Monitoring optic nerve function during craniotomy.

During surgical removal of a pituitary adenoma, conduction in the anterior visual pathways was monitored by continuous recording of visual evoked responses (VER). The method employed a scleral contact lens with an embedded flashing diode for delivery of visual stimuli. Evoked potentials of nearly normal latency, amplitude, and form were recorded from occipital scalp electrodes immediately after the optic nerves were decompressed. Restoration of the VER was correlated with restoration of normal vision.