Visual Evoked Potential Testing

visual evoked testing

At Trinity Eye Care, we offer the latest in diagnostic testing to ensure that your eyes and vision have the best possible care and treatment. That is why we offer Evoked Potential Testing. This cutting-edge testing helps to measure the brain’s response from a visual context to the primary visual cortex. This test can help to identify issues that are associated with problems in the optical nerve and the primary visual cortex. These issues can affect the shape and timing of the Visual Evoked Potential or VEP response.

Understanding The Test

The VEP test is a painless and straightforward procedure. It involves the placement of three electrodes on the scalp to help measure electrical activity. The electrode that measures the actual response is placed directly over the primary visual cortex, located toward the back of the head. The second electrode is placed at a reference point, typically on the forehead or top of the head. The third and final electrode is attached to the ear. This electrode is considered the ground. All of the readings from the VEP test electrodes are transmitted to the LKC visual electrodiagnostic test system.

The test is then conducted by creating a visual stimulus that is designed to evoke a response from the primary visual cortex. The amplitude of the stimulus is generally very small. Due to this low amplitude, it is necessary to receive multiple signals and then average those to get an accurate reading and determine the presence of a condition.

Many studies suggest that there is significant variability that can occur between patients due to the thickness in skulls, the morphology or shape of the visual cortex, and the specific placement of the electrodes. This means that its numbers cannot be directly compared between patients and that interpreting the results must be done by professional staff with the skill and training to conduct the VEP Test. Trinity Eye Care offers experts in the field to make sure that we accurately identify any issues and can help lead you toward the best treatment options available.

How The Test Works

There are a few different types of VEP tests used that each stimulates the visual cortex. One of these tests is called the pattern test. Typically, this test utilizes a screen that shows a black and white checkerboard pattern. The pattern alternates at around 2 Hz, and every time it alternates a measurement can be taken based on the patient’s electrical response. The pattern test is one of the most common tests used, but can only be done on patients who are conscious.

In contrast with the pattern test, the flash test can be used on patients who are uncooperative, or unconscious. This test utilizes flashes and then measures the electrical response. In this test, the variation in the electrical response is within the variation of the stimulus that is used.

Identifying Conditions

The VEP test can help to diagnose a wide range of potential issues. The VEP test may be used as just one part of an overall diagnosis to help your medical team identify the underlying issue. However, some examples of issues that are diagnosed or times when VEP are used are:

  • Multiple Sclerosis or MS

  • Optic Neuritis

  • Optic Nerve Disorders

  • Compressive Optic Neuropathy

  • Malingering

  • Unexplained Visual Acuity Loss

  • Evaluation of the Visual Cortex in advance of surgery.


If you think that you may have one of these conditions, or are interested in how Trinity Eye Care can benefit you or your family, call today to schedule an appointment. Our professional staff has a wide variety of tools to identify and treat issues associated with your optical health. Call Trinity Eye Care in Plano, TX today to see the difference we can make (972) 895-9260.