Abstract: The perception times (PT) of stereopsis and form vision in normaland anisometropic amblyopic subjects were measured using StereoscopicTest Charts (S-M Yan, and Z-Y Zheng, 1985). These charts consist ofanaglyph (red-green) random dot stereograms (RDS) which have a rangeof zero (20-320 sec arc), and crossed, uncrossed (12-60 min arc) dispa-rities. The forms defined by stereoscopic disparity include common figuressuch as triangles, squares, etc. Tachistoscopic (Gl136, Gerbrands Corp.)presentations were used to control test stimulus and mask durations. Forboth normal and amblyopic subjects the perception of depth preceded theperception of form. For normal subjects about 100 ms were required toperceive depth while an additional 10 or more ms were needed to perceiveform. Stereopsis and form PT were independent of absolute disparity.Amblyopic subjects needed longer time for stereopsis and form perceptionscompared to normal subjects, The difference of PT between stereopsis andform in the amblyopic subjects was also longer than those of the normal. Two recovered amblyopes were also tested. The long term recoveredsubject had perception times within the normal range. Interestingly, therecent recovered patient who appeared clinically normal, still had eleva-ted perception times. This technique may prove to be a particularly sensi-tive measure of recovery from amblyopia beyond that of visual acuity.

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