The Contribution Of Central And Peripheral Vision To The Postural Sway Response Elicited By Moving Visual Environments In Healthy Children Aged 8-12 Sparto PJ, Brown KE, Redfern MS, Furman JM, Casselbrant ML, Mandel EM Department of Otolaryngology University of Pittsburgh, PA, USA Sponsors: Eye and Ear Foundation, NIH: DC02490, DC05205, 1 K25 AG A1

Introduction Otitis media with effusion appears to affect balance function in children aged 1-9 years Effects of otitis media on balance in older children are not as well known Previously our group has explored the effect of optic flow environments on balance in children aged 3-9 Pilot experiment to obtain normative balance data children aged 8-12

Purpose Compare magnitude of postural sway in healthy children aged 8-12 with healthy adults to examine the visual dependence of children in this age group Examine if children utilize peripheral and central fields of view to control balance in a similar manner as adults

Balance NAVE Automatic Virtual Environment (BNAVE) Virtual Reality Facility used to generate moving visual environments Can control many factors: Field of view Spatial and temporal characteristics of movement Texture complexity Monoscopic vs. stereoscopic

Experimental Design Independent Variables Subject Age Group Field of View Frequency of Moving Visual Field Stimulation Dependent Variable Anterior – Posterior (A-P) Head Sway

Subjects Children 5 Males, 5 Females Age years, mean yrs Adults 5 Males, 6 Females Age years, mean yrs No abnormalities on clinical vestibular tests

Repeated Measures Field of View Full – full visual field stimulation Peripheral – central 30 o occluded Central – complement of peripheral Frequency of Movement 0.1 Hz 0.25 Hz RMS velocity was 1.2 m/s for both freq.

Procedure 6 trials of standing quietly while viewing: Each trial was 80 seconds long 10 sec no tunnel movement 60 sec tunnel movement 10 sec no tunnel movement

Data Analysis A-P Head Position sampled at 20 Hz using electromagnetic tracker Data processed using phaseless digital bandpass filter 0.1 or 0.25 Hz, depending on stimulus RMS sway computed for 60 sec of moving visual stimulus ANOVA Age, Field of View, Frequency

Sway v. FOV & Age

Sway v. Freq & Age

Discussion Moving visual environments generate more sway in children aged 8-12 vs. adults Children more visually dependent – transitioning to adult patterns of vestibular and proprioceptive feedback

Discussion Greater sway with full/peripheral field of view in both children and adults Due to optic flow field - peripheral retina sensitive to lamellar component

Discussion Children sway more at 0.25 Hz vs. 0.1 Hz Children have higher natural frequency of sway - easier to induce sway More visually dependent at higher frequencies because integration of vestibular and proprioceptive systems at these frequencies has not been completed