The influence of vision on the vestibule-ocular reflex in head autorotation test

Introduction: The head autorotation test (HART) can be used to quantify high-frequency vestibulo-ocular reflex (VOR). In this study the HART results with and without visual input were compared to evaluate the effect of vision on high-frequency VOR results. Subjects and methods: In the HART 30 healthy subjects rotated their heads horizontally from left to right and back according to accelerating auditory cues during the measurement of 30 s. Gain and phase were calculated in five frequency bands of 1-5 Hz. Results: The gain in the EC condition was lower (about 0.1) in all frequency bands, but the difference was statistically significant (p < 0.01) only in the frequency bands of 1, 2 and 3 Hz. The phase did not differ significantly between EO :md EC test conditions. Ten healthy subjects were not able to fixate their gaze during HART in EC condition. Conclusion: The difficulties of 33% of the healthy subjects to perform the HART in EC condition and similarity of the high-frequency VOR results of EO and EC test conditions indicate that it may not be advantageous to use BC test condition in the HART.