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L.S. Gray, S. Stanger, L. Hobden, D. Orr; The Time Course of Ocular Motor Adaptation to Virtual Reality Exposure . Invest. Ophthalmol. Vis. Sci. 2003;44(13):2733.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To determine the length of exposure to a virtual reality (VR) stimulus necessary to produce ocular motor adaptation and to monitor the post-exposure time course of this adaptation Methods: 15 emmetropic subjects (mean age 19.4±2.2 years) participated with informed consent in the experiment. Tonic accommodation (TA) was measured in darkness using the Shin-Nippon SRW-5000 infrared autorefractor. Tonic vergence (TV) was measured in darkness using an Eyetrace 300X infrared limbal eyetracker. The VR stimulus was generated using SimulEyes field-sequential shutter goggles controlled by a Dell XPS R450 PC. The VR display required a constant accommodation response of 3D, while the vergence response varied between 0 and 5MA. Subjects were placed in darkness for 5 minutes prior to the experiment to dissipate the effects of any previous near work. Pre-exposure TA and TV were measured over a period of 3 minutes and the mean level calculated. Subjects were immersed in the VR environment for 10, 20 and 30 minute periods and the TA and TV levels were sampled continuously for the first ten minutes post-exposure and then at 30s intervals for a further 50 minutes. Results: Significant (p<0.01) TV adaptation was found for all exposure periods. The magnitude of TV adaptation was not related to the exposure duration. The mean post-task vergence shift was +0.80±1.97MA, with considerable intersubject variability in the magnitude and direction of vergence adaptation being evident. Subjects with convergent baseline TV tended to exhibit divergent adaptative shifts, while those with divergent baseline TV adapted in the convergent direction. For a 10 minute exposure the mean time for vergence adaptation to drop to half-height was 32.44±12.67 minutes and for most subjects TV had returned to baseline by 60 minutes. No significant adaptation of TA was found. Conclusions: Vergence adaptation is a significant component of the near response to a VR environment. TV adaptation can be induced by relatively short durations of VR exposure. There is considerable intersubject variability in both the magnitude and direction of the adaptation. The magnitudes of vergence adaptation identified would be sufficient to produce diplopia in susceptible individuals.
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