Comparison of static ocular counter-roll induced by active and passive head tilt and whole body roll

Background: When humans are roll-tilted around the naso-occipital axis, a compensatory torsional rotation of the eyes in the opposite direction occurs known as ocular counterroll (OCR). This is thought to be mainly a vestibular (otolithic) response. The contributions of cervico-ocular reflexes to OCR are still unknown. Moreover, mainly for technical reasons there are still no standardized OCR tests. Therefore, the aim of this study was (1) to compare OCR in response to active and passive lateral head tilts and whole body roll and (2) to develop a test for the evaluation of otolith function which can be used in t…