Visual evoked potential and pupillary signs. A comparison in optic nerve disease
T. A. Cox, H. S. Thompson, S. S. Hayreh and J. E. Snyder
We measured the pupil cycle time, the relative afferent pupillary defect,
and the pattern-reversal visual evoked potential (VEP) in 41 patients with
unilateral anterior ischemic optic neuropathy (AION) and 24 patients with
unilateral optic neuritis. We speculated that the relative afferent
pupillary defect would match the VEP amplitude and that the pupil cycle
time would correspond to the VEP latency. We found a correlation between
the relative afferent pupillary defect and VEP amplitude in patients with
AION, but not in patients with optic neuritis. We also found that the pupil
cycle time and VEP latency were weakly correlated, but only in patients
with optic neuritis. In these two groups of patients with unilateral optic
neuropathy, the most sensitive objective indicator of disease was the
relative afferent pupillary defect. The least sensitive indicator was the
pupil cycle time.
