[Topographic distribution of visual evoked potentials in optic neuropathy].

INTRODUCTION

Digital treatment of electrical signals coming from the central nervous system on stimulation of the optic nerve path offers an objective method for evaluation of visual evoked potentials (VEP) shown graphically on a cerebral map.

OBJECTIVE

To evaluate the topographical distribution of VEP in cases of optic neuropathy adding this parameter to the usual parameters of latency and amplitude.

MATERIAL AND METHODS

We studied 35 patients with suspected optic neuropathy and normal findings on basic ophthalmological examination, in whom VEP and VEP mapping (VEPM) was done.

RESULTS

In 26% of the cases there was no response for evaluation with the usual VEP recording techniques, whilst in those with VEPM this percentage was reduced to 11.5%. In the other cases there was a potential with characteristic distribution in the occipital areas and a maximally positive dipole posteriorly.

CONCLUSION

VEPM is an objective method for evaluation of the visual pathway offering better discrimination than the usual VEP in more severe cases of neuropathy.