EFFECT OF FIXATION DISPARITY ON DISTANCE BINOCULAR VISUAL-ACUITY

Subjects with appreciable values (2 DELTA and greater) of associated ' phoria, as measured by a Mallett unit, had their distance monocular an d binocular visual acuities measured. In the latter case measurements were taken both with the associated 'phoria corrected by prisms and wi thout such a correction. The improvement in binocular acuity compared to monocular acuity was less than would occur in normal subjects with minimal associated 'phorias although the improvement differed accordin gly as to whether the readings were eso- or exo-in nature. When the as sociated 'phorias were corrected with prisms the improvement in binocu lar over monocular visual acuity was similar to that found in normal s ubjects.