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VER & VEP

Services / Nuero Physiology / VER & VEP



VER & VEP

The Visually Evoked Response test (VER), also known as the Visually Evoked Potential test (VEP), is a test for Optic Neuritis or other demyelinating events along the Optic Nerve or further back along the optic pathways. VEPs are very sensitive at measuring slowed responses to visual events and can often detect dysfunction which is undetectable through clinical examination.

A doctor may recommend that you go for a VEP test when you are experiencing changes in your vision that can be due to problems along the pathways of certain nerves. Some of these symptoms may include:


Loss of vision (this can be painful or non-painful);

  • Double vision
  • Blurred vision
  • Flashing lights
  • Alterations in colour vision; or
  • Weakness of the eyes, arms or legs.

Procedures :

  • The VEP will take approximately 30 minutes to complete. The technologist at City X-Ray and Scan Clinic will begin by measuring the patients head and marking electrode positions with a non-toxic, washable marker.
  • These positions will then be rubbed with an exfoliating cream. Four electrodes will be applied using a conductive cream and cotton balls.
  • The technologist will then test the patient’s eye sight. If you wear corrective lenses be sure to bring and wear them to the test.
  • Then the lights will be turned off and the patient will be asked to focus on a dot in the middle of a black and white checkerboard screen.
  • The checkers will move back and forth, and for the best result the patient must remain focused on the dot in the middle. Each eye will be tested a few times.
  • Once the results are stored and printed correctly, the test is complete.
  • The results of the test will be interpreted by a specialist and the final report is sent to the ordering physician.

How to prepare :

  • 1. Please come with clean, dry hair with no hair gel or other hair products. We will NOT have to shave or cut hair for the test.
    (**If you are found to have LICE your test will be rescheduled after the lice have been treated.)
  • 2. It is helpful to bring a list of current medications as the technologist will ask what medications you are taking.
  • 3. If you wear corrective lenses, be sure to wear these when you come for the test. (glasses or contacts).
  • 4. Continue taking scheduled medications unless told otherwise by your physician. Continue eating and drinking normally before the test.
  • 5. Please report to admitting 30 minutes before your scheduled appointment time.
  • Late arrivals may necessitate rebooking for another date.

If you are going to be late due to traffic, road conditions, etc. Please call 011 47252000 to advise of your situation or rebook if necessary.

Frequently Asked Questions

Visual evoked potentials (VEP).
This test detects loss of vision from optic nerve damage. The patient is seated in front of a screen and focuses on the center, where a check board pattern is shifting. One eye is tested at a time and each eye is tested twice.
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. It is used to determine if there is any damage to this pathway that may be causing certain visual symptoms.