A prospective cohort study of vitamin D in optic neuritis recovery

Background: Vitamin D sufficiency is associated with better inflammatory outcomes in multiple sclerosis (MS). We hypothesize that it is also associated with better long-term neurodegenerative measures. Objectives: To show that vitamin D sufficient patients (25-hydroxy vitamin D (25(OH) D) >80 nmol/L) have better optical coherence tomography (OCT) neuroaxonal measures of ganglion cell layer (GCL) and retinal nerve fiber layer (RNFL) thickness after optic neuritis. Methods: In this prospective cohort study, acute optic neuritis patients underwent OCT and serum 25(OH) D assessments at baseline and at month 6, with comparisons between vitamin D sufficient and insufficient patients, and men and women. Potential confounding variables were evaluated. Results: Of 49 enrolled, 36 had complete, analyzable data. At baseline, vitamin D insufficiency was associated with greater RNFL thickness (134.3 vs. 95.2 mu m; p = 0.003) in affected eyes. At month 6, insufficient patients had greater GCL thinning (GCL inter-eye difference: 14.2 vs. 4.0 mu m, p = 0.008). Men had greater RNFL and GCL thinning than women (GCL: 61.2 vs. 69.6 mu m, p = 0.036). Conclusion: Acutely, in optic neuritis, RNFL thickness is increased with vitamin D insufficiency. Chronically, neuronal, and possibly axonal loss are associated with vitamin D insufficiency and male gender, suggesting vitamin D and female gender may confer neuroprotection in optic neuritis, and possibly, central nervous system (CNS) inflammatory disease.