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) beta-amyloid(1-42) (A beta) 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 A beta 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. A beta(low) subgroup of patients showed a reduction of retinal nerve fiber layer thickness.