The effect of tilt degree and position changes on video ocular counter-roll test performance

BackgroundThe vestibular system is essential for balance and visual stability and relies on the ocular counter-roll (OCR) reflex to regulate torsional eye movements during head tilt.ObjectiveThis study aimed to investigate how different tilt angles (15° and 45°) and tilt positions (head and body) influence static video Ocular Counter-Rolling (vOCR) responses in healthy individuals.MethodsA total of 30 healthy volunteers (17 females and 13 males), aged between 18 and 30 years, participated in the study. vOCR testing was conducted using the Interacoustics VisualEyes™ 525 video-oculography (VOG) system. Torsional eye movements were recorded at 15° and 45° during both lateral head tilt and body block tilt. Torsion degree, asymmetry, and gain values were analyzed and compared across all conditions.ResultsGain values did not significantly differ based on tilt angle or position (p > 0.05). The degree of torsional eye movement was significantly higher at 45° tilts compared to 15°, and greater during body tilt than head tilt (p < 0.0001). Asymmetry values remained within normal limits under all conditions and showed no significant differences (p > 0.05).ConclusionsThese findings indicate that the angle and position of tilt affect the magnitude of the rotational response, but that gain and asymmetry values remain consistent across conditions. This suggests that comparable gains can be obtained at different angles, such as 15° and 45°, and that low-angle tilts may be sufficient for evaluating otolith-ocular gain.