Purpose: In uncorrected anisometropia, protracted dichoptic stimulation may result in interocular inhibition, which may be a contributing factor in the development of amblyopia. The present research was undertaken to investigate any relationship between interocular interactions and the development of and recovery from anisometropic amblyopia, and to investigate the maturation of interocular interactions in childhood.Methods: Computerized tests were used to measure low contrast visual acuity, contrast sensitivity and alignment sensitivity in dominant and non-dominant eyes of normally sighted children and anisometropic children with and without amblyopia (35 subjects in each group, from 5 to 11 years), with full (opaque) and partial (central region only) occlusion of the non-tested eye. Two viewing systems were used, shutter goggles and a customized Trial Frame Apparatus (TFA). Interocular interactions were indicated by an Interocular Interaction Index (Index) and were compared between these three subject groups. Amblyopic treatments including refractive correction and occlusion were prescribed to all amblyopes. Identical measures as the baseline test were conducted using TFA in the amblyopes who had good compliance with treatments after six months of therapy. Index evaluated using TFA was compared between these two tests (before and after therapy) in these amblyopes. It was also compared between normally sighted children at different age ranges and normally sighted adults.Results: (1) Inhibitory interactions for acuity and contrast sensitivity are significantly stronger in anisometropes with amblyopia than in those without; (2) Inhibitory effect of occlusion of the dominant eye on vision of the non-dominant eye is significantly stronger than the effect of occlusion of the non-dominant eye on vision of the dominant eye in anisometropic amblyopes; (3) Inhibitory interactions for acuity are significantly decreased after amblyopia therapy, and these interactions in subjects recovered from amblyopia are not significantly different from those in anisometropes without amblyopia; (4) In groups with normal vision, inhibitory interactions for acuity and alignment sensitivity are stronger in older children than in younger children and adults.Conclusions: Anisometropic amblyopes have stronger inhibitory interactions than anisometropes without amblyopia. These interactions decrease after amblyopia therapy, indicating that interactions of this kind may play a role in the development of and recovery from anisometropic amblyopia.
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