Optic neuritis (ON)
ON is the most common clinical presentation of MOGAD in adults,
comprising around 50% of MOGAD phenotypes at onset, as shown by three
large national studies from the UK, France, and Sri Lanka (6,25,36).
Clinical symptoms of ON include blurred vision and reduced visual acuity
or visual loss, as well as eye pain especially retrobulbar pain with eye
movement (37). ON in MOGAD is often bilateral, either concurrently or
sequentially (38,39). Therefore, bilateral ON represents an important
clinical presentation that can help differentiate MOGAD-ON from ON in
multiple sclerosis (MS-ON). However, incidence of bilateral ON in
paediatric patients is similarly common in AQP4-IgG positive NMOSD as it
is in MOGAD patients. Differences include a more anterior affection of
the optic nerve in MOGAD with optic nerve head swelling and retrobulbar
involvement (40).