Entoptic [corrected] phenomena in pregeniculate and postgeniculate hemianopsia with splitting of macula by perimetry.

With splitting of macula by perimetry, the entopic phenomena (the perception of one's own foveal xanthophilic pigment and macular vessel leukocytes) were utilized to study the character of macular sparing or splitting in patients with pregeniculate or postgeniculate hemianopsia. In the pregeniculate group, 11 of 14 eyes perceived the Haidinger brushes figure as a half circle corresponding to the perimetric macular splitting, whereas flying corpuscles were not perceived at all or were less numerous on the hemianoptic side than on the normal field side. In contrast, six of seven patients with postgeniculate lesions perceived the Haidinger brushes figure as a complete circle, four of six perceived fewer flying corpuscles on the hemianoptic side than on the normal field side, and two patients reported perceiving an equal number in all quadrants. This study indicated that in pregeniculate hemianopsia there is usually a true splitting of the macula, whereas in postgeniculate hemianopsia, there is some macular sparing even when perimetry shows macular splitting.