Hysterical hemianopia. The 'missing half' field defect.

Hysterical hemianopias are uncommon and usually occur in association with other lateralized complaints. The most frequent pattern consists of decreased vision in one eye, an ipsilateral hemianopia on testing the "affected" eye, full fields in the other eye, and a complete hemianopia toward the affected side on testng with both eyes open. The incompatibility of the monocular and binocular fields quickly demonstrates the functional nature of this alleged visual loss.