Visual electrophysiology (VEP) is an evaluation of the entire visual system from the retina to the primary visual cortex. It measures the conduction time of neuronal activity from the retina to the occipital cortex and is used clinically as a measure of the functional integrity of the visual system.
VEP was first described by Adrian et al2 in 1934 and has been used in clinical and research laboratories for almost 50 years. Indeed, it is the pioneering work of Halliday et al, 3, 4, 5 in the early 1970s that demonstrated that PEVs with reversal of pattern (PEVP) are often delayed in optic nerve demyelination. They were also the first group to report that VEP delays due to pattern reversal in optic nerve demyelination can occur without signs or symptoms of optic nerve involvement. For many years, visual electrophysiology laboratories around the world recorded PEVs using different techniques. Consequently, there were many divergent opinions on the neurophysiological basis of the components of the responses, the clinical utility of the technique, and the abnormalities associated with specific diseases.
Visual electrophysiology is a collection of advanced techniques used to test the functioning of cells along the full visual pathway – from the retina to the optic nerve to the primary visual cortex in the brain. ... These tests are used to help detect, diagnose and evaluate a variety of visual disorders.
ERG and VEP tests are a useful addition to a clinician’s arsenal. Visual electrophysiology testing can aid in the diagnosis of patients who exhibit:
The technology can also be useful in helping differentiate visual pathway disease in children and special needs patients who either cannot be examined with traditional testing or who are uncooperative for procedures such as visual field testing.