The role of the corpus callosum in the development of interocular eye alignment and the organization of the visual field in the cat.

In young cats, the posterior portion of the corpus callosum was sectioned 13--29 days after birth. The animal's eyes were photographed at weekly intervals for six months using the pupil-reflex method. From the corneal reflection evident in the photographs the degree of alignment for the optical axes of each cat was estimated (Sherman, 1972). The 17 experimental cats all showed a significant tendency toward permanent divergent strabismus, as compared to six normal cats. The limits of the visual field were determined for both groups of cats using a perimetry technique similar to that of Sprague and Meikle (1965) and Sherman (1973). With one eye open normal cats responsed from 90 degrees ipsilateral to 45 degrees past the vertical midline into the contralateral visual field. With either eye the experimental cats responsed from 90 degrees ipsilateral to approximately the vertical midline. The loss of visual responsiveness is within the contralateral region of the normally binocular zone. Three cats received the same operation at 9, 13, or 20 months old. Eye alignment and visual field perimetry were unaffected by the surgery. It is not known whether the observed abnormalities result from arrested development, or disruption of intrinsically determined ocular alignment.