F. Y. EYE

Neuromyelitis optica spectrum disorder typically presents with acute episodes of optic neuritis or transverse myelitis that come on suddenly and then have a variable recovery rate. Although sharing some clinical features with multiple sclerosis, it is known to be a distinctive disease entity in terms of the underlying causative factors as well as the histopathologic and anatomic findings. Researchers conducted a study to determine if NMOSD patients have subclinical disease progression independent of acute attacks involving the visual pathway. The researchers retrospectively evaluated full-field visual evoked potentials (VEP) of patients with NMOSD, looking for changes over time in P100 latencies and P100-N140 amplitudes. They analyzed 548 VEPs of 167 patients with NMOSD, assessing the rates of change in latencies and amplitudes for each eye of the 167 patients. The study compared VEPs separated by at least 3 months and then 12 months in the absence of acute optic neuritis episodes. For the 3 month interval, the rate of change for P100 latencies was +1.951 ms/y (n=101 eyes, SD 6.274, p = 0.012) while for the 12 month interval it was +1.768 ms/y (n=59 eyes, SD 4.558, p = 0.024). For the P100-N140 amplitudes it was -2.149 uV/y (n=64 eyes, SD 5.013, p =0/005) at 3 months and -0.527 uV/y (n=44 eyes, SD 2.123, p=0.111) at 12 months. For patients who had a remote history of optic neuritis more than 6 months before the baseline VEP was recorded, there were no statistically significant differences in P100 or P100-N140 values. For patients who had an episode of optic neuritis during the study period, the rate of change of the P100 latencies was +11.689 ms/y (n=16 eyes, SD 17.539, p= 0.003) and for the rate of change in P100-N140 amplitudes the results were -1.238 uV/y (n=11 eyes, SD 3.708, p=0.308). The authors concluded that patients with NMOSD had disease progression independent of acute clinical episodes.