Abstract
Purpose :
Stereoscopic displays require fixed levels of accommodation, despite large change in vergence response to maintain single vision.The aim of this experiment is to compare vergence and accommodation responses to step changes in pure disparity vergence presented upon a stereoscopic display with step changes in real space
Methods :
17 emmetropic subjects (mean age 23±1.7 years) with normal binocular function participated in the experiments. In the first experiment, a Maltese cross (90% contrast) target was presented on stereoscopic display (Zalman ZMW215W), while in the second experiment a Maltese cross with the same characteristics was mounted on a moving platform (Movopart M55) in real space. In both experiments the initial target position was 40cm from which step changes in target position equating to 6Δ convergence or divergence were presented randomly at 10s intervals over a period of 6 minutes in both conditions. The target was aligned with the right eye to enable continuous accommodation recording with a specially modified Shin-Nippon SRW-5000 infrared, open-field autorefractor. An infrared, limbal eyetracker (Skalar IRIS 6500) was used to record eye movements. 10 clean traces of accommodation and vergence were selected for analysis
Results :
The group mean vergence response in real space was +6.3± 0.34Δ for convergence and -6.05± 0.34Δ for divergence. Group mean response time for convergence was 688±119ms and 756±211ms for divergence. Real space accommodation responses were 0.91±0.24D for convergence and -0.92±0.24D for divergence. For pure disparity stimuli (stereoscopic display) the group mean vergence response was significantly (p<0.01) lower for both convergence +5.02±0.54Δ and divergence -5.25±0.44Δ. Response times were significantly (p<0.01) longer for convergen ce 1095±315ms and divergence 1082±303ms. The mean accommodation response to the stereoscopic display in the absence of any additional convergence or divergence was 2.28±0.25D. There was no significant alteration observed in the accommodation response with either disparity stimulus
Conclusions :
Vergence responses are substantially degraded in the stereoscopic environment. The absence of any substantial accommodation response to pure disparity stimulation is to be expected due to the fixed dioptric position of the display. Accommodation. Both of these factors may contribute to the asthenopia reported during stereoscopic viewing
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.