The conflict between accommodation and vergence stimuli has been identified as a possible cause of visual fatigue from viewing stereoscopic images. We examined static and dynamic characteristics of accommodation and vergence responses while viewing stereoscopic displays and real objects to clarify the effect of stereoscopic images on the visual function. We used an instrument based on the Shack-Hartmann wavefront sensor to measure accommodation and vergence responses simultaneously. Accommodation responses to the static stereoscopic target with large binocular disparity were deviated from those to the real target, i.e., static characteristics. The step responses of the accommodation response showed considerable individual differences, i.e., dynamic characteristics. In addition, the asymmetries of step responses of accommodation were observed between the near-to-far and the far-to-near step directions. These results suggest that we need to examine both static and dynamic characteristics of accommodation and vergence responses to clarify the biological effect of stereoscopic images.
