Electrode position and the multi-focal visual-evoked potential: role in objective visual field assessment.
OBJECTIVE
To improve the performance of visual-evoked potentials (VEP) in the assessment of the human visual field, the multi-focal cortically scaled pattern VEP was recorded up to 250 of eccentricity in normal subjects. Monopolar and varying bipolar electrode positions were used.


RESULTS
The monopolar response was strongly biased towards the lower hemifield. Bipolar leads straddling the inion (2 cm above and below) achieved approximately equal signals from the upper and lower visual field. Division into sectors of similar wave-form augments the analysis compared with summed full-field responses.


CONCLUSIONS
With this technique, the multi-focal VEP can be used to objectively assess the visual field.
Save Sight and Eye Health Institute, Sydney University, Department of Ophthalmology, New South Wales, Australia. sasha@eye.usyd.edu.au
A I
AI
Klistorner
S L
SL
Graham
J R
JR
Grigg
F A
FA
Billson
D002540:Cerebral Cortex / Q000033:anatomy & histology; D004566:Electrodes; D005074:Evoked Potentials, Visual / Q000502:physiology*; D006801:Humans; D009885:Ophthalmology / Q000379:methods; D014794:Visual Fields / Q000502:physiology*