Optometric and Perceptual Issues with Head-mounted Displays

Most virtual reality (VR) systems employ head-mounted displays (HMDs). Many such systems are also designed to provide stereo depth and use head tracking to enable the virtual world to change in response to the user's movements. The current state of HMDs and other VR technology falls short of accurately simulating many aspects of the visual world. Differences between the real world, for which the human visual system had a few million years to adapt, and the novel HMD may result in degradation ofimage quality and/or cause discomfort and visual changes. Concerns about possible harmful.effects are reminiscent of similar worries that accompany the introduction of almost any new wide-use technology. Such concerns were raised with the introduction of television, computers and visual display terminals (VDTs), microwave ovens, and, most recently, cellular phones. This chapter describes a few possible mismatches between the visual system's response to the real world and its response to the virtual world of the HMD. Some of these mismatches result in unwanted perceptual effects including stress to the visual system, discomfort, and, presumably, long-term changes to the visual system. These unwanted effects mayor may not impact the acceptance of the technology. Many of the mismatches that result in these negative consequences can be