Saccadic latency as a measure of afferent visual conduction.

Latency to initiate a saccadic eye movement to a visual target, and visual evoked potential, were measured in seven patients with resolved unilateral optic neuritis. Saccades were delayed when the target was presented to the clinically involved eye, but were normal when the contralateral eye was tested. With binocular target presentation, saccades were symmetric between eyes and normal in latency. In two patients with pituitary adenoma and low-grade bitemporal field defects, saccades were delayed when targets were presented in the temporal field, but were within normal limits when presented in the nasal field. These results cannot be attributed to lesions in the motor pathways. It is concluded that saccadic latency to visual targets is a valid measure of afferent conduction. If the robust delays found in this study prove to have test-retest reliability, saccadic latency may provide a measure of afferent function which is sensitive to the demyelination that preceeds neuronal degeneration and sensitivity loss in patients suspected of having optic neuropathy.