The Effect of a Projected Virtual Reality Training Environment on Vision Symptoms in Undergraduates

摘要

Purpose: : Virtual reality (VR) is known to induce a range of unwelcome symptoms (collectively known as "cybersickness") in a proportion of the population. Most attention has focussed on head mounted VR systems. What of projected systems, which are increasingly being used in various types of training? We investigated the effects of one system, the Liverpool Virtual Environment for Radiotherapy (VERT), on a group of undergraduates. Methods: : The VERT comprises a 3D stereoscopic back-projector system with a 2.5 x 5 m screen. Active stereo glasses worn by users automatically shutter between stereo projector views to simulate a 3D environment. 32 first-year Radiotherapy students from the University of Liverpool (mean age 22.2y) had a refraction and an orthoptic assessment. These included measurement of habitual visual acuity (with correction if worn) and stereovision prior to their first exposure to VERT. Students completed the Virtual Reality Symptom Questionnaire (VRSQ) before and after exposures of approximately 1hr on two occasions. Results: : The group distance and near acuities were 0.053?±0.18 and 0.010?±0.15 respectively (LogMAR, mean?±SD); median stereopsis was 45" with 28 out of 32 subjects (87.5%) having 60" or better (TNO). No subject reported any gross general (eg fatigue, headache) or eye (eye strain, blurring) discomfort after either first or second VERT sessions. There was a statistically significant increase in symptom scores from pre- to post-exposure on the first session (group median score 1 to 2.5 respectively; Wilcoxon Signed Ranks, Z=-3.457, p=0.001, n=32), but this was not repeated in the second session (2.5 to 3; Z=-1.147, p=0.251, n=28). Further, analysis of the difference between the individual pre- and post-exposure results in both sessions revealed no consistent effect in individuals over the two sessions. Conclusions: : We found that the VERT does not induce uncomfortable symptoms in a group of undergraduate students. It is possible that projected systems, in which participants are largely passive observers of a VR environment, are less likely to induce eye symptoms than head mounted systems which make higher demands on the visual system.