NASO-TEMPORAL ASYMMETRY OF SPATIAL INTERACTIONS IN STRABISMIC AMBLYOPIA

Purpose. Naso-temporal asymmetries of visual acuity and contrast sensi tivity have been reported in strabismic amblyopia and attributed to as ymmetries of interocular suppression. In this study, we investigated t he naso-temporal asymmetry of cortical spatial interactions in two str abismic amblyopes (one esotrope and one exotrope). Methods. Length and width Westheimer functions were measured on both amblyopes at the 10 deg retinal eccentricity of both nasal and temporal visual fields. Res ults. Spatial interactions in the two amblyopic eyes were more degrade d in the temporal visual fields than in the nasal visual fields. A com parison with results from the preferred eyes suggested that this asymm etry was caused mainly by a loss of spatial interactions in the tempor al visual fields of amblyopic eyes, with those in the nasal visual fie lds being normal. Conclusion. Our results suggest that intracortical c onnections underlying cortical spatial interactions might have been de graded by amblyopia. This degradation exists not only in the areas of the strabismic visual cortex responding to foveal stimuli but also in those responding to stimuli presented in the temporal visual fields.