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Visual Evoked Potential Test

(VEP)

Definition

A visual evoked potential test (VEP) is used to look for problems in the brain that affect vision. A machine records brain waves related to the nerves that make up the visual pathway. This test can evaluate a large part of the brain.

Optic Nerve and Muscles

Reasons for Test

This test is often used to:

Diagnose and follow multiple sclerosis (MS)
Test vision in children and adults who are unable to read eye charts

There are many symptoms that might lead your doctor to order a VEP. You may be having double vision, blurred vision, or loss of part or all of your vision.

Possible Complications

There are no major complications associated with this procedure.

What to Expect

Prior to Test

You will be given instructions to prepare for the test, such as:

Wash your hair. Avoid hair chemicals (eg, hair sprays, gels).
Get a good night’s sleep.
Bring your corrective eyewear.

Description of Test

Wires will be attached to your scalp with adhesive. 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.

The wires will be removed from your head.

After Test

You will be able to leave after the test is done.

How Long Will It Take?

About 45 minutes

Will It Hurt?

Results

Your doctor will discuss the results with you and any further treatment that may be needed.

Call Your Doctor

Call your doctor if you have any concerns.

In case of an emergency, GET MEDICAL CARE RIGHT AWAY .

RESOURCES

National Eye Institute http://www.nei.nih.gov/

National Multiple Sclerosis Society http://www.nationalmssociety.org/

CANADIAN RESOURCES

Canadian Association of Optometrists http://www.opto.ca/en/index.html

Canadian Ophthalmological Society http://www.eyesite.ca/

References

Evoked potential studies. St. John's Mercy Healthcare website. Available at: http://www.stjohnsmercy.org/healthinfo/test/neuro/TP014.asp . Accessed September 8, 2005.

Merck Medicus website. Available at: http://www.merckmedicus.com/pp/us/hcp/thcp%5Fraj%5Fcontent.jsp?pg=/ppdocs/us/hcp/content/raj/chapters/raj-ch-026-s003.htm . Accessed September 8, 2005.

Revision Information

Reviewer: Eric L. Berman, MD
Update Date: 00/22/2012

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.