An unusual homonymous visual field defect.

A 75-year-old man suddenly became aware of an inferior right homonymous visual field defect. Although static perimetry suggested a lesion of the left lateral geniculate nucleus, kinetic perimetry indicated that the presumed homonymous horizontal sectoranopia noted on static perimetry was actually an incomplete homonymous hemianopia with incomplete sparing of the temporal crescent. The location of the lesion was subsequently confirmed by magnetic resonance imaging. This case shows the value of kinetic perimetry in assessing homonymous visual field defects.