To report a case of functional bilateral hemianopia which was not associated with any organic causes.

A 35-year-old female patient presented with bilateral disturbance of visual acuity and visual field, which had begun 8 months prior. Goldmann perimetry showed bitemporal hemianopsia respecting the vertical meridian. Pupillary response was normal, and the anterior segment, fundus, and optic nerve were also normal bilaterally. However, the tangent screen test and Humphrey visual field test showed a widening of hemianopia not respecting the vertical meridian, and the crossing of isopters at 1 m and 2 m with the tangent screen test. In addition, multifocal electroretinogram and multifocal visual evoked potential did not reveal any abnormal findings corresponding to the bitemporal hemianopia. Brain magnetic resonance imaging showed no abnormal findings in the orbit and brain.

Bitemporal hemianopsia can be developed functionally, although it may be rare. Repetition of various visual field tests and use of multifocal electrophysiologic studies can be helpful in the differential diagnosis.