Retinal Layer Thinning After Optic Neuritis is Associated With Future Relapse Remission in Relapsing Multiple Sclerosis

Abstract

Introduction:Remission of relapses is an important contributor to both short- and long-term prognosis in relapsing multiple sclerosis (RMS). In MS-associated acute optic neuritis (MS-ON), retinal layer thinning measured by optical coherence tomography (OCT) is a reliable biomarker of both functional recovery and the degree of neuroaxonal damage. However, prediction of non-ON relapse remission is challenging. We aimed to investigate whether retinal thinning after ON is associated with relapse remission after subsequent non-ON relapses.Methods:For this longitudinal observational study from the Vienna MS database (VMSD), we included MS patients with 1) an episode of acute ON, 2) available spectral-domain OCT scans within 12 months before ON onset (OCTbaseline), within 1 week after ON onset (OCTacute) and 3-6 months after ON (OCTfollow-up), and 3) at least one non-ON relapse after the ON episode. Subsequent non-ON relapses were classified as displaying either complete or incomplete remission based on change in expanded disability status scale (EDSS) assessed 6 months post-relapse. Association of retinal thinning in peripapillary retinal nerve fiber layer (ΔpRNFL) and macular ganglion-cell-and-inner-plexiform-layer (ΔGCIPL) with incomplete remission was tested by multivariate logistic regression models adjusting for age, sex, disease duration, relapse severity, time to steroid treatment, and DMT status.Results:We analyzed 167 MS patients (mean age 36.5 years [SD 12.3], 71.3% female, mean disease duration 3.1 years [SD 4.5]) during a mean observation period of 3.4 years (SD 2.8) after the ON episode. In 61 patients (36.5%) at least one relapse showed incomplete remission. In the multivariable analyses, incomplete remission of non-ON relapse was associated with ΔGCIPL thinning both from OCTbaseline to OCTfollow-up and from OCTacute to OCTfollow-up (odds ratio [OR] 2.4 per 5µm, p<0.001, respectively), independently explaining 29% and 27% of variance respectively. ΔpRNFL was also associated with incomplete relapse remission when measured from OCTbaseline to OCTfollow-up (OR 1.9 per 10µm, p<0.001) independently accounting for 22% of variance, but not when measured from OCTacute to OCTfollow-up.Conclusions:Retinal layer thinning after optic neuritis may be useful as a marker of future relapse remission in RMS.