Visually evoked response tests for issues of the optic nerve The visual evoked response test, also known as visual evoked potential test is a test used to determine whether a disease is the deletion of the myelin sheath along the optic nerve. Because of damage to the sheath is often overlooked by the patient due to lack of symptoms, evoked visual test is credited to clarify a number of diagnoses well in advance of symptoms that have been noticed.
There are a number of reasons that the myelin sheath along the nerve can be damaged. Optic neuritis and other demyelinating events such as multiple sclerosis can cause disturbances in the sheath without noticeable symptoms. Because of the visual evoked response test can detect silent lesions and even the episodes that have removed the sheath in the past, they are very useful diagnostic tools. A definitive diagnosis of MS requires at least two separate times that the myelin was removed or damaged in two different sites in the central nervous system that are separated by at least a month. Even when other tests such as MRI can not, visually evoked potential tests can often provide evidence of such occurrences.
The test is painless and consists mainly of the patient to be equipped with EEG sensors at different locations on their heads. One eye is tested while the other has a patch over one eye on her. The patient watches, and a lack and white checkerboard on a television screen in a darkened room. The black and white squares alternate in a regular cycle, generates electrical impulses along the optic nerve and brain.
Whenever the pattern on the TV screen is reversed there is a transmission along the optic nerve all the way through optical zones of the brain. When the signal is completely at the end of the optical channel, the time the signal took to arrive at the end is to be noted. If time is slower than normal (normal being about 100 milliseconds), then there is a problem along the optic pathway.
The cause for idle time on the visual evoked response test can be many things. white matter lesions along the way, optic neuritis, multiple sclerosis or even a deficiency in vitamin B12 can cause a slow time. Find this information is quickly and painlessly the visual evoked response test is useful and accurate diagnostic tools available for most issues in optical path.
Posted on March 6, 2010.
