A visual evoked potential test (VEP) measures electrical activity in the brain when a person is exposed to brief visual stimuli.
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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
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: https://secure.nationalmssociety.org/docs/HOM/evoked.pdf. 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: http://www.hopkinsmedicine.org/healthlibrary/test_procedures/neurological/evoked_potentials_studies_92,P07658. Accessed October 1, 2020.
Visually evoked potentials. Webvision website. Available at: http://webvision.med.utah.edu/book/electrophysiology/visually-evoked-potentials. Accessed October 1, 2020.
Last reviewed September 2020 by EBSCO Medical Review Board Rimas Lukas, MD Last Updated: 5/25/2021