Comparison of Stereoscopic Fusional Area between People with Good and Poor Stereo Acuity

Purpose: This study investigated differences in stereoscopic fusional area between those with good and poor stereo acuity in viewing stereoscopic displays. Methods: Stereo acuity of 39 participants (18 males and 21 females, $23.6{\pm}3.15years$) was measured with the random dot stereo butterfly method. Participants with stereo-blindness were not included. Stereoscopic fusional area was measured using stereoscopic stimulus by varying the amount of horizontal disparity in a stereoscopic 3D TV. Participants were divided into two groups of good and poor stereo acuity. Criterion for good stereo acuity was determined as less than 60 arc seconds. Measurements arising from the participants were statistically analyzed. Results: 26 participants were measured to have good stereo acuity and 13 participants poor stereo acuity. In case of the stereoscopic stimulus farther than the fixation point, threshold of horizontal disparity for those with poor stereo acuity were measured to be smaller than the threshold for those with good stereo acuity, with a statistically significant difference. On the other hand, there was no statistically significant difference between the two groups, in case of the stereoscopic stimulus nearer to the fixation point. Conclusions: In viewing stereoscopic displays, the boundary of stereoscopic fusional area for the poor stereo acuity group was smaller than the boundary of good stereo acuity group only for the range behind the display. Hence, in viewing stereoscopic displays, participants with poor stereo acuity would have more difficulty perceiving the fused image at farther distances compared to participants with good stereo acuity.