A prospective study of disease modifying therapy and retinal atrophy in relapsing-remitting multiple sclerosis.

BACKGROUND:To compare the rate of retinal atrophy over time in patients with relapsing-remitting multiple sclerosis (RRMS) treated with various disease-modifying therapies (DMT). METHODS:Patients with RRMS on various DMT and those observed without treatment were prospectively enrolled into the study between September 2015 and June 2018. All subjects with follow-up of 1-4 years were included and categorized into groups as "no drug", "low efficacy drug", "high efficacy drug", or "dimethyl fumarate" (DMF), based on treatment modality used for the longest duration of their follow-up. Ocular coherence tomography (OCT) was used to measure peripapillary retinal nerve fiber layer thickness (RNFL) and ganglion cell/inner plexiform layer (GC-IPL) thickness at baseline and every 6 months. A linear mixed effects regression model was performed to compare rates of retinal atrophy across treatment groups. RESULTS:Out of 67 participants who met inclusion criteria (mean age = 37; 76% female), 13 were untreated, 12 on low efficacy therapy, 18 on DMF, and 24 on high efficacy therapy. History of optic neuritis was associated with lower baseline GC-IPL thickness (p = 0.003). Higher baseline GC-IPL thickness was associated with increased rate of GC-IPL thinning (p = 0.009). Age, disease duration, and ethnicity were not predictors of baseline RNFL or GC-IPL thickness, or rate of atrophy of these layers. CONCLUSIONS:There were no differences in rate of GC-IPL atrophy between patients with RRMS on different treatments in this cohort. Age, disease duration, and ethnicity also did not predict retinal atrophy. History of ON was associated with reduced GC-IPL thickness at baseline, consistent with previous research. Rate of GC-IPL thinning was higher for subjects with higher baseline GC-IPL thickness, suggesting a plateau effect.