Journal of Neurology, Neurosurgery, and Psychiatry, 1990, Vol 53, 890-895
Visual evoked potential monitoring of optic nerve function during surgery
GF Harding, JD Bland and VH Smith
Department of Vision Sciences, University of Aston, Birmingham, United Kingdom.
A study was made with intra-operative flash--visual evoked potentials (VEP)
monitored using a fibre-optic/contact lens photo stimulator in 57 patients
undergoing intra-orbital surgical procedures with potential risk to the
optic nerve. The VEPs recorded under enflurane and nitrous oxide
anaesthesia did not differ significantly in latency or amplitude from the
pre-operative recordings. Transient abolition of the VEP was seen under
many circumstances and did not correlate with the outcome of surgery, but
absence of a previously normal VEP for more than four minutes during
surgical manipulation within the orbit did show a correlation with post
operative impairment of vision. The technique provides early warning to the
surgeon of threats to the integrity of the optic nerve.
