Visual evoked potentials
Measurement of visual evoked potential (VEP) involves recording changes in brain activity due to visual stimulation. These changes are recorded by surface electrodes which measure changes in electrical fields. The investigation is performed in a central nervous system functional investigation laboratory in a hospital. It is performed by a technician or doctor.
VEP - the process
VEP may be indicated in two types of circumstances. Firstly, it may be used for ophthalmic purposes in people with a sudden loss of visual acuity or to investigate optic nerve damage. Secondly, the investigation is used in neurology to assess diseases such as multiple sclerosisor to assess the consequences of a cerebral vascular accident or head injury…
VEP - the procedure
The patient is seated comfortably in front of a television screen. The patient is then asked to fix their vision on an immobile black dot in the centre of the screen while a chequered board passes in front of his/her eyes. The investigation lasts approximately one hour and does not require any special precautions. The patient needs to keep calm and relaxed. Patients can return to their usual activities after the investigation without restriction, including driving.
Possible risks of VEP
No risks have been reported in the scientific literature for this examination.
Source: Patient education group André-Vésale, Montigny-le-Tilleul, website accessed on 18 February 2011.
The eye at the VEP centre. © Phovoir
Visual evoked potentials - 1 Photo