A common cause of asthenopia is viewing objects from a short distance, as is the case when working at a VDT (Visual Display Terminal). In general, recovery from asthenopia, especially accommodative asthenopia, is aided by looking into the distance. The authors have developed a stereoscopic 3-D display with dynamic optical correction that may reduce asthenopia. The display does this by reducing the discrepancy between accommodation and convergence, thereby presenting images as if they were actually in the distance. The results of visual acuity tests given before and after presenting stereoscopic 3-D images with this display show a tendency towards less asthenopia. In this study, the authors developed a refraction feedback function that makes the viewer's distance vision more effective when viewing stereoscopic 3-D images on the this display. Using this function, refraction is fed back during viewing and the viewer gradually acquires distance vision. The results of the study suggest that stereoscopic 3-D images are more effective than 2-D images for recovery from asthenopia.
The purpose of this study was to consider a practical application of a newly developed stereoscopic 3-D display that solves the problem of discrepancy between accommodation and convergence. The display uses dynamic optical correction to reduce the discrepancy, and can present images as if they are actually remote objects. The authors thought the display may assist in recovery from asthenopia, which is often caused when the eyes focus on a nearby object for a long time, such as in VDT (Visual Display Terminal) work. In general, recovery from asthenopia, and especially accommodative asthenopia, is achieved by focusing on distant objects. In order to verify this hypothesis, the authors performed visual acuity tests using Landolt rings before and after presenting stereoscopic 3-D images, and evaluated the degree of recovery from asthenopia. The experiment led to three main conclusions: (1) Visual acuity rose after viewing stereoscopic 3-D images on the developed display. (2) Recovery from asthenopia was particularly effective for the dominant eye in comparison with the other eye. (3) Interviews with the subjects indicated that the Landolt rings were particularly clear after viewing the stereoscopic 3-D images.
This paper describes an examination of a stereoscopic 3-D display system using a correction lens. The purpose of the system is to reduce the accommodation and convergence difference during viewing stereoscopic 3-D images by using simple technique. This correction lens is a mono-focal lens, and added to the polarized filter glasses.
In this study, the authors carried out three experiments in order to examine the appropriate utilization conditions and effects of the correction lens. In experiment 1, the refractive power of correction lens was examined under six conditions in which distances of accommodation and convergence were theoretically equal. In experiment 2, the presenting condition of stereoscopic 3-D images suitable for the correction lens was examined by measurement of refractions during viewing visual target that moved in depth direction. In experiment 3, the effectiveness of the correction lens was examined by using the utilization conditions obtained in experiment 1 and 2.
From the results of the experiments, the following conclusions were drawn.
(1) Correction lenses shift the accommodation distance.
(2) Using a correction lens with the appropriate refractive power and setting the appropriate conditions for presenting stereoscopic 3-D images reduced the difference between accommodation and convergence.
(3) The use of a correction lens affected the subjective symptoms of asthenopia.