We have invested in an advanced technology called

Visual Evoked Potential (VEP) that allows our eye doctors to diagnose vision problems and neurological disorders.

What is a visual evoked potential? (VEP)

A visual evoked potential is a non-invasive test used by our eye doctors to measure the response of the brain to visual information. We use the VEP test at American Family Vision Clinic to have a deeper understanding of the visual system and to identify mechanical or neurological obstructions to the visual process. It is often used to diagnose vision problems and neurological disorders, such as multiple sclerosis and brain tumors.

What conditions can the VEP detect?

Visual evoked potential (VEP) tests are often used to diagnose vision problems and neurological disorders that affect the optic nerve and visual pathways. Some conditions that can be detected with a VEP test include:

Optic neuritis: inflammation of the optic nerve, which can cause vision loss and color perception problems

Multiple sclerosis: is a chronic neurological disorder that affects the brain and spinal cord. Learn more about multiple sclerosis here.

Brain tumors: abnormal growths that can disrupt the normal functioning of the brain

Glaucoma: a condition that damages the optic nerve, leading to vision loss. Learn more about glaucoma here.

Cortical blindness: a rare condition in which the visual cortex, the part of the brain responsible for processing visual information, is damaged or not functioning properly

Amblyopia: a vision development disorder in which the brain and eye do not work together properly. Learn more about amblyopia here.

VEP tests may also be used to assess the effectiveness of treatment for these conditions or to monitor their progression. 

If you have been diagnosed with any of these conditions or you think you might be at risk, please schedule an eye exam with our eye doctor in Olympia.

What can you do to prepare for a VEP test?

To prepare for a visual evoked potential (VEP) test, you should:

  • Avoid caffeine and other stimulants: Avoid caffeine and other stimulants for a few hours prior to the VEP test since they can affect the results.
  • Follow your doctor's instructions: Your doctor might require you to avoid certain medications or to stop eating for a specific period of time before the test. For accurate test results, it's important to carefully follow these instructions.
  • Bring a list of your medications: Some medications may affect the results of your VEP test, so it's important to tell your doctor about them.
  • Arrange for transportation: After the VEP test, you may be given eye drops or other medications that may affect your vision or make you drowsy, so arrange for someone to drive you home.

How does a VEP work?

During a visual evoked potential (VEP) test, the patient sits in a chair facing a computer screen and watches a series of visual stimuli such as flashing lights or a checkerboard pattern. Electrodes are placed on the patient's head to measure the brain's electrical activity in response to the stimuli. The test takes about 30 minutes to an hour and is non-invasive and painless. The patient may be asked to wear special glasses or to focus on a specific point on the screen and should try to stay still during the test to ensure accurate results.

If you would like to learn more about the VEP, call us at (360) 491-2121.

What factors may influence VEP?

There are several factors that can influence the results of a visual evoked potential (VEP) test:

Age: The VEP test may be less reliable in older adults, as the visual pathways may become slower with age.

Medications: The use of drugs that cause drowsiness or are administered as an anesthetic can significantly influence the results of a visual evoked potential (VEP) test. If you have taken any medications that may affect your alertness or level of consciousness, it's important to let your doctor know before the test.

Eye movement: If you move your eyes during the test, it can affect the accuracy of the results. It's important for you to try to remain as still as possible during the test.

Light sensitivity: You may be sensitive to the flashing lights used in the VEP test, which can affect the accuracy of the results. It's important to let your doctor know if you are sensitive to light before the test.

How do VEP results indicate different visual and neurological conditions?

Visual evoked potential (VEP) results can indicate different visual and neurological conditions by showing abnormalities in the speed and timing of the brain's response to visual stimuli. Abnormal results may suggest a problem with the optic nerve or visual pathways, such as inflammation, damage, or a neurological disorder. By analyzing the specific findings of the VEP test, doctors can determine the cause of the problem and the best course of treatment.

The following conditions may cause abnormal results on a visual evoked potential (VEP) test:

Optic neuropathy 

Optic neuropathy is a condition in which the optic nerve is damaged. This damage can be caused by a variety of factors, such as a blockage of the nerve's blood supply, nutritional deficiencies, or toxins. As the nerve is damaged, the transmission of electrical signals is impaired, leading to problems with vision. Examples of conditions that can cause optic neuropathy include advanced stages of diabetes, which can damage the blood vessels and nerves supplying the eyes, and toxic amblyopia, a condition in which vision is decreased due to a toxic reaction in the optic nerve.

Tumors or lesions compressing the optic nerve

If the optic nerve is compressed by tumors or lesions, the pathway for conducting signals may be affected, leading to abnormal results on a visual evoked potential (VEP) test. Compression of the optic nerve can interfere with the transmission of electrical signals and cause problems with vision.


Glaucoma is a condition in which the pressure inside the eye (intraocular pressure) is higher than normal. This increased pressure can damage the optic nerve, leading to prolonged results on a visual evoked potential (VEP) test. Prolonged VEP results may indicate that the optic nerve is not functioning properly and that further evaluation is needed to diagnose and treat the problem.

Ocular hypertension (high eye pressure)

It is a condition in which the intraocular pressure inside the eye is higher than normal. While there may be no signs of glaucoma, patients with ocular hypertension may be at increased risk of developing glaucoma later in life. Patients with ocular hypertension need to have regular eye exams to monitor the pressure inside the eye and identify any potential problems early on.

Does the VEP test cause any side effects?

As a painless and non-invasive test the Visual Evoked potential is generally without side effects and well tolerated. The vast majority of patients undergoing the visual evoked potential (VEP) test well and experience no discomfort or side effects. Patients may experience a mild headache or eye strain after the test, but these symptoms usually go away on their own and do not require treatment.
Patients with prior seizures or epilepsy may experience a seizure as a result of the VEP test in rare cases. Be sure to inform your eye doctor about your history of seizures and any medications you are taking that may increase your risk of seizures before taking the test.
Overall, the VEP test is a safe and effective way to assess the function of the optic nerve and visual pathways. If you have any concerns about the test, please schedule an appointment by calling (360) 491-2121.

Advanced testing with a VEP for Optic neuritis, Multiple sclerosis, Brain tumors, Glaucoma, Cortical blindness, Amblyopia

The VEP is an important test that is very good at detecting problems with the optic nerve and lesions in the anterior part of our visual pathway before the optic nerves merge. However, it is a non-specific test, and to determine the exact underlying problem in each patient, a good history and examination are also very important.
To schedule a VEP test, you can call us at (360) 491-2121 or fill out this form Book an Appointment . Patients searching for advanced medical eye care visit our clinic from all over Washington. We are proud to be a leading provider of medical eye care services for patients from Olympia, Lakewood, Tacoma, and Lacey.


Such a nice optician. My grandson is only 4 and needs glasses. We were so sad, but he explained the issues, and we will follow up as he suggested.

Anna P.

I had such a good experience with the clinic. Very friendly staff and doctor, did not have to wait for long to be called, and was treated respectfully. Thanks, American Family.

June S.

Dr. Zurcher has gone above and beyond what any other eye doctor has ever done to figure out what is going on with my eyes. Very happy with American Family Vision.

Christine R.

Family Vision Clinic changed our lives! My daughter was frequently car sick, and she was getting headaches every day, often painful enough that they brought her to tears. We saw a string of doctors and therapists, but we made no progress. Finally, we found Dr. Levi Zurcher and his eye therapist Rain. After ten weeks of eye therapy my daughter no longer gets headaches, and she no longer gets car sick. Daily tears are a thing of the past. I really can’t say enough about this clinic. It was fascinating to watch Dr. Zurcher work. For the first time, someone who knew what they were doing was intently studying my daughter, really trying to figure out all of her eye issues, and his therapist Rain is one of the most patient and lovely people that I’ve ever had the good fortune to meet. We’re finished with eye therapy—yay!—and I have switched to American Family Vision Clinic for all of my family’s other eye health needs.

Lars Wulff

Very professional, yet kind and helpful. They do what they can to make the appointment comfortable. I was running a bit late, I made sure ti call. They were able to switch me with a patient who was already there, they treated me with respect, and helped my son have confidence by getting him the eye care he needed that day. Thank you so much! Would recommend to anyone. It's a blessing that they care enough to work with people who have all different types of insurance from work to state coverage.

Justin E.

The staff is friendly. The Doc is very knowledgeable. The office is family friendly and everyone is so patient with the little ones.

Amy Fagerness
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