by EBSCO Medical Review Board


A visual evoked potential test (VEP) measures electrical activity in the brain when a person is exposed to brief visual stimuli.

Optic Nerve and Muscles
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Reasons for Test

This test is done to:

  • Diagnose and monitor multiple sclerosis (MS)
  • Test vision in children and adults who are unable to read eye charts
  • Look for signs of optic nerve damage, tumors, or neuritis

Possible Complications

There are no complications from having this test.

What to Expect

Prior to Test

The care team may meet with you to talk about:

  • Washing your hair before the test.
  • Avoiding hair chemicals such as hair sprays and gels

Description of Test

Wires will be attached to your scalp with tape. A patch will be placed over one eye. You will watch a screen with your other eye. The process is then repeated with the opposite eye covered. A machine will record your brain wave activity.

The wires will be removed from your head.

How Long Will It Take?

About 45 minutes

Will It Hurt?

This test will not hurt.


The doctor will discuss the results of the test with you.

Call Your Doctor

Call your doctor if you have any questions or concerns after the test.

If you think you have an emergency, call for medical help right away.


National Eye Institute 

National Multiple Sclerosis Society 


Canadian Association of Optometrists 

Canadian Ophthalmological Society 


Evoked potentials (EP). National Multiple Sclerosis Society website. Available at: Accessed October 1, 2020.

National Institute for Health and Care Excellence (NICE). Management of multiple sclerosis in primary and secondary care. NICE 2014 Oct:CG186.

Sensory evoked potentials studies. Johns Hopkins Medicine website. Available at:,P07658. Accessed October 1, 2020.

Visually evoked potentials. Webvision website. Available at: Accessed October 1, 2020.

Revision Information

  • Reviewer: EBSCO Medical Review Board Rimas Lukas, MD
  • Review Date: 09/2020
  • Update Date: 05/25/2021