Serum NfL predicts visual recovery and neuronal loss after optic neuritis.

Optic neuritis, a common manifestation of multiple sclerosis, involves acute axonal injury and variable visual recovery. We evaluated whether serum neurofilament light chain predicts visual and structural outcomes after first-episode optic neuritis. Fifty-one patients (mean age = 33 years, 71% women) were followed for 24 ± 6 months with low-contrast letter acuity testing and optical coherence tomography. Adjusting for age and sex, higher baseline serum neurofilament light chain predicted greater inter-eye differences in retinal nerve fibre layer (-4.65 µm per SD, p = 0.02), ganglion cell/inner plexiform layer (-1.39 µm, p = 0.02) and 2.5% low-contrast letter acuity (-0.73, p = 0.05), but not high-contrast acuity. Early serum neurofilament light chain may stratify optic neuritis severity and guide neuroprotective trial selection.