Electrodiagnostic assessment in optic nerve disease.

PURPOSE OF REVIEW: Complementary electrophysiological techniques can be useful in detecting and localizing dysfunction within the visual pathway. Recent developments are outlined in the context of neuro-ophthalmology.

RECENT FINDINGS: The relationship between nerve fibre layer anatomy and the pattern visual evoked potential has been addressed, correlating axonal loss with visual pathway dysfunction. Longitudinal assessment of multiple sclerosis patients has defined parameters affecting the utility of the pattern visual evoked potential as an outcome measure in potential treatment trials. In optic nerve tumours, the pattern visual evoked potential may help identify and monitor the disorder. The pattern electroretinogram assesses retinal ganglion cell function and can identify macular dysfunction, possibly mimicking optic nerve disease clinically. The spatial extent of macular dysfunction can be assessed using the multifocal electroretinogram. Objective visual evoked potential assessment of visual acuity can be important in the management of nonorganic visual loss. The multifocal visual evoked potential is a relatively new technique that is attracting increasing research interest, particularly as a measure of visual field loss, but has yet to be established as a reliable diagnostic tool.

SUMMARY: Electrophysiology, combined with clinical and imaging investigations, is a powerful diagnostic and monitoring tool. Macular dysfunction can mimic optic nerve disease in the absence of fundus abnormality.