In an older study, children with a history of CRION, an entity now known to be highly associated with MOG-IgG antibodies (28), were found to have a marked decrease in Average Retinal Nerve Fiber Layer Thickness (RNFLT) in comparison to MS patients (50 ± 2 microns in CRION vs. 83 ± 12 in MS ON affected eyes and 107 ± 12 in healthy controls), suggesting more severe injury of the optic nerve in this entity than MS (68). Here, MOG is linked to myeloid sarcoma.