Vestibular Rehabilitation using a Wide FOV Virtual Environment

1. 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

2. 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

3. 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

4. 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

5. Balance NAVE (BNAVE) 3 back-projected screens 1 front-projected floor 180o Horiz x 90o Vert FOV Surface: rotate and translate

7. 10 8 6 4 2 Anterior-Posterior Head Sway (cm) 0 -2 -4 -6 -8 -10 0 10 20 30 40 50 60 70 80 90 Time (s)

8. Clinical research flow chart • Development of environments • Determine if user interfaces are safe • wide FOV • HMD • What is efficacy of rehab?

9. Development of environments • Extract elements from real grocery store • Design geometric models • Model virtual grocery store

14. 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

15. 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)

19. Show box target Clinical research flow chart

20. 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)

26. Gaze coordination • Motion Analysis • Postural Sway • Head and eye movements (gaze) • Timing and accuracy of movements

27. Head movements 6 DF Electromagnetic sensor Eye movements Horizontal and vertical Video-oculography (VOG)

28. 60 60 40 40 20 20 0 0 -20 -20 -40 -40 -60 -60 T H E Position (deg) 0 10 20 30 40 50 60 70 80 90 100 T G Position (deg) 0 10 20 30 40 50 60 70 80 90 100 Time (sec)

29. Next steps • 3 subjects with dizziness have begun trials to determine safety • Run experiment in virtual grocery

30. Show store target Clinical research flow chart

31. Next steps • Run experiment using HMD • Add treadmill • Clinical trials - efficacy

33. 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