The visually evoked response (VER) or visually evoked potential (VEP), measures the electrical response of the brain’s primary visual cortex to a visual stimulus. To measure the electrical response, electrodes are placed on the scalp. The electrodes connect to an electrodiagostic test system. When a visual simulus is presented, an evoked response is created from the visual cortex. The response is detected by the electrodes and sent to a special diagnostic computer.