What is VEP?

A visual evoked potential, or visual evoked response (VEP or VER) is a test that measures the integrity of the optical pathway from your eyes to the occipital lobe of your brain. A VEP shows if the brain is receiving information from the child’s eyes.It is used to determine if there is any damage to this pathway that may be causing certain visual symptoms.

What does the VEP detect?

VEP uses visual stimuli from a computer screen in different patterns and contrasts to elicit the electrical response from your retina. The VEP measures the time that it takes for a visual stimulus to travel from the eye to the occipital cortex. It can give the doctor an idea of whether the nerve pathways are abnormal in any way.

How to prepare Child for a VEP test

  • Wash your child’s hair, but avoid hair chemicals, oils and lotions.
  • Make sure the child gets plenty of sleep the night before and is awake and co-operative for the test.
  • If you wear glasses, make sure you bring these along with you to the test.
  • Give the child a normal meal and usual medications prior to the test. However any medications that may make the child sleepy should be avoided.
  • If the child wears glasses or contact lens, they should be worn during the test.
  • Arrive on time so that the child is relaxed before the test.
  • On the day of the test, you should also let the technician know if you have any eye conditions such as cataracts or glaucoma as this can affect the test and should be noted in your records by the doctor.

What happens during a VEP test?

The procedure is very safe and non-invasive.

  • Firstly, some wires will be glued to the top of your head to detect the brain waves.
  • A technician will give you further instructions on what to do during the test. Normally, each eye will be tested separately.
  1. There are two types of VEP test that can be done: pattern VEP and flash VEP. In younger children, who cannot co-operate, usually Flash VEP is done. In older children, pattern VEP is done.
  • Goggles will be put on and child should be lying down or in parent’s lap.
  1. Older Children will be sitting and will be asked to look at a screen similar to a television screen, with various visual patterns.
  • Readings will be recorded through the wires on top of your head.

After the test

  1. After the procedure, the glue and wires are removed from your child’s head. You can wash the hair with shampoo.
  2. Your doctor will discuss the results of the test with you after they have been analysed 3. Usually the procedure takes about 30 to 45 minutes.