Department of Neurology
Department of Neurosurgery
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Visual Evoked Potential Test (VEP)
University of Iowa Department of Neurology
Peer Review Status: Internally Peer Reviewed
Creation Date: 1999
Last Revision Date: March 2004
A VEP test evaluates the visual pathways in your brain. During the test, you watch a video monitor with a moving pattern. Watching the moving pattern produces electrical activity in your brain that is measured by several electrodes attached to your head.
What is it?
- The test evaluates the visual pathways in your brain.
- It checks on the health of the "internal" parts of your visual system.
How long does it take?
How many are conducted each year?
Why is a VEP performed?
- It is used if you are experiencing double vision, blurred vision, loss of part or all of your vision, eye injuries, head injuries, or weakness of eyes, arms, or legs.
Where is it conducted
- The EEG and Evoked Potential Labs.
- Lower Level of Carver Pavilion.
Does it hurt?
- No, you will experience no pain or discomfort.
- The VEP is not a vision test such as is done for glasses, nor is it a treatment of any kind.
What should you do to prepare for the test?
- Wash your hair before coming to the test. Do NOT use sprays, oils, or dressings of any kind.
- Eat normal meals.
- Continue taking prescribed medications unless given other instructions by your doctor.
- Bring glasses or contact lenses with you if you wear them.
- Come well rested so you can be alert during the test.
How is the VEP performed?
- After your head is measured, electrodes are glued on specific locations on your scalp.
- Nothing goes into or under your skin.
- Each electrode is checked with a meter to ensure proper functioning.
- A patch will be placed over one of your eyes.
- You will recline in a special chair and be asked to stare at a little red dot on a video monitor.
- Each eye will be tested separately.
Following the test
- The electrodes are removed with acetone, which dissolves the glue and leaves your hair and skin intact.
- You may wash your hair when you wish.
- You may return to your hospital room or home, unless your doctor gives you other instructions.
- You will learn the test results either from the doctor before you leave, or from a copy of the letter sent to your personal physician.