Diagnosis of ON With or Without MS or NMOSD

This is both a prospective and retrospective study of patients with a known diagnosis of optic neuritis (ON) only, multiple sclerosis (MS) with ON, or neuromyelitis spectrum disorder (NMOSD) with ON. There will be no requirement for blinding (patient or assessor) and data collected with the Reflex app will be compared against other data that track optic nerve functional status, such as optical coherence tomography (OCT), visual fields (VF), low-contrast sensitivity, MRI orbits/brain and visual evoked potentials (VEP). Patients who have any diagnosis of ON, with or without a diagnosis of MS or NMOSD and who have had testing using other modalities such as VEPs, VF, low-contrast sensitivity studies, OCT, and MRI of brain or orbits will be included as retrospective subjects in the study. In this cohort, RAPD assessments will be completed and compared to against the data that has accrued as noted.