Correlation of CAT scan and visual field defects in vascular lesions of the posterior visual pathways.

Thirty-nine patients with various types of isolated homonymous hemianopias resulting from ischaemic lesions in the posterior parts of the cerebral hemisphere was examined by CAT scanning. Most had localised low density lesions withing the distribution of the posterior cerebral artery. The location of the lesion (deduced from a separate anatomical study of postmortem brain cut in the plane of the CAT scanner) was correlated with visual field defects. Lesions giving rise to quadrantic defects were smaller than those causing total hemianopias; lower quadrantic defects tended to occur in superior cuts and vice versa. Macular sparing was associated with survival of the occipital pole in some instances. Bilateral cases had a higher prevalence of associated defects.