Dissociated Vertical Divergence

Abstract

This article deals with the complex issue of why the torsional eye movements in DVD are opposite in direction to those produced by the vestibular pathways. In my original analysis of DVD, I had previously explained this phenomenon teleologically by stating that the torsional directions between vestibular and visual pathways had to be opposite in direction to summate to zero under conditions of normal functioning. In this analysis, I demonstrate that monocular occlusion is associated with a subjective sensation of tilt, which is rapidly corrected by the DVD. The absence of any subjective tilt after a DVD torsional movement occurs suggests that these movements are corrective in nature (i.e. that DVD is indeed a righting reflex).