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

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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)

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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