AQP4 and intervertebral disk degenerative disorder: We conducted a prospective study on a cohort of non-acute IDD patients both with (ON+) and without (ON−) previous ON to assess (1) microstructural OC MTR changes between ON+ and ON− patients; (2) whether the degree of the OC MTR changes differs between RRMS, AQP4 + NMOSD and MOGAD and (3) and if OC MTR is associated with residual visual/ophthalmic outcomes in these patients.