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Effect of compensatory viewing strategies on practical fitness to drive

Effect of compensatory viewing strategies on practical fitness to drive in subjects with visual field defects caused by ocular pathology. Tanja Coeckelbergh W.H. Brouwer, F.W. Cornelissen, A.C. Kooijman University of Groningen, The Netherlands current address:

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Effect of compensatory viewing strategies on practical fitness to drive

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  1. Effect of compensatory viewing strategies on practical fitness to drive in subjects with visual field defects caused by ocular pathology. Tanja Coeckelbergh W.H. Brouwer, F.W. Cornelissen, A.C. Kooijman University of Groningen, The Netherlands current address: University Hospital Antwerp, Belgium

  2. Bioptic telescopes are intended for • detailed vision (street names, signs, etc.) • not for regular driving •  are subjects with decreased visual acuity able to drive safely?

  3. Subjects central VFD peripheral central and mild VFD (n=24) VFD (n=36) peripheral (n=7) (n=33) vision parameters visual acuity (logMAR) 0.64 (0.03) 0.14 (0.02) 0.72 (0.08) 0.11 (0.02) horizontal field *(°) 142 (13) 84 (35) 91 (35) 141 (13) sample characteristics male : female 16:8 29:7 4:3 14:19 age 65 (13) 60 (12) 63 (15) 67 (9) driving license (# years) 38 (11) 37 (10) 39 (17) 38 (8) * Goldmann III4 isopter

  4. On-road driving test • own car • own neighbourhood • official driving examiner (CBR) • 1 hour • score: viewing behaviour, lateral position, anticipation, changing lanes, turning left, … • pass/fail score www.cbr.nl

  5. On-road driving test central VFDmild VFD passed: 6 (25%) 21 (64%) unfit to drive: 5 (21%) 0 (0%) not yet fit to drive: 13 (54%) 12 (36%) fit to drive, limited: 6 (25%) 9 (27%) fit to drive: 0 (0%) 12 (36%)

  6. Percentage of subjects passing TRIP items: central VFDmild VFD lateral position 66.7 84.8 lane choice 70.8 66.7 car following 95.8 97.0 speed 66.7 69.4 viewing behaviour 33.3 39.4 detection of traffic signs 58.3** 93.9 overtaking 45.8 72.7 mechanical operations 75.0 84.8 anticipatory behaviour 37.5 63.6 communication 45.8 78.8 turning left 37.5 51.5 merging into another lane 37.5 57.6

  7. Driving simulator

  8. Driving simulator: subjects

  9. Driving simulator: results central VFDmild VFD speed (km/h) 67(9)** 74(9) lateral position SD (m) n.s. thw-average n.s. thw-minimum n.s. ttc-minimum (log) 0.61 (.16)** 0.70 (.15) breaking dti n.s. release accelerator dti n.s. accident (% drivers) n.s.

  10. 1.9 1.8 1.7 lateral position 1.6 1.5 central VFD peripheral VFD 1.4 mild VFD 1.3 50 km/h 80 km/h left curve 80 right curve 80 km/h km/h path

  11. 0.4 0.3 0.2 0.1 log THWmin 0 central VFD -0.1 peripheral VFD mild VFD -0.2 constant variable driving speed of lead car

  12. Compensatory behaviour viewing behaviour – pass/fail score central VFD: no relationship speed – pass/fail score: central VFD: drive more slowly => pass

  13. bioptics! bioptics? Conclusions before training On-road driving test: detection of traffic signs was (too) late Driving simulator: decreased driving speed (compensation) shorter following distance lateral position independent of road curvature

  14. Training • aim: teach compensatory viewing strategies • laboratory training computer based tasks • mobility training while walking or cycling • motor traffic training while driving a car

  15. threshold presentation time (s) 15 10 24 degrees 4 5 3 0 2 -5 1 -10 0 60 degrees -15 -30 -20 -10 0 10 20 30 AFOV Dependent variables: mean threshold presentation time variation (PDM)

  16. Subjects motor laboratory mobility traffic central VFD 5 5 7 peripheral VFD 6 8 7 centr+periph VFD 2 2 1 mild VFD 3 1 4

  17. AFOV 100 thresh. present. time 0.4 PDM 80 0.3 60 PDM log threshold 0.2 presentation time 40 0.1 20 0 0 pre1 pre2 post1 post2 assessment

  18. Driving simulator 70 30 60 25 50 20 40 15 number of head movements distance to intersection (m) 30 10 20 number 5 10 dti 0 0 pre1 pre2 post1 post2 session

  19. On-road driving test 2.5 2 1.5 viewing behaviour (0-3) 1 laboratory mobility 0.5 motor traffic 0 pre1 pre2 post1 post2 session

  20. On-road driving test 60 pre2 50 post1 post2 40 % pass 30 20 10 0 function mobility motor traffic training

  21. Conclusions after training • Positive training results: • compensatory viewing behaviour (AFOV) • viewing behaviour while driving • practical fitness to drive (pass/fail score) • best results: motor traffic training

  22. Central VFD before training: 6/24 passed on-road driving test training: 17/24 (14 failed, 3 passed) after training: 8/17 passed on-road driving test (5 had failed before training)

  23. Conclusion • Are subjects with decreased visual acuity due to a central visual field defect able to drive safely? • Yes, 11/24 (46%) passed on-road driving test. • Might bioptic telescopes be helpful to these subjects? • Yes, to improve ‘detection of traffic signs’ and ‘following distance’.

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