Stereoacuity improves after short-term binocular pattern mismatch.
visual deprivation, stereoscopic vision, monocular deprivation
Behavioral Neurobiology | Cognition and Perception | Cognitive Neuroscience | Optometry
Monocular deprivation can chronically suppress vision in the deprived eye, if it is applied for sufficient duration early in life. However, it can have a transient effect in the opposite direction if applied briefly (a few hours) to normal adults. This short-term monocular deprivation appears to increase the gain for the deprived eye relative to the undeprived eye, affecting binocular vision by shifting the interocular balance. An interocular gain difference produced by patching a single eye might be expected to lower stereoacuity in normal observers, since raising contrast in just one eye reduces stereoacuity (the ‘contrast paradox’). We hypothesized that alternately depriving each eye in turn might benefit stereoacuity by increasing post‐deprivation gain in both eyes and dampening interocular suppression. We switched a translucent patch between the eyes of visually normal adult observers hourly for 6 hours. The unpatched eye viewed the natural visual environment. Compared to pre-patch performance, post-patch grating stereoacuity, measured during 20 minutes following patch removal, improved by 20% to 33%. In a second experiment, we alternately covered the left and right eyes of two observers with cylinder lenses to determine the existence of orientation-specific gain. Each eye was ‘patched’ with the lens for 45 or 60 minute periods, giving a total through-the-lens viewing of 4 to 6 hours. Unexpectedly, post-patching stereoacuity improved for test gratings with the same orientation as seen through the lens and worsened for orthogonal gratings. This result cannot be explained by monocular orientation adaptation. It implies that the interocular balance has a channel structure that is modulated not specifically by monocular deprivation but rather by interocular pattern mismatch. The post-patching enhancement evident in both experiments indicates that interocular suppression may limit stereoacuity under natural viewing conditions.
Farell, B. & Ng, C. J. (2015). Stereoacuity improves after short-term binocular pattern mismatch. Journal of Vision, 15, 826. doi:10.1167/15.12.826