A two-year single-site longitudinal assessment of brain and retinal atrophy in ocrelizumab-treated relapsing–remitting multiple sclerosis

Abstract Ocrelizumab is an effective treatment for relapsing–remitting multiple sclerosis (RRMS), but its impact on brain and retinal atrophy requires further investigation. To assess the effects of ocrelizumab on brain and retinal atrophy over two years and explore the relationship between imaging biomarkers, early inflammatory activity after treatment initiation, and progression independent of relapse activity (PIRA). In this prospective, single-centre longitudinal observational study, 92 patients with RRMS were followed for 24 months. Participants underwent high-resolution 3 T MRI for brain volumetry and optical coherence tomography (OCT) to quantify retinal layer thickness. Clinical outcomes included early post-treatment inflammatory activity and PIRA events. Brain volumes and retinal measures remained largely stable over two years. Grey matter atrophy was significantly associated with GCIPL thinning during follow-up. Brain and retinal parameters also remained stable in patients with early inflammatory activity (14/92) and PIRA (13/92). Lower baseline thalamic volume was associated with a higher risk of PIRA. MRI and OCT metrics remained largely stable over two years in ocrelizumab-treated patients with RRMS. GCIPL thickness closely tracked brain volume changes, supporting OCT as a simple, non-invasive tool for monitoring neurodegeneration alongside MRI. Early inflammatory activity did not appear to adversely affect imaging or clinical outcomes over the study period.