What is an EEG?

An electroencephalogram (EEG) is a test used to evaluate the electrical activity in the brain. Brain cells communicate with each other through electrical impulses. An EEG can be used to help detect potential problems associated with this activity.

An EEG tracks and records brain wave patterns. Small flat metal discs called electrodes are attached to the scalp with wires. The electrodes analyze the electrical impulses in the brain and send signals to a computer that records the results.

The electrical impulses in an EEG recording look like wavy lines with peaks and valleys. These lines allow doctors to quickly assess whether there are abnormal patterns. Any irregularities may be a sign of seizures or other brain disorders.


What is a visual evoked potential (VEP) vision test?

The Diopsys® VEP vision test is a painless, safe, non-invasive way for your eye care provider to objectively measure the function of your entire vision system.

When light from an image enters your eye, it is turned into electrical energy by cells in the retina – the light-sensitive layer at the back of your eye. These cells send the electrical energy back to the visual cortex, the part of your brain where the image is processed.

VEP, or Visual Evoked Potential, uses visual stimuli from a computer screen in different patterns and contrasts to elicit the electrical response from your retina. The electrical energy is then sent to your visual cortex, where the Diopsys® VEP vision test records the electrical signal, and creates a report for your doctor. It is similar to an EKG, but for your entire vision system.


How do I prepare for the VEP test?

Your face and hair should be clean, dry, and free of any gels, sprays, oils, makeup, or lotion.


How is the Diopsys® VEP vision test done?

A technician will clean and dry three small areas on your head, and then place sensory pads on the cleansed areas.

The technician will ask you to cover one eye at a time while the VEP vision test is being run.

Once the test begins, you will see black and white patterns that appear to “flip” quickly over and over again on a computer screen. You will be asked to focus on the pattern during the test. The computer will record the electrical energy that reaches the visual processing center of your brain and produce a report for your doctor.