[Visual field defects in strabismic amblyopes].

Abstract

Kittens raised with different kinds of abnormal early visual experience (monocular and binocular deprivation, convergent strabismus, eye rotation, asymmetric alternating occlusion, early callosal split) show systematic deficits in the nasal field of the affected eye. Since the kittens' visual field is tested by monitoring their orienting toward visual stimuli, it is not clear whether these deficits are due to a genuine sensory loss (involving the geniculocortical pathway) or to a sensory-motor impairment (involving the projection through the visual cortex to the superior colliculus). To answer this question, the authors measured the monocular visual field of humans with subnormal binocular vision (strabismic and anisometropic amblyopes, strabismics with alternating fixation). Eight amblyopes were tested with a computerized static perimetry (Octopus 2000). Twenty other subjects were tested with static and kinetic perimetry (Goldmann 940). In some of these subjects, we also tested the latency of saccades and the accuracy of visually guided pointing toward stimuli presented in the nasal or the temporal visual field. Both strabismic and anisometropic amblyopes occasionally showed deficits of visual sensitivity in the central part of the visual field, but no systematic deficits in the peripheral visual field. Strabismic alternators had practically equal fields in the two eyes. Neither saccadic latency nor pointing accuracy showed any asymmetries between the nasal and temporal visual fields. These results seem to contradict a recent report of a nasal hemianopia in deep amblyopia (Mehdorn, 1986); taken together, these results suggest that in adult strabismic humans, a nasal field loss is the exception rather than the rule.(ABSTRACT TRUNCATED AT 250 WORDS)