Predictive factors for the perceptual learning in stereodeficient subjects

BACKGROUND: Stereopsis is a valuable feature of human visual perception which is critically impaired in amblyopia, but can be improved through perceptual learning (PL). This article aims to determine the variables affecting the outcomes and intensity of a stereoacuity stimulation program. METHODS: Re-analysis of a previous study in stereodeficient subjects with a history of amblyopia. Sixteen subjects (12 females, 4 males) aged between 7 and 14 received stereopsis stimulation through a PL program at home. A correlation analysis evaluated whether treatment intensity or percentage improvement were related to age or baseline stereoacuity measurements. Further analysis was performed to assess whether the type of amblyopia conditioned the PL treatment (Fischer Statistical Test). RESULTS: No significant correlation was found between age and percentage improvement (rho = −0.08, p = 0.749), nor was age correlated with treatment intensity (rho = 0.170, p = 0.544). However, a correlation did exist between baseline stereoacuity levels and treatment intensity (rho = 0.734, p = 0.001). Baseline stereoacuity and percentage improvement had a negative correlation (rho = −0.748, p = 0.005), while treatment intensity showed only a weak association with the type of amblyopia (p = 0.064). CONCLUSIONS: Present results suggest that perceptual learning in stereodeficient subjects is not influenced by either the subject's age or the type of amblyopia. Baseline stereoacuity, on the other hand, seems to be a predicting factor for perceptual learning outcomes. According to our study, subjects with poor basal stereoacuity needed more sessions to improve and their percentage improvement was lower. However, due to the reduced size of the sample, the results should be considered with caution.