The effect of myopia level on the vestibulo-ocular reflex

Aim: The aim of this study is to evaluate the effect of myopia on the vestibulo-ocular reflex (VOR) using the Video Head Impulse Test (vHIT) and the Functional Head Impulse Test (fHIT). Material and method: The study was conducted at the Audiology Clinic of İnönü University Turgut Özal Medical Center between January 2024 and May 2024. It included individuals aged 18-60 with myopia and a control group of volunteers with no visual impairments in a similar age range. A total of 50 individuals with low myopia, 51 individuals with moderate myopia, and 50 healthy controls were included. All participants completed a Demographic Data Form, vHIT, and fHIT. Results: No statistically significant differences were found between the groups in vHIT lateral and posterior semicircular canal (SSC) gain values or lateral and LARP asymmetry values (p>0.05). However, significant differences were found in anterior SSC gain and RALP asymmetry values (p<0.05). In the fHIT, statistically significant differences were observed in the percentage of correct answers (PCA) for lateral, posterior, and anterior SSC planes (3000°/s², 4000°/s², 5000°/s², 6000°/s2 and total) (p<0.05). A positive correlation between fHIT lateral SSC 4000°/s² PCA and vHIT lateral SSC gain was found only in the control group (p<0.05), while no significant correlations were observed in other groups (p>0.05). Conclusion: Myopia was found to affect static visual acuity and functional vestibulo-ocular reflex. In the fHIT results, it was concluded that the percentage of correct responses decreased with increasing myopia, but myopia did not affect vHIT gain values.