Sweep Visual Evoked Potential Test
The Sweep Visual Evoked Potential (SVEP) test is used to measure visual acuity, that is, vision for detail and patterns.
In adults, visual acuity is measured with lines of letters. The SVEP measures acuity by assessing the response of brain waves to moving black and white stripes. The SVEP acuity test is, perhaps, most helpful in those youngsters for whom behavioral measures (Preferential Looking) give ambiguous or incomplete information about visual acuity.
How the test is done
To do this test, your child will be positioned to view a monitor. Moving ("sweeping") black and white stripes will be shown on the monitor. Your child may sit on your lap or in a chair.
The vision of the stripes is passed from the eye and along the visual pathways to the visual part of the brain. The SVEP is designed to find the finest black and white stripes that produce a reliable response.
For the test, small metal discs, about the diameter of the tip of the little finger, are placed on the head. The discs are connected to a computer by fine cables. The discs are held in place by a paste like toothpaste. Three discs are placed at the back of the head, one disc is placed on top of the head and one is placed on the forehead. A band is wrapped around the child's head to hold the electrodes in place during the test.
How long it takes
Although the test doesn't always take the full amount time, we allow an hour for the test to be done. This includes the time it takes to place the metal discs and to accommodate for wiggly or intermittently inattentive children. Often, because of the child's eye condition, it is important to test the vision of each eye separately. To do this, we place a patch over one eye while the other is being tested.
We know the visual acuity portion of the results at the time of the visit. After the recordings are completed, the records are analyzed and the final results are included in the written report of the visit. The report will be forwarded to you, and also to any of your child's doctors as designated by you. We are more than happy to discuss the report with you and your child's other physicians.
For more information
When you are here for the SVEP, we will show you the equipment and answer any questions you may have about the nature and purpose of the procedure. Please contact us at 617-355-5685, if you have any questions prior to the visit.