Hemifield slide from traumatic optic chiasmopathy.

A 56-year-old man suffered a high velocity linear acceleration closed head injury, resulting in skull fractures including bone dehiscence at the planum sphenoidale and tuberculum sellae. After regaining consciousness, he reported blurry vision and episodic diplopia. Visual field testing showed a bitemporal hemianopia. Ocular motility testing uncovered no misalignment. Brain MRI revealed post-traumatic encephalomalacia within the optic chiasm, resulting in the visual field defect and subsequent hemifield slide. Normally, cerebral processing of overlap between the visual fields prevents hemifield slide, which is caused by episodic loss of visual field overlap with subsequent slipping or sliding apart of images.