Retinal image velocity, a parameter a of vestibulo-ocular reflex dysfunction

The vestibulo-ocular reflex (VOR) helps to stabilize a person's gaze during head movement so that vision will not be blurred. It can be measured with head autorotation test, in which the eye and head movement of the subject are simultaneously recorded, and from which VOR parameters are calculated. Retinal image velocity (RIV) is an objective parameter that is better related to the deficiency of the VOR (objective oscillopsia) than to the subjectively observed oscillopsia. Theoretical calculations show that it is sensitive to the time difference between eye and head movements. An example of a measured signal demonstrates that when the eye velocity signal is derived from the eye position signal the noise level increases harmfully. Therefore, an accurate signal processing chain is required, and effective noise reduction must be used before the RIV can be calculated reliably.