Inclusion Criteria:

Children who present with unilateral or bilateral optic neuritis will be eligible for the study if they meet each of the following criteria:

• 3 to < 16 years of age
• Optic neuritis in at least one eye based upon clinical diagnosis
• Visual loss and/or pain on eye movements for 2 weeks or less
• Ipsilateral relative afferent pupillary defect if unilateral PON
• At least one of the following in the affected eye:
  • Visual acuity deficit at least 0.2 logMAR below age-based norms from EVA ATS-HOTV 316 or e-ETDRS testing; OR
  • Diminished color vision; OR
  • Abnormal visual field; OR
  • Optic disk swelling
• Requirements for refractive error correction (based on a cycloplegic refraction performed at enrollment or as part of the examination by a referring pediatric ophthalmologist within the past 1 month): Myopia of -0.75D, hyperopia 4.00D, and cylinder 1.50D must be corrected using habitual glasses or trial frames if there is a change in the best correction.
  • Refractive error correction prescribing instructions:
    • Hyperopic spherical equivalent (SE) must not be under corrected by more than 326 2.00D SE
    • Cylinder power in both eyes must be within 0.75D of fully correcting the astigmatism.
    • Axis must be within +/- 10 degrees if cylinder power is 1.00D, and within +/- 5 degrees if cylinder power is >1.00D.
    • Myopia SE must not be under-corrected by more than 0.25D or over corrected by more than 0.75
• MRI of the orbits has been done with evidence of enhancement of the optic nerve (s) or will be done in the next two weeks as standard care.
• Idiopathic optic neuritis, optic neuritis associated with MS, and optic neuritis associated with other causes not known at presentation.

Exclusion Criteria:

• Study participants who do not expect to remain in area for the next two years and follow up at another study center is not possible
• Participants whose parents/guardians in the opinion of the Investigator, may be non-compliant with study schedules or procedures.
• Neuro-retinitis (if the diagnosis is made after enrollment they will be followed, but not included in the primary cohort)
• Previous episode of optic neuritis in the same (currently affected) eye (established or 351 presumed due to optic atrophy). Prior episode in fellow eye does not exclude enrollment.
• CSF or laboratory values suggesting a condition other than optic neuritis.
• Ocular or systemic findings suggestive of non-demyelinating cause for optic neuritis in the affected eye(s) such as an associated history of sarcoidosis, systemic lupus erythematosus, collagen vascular disease, or Lyme disease with overt symptoms beyond serum markers such 356 as rash, peripheral neuropathy, or liver disease.
• Preexisting ocular abnormalities that might affect assessment of visual function in the affected eye(s). (Preexisting ocular abnormalities in the fellow eye are not an exclusion criterion.)