Abstract
Impediments to binocularity coupled with a lack of early-life intervention often lead to impaired binocular disparity processing (stereopsis). A visuomotor task was developed to simultaneously train stereopsis and assess the degree to which subjects rely on disparity cues (relative to monocular depth cues) to estimate surface orientation. We asked whether repeated practice on this naturalistic task, akin to object placement on a surface, could aid in recovering stereopsis in stereo-anomalous subjects. Subjects viewed virtual images of planar texture patterns at a range of 3D slants and were required to squash a virtual bug by placing a cylinder flush onto a real, but optically hidden, slanted surface that was co-aligned optically with the virtual surface. One anisometropic amblyopic subject and three strabismic subjects with impaired stereopsis, aged 18-56, participated in this pilot training study. A range of visual functions (visual acuity, contrast sensitivity, vernier, and stereopsis) was measured pre- and post-training both clinically and psychophysically. Subjects completed at least thirty, 360 trial sessions lasting ~75 minutes each. Image contrast to the dominant eye was adjusted to match the non-dominant eye regularly. Stereopsis recovered in three of four subjects as evidenced by (a) increased weights given to disparity cues in the visuomotor task, (b) improved sensitivity in low spatial frequency edge disparity tests, and (c) decreased clinical Randot stereo-thresholds. We conclude that our paradigm successfully restored stereopsis in some adult subjects. Our results add to the growing body of literature documenting residual neural plasticity beyond the sensitive period for damage recovery.
Meeting abstract presented at OSA Fall Vision 2012