Longitudinal optic neuritis-unrelated visual evoked potential changes in NMO spectrum disorders

Objective: To investigate, if neuromyelitis optica spectrum disorder (NMOSD) patients develop subclinical visual pathway impairment independent of acute attacks.
Methods: 548 longitudinally assessed full-field visual evoked potentials (VEP) of 167 NMOSD patients from 16 centers were retrospectively evaluated for changes of P100-latencies and P100-N140-amplitudes. Rates of change in latencies (RCL) and amplitudes (RCA) over time were analyzed for each individual eye using linear regression and compared using generalized estimating equation models.
Results: The rates of change in the absence of optic neuritis (ON) for minimal VEP intervals of ≥3 months between baseline and last follow-up were +1.951ms/year (N=101 eyes; SD=6.274; p=0.012) for the P100-latencies and -2.149µV/year (N=64 eyes; SD=5.013; p=0.005) for the P100-N140-amplitudes. For minimal VEP intervals of ≥12 months the RCL was +1.768ms/year (N=59 eyes; SD=4.558; p=0.024) and the RCA was -0.527µV/year (N=44 eyes; SD=2.123; p=...