Can diffusion tensor imaging (DTI) of the optic ways contributes to predict the 6 months prognosis of Optic Neuritis (ON)?

Inclusion Criteria:

• Age from 18 to 55 years old
• Clinically suspected optic neuritis defined as a sudden decrease of the visual acuity and/or a damage to the field of vision and/or a defect of the colour vision and/or retro-orbital pain with a relative afferent pupillary defect (except if the optic neuropathy is bilateral or symmetrical), in the absence of a severe retinal macular pathology, and in the absence of a toxic or iatrogenic intake (ethambutol, vfend)
• Clinical optic neuritis duration < 15 days
• First episode of an inflammatory ON
• No corticosteroids in the month before
• Indication to a corticosteroid therapy at high dose to cure the felt symptomatology
• Retinal nerve fibre layer (RNFL) thickness upper 75 µm at initial stage
• Isolated ON, multiple sclerosis or NMO (Neuro Myelitis Optica) - SD (Spectrum Disorder) context
• Having signed informed consent for participating in the study

Exclusion Criteria:

• Contra-indication to MRI

  • Cardiac pacemaker or defibrillator implant
  • Neurosurgical clips
  • Cochlear implants
  • Intra-orbital or encephalic foreign bodies
  • Stents implanted since less than 4 weeks and osteosynthesis equipment implanted since less than 6 weeks
  • Claustrophobia

• Persons subject to major legal protection (safeguarding justice, guardianship, trusteeship), persons deprived of liberty

• Eye examination suggests a pre-existing eye abnormality that could affect the visual function (amblyopia, strong myopia…)

• Pregnant or breastfeeding women