Abstract
Purpose :
Recent commercialization of Virtual Reality head-mounted displays (VRHMD), poses a question about the ocular effects of decoupling vergence and accommodation. In the real world, a change in one system causes a change in the other. However, in a VRHMD, accommodation is fixed to the screen (~1-2 meters) while vergence varies to meet the display’s disparity demands. Possibly related, studies have shown an increase in overall discomfort and eye strain after VRHMD use. Our aim was to measure and compare oculomotor changes after VRHMD and more traditional computer (PC) “play”.
Methods :
Healthy young adult students (n=20) aged 18-24 years participated in this study. At each of two visits, participants performed an identical gaming task on either a VRHMD or a PC for a sustained (40 min) period (order randomized). Immediately before and after each task, distance and near vergence ranges (prism bar), accommodative amplitude (pull away), and horizontal distance and near phoria (Modified Thorington) were measured in random order.
Results :
Following VRHMD play, participants showed a significant increase relative to PC play in their convergence blur ranges at both near (Mean change: PC = -2.33Δ; VRHMD = +2.68Δ, p=0.014) and distance (Mean change: PC = -1.1Δ; VRHMD = +2.55Δ, p=0.022). Participants showed a similar but smaller increase in divergence blur ranges at far following VRHMD play (Mean change: PC = -0.3Δ; VRHMD = +1.35Δ, p=0.045). There was a small but not statistically significant increase in accommodative amplitude following both PC and VRHMD tasks (Mean change: PC = +0.34Δ; VRHMD = +0.31Δ, p=0.077). There was a borderline significant change in phoria at distance (Absolute change: PC M = 1.79Δ; VRHMD M = 0.75Δ, p=0.058), but no significant change in phoria at near (Absolute change: PC M= 2.66Δ; VRHMD M = 02.85Δ, p=0.79) between VRHMD and PC play.
Conclusions :
In this small-scale study, we observed increases in the blur convergence ranges (BO) following sustained virtual reality play as compared to traditional computer play. We speculate that these changes may be due to changes in the tonic accommodative system during sustained VRHMD play, however further more sensitive measures of accommodative function following VRHMD play is required.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.