THE CENTRAL VISUAL SYSTEM

Abstract

It has been consistently demonstrated that unilateral occipital lobectomies in man result in homonymous hemianopia with sparing of central vision. 1 This has also been my experience in 5 cases of occipital lobectomy. It has also been adequately demonstrated that lesions which destroy the posterior aspect of the temporal lobe down to the temporal horn produce complete homonymous hemianopia. 1b The explanation of these findings with reference to the mechanism of central vision is controversial. In short, two schools have evolved. One proposes that macular vision is bilaterally represented. 2 The geniculostriate fibers subserving macular vision not only lead to the visual cortex of the same side but send collaterals through the splenium of the corpus callosum to the opposite visual cortex. The latter fibers are far enough anterior to escape injury by an occipital lobectomy, provided the coronal plane of excision is not carried farther forward than the posterior tip of