A Theory for Treating Dizziness Due to Optical Flow (Visual Vertigo)

Virtual reality (VR) training that provides optic flow stimuli and visuo-vestibular conflict has been suggested as a way to treat patients with inappropriate visual dependence (sometimes called visual vertigo even though spinning sensation is often absent). We propose a simple framework based on a hypothesis that the degree of dizziness depends on the offsetting between the destabilizing effect of optical flow and the stabilizing effect provided by stationary objects in the visual field. We define a total destabilizing potential (TDP), which is the ratio of the destabilizing effect over the stabilizing effect. The approach is to gradually increase the person's tolerance of a higher TDP through exercises that may be described as an inverse of the traditional gaze stabilization exercises for vestibular rehabilitation. The theory proposes that an important ingredient in VR training is to incorporate a stationary anchor to help synchronizing the visual sensory to vestibular and somatosensory inputs. The scheme can also be adopted economically with computer-generated imagery or used by individuals in certain everyday environments.