Evaluation of the Peripheral Vestibular System in Individuals with Vision Loss

BACKGROUND: The aim of this study was to determine whether there are differences in the balance system between individuals with vision loss and a healthy control group using the video head impulse test (vHIT), cervical vestibular evoked myogenic potentials (cVEMP) and ocular vestibular evoked myogenic potentials (oVEMP) tests. METHODS: The study included 23 individuals diagnosed with bilateral low vision, 20 individuals diagnosed with bilateral blindness, and 50 healthy control subjects. vHIT, cVEMP, and oVEMP tests were applied to all participants to evaluate the vestibular system. In addition to the standard vHIT, 2-condition vHIT (in the dark and in daylight without a target) was performed on the control group to evaluate the effect of visual input. RESULTS: In vHIT responses, a significant difference in vestibulo-ocular reflex (VOR) gains was detected in the comparison between the bilateral low vision, bilateral blind, and control groups in all semicircular canals (SSC) (P < .001). When the vHIT responses in the 3 conditional groups of the control group (untargeted daylight, darkness, and standard) were examined, a significant difference in VOR gains was detected in the comparison of all 3 groups in the entire SSC (P < .001). CONCLUSION: The findings of statistically significantly low VOR gains obtained in individuals with low vision and the blind group showed the great effect of visual input on the vestibular system. This hypothesis was also supported by the results of vHIT, which was applied in 3 stages (dark, untargeted daylight, and standard) in healthy individuals.