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Updated: Jun 7, 2026
Stimulus-specific Cortical Visual Evoked Potential Morphological Patterns
Published on: May 12, 2019
When do asymmetrical full-field pattern reversal visual evoked potentials indicate visual pathway dysfunction in
Tessa B Mellow1, Alki Liasis, Ruth Lyons
1Clinical and Academic Department of Ophthalmology, Great Ormond Street Hospital for Children, London, UK.
Insights
Half-field pattern reversal visual evoked potentials (pVEPs) can clarify full-field asymmetries in children. This testing is valuable for diagnosing visual pathway dysfunction when full-field results are unclear.
Area of Science:
- Ophthalmology
- Neuroscience
- Pediatric Vision
Background:
- Visual evoked potentials (VEPs) assess the visual pathway's integrity.
- Transoccipital asymmetries in pattern reversal VEPs (pVEPs) can indicate visual dysfunction.
- Understanding these asymmetries in children is crucial for diagnosis.
Purpose of the Study:
- To investigate the association between full-field and half-field pVEP transoccipital asymmetries in children.
- To determine if half-field pVEP distributions can explain observed full-field asymmetries.
Main Methods:
- Monocular full-field and half-field pVEPs were recorded in 46 children.
- Electrodes were placed at Oz, O1, and O2, referenced to Fz.
- Data were analyzed to categorize asymmetry and assess half-field contributions.
Main Results:
- 17% of patients had symmetrical full-field pVEPs; four of these showed half-field deficits.
- Among 38 patients with asymmetrical full-field pVEPs, 44% exhibited a half-field deficit.
- 53% showed symmetrical half-field responses despite full-field asymmetry.
Conclusions:
- Half-field pVEPs are effective in explaining full-field pVEP asymmetries in pediatric patients.
- This method should be considered for children with suspected visual pathway dysfunction who can cooperate.
- Half-field pVEP testing aids in the detailed assessment of visual pathway integrity in children.
Abstract:
Our study aimed to find out the association between full-field pattern reversal visual evoked potential (pVEP) transoccipital asymmetries and half-field pVEP transoccipital distributions in children. Over a six-month period, 46 patients (mean age: 9 years 9 months) had both monocular full-field and half-field pVEPs to test checks subtending 50 min of arc in a 35 degree full-field and 0-17.5 degree lateral half-field. Silver-silver chloride electrodes placed at Oz, O1 and O2 were referred to Fz. Monocular full-field data were categorised according to the degree of transoccipital asymmetry. Half-field data were measured and summated to see whether they explained any full-field asymmetry. In this cohort of 46 patients, eight (17%) patients had symmetrically distributed monocular full-field pVEPs for each eye. Four of these patients had normal half-field pVEP distributions for each eye, but the other four showed a half-field deficit in one or both eyes. Of the 38 patients with asymmetrically distributed full-field pVEPs in at least one eye, 17 (44%) patients showed a half-field deficit, 20 (53%) showed responsive, but symmetrically distributed half-field responses, and one patient (3%) showed typical half-field distributions. Half-field pVEPs can help explain full-field asymmetries and should be attempted in any child able to co-operate with testing and in whom visual pathway dysfunction is suspected.
