Discriminative power of intra-retinal layers in early multiple sclerosis using 3D OCT imaging

To evaluate volumetric changes and discriminative power of intra-retinal layers in early-stage multiple sclerosis (MS) using a 3D optical coherence tomography (OCT) imaging method based on an in-house segmentation algorithm. 3D analysis of intra-retinal layers was performed in 71 patients with early-stage MS (mean disease duration 2.2 +/- 3.5 years) at baseline and 40 healthy controls (HCs). All patients underwent a follow-up OCT scan within 23 +/- 9 months. Patients with a clinical episode of optic neuritis (ON) more than 6 months prior to study entrance were compared with patients who never experienced clinical symptoms of an ON episode (NON). Significantly decreased total retinal volume (TRV), macular retinal nerve fiber layer (mRNFL) and ganglion cell-inner plexiform layer (GCIPL) volumes were detected in ON patients compared to NON patients (all p values < 0.05) at baseline. Each parameter on its own allowed identification of prior clinical ON based on a discriminative model (ROC analysis). Over time, TRV decreased in both ON (p = 0.013) and NON patients (p = 0.002), whereas mRNFL volume (p = 0.028) decreased only in ON and GCIPL volume (p = 0.003) decreased only in NON patients. Our 3D-OCT data demonstrated that TRV, mRNFL and GCIPL allow discrimination between ON and NON patients in a cross-sectional analysis. However, the subsequent retinal atrophy pattern diverges in the initial phase of MS: Prior ON promotes sustained axonal thinning over time indicated by mRNFL loss, whereas longitudinal measurement of GCIPL volume better depicts continuous retrograde neurodegeneration in NON patients in early-stage MS.