Occipital Visual Field Defects Respecting the Horizontal Meridian: A Hallmark of Extrastriate Cortical Lesions

Rarely examples are encountered in clinical practice of homonymous visual field defects that respect the horizontal meridian. Holmes reported pure quadrantic hemianopia resulting from penetrating missile wounds to the occipital. He recognized that gross Injury to the upper or lower bank of the calcarine sulcus should not produce a field cut with a sharp horizontal margin, He attributed quadrantic defects to lesions off the optic radiations, suggesting that fibers representing the upper and lower hemiretina are separated by an anatomical interval. Ronne hypothesized that this Interval is filled with fibers corresponding to the macula.