Quadrantanopia (quadrantanopsia), a defect in one quarter of the visual field, suggests an optic radiation lesion. Occipital lobe pathology is the most common cause of both inferior and superior quadrantanopias, although temporal lobe pathology damaging Meyer’s loop typically must be considered with a superior homonymous quadrantanopia ("pie-in-the-sky" defect). Parietal lobe lesions may produce inferior quadrantic defects, usually accompanied by other localizing signs. Damage to extrastriate visual cortex (areas V2 and V3) has also been suggested to cause quadrantanopia; concurrent central achromatopsia favors this localization.
Horton JC, Hoyt WF. Quadrantic visual field defects. A hallmark of lesions in extrastriate (V2/V3) cortex. Brain 1991; 114: 1703-1718 Jacobson DM. The localizing value of quadrantanopia. Archives of Neurology 1997; 54: 401-404