"Impaired vision does not exclude practical fitness to drive" Aart C. Kooijman, Wiebo W. Brouwer, Ruud A. Bredewoud, Tanja R.M. Coeckelbergh, Frans W. Cornelissen, Mark L.M. Tant Groningen, The Netherlands University of Groningen Visio CBR

Study on Practical Fitness to Drive of Subjects with Central or Peripheral Visual Field Defects.

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Inclusion Criteria and Tests inclusion: 0.1 < VA < 0.5 and / or horizontal VF < driving experience > km no cognitive impairment (MMSE, Bell’s Test) ophthalmic screening visual function: refraction, VA, VF, CS, DA, stereopsis visual attention: UFOV-like, AFOV, fixation and saccades practical fitness to drive assessment on the road driving test in a driving simulator practical fitness to drive assessment on the road

Assessment of practical fitness to drive intermediate level between medical fitness to drive and driving skill

On-road driving test for assessment of practical fitness to drive Evaluation by an expert in assessing on-road driving in handicapped persons –using candidate’s own car, if possible –in the regional area of the candidate –comprises city, rural, and highway driving

On-road driving test for assessment of practical fitness to drive It is evaluated whether someone can drive fluently and safely given his/her impairments and including use of compensations and adaptations

Assessing practical fitness to drive Test Ride to Investigate Practical Fitness to Drive (TRIP) comprises tactical and operational aspects: lateral position control following distance speed control visual scanning and viewing behaviour perception of traffic signals passing and overtaking use of car controls anticipation and traffic insight interaction with other traffic participants

Assessing practical fitness to drive Test Ride to Investigate Practical Fitness to Drive (TRIP) comprises tactical and operational aspects: Mostly 4-point-rating scales on each item Most aspects broken down to specific situations

Scores derived from TRIP Operational score (mechanical handling and dealing with external stimuli) Tactical score (choice of manoeuvres, safety margins, anticipation) Visual score: operational and tactical items with a visual (scanning) component Total score: average of all TRIP items Global score: final expert judgement: fit or unfit

100 Subjects CentralPeripheralCentral and Peripheral Mild visual acuity (logMAR) horizontal field diameter* (deg) male : female age # year (SD) driving license # year (SD) (n=24) 0.23 (0.64) :8 65 (13) 38 (11) (n=36) 0.74 (0.14) 84 29:7 60 (12) 37 (10) (n=7) 0.19 (0.72) 91 4:3 63 (15) 39 (17) (n=33) 0.77 (0.11) :19 67 (9) 38 (8) * Goldmann III4 isopter Visual Field Defect

Visual Field Diameter (ODS) Goldmann III Visual Acuity (ODS) Passed Failed Central + Peripheral Mild 62% passed Central 25% passed Peripheral 42% passed

Percentage passing the Practical Fitness to Drive Test vs Visual Acuity Percentage passed ,511,52 Decimal Visual Acuity Of our population 25% of the subjects with VA < 0.5 is “Fit to Drive” 100 subjects

Percentage passing the Practical Fitness to Drive Test vs Visual Field Diameter Visual Field Diameter (degree) Percentage passed 100 subjects In our population visual field diameter shows a weak relation with “Fitness to Drive”

Predictive power (regression analysis) pass/fail Practical Fitness to Drive test predictor model 1 visual acuity (logMAR) visual field (VFS) explained variance R

predictor model 1 visual acuity (logMAR) visual field (VFS) AFOV, threshold presentation time model 2 visual attention (UFOV-like) contrast sensitivity (log CS) age Predictive power (regression analysis) pass/fail Practical Fitness to Drive test explained variance R 2

Predictive power (regression analysis) pass/fail Practical Fitness to Drive test Contribution of driving simulator performance

180 degree horizontal field ‘3 km in town centre’ ‘15 km on a 2-lane road’ ‘20 km on a highway’ 14 intersections

Visual Field Diameter (ODS) Goldmann III Visual Acuity (ODS) Central + Peripheral Mild 62% passed Central 25% passed Peripheral 42% passed peripheral visual field defect accidents: 23% Results in the driving simulator mild visual field defect accidents: 9% central visual field defect accidents: 35%

predictor model 1 visual acuity (logMAR) visual field (VFS) AFOV, threshold presentation time Predictive power (regression analysis) pass/fail Practical Fitness to Drive test explained variance R 2.38 model 2 visual attention (UFOV-like) contrast sensitivity (log CS) age plus driving simulator variables.47.45

Conclusions a considerable percentage of the subjects demonstrated to drive safely selection based on vision, attention and driving simulator data exclude many people who are fit to drive selection based on the performance on the task itself (driving) seems to be more fair

General Conclusion: Compensatory Driving Behaviour has to be assessed in an Practical Fitness to Drive test study 1: study 2: