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Updated: Jun 21, 2026
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Multifocal Electroretinograms
Published on: December 4, 2011
The influence of defocus on multifocal visual evoked potentials
Christina Pieh1, Michael B Hoffmann, Michael Bach
1Sektion Funktionelle Sehforschung, Universitäts-Augenklinik, Killianstrasse 5, 79106 Freiburg, Germany.
Summary
Optimal refraction is crucial for accurate multifocal visual evoked potential (mfVEP) testing. Optical defocus significantly impacts central mfVEP responses, highlighting the need for precise visual correction in cortical response assessments.
Area of Science:
- Ophthalmology
- Neuroscience
- Visual Science
Background:
- Optical factors can influence electrophysiological measures of visual function.
- The multifocal visual evoked potential (mfVEP) assesses cortical responses to visual stimuli.
- Understanding the impact of refraction on mfVEP is essential for reliable clinical interpretation.
Purpose of the Study:
- To investigate the influence of dioptrical defocus on multifocal visual evoked potential (mfVEP) recordings.
- To compare mfVEP responses under optimal refraction versus varying levels of defocus.
Main Methods:
- Monocular mfVEPs were recorded from eight normal subjects using a VERIS system with dartboard stimuli.
- Recordings were obtained with best-corrected visual acuity and with +1.0, +2.0, and +3.0 D of defocus.
- Signal-to-noise ratio (SNR) was calculated for each mfVEP response.
Main Results:
- Defocus significantly reduced central mfVEP responses (by ~60%) at +2.0 D and higher, corresponding to reduced visual acuity (<0.3).
- Optical defocus had minimal impact on mfVEP responses at eccentricities greater than 7 degrees.
- The effect of defocus on mfVEP amplitude was eccentricity-dependent.
Conclusions:
- Optimal refraction is necessary for accurate assessment of cortical responses using mfVEP.
- Unlike multifocal electroretinography (mfERG), mfVEP is highly sensitive to refractive error.
- These findings underscore the importance of precise visual correction in mfVEP testing.
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