Positional acuity in amblyopia: does a perceptual consequence of neural recruitment exist?

Animal models of amblyopia have shown that visual deprivation for even brief periods can result in dramatic changes in cortical architecture. Active neural recruitment mechanisms present the possibility that the non-deprived eye of amblyopes may show enhanced visual capacity. This idea was tested by measuring a form of positional acuity which we have termed alignment threshold. Three subject groups were examined, adults, visually normal children, and children with amblyopia in which the non-deprived eye was tested. Alignment thresholds in adults were significantly better (approximately 0.3 log unit) than the thresholds for visually normal children. No significant difference was found in thresholds between the visually normal children and the non-deprived eye of the amblyopic children. The results of this study suggest that subjects with unilateral amblyopia do not show enhanced visual alignment performance in their non-deprived eye.