Abstract
Failure to perceive the disparity-defined form in autostereograms by those with clinically normal stereoacuity can occur when achieving or maintaining the precise vergence angle required to place the intended left and right images on corresponding areas of the two retinas is difficult. Since vergence and accommodation must be maintained at different depth planes to permit sensory fusion of an autostereogram, poor autostereogram skill has been suggested by different investigators to be related either to the presence of a binocular vision anomaly (i.e., a poorly-tuned binocular system) or to a binocular system that is well- coordinated. To clarify the relationship between binocular visual performance and autostereogram skill, we asked subjects with equal visual acuity OU at near and no manifest misalignment of the visual axes to rate their own autostereogram skill. We then compared common clinical indicators of vergence ability (near point phoria, near point of convergence, vergence ranges, vergence facility, stereoacuity, and a symptom survey) with both their self-reported and measured autostereogram skills. Our results indicate that subjects with poor self-assessed and/or measured autostereogram skill have significantly poorer vergence facility (p = 0.012 for self-assessed; p<0.001 for measured), smaller prism base-out vergence break point (p = 0.05 for self-assessed; p = 0.02 for measured), greater exophoria (measured only, p = 0.02), and poorer TNO stereoacuity (self-assessed, p = 0.02 for crossed disparities; measured, p = 0.03 for crossed disparities, p = 0.05 for uncrossed disparities) than do subjects with good self-assessed or measured autostereogram skill. After practice significant differences between those with poor versus good measured autostereogram skill remained only for vergence facility (p = 0.05), near phoria (p = 0.02), and TNO stereoacuity (p = 0.01 for crossed disparities, p = 0.003 for uncrossed disparities). Binocular visual symptoms at near were not significantly different for the two groups.
SCO Summer Research Program is supported in part by Alcon Partner's in Education Program.