GAZE ANGLE - A POSSIBLE MECHANISM OF VISUAL STRESS IN VIRTUAL-REALITYHEADSETS

It is known that some Virtual Reality (VR) head-mounted displays (HMDs ) can cause temporary deficits in binocular vision. On the other hand, the precise mechanism by which visual stress occurs is unclear. This paper is concerned with a potential source of visual stress that has n ot been previously considered with regard to VR systems: inappropriate vertical gaze angle. As vertical gaze angle is raised or lowered the 'effort' required of the binocular system also changes. The extent to which changes in vertical gaze angle alter the demands placed upon the vergence eye movement system was explored. The results suggested that visual stress may depend, in part, on vertical gaze angle. The proxim ity of the display screens within an HMD means that a VR headset shoul d be in the correct vertical location for any individual user. This fa ctor may explain some previous empirical results and has important imp lications for headset design. Fortuitously, a reasonably simple soluti on exists.