1. Simulator based assessment of drivers with visual field defects Björn Peters, VTI

2. Sweden – some basic facts EU member state EU driving license directive – specification of minimum medical requirements 9.6 million inhabitants 6.1 million driving license group 1 1.6 million license holders +65 y 40 000 revoked licenses (all reasons) (2013) 4 500 revoked licenses for medical reasons annually (2013) ?? due to visual problem 100 applications for exemptions annually

3. Swedish requirements for peripheral visual field Group I 2015-10-013 Binocular Esterman screening test

4. Swedish requirements for central visual field Group I 2015-10-014 Within 10° from fixation: Threshold in each corresponding test point should be 20 dB or more Within 20° from fixation: Threshold in each corresponding test point should be 10 dB or more (one missing point is accepted) ≥10 dB ≥20 dB Static threshold perimetry (Humphrey 24-2 or equivalent)

5. The process in Sweden Mandatory for all physicians to report if medical requirement not fulfil or agree with the patient to refrain from driving (written consent) Swedish Transport Agency (STA) decides if requirements fulfilled –> OK, If not -> revoked license Agree -> apply for exemption or Disagree -> appeal in court 3 levels Apply for exemption -> added evidence of fitness to drive required e.g. Simulator Based Assessment in Norway - SINTEF On-road assessment not sufficient Demand for a new Simulator Based Assessment Method  License with exemption – conditions can apply e.g. geographical restrictions (2012 – 103, 2013 – 110)

6. Simulator test at SINTEF – reaction time Reaction times were recorded from 20 stimuli over a 15 minutes drive. Press buttons to respond Results compared to normative data 6 positions – rural road 1 11 positions – city road 1 Stimuli size: 1. child head at 30 m, 2. adult body at 30 m, Stimuli: duration 4 seconds

7. Developing a new assessment method at VTI Aim: determine if a driver with a visual field loss can compensate and drive equally well as a driver without field loss Approach: develop a relevant and realistic diving task with more or less critical situations and build a matched reference database (100+) Simulator: high end simulator, dynamic, good visual system Consider: simulator sickness and test conditions Output: certificate stating driving performance/ability compared to normative data Assessment Validity: continuous follow-up and improvements

8. StrengthsWeaknesses Simulator based assessment - pros and cons StrengthsWeaknesses  High level of control  Good internal validity  Same conditions for all  Critical situations with no risk  Realistic compared to clinical testing  Reliable S-R testing  Eye tracking feasible StrengthsWeaknesses  High level of control  Good internal validity  Same conditions for all  Critical situations with no risk  Realistic compared to clinical testing  Reliable S-R testing  Eye tracking feasible  Simulator driving - 3D in a 2D world  Speed perception not ideal – offset  Situations simplified compared to real life  External validity partly good – follow up needed  Simulator sickness

9. VTI Driving Simulator IV - Volvo XC 60 cabin Force Feedback Steering Wheel Virtual Cockpit Display Shaker Sound System Rear- and Side- Mirror Displays 5 Gaze Tracking Cameras 4 Video Cameras Rexroth hexapod X-Y Sled 2,3 * 2,5 m

10. Sim IV visual projection system 9x Epson EB-410W projectors Mersive SOL software  Auto calibration  Edge blending  Color correction >180 degree field-of-view Tillfälle att prova under dagen

11. Driving task and assesment criteria Approx. 50 km driving (rural, motorway, city) Critical situations (pedestrians, vehicles, bicycles, road works, traffic light etc.) Assessment measures: speed, time, lateral position, (collisions/incidents) Also: Time based safety margins (combination of TTC and THW ) Reaction time to artificial stimuli (SINTEF like) Tentative assessment criteria exclude 2,5% of “low performers” (previously used at SINTEF) - several measures Tool for development, runs on a PC

12. SINTEF test - proposal Motive: compare data with SINTEF and other studies Stimuli as SINTEF – traffic signs in 6 different positions (false and true (STOP sign)) Simultaneous stimuli – right/left – controlling for over compensation Two buttons on the steering wheel One true stimuli (also combination with false) – press one button Two true stimuli – press two buttons One single or two false stimuli – press no buttons Separate part of the driving task Clear written and oral instructions Training before

13. Defining assessment criteria – a difficult task  Considering own and other road users’ safety  Not restrict if driving ability deemed sufficient  No solid scientific evidence for how much we need to see in order to drive safely  Other examples  Alcohol (BAC - 0,2‰) fixed – should it be differentiated?  Deafness OK to drive – why?  Epilepsy – OK with medication and no seizure for 3 months  Dementia – when is the right time to stop?  Mobility impairments – what is sufficient adaptation?  Whatever we do we need to follow-up!

14. Visual and cognitive tests Useful field of view (UFOV)Dynamic Trail Making Test Visual acuity Visual field of view test - Humphrey Useful Field of View (UFOV) Trail Making Test (TMT A&B) Dynamic TMT (New) Perceptual speed (Operative) Attentional demanding (Operative/Tactical) Working memory (Tactical/strategic) Meta memory (Strategic)

15. Persons with visual field defects interested to participate Until 15 April 222 interested 189 replied a short survey Data for recruiting 100 reference drivers Most have sent their visual field data Select a small, relevant group of drivers to participate in the project Delivery date mid - 2014

16. Age, gender, experience for selection of reference drivers Age MaleFemaleTotal 18-24415 25-34112 35-4412921 45-5422527 55-6436844 65-7463265 75-250 Total 16326189 Age Num Median distance km/week 18-24540,0 25-342202,5 35-4421250,0 45-5427300,0 55-6444200,0 65-7465200,0 75-25150,0 Totalt189200,0 Most male, < 70% 55 + Min 10000 km/y Max 25000 km/y

17. Diagnoses Diagnosis, freeNum% % of those with a diagnosis Cumulative % of those with a diagnosis Stroke6936,538,8 Glaucoma6031,733,772,5 Diabetes2111,111,884,3 Eye injury179,09,693,8 Brain tumor73,73,997,8 Other42,12,2100,0 Total17894,2100,0 Missing115,8 Totalt189100,0 Select based on diagnosis and visual field defect

18. Difficult driving situations

19. Questions, comments?