Visual discomfort has been a major barrier to the popularization of Virtual Reality (VR) systems. There have been many studies on visual discomfort provoked by vection-inducing VR stimuli or mismatches between accommodations and binocular convergence during VR simulation. However, visual discomfort due to distorted images induced by optical aberration of lens inside VR headsets has received little attention. During head rotations, eye fixations are stabilized by vestibulo-ocular reflex (VOR) so that the projected image of an object remains stabilize on the retina. In VR simulations, because of inevitable imperfections in correction for lens optical aberration, visual distortions will occur during head motions when foveal view is stabilized by VOR. Little is known on how these distortion...[ Read more ]

Visual discomfort has been a major barrier to the popularization of Virtual Reality (VR) systems. There have been many studies on visual discomfort provoked by vection-inducing VR stimuli or mismatches between accommodations and binocular convergence during VR simulation. However, visual discomfort due to distorted images induced by optical aberration of lens inside VR headsets has received little attention. During head rotations, eye fixations are stabilized by vestibulo-ocular reflex (VOR) so that the projected image of an object remains stabilize on the retina. In VR simulations, because of inevitable imperfections in correction for lens optical aberration, visual distortions will occur during head motions when foveal view is stabilized by VOR. Little is known on how these distortions can affect human experience with different types and levels of lens aberration. The present work investigated the subjective discomfort induced by the dynamic distortion during active horizontal head rotation with a fixed gaze stabilized by VOR. Three experiments have been conducted, in which participants were instructed to rate their perceived visual discomfort in terms of disorientation and dizziness with different types and levels of dynamic distortion in a controlled VR scene. Higher subjective visual discomfort ratings were reported with increasing visual distortion even when the distortion was small. Significant effects of lens types on visual discomfort have been found. In addition to empirical investigation, an analytical model has been developed to predict the severity of such discomfort. The model can be a useful tool for VR headset industry because it takes in lens design parameters and predicts the associated visual discomfort. Results have been well received by the industry and is being deployed.