A comparison of self-reported and measured autostereogram skills with clinical indicators of vergence ability in esophores

Abstract

Perception of the disparity-defined form in autostereograms requires achieving and maintaining the precise vergence angle necessary to place the intended left and right images on corresponding areas of the two retinas. Most commercially available autostereograms are designed to be viewed only with one vergence posture, usually the parallel or “wall-eyed” technique¹, meaning that the visual axes need to converge by one or more periods of the pattern to a point farther from the viewer than the plane of the stereogram. Converging the eyes (“cross-eyed” technique) in front of these autostereograms by one or more periods of the pattern will reverse the depth direction of the stereoscopic image, perhaps making the form more difficult to perceive. Our previous work² compared common clinical indicators of vergence ability with subjects' self-reported and measured autostereogram skills and found significant differences between those with poor versus good self-reported and measured autostereogram skill for vergence facility, near phoria, and TNO stereoacuity for subjects who were exophoric at near. The present study was undertaken to compare clinical indicators of vergence ability to perceived and measured autostereogram skills in esophores. Our results show that esophores whose self-rated and measured autosterogram skills were “poor” demonstrated significantly poorer performance on clinical tests of vergence facility and were more likely to demonstrate differences in threshold performance for crossed vs. uncrossed disparities on the TNO stereoacuity test than were subjects with “excellent” autostereogram skills. Attempts to fuse using “wall-eyed” vs. “cross-eyed” viewing did not differ between the two groups for those subjects able to perceive the autostereogram form.