Subclinical optic neuropathy in multiple sclerosis. How early VER components reflect axon loss and conduction defects in optic pathways.

The pathological effect of multiple sclerosis in the visual pathways consists of axonal demyelination and axonal loss. These two consequences of the disease, even in its subclinical stages, are reflected in changes in the initial component of the visual evoked response (VER) affecting its latency, configuration, or both. These abnormal early components of the VER were recorded in 25 patients with multiple sclerosis, only 10 of whom had any indication of visual involvement that could be documented historically or by conventional ophthalmic investigation.