A study of the relationship between stereoanomalies and fixation disparity curves

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The relationship between anomalies in processing stereopsis information and types of fixation disparity curves was investigated. The study was designed to investigate the hypothesis proposed by Richards (1975) that persons lacking uncrossed stereo-detector pools would also manifest a constant exo fixation disparity over a wide range of convergence induced by base-out prisms. In the present study, depth discrimination data for simple line targets and fixation disparity-forced vergence functions were compared for 22 subjects. The data from the stereopsis experiments did not confirm Richards' report of an all-or-none presence or absence of stereo-detector pools. The results also failed to support the hypothesis of a correlation between quality of stereo detection and type of fixation disparity manifested by a single subject. However, the results of the study are in agreement with the suggestion made by Jones (1980) that two different processes, operating independently of each other, co-exist in the fusional system, and that fixation disparity is not responsible for initiation of fusion.

Eye, Physiological optics