Evidence of retinal anterograde neurodegeneration in the very early stages of multiple sclerosis: a longitudinal OCT study

Background: Neurodegenerative processes are present since the early stages of multiple sclerosis (MS), constituting the primary substrate of disability. As part of the CNS, retinal damage could be considered a reliable prognostic biomarker of neurodegeneration in MS. Objectives: To characterize longitudinal changes in the retinal layers’ thickness and to investigate correlations between retinal atrophy and other prognostic biomarkers, i.e., cerebrospinal fluid (CSF) β-amyloid1–42 (Aβ) levels. Methods: Forty-two eyes without a history of optic neuritis of 23 MS patients were recruited. All patients underwent spectral-domain-OCT scans (SD-OCT), brain magnetic resonance imaging (MRI), and lumbar puncture at baseline. SD-OCT and brain MRI were repeated after 12 months. Ten controls underwent the same OCT procedure. Results: At baseline, macular ganglion cell/inner plexiform layer (mGCIPL) thickness was reduced in patients compared to controls (p = 0.008), without retinal nerve fiber layer (RNFL) thinning, that was revealed only at follow-up (p = 0.005). Patients with lower CSF Aβ levels displayed reduced RNFL thickness values, both at baseline and follow-up. Conclusions: At very early clinical stages, mGCIPL thickness values were reduced without a concomitant peripapillary RNFL thinning. The longitudinal assessment demonstrated a RNFL loss in patients compared to HC, together with a plateau of mGCIPL thinning. Aβlow subgroup of patients showed a reduction of retinal nerve fiber layer thickness.