The VEP test costs very little to perform–about $2 per tests when taking into account the disposable electrodes, the prepping gel and the conductive paste. The VEP takes approximately 10 minutes to get the patient set up and to perform the test on both eyes, much better than some of the field tests.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. … This means that it takes a longer time for electrical signals to be conducted from the eyes, resulting in an abnormal VEP.Evoked potential test and results. Evoked potential tests measure the time it takes for the brain to respond to sensory stimulation either through sight, sound, or touch. Doctors use the test to help diagnose multiple sclerosis (MS) and other conditions that can cause a person’s reactions to slow.