Vestibular Rehabilitation using a Wide FOV Virtual Environment
PJ Sparto, JM Furman, SL Whitney, LF Hodges, MS Redfern
Sponsors
Eye and Ear Foundation
NIH: P30DC005205, R21DC005372, K23DC005384, K25AG001049
Rationale for use of VR
Inner ear disorder will result in dysfunction of the vestibulo-ocular reflex (VOR), which allows us to maintain stationary gaze position during head turns
Recovery of abnormal VOR requires visual input and head movement
Viirre et al. (1996) and Kramer et al. (1998) proposed use of VR for vestibular rehab
Stimuli can be delivered in controlled manner
Rationale for use of VR
Greater incidence of anxiety and panic disorders in people with dizziness
Dizziness/anxiety often induced by complex visual environments– Grocery stores, shopping mall– Driving through tunnels– Head movements and optic flow
Habituation/exposure therapy is a common treatment strategy for these patients
Rationale for wide FOV
Wide FOV– Peripheral motion cues provide greater sense of
vection, which is important for postural control– Higher cost and greater space
HMD– Cost-effective– Eyestrain, headache, binocular vision changes– Maladaptive response because of extra inertia
Balance NAVE (BNAVE)
3 back-projected screens
1 front-projected floor
180o Horiz x 90o Vert FOV
Surface: rotate and translate
0 10 20 30 40 50 60 70 80 90-10
-8
-6
-4
-2
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2
4
6
8
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Time (s)
An
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(cm
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Clinical research flow chart
Development of environments
Determine if user interfaces are safe – wide FOV– HMD
What is efficacy of rehab?
Development of environments
Extract elements from real grocery store
Design geometric models
Model virtual grocery store
Virtual grocery store
Complexity of store can be easily changed– Size of product– Height of shelves– Width of aisle– Pattern on floor– Reflection of light on floor
Device safety
Can subjects perform coordinated head/eye movements without getting sick
9 healthy subjects performed 8 different coordinated head and eye movements on each visit
6 visits, consisting of a different background– 1: Solid background– 1: Geometrical elements (stripes), stationary– 4: Optic flow (moving stripes)
Show box target
Clinical research flow chart
Device safety
Subject Tolerance Subjective Units of Discomfort (SUDS)
0 to 10
– Simulator Sickness Questionnaire (SSQ, Kennedy et al.)
16 items rated 0 to 3 (none, slight, moderate, severe) Disorientation (blurred vision, dizziness, vertigo) Nausea (e.g. sweating, nausea, concentration) Oculomotor stress (e.g. fatigue, headache, eyestrain)
SUDS
R=23%
R=31%
R=44%
R>41%
Other24%
R<110%
R=15%
R=076%
SSQ:Eyestrain
R=30%
Other21%
R=118%
R=23%
R=079%
SSQ:# SSQ Symptoms
R=35%
R=41%
R>44%
Other31%
R=113%
R=27%
R=070%
SSQ:# Oculomotor Stress Symptoms
R=35%
R=43%
R>42%
Other29%
R=113%
R=26%
R=071%
SSQ:# Disorientation Symptoms
R=31%
R=40%
R>40%
Other5%
R=13%
R=21%
R=095%
Gaze coordination
Motion Analysis
– Postural Sway– Head and eye movements (gaze)– Timing and accuracy of movements
Head movements
6 DF Electromagnetic sensor
Eye movements
Horizontal and vertical
Video-oculography (VOG)
0 10 20 30 40 50 60 70 80 90 100-60
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60P
ositi
on (
deg)
0 10 20 30 40 50 60 70 80 90 100
Time (sec)
-60
-40
-20
0
20
40
60
THE
TG
Pos
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(de
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3 subjects with dizziness have begun trials to determine safety
Run experiment in virtual grocery
Next steps
Show store target
Clinical research flow chart
Run experiment using HMD
Add treadmill
Clinical trials - efficacy
Next steps
University of Pittsburgh
Depts of Physical Therapy, Otolaryngology, BioEngineering
UNC-Charlotte
Dept of Computer Science
Invaluable contributors
Jeffrey Jacobson, Leigh Mahoney, Sabarish Babu, Chad Wingrave,
many others
www.mvrc.pitt.edu