Investigation of the effect of the alignment of the eye and the virtual image of virtual reality on fatigue in viewing VR device

Cybersickness is a major problem hindering the use of fully immersive virtual reality (VR) systems. A mismatch between the interpupillary distance (IPD) and the inter-optical system distance (IOSD) can cause discomfort when using VR devices. To solve this, the IOSD must be aligned according to the user's IPD. Herein, we investigated the effects of the optimum alignment of IPD and IOSD on eye fatigue when using VR systems. A method was used such that the IPD and IOSD for each participant were initially aligned under the condition that binocular fusion did not occur by displaying different left and right images. Fifteen university students aged 20–26 years were included. In the alignment and misalignment states, a symptom questionnaire was used to evaluate changes in the symptoms of participants after viewing a short movie using the VR device. We found that the obtained results in the eye strain category were statistically improved in the aligned state compared with those in the misaligned state. However, there were no significant differences in the general discomfort, nausea, focusing difficulty, or headache categories. Consequently, we confirmed that the alignment of the VR device using the proposed method can reduce eye fatigue when viewing VR content.