Intraoperative Continuous Flash Visual Evoked Potentials Monitoring During Endoscopic Skull Base Surgery

During the surgery, a pair of goggles (similar to the swimming goggles) will be placed on patient's closed eyes. The goggles equipped with red LEDs will apply no pressure or minimal pressure on patient's closed eyes. Patient's left eye then right eye will be stimulated with flashing red light emitted by the goggles. Two subdermal needle electrodes will be placed under the skin behind patient's ears, and one subdermal needle electrode will be placed under the skin above the bridge of patient's nose. The two electrodes placed behind patient's ears, will record intraoperative flash visual evoked potentials (FVEPs) resulted from red light stimulation of patient's visual pathway through the eyes and the electrode above the bridge of the nose will record, at the same time, the activity of each eye's retina.