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 180 o Horiz x 90 o Vert FOV Surface: rotate and translate

Time (s) Anterior-Posterior Head Sway (cm)

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)

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)

Position (deg) Time (sec) T H E T G Position (deg)

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