Retinal nerve fibre layer thinning is associated with worse visual outcome after optic neuritis in children with a relapsing demyelinating syndrome

AIM: Optic neuritis may be monophasic or occur as part of a relapsing demyelinating syndrome (RDS), such as multiple sclerosis, aquaporin-4 antibody (AQP4-Ab) neuromyelitis optical spectrum disorder (NMOSD), or myelin oligodendrocyte glycoprotein antibody (MOG-Ab)-associated disease. The aims of this study were to test whether clinical, electrophysiological, and microstructural parameters differ in multiple-sclerosis-associated optic neuritis (MS-ON) and antibody-associated optic neuritis (Ab-ON); to identify the clinical and paraclinical characteristics of children suffering worse long-term visual outcome of RDS-optic neuritis; and to explore the relationship between RNFL thickness and clinical parameters in RDS-optic neuritis.

METHOD: Forty-two children with optic neuritis were retrospectively studied: 22 with multiple sclerosis (MS-ON) and 20 with antibody-associated demyelination (Ab-ON: MOG-Ab=16 and AQP4-Ab=4). Clinical and paraclinical features were analysed.

RESULTS: Complete recovery of visual acuity was reported in 25 out of 42 children; eight out of 38 (21%) suffered moderate or severe visual impairment (logarithm of the minimum angle of resolution [logMAR]>0.5) in their worse eye, including four out of 38 who were blind (logMAR>1.3) in their worse eye (two with multiple sclerosis, two with AQP4-Ab NMOSD). None of the children with MOG-Ab were blind. Recurrence of optic neuritis was more common in the Ab-ON group than the MS-ON group (15 out of 20 vs seven out of 22, p=0.007). Retinal nerve fibre layer (RNFL) thickness at baseline inversely correlated with visual acuity at final follow-up (r=-0.41, p=0.008). There was no significant relationship between the number of episodes of optic neuritis and mean RNFL (r=-0.08, p=0.628), nor any significant relationship between the number of episodes of optic neuritis and visual impairment (r=0.03, p=0.794).

INTERPRETATION: In children with RDS, long-term visual impairment inversely correlated with RNFL thickness, but not with the number of relapses of optic neuritis. Optical coherence tomography may have a role in assessing children with optic neuritis to monitor disease activity and inform treatment decisions.

WHAT THIS PAPER ADDS: Long-term visual impairment is reported in 40% of children with a relapsing demyelinating syndrome following optic neuritis. Relapse of optic neuritis, occurring more frequently in the non-multiple-sclerosis group. Retinal nerve fibre layer thinning is associated with worse visual outcome. Optical coherence tomography can be used alongside clinical parameters as an objective measure of neuroretinal loss.