The Diopsys® NOVA-VEP allows clinicians to objectively assess vision disorders earlier than traditional vision tests because it uses Visual Evoked Potential (VEP) technology and proprietary software to evaluate the entire vision system from the eye to the visual cortex. “VEP is an objective, functional test that can help discriminate between healthy and glaucomatous eyes,” says Alberto González García, M.D., neuro-ophthalmologist and Research Director at Diopsys, Inc., the device manufacturer. Eye care professionals may use VEP in addition to traditional testing methods to enhance diagnosis and treatment.
Glaucoma is the second leading cause of blindness in the world, reports the World Health Organization. According to Prevent Blindness America, glaucoma is often called the "sneak thief of sight" because half of all patients who have it do not know it. Many optic nerve disorders are asymptomatic since central vision may not be affected until later stages of the disease. Also, diagnosis and management of optic nerve disorders are often based on structural or visual field tests which are limited in their ability to detect disease early.
Here are some common questions and answers about the VEP.
Q: Why would my doctor order the VEP procedure?
A: The VEP is used primarily to determine how well each eye sends its signals through the optic nerve to the brain. VEP has been demonstrated to aid in the diagnosis and treatment of many disorders including amblyopia, brain injury, stroke, multiple sclerosis, and other vision-related issues.
Q: How is the VEP recorded?
A: The VEP is the visual version of the EEG (electroencephalogram), and is recorded with three electrodes that are briefly pasted to the front, middle and back of the head. It is non-invasive and very safe.
Q: How much time does the VEP take?
A: About 30 minutes total, though obtaining the recordings once we're ready is a matter of only 10 or 60 second of looking at a checkerboard pattern on a screen for each recording.
Q: What if my child can't pay attention?
A: There are cartoon pictures that we interpose to help. Sometimes an assistant will tap the screen. In fact, there is a version of the VEP that we use to help evaluate infants. Features of the VEP can even give us objective information about visual attention. It might be helpful to bring a favorite item such as a blanket, pacifier, or toy to make them feel more comfortable during the test.
Q: Is there any special preparation needed?
A: It helps to get a good night's sleep before, and to shampoo the hair before coming in. We clean a few areas of the scalp carefully before applying the electrodes with some paste, so the scalp is a little sticky when we're done.
Q: Does insurance pay for this test?
A: Many carriers do reimburse for this procedure.