Normality of spatial resolution of retinal ganglion cells in cats with strabismic amblyopia.

Abstract

A convergent or divergent strabismus was induced surgically in 8 kittens and a cyclotropia of .apprx. 90.degree. in 2 additional kittens. Behavioral measurements were made of the visual acuity of each eye for square-wave gratings. All 8 animals that were so tested displayed a reduction of acuity in 1 eye relative to the other of 1.3-2.5 octaves. The activity of retinal ganglion cells was recorded within the amblyopic eye of 6 cats, 3 with a convergent strabismus, 2 with a divergent strabismus and 1 with a cyclotropia. Measurements were made of the spatial resolution of 215 on-center cells for horizontal and vertical gratings. The spatial resolution of ganglion cells in the amblyopic eye of the strabismic animals to be comparable to those of normal cats at all retinal eccentricities. There was no evidence for a loss of resolution in the vicinity of the area centralis. Measurement of the cross-sectional area of cells in the lateral geniculate nucleus revealed no evidence of cell shrinkage in laminae receiving a projection from the amblyopic eye. The neural deficit responsible for the strabismic amblyopia in these animals did not lie in the retina but rather at more central levels of the visual pathway.