs Physician's Guide to Assessing and
  Counseling Older Drivers www.ama-assn.org/ama/pub
  /category/10791.html
• Staplin, L., Ball, K., Park, D., Decina, L.,
  Lococo, K., Gish, K., and Kotwal, B. (1997).
  Synthesis of Human Factors Research on Older
  Drivers and Highway Safety, Volume I Older
  Driver Research Synthesis. USDOT/FHWA Publication
  No. FHWA-RD-97-094. Washington, DC.
• Indiana Form 22106, Certificate of Vision
  http//www.in.gov/icpr/webfile/formsdiv/22106.pdf
  
• 140 IAC 4-3-1 Vision test chart (state form
  27738) Authority IC 9-14-2-2 IC 9-27-4
  Affected IC 9-24 IC 9-27-4
• Sec. 1. The bureau of motor vehicles shall use
  the Indiana drivers vision test chart (state
  form 27738), which form is incorporated by
  reference, to determine the vision capabilities
  of an individual being tested and the guidelines
  to be followed for issuing vision license
  restrictions. The incorporation does not include
  any later amendments or editions. A person may
  obtain a copy of the incorporated vision chart by
  contacting Bureau of Motor Vehicles, Driver
  Examiner Division, Indiana Government
  Center-North 100 North Senate Avenue, Room 403
  Indianapolis, Indiana 46204 (Bureau of Motor
  Vehicles 140 IAC 4-3-1 filed Nov 9, 1983, 342
  p.m. 7 IR 35 errata, 7 IR 2546)