The VEP measures the time that it takes for a visual stimulus to travel from the eye to the occipital cortex. It can give the doctor an idea of whether the nerve pathways are abnormal in any way. A visual evoked potential, or visual evoked response (VEP or VER) is a test that measures the integrity of the optical pathway from your eyes to the occipital lobe of your brain. It is used to determine if there is any damage to this pathway that may be causing certain visual symptoms.