Visual Evoked Potential (VEP)

What's a VEP?

A visual evoked potential is an evoked potential caused by a visual stimulus, such as an alternating checkerboard pattern on a computer screen. Responses are recorded from electrodes that are placed on the back of your head and are observed as a reading on an electroencephalogram (EEG).

Visual evoked potentials (VEPs) are electrical signals generated by the visual cortex in response to visual stimulation. VEPs are elicited by light flashes or by patterned stimuli and recorded from occipital electrodes. Visual acuity can be estimated using patterned stimuli, but patterned VEPs are not always feasible in the assessment of neonates. In newborn infants with visual imparement, VEPs are not recordable or only recordable in response to large patterns or flashes. Flash VEPs are used easily in the NICU and can be recorded as soon as several days after birth in preterm and term infants.

When measuring VEPs in preterm infants, the GA of the infant at birth and its postmenstrual age need to be taken into account, as maturation in the visual system is accelerated in preterm infants. Abnormal VEP findings are reliable measures of hypoxic–ischemic encephalopathy. In addition, VEPs have been associated with later neurodevelopmental outcome in term newborns with asphyxia and in preterm newborns, although the findings for the latter group are more variable.

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