Visual Evoked Potentials (VEPs)
With VEPs, the patient is treated as a “black box” and the patient looks at checks (usually black and white) that pattern reverse – white checks to black and black checks to white at a specific reversal rate. The pattern reversal stimulus creates a change across the central retina and this change is transmitted via the optic nerve pathway to the occipital lobe. The response is measured from the back of the head with a surface electrode. (Two other electrodes, one a reference and the other a ground, are also used.)