Recently we developed a device by combining a binocular autorefractometer and an eye mark recorder. Then, using the device together with images of very natural and high quality, we have carried out a sequence of experiments on simultaneous measurements of both accommodation and convergence while viewing virtual 3D objects.The results show that there is essentially no discrepancy in the dynamical behaviors of accommodation and convergence especially for young subjects and that they are hence very close to the case of natural viewing of real 3D objects.Following our previous experiments, we now investigate effects of longtime viewing of virtual 3D objects on the eye function of accommodation and convergence. We show that the synchronous dynamical behaviors of accommodation and convergence are definitely not a temporal effect but last for a long time.