Abstract
Purpose:
To evaluate Center of Pressure measures obtained on a commercially available Nintendo Wii Balance BoardTM (WBB) in a group of low vision (LV) and normal participants.
Methods:
Subjects with low vision (visual acuity worse than 20/70 and/or visual field less than 40°, in the better eye, N=7) and subjects with corrected-to-normal vision (N=5), completed the modified Clinical Test of Sensory Interaction on Balance (mCTSIB) which includes four sensory conditions: double-leg standing on a firm surface with eyes open (EO-firm); standing on a firm surface with eyes closed (EC-firm); standing on an unstable (3” thick) surface with EO (EO-foam); and standing on an unstable surface with EC (EC-foam). Subjects performed each condition for 4 successive trials for up to 30 seconds with a one-minute rest period in between. The conditions were randomly ordered. Center of Pressure (COP) outcomes were derived from data sent by the 4 force plate sensors in the WBB to a laptop via Bluetooth. The COP measures include root mean square (RMS) of the COP excursion (mm), RMS of velocity (mm/s), mean total velocity (MTV, mm/s), and area (mm2).
Results:
In the LV group, all COP measures differed significantly between firm and foam conditions with EC and EO (all p<0.05) with the exception of SD of velocity in the M-L direction. In both groups, no significant differences across COP measures were found in an independent samples t-test between the EO-firm and EC-firm conditions (all p>0.05) and between the EO-foam and EC-foam condition. No significant differences were found across all variables when comparing LV participant COP measures to normal participants with the exception of MTV and area in the EO-firm condition (p=0.01 and p = 0.03, respectively).
Conclusions:
This pilot study uses the WBB for determining postural stability in a LV and normal group. As expected, differences were found between the firm and foam conditions both with EO and EC in the LV group suggesting that visual and sensorimotor challenges exist. In comparison, the normal group performed well across all conditions suggesting more stability. MTV and area measures differed between the LV and normal group in the EO-firm condition suggesting that these variables might by predictors of balance impairment. A larger sample size is needed to determine test-retest reliability of each COP measure.