The effect of camera side on the VOR gain in video head impulse test

Objective This study aims to investigate the effect of camera positioning (left-sided vs right-sided) on the vestibulo-ocular reflex (VOR) gain values of normal subjects during the video head impulse test (vHIT), thereby providing valuable reference data for otology clinical practice. Methods Thirty healthy adults (60 ears) were recruited and examined by vHIT for the three pairs of semicircular canals (SCs). During the examination, we meticulously recorded and compared the VOR gain values in the six canal planes—right lateral (RL), left lateral (LL), right anterior-left posterior (RALP), and left anterior-right posterior (LARP)—with the camera positioned on the left side first, followed by repositioning on the right side. We evaluated instantaneous gain (40 ms, 60 ms, and 80 ms), 0–100 ms median gain, and regression gain in 0–100 ms for all SCs. Results For horizontal canals, higher VOR gain values were recorded when the camera was positioned on the same side as the canal being tested. The gain value in LARP was higher when the camera was on the left side than on the right side, while the gain value in RALP was higher when the camera was on the right side than on the left side. Conclusion This study underscores the importance of camera positioning on VOR gain values for both lateral and vertical canals during vHIT. To mitigate the effects of these variables, standardization of operational procedures and equipment settings is crucial.