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Electrode position and the multi-focal visual-evoked potential: role in objective visual field assessment
A I Klistorner1, S L Graham, J R Grigg
1Save Sight and Eye Health Institute, Sydney University, Department of Ophthalmology, New South Wales, Australia. sasha@eye.usyd.edu.au
Australian and New Zealand Journal of Ophthalmology
|July 31, 1998
Summary
This study demonstrates that multi-focal visually-evoked potentials (VEP) can objectively assess the human visual field. Bipolar electrode placement improved signal accuracy across the entire visual field compared to monopolar methods.
Area of Science:
- Neuroscience
- Ophthalmology
- Visual Science
Background:
- Visual field assessment is crucial for diagnosing and monitoring visual impairments.
- Current methods for visual field testing have limitations in accuracy and efficiency.
- Visually-evoked potentials (VEP) offer a potential objective measure of visual function.
Purpose of the Study:
- To enhance the performance of VEP in assessing the human visual field.
- To evaluate the utility of multi-focal cortically scaled pattern VEP.
- To compare monopolar and bipolar electrode placements for VEP recording.
Main Methods:
- Recorded multi-focal cortically scaled pattern VEP in normal subjects up to 25 degrees of eccentricity.
- Utilized both monopolar and various bipolar electrode configurations.
- Analyzed VEP responses based on electrode placement and visual field sectors.
Main Results:
- Monopolar electrode placement showed a bias towards the lower visual hemifield.
- Bipolar electrodes placed around the inion provided balanced signals from upper and lower visual fields.
- Sectoral analysis of VEP waveforms improved data interpretation compared to full-field summation.
Conclusions:
- The described multi-focal VEP technique enables objective assessment of the visual field.
- Bipolar electrode placement is superior for balanced visual field representation.
- This method offers a promising tool for clinical visual field evaluation.