MOG and optic neuritis: Comparison of T-Helper Cell 17-Related Serum Cytokine/Chemokine Levels Between the Myelin Oligodendrocyte Glycoprotein Antibody-Seropositive Optic Neuritis, Aquaporin 4-IgG-Seropositive Optic Neuritis, Idiopathic Demyelinating Optic Neuritis Patients, and the Healthy Controls