UZ Antwerp Effect of compensatory viewing strategies on practical fitness to drive in subjects with...

UZ AntwerpUZ AntwerpUZ AntwerpUZ Antwerp

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


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?


SubjectsSubjectscentral VFD

(n=24)

peripheral

VFD (n=36)

central and

peripheral (n=7)

mild VFD

(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


On-road driving testOn-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



central VFD mild 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%)

UZ AntwerpUZ AntwerpUZ AntwerpUZ AntwerpPercentage of subjects passing TRIP items:

central VFD mild 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


Driving simulatorDriving simulator


Central VFD

(n=23)

Mild VFD

(n=23)

visual acuity (dec. not.) 0.24 (0.09) 0.83 (0.27)

horizontal field extent*( ) 142 (14) 142 (14)

* Goldmann I I I 4 isopter

Driving simulator: subjectsDriving simulator: subjects


Driving simulator: resultsDriving simulator: resultscentral VFD mild 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.


1.3

1.4

1.5

1.6

1.7

1.8

1.9

50 km/h 80 km/h left curve 80km/h

right curve 80km/h

path

late

ral p

osi

tio

n

central VFD

peripheral VFD

mild VFD


-0.2

-0.1

0

0.1

0.2

0.3

0.4

constant variable

driving speed of lead car

log

TH

Wm

in

central VFD

peripheral VFD

mild VFD


Compensatory behaviourCompensatory behaviour

viewing behaviour – pass/fail score

central VFD: no relationship

speed – pass/fail score:

central VFD: drive more slowly => pass


Conclusions before trainingConclusions 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

bioptics!

bioptics?


TrainingTraining

aim: teach compensatory viewing strategies

• laboratory training computer based tasks

• mobility training while walking or cycling

• motor traffic training while driving a car


AFOVAFOV

60 degrees

24

degre

es

-15

-10-5

05

1015

-30 -20 -10 0 10 20 30

0

1

2

3

4

threshold presentation time (s)

Dependent variables:

mean threshold presentation time

variation (PDM)


SubjectsSubjects

motor

laboratory mobility traffic

central VFD 5 5 7

peripheral VFD 6 8 7

centr+periph VFD 2 21

mild VFD 3 1 4


AFOVAFOV

0

0.1

0.2

0.3

0.4

pre1 pre2 post1 post2

assessment

log

th

resh

old

pre

sen

tati

on

tim

e

0

20

40

60

80

100

PD

M

thresh. present. timePDM


Driving simulatorDriving simulator

0

10

20

30

40

50

60

70

pre1 pre2 post1 post2session

nu

mb

er o

f h

ead

mo

vem

ents

0

5

10

15

20

25

30

dis

tan

ce t

o in

ters

ecti

on

(m

)

numberdti



0

0.5

1

1.5

2

2.5

pre1 pre2 post1 post2session

view

ing

beh

avio

ur

(0-3

)

laboratory

mobility

motor traffic



0

10

20

30

40

50

60

function mobility motor traffic

training

% p

ass

pre2post1post2


Positive training results:

• compensatory viewing behaviour (AFOV)

• viewing behaviour while driving

• practical fitness to drive (pass/fail score)

• best results: motor traffic training

Conclusions after trainingConclusions after training


Central VFDCentral 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)


ConclusionConclusion

• 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’.

UZ Antwerp Effect of compensatory viewing strategies on practical fitness to drive in subjects with...

Documents

Transcript of UZ Antwerp Effect of compensatory viewing strategies on practical fitness to drive in subjects with...