Optokinetic nystagmus in homonymous hemianopia due to a strictly occipital lesion.

Optokinetic nystagmus (OKN) was tested in 15 patients with unilateral strictly occipital brain lesions and complete homonymous hemianopia and compared with findings in a group of normal controls. Quantitative analysis of the results in the patients revealed a bilateral disorder of OKN. When the stimulus was moved in the direction opposite to the hemianopic field, there was a significant decrease in optokinetic gain, and the amplitude of nystagmus decreased. There was no correlation between OKN and size of the residual macular field.