Tracking changes over time in retinal nerve fiber layer and ganglion cell-inner plexiform layer thickness in multiple sclerosis

Abstract

Background: Neurodegeneration plays an important role in permanent disability in multiple sclerosis (MS). Objective: The objective of this paper is to determine whether progressive neurodegeneration occurs in MS eyes without clinically evident inflammation. Methods: Retinal nerve fiver layer thickness (RNFLT) and ganglion cell-inner plexiform layer thickness (GCIPT) were measured using Cirrus optical coherence tomography (OCT) in 133 relapsing–remitting MS (RRMS) patients (149 non-optic neuritis (ON), 97 ON eyes, last ON ≥6 months). Ninety-three patients were scanned at two visits. Percentages of abnormal GCIPT vs RNFLT (<5% of machine norms) in cross-sectional data were compared. Relations between RNFLT/GCIPT and MS duration (cross-sectional) and follow-up time (longitudinal) were assessed. Results: GCIPT was abnormal in more eyes than RNFLT (27% vs 16% p = 0.004 in non-ON, 82% vs 72% p = 0.007 in ON). RNFLT and GCIPT decreased with MS duration by −0.49 µm/yr ( p = 0.0001) and −0.36 ( p = 0.005) for non-ON; −0.52 ( p = 0.003) and −0.41 ( p = 0.007) for ON. RNFLT and GCIPT decreased with follow-up time by −1.49 µm/yr ( p < 0.0001) and −0.53 ( p = 0.004) for non-ON, −1.27 ( p = 0.002) and −0.49 ( p = 0.04) for ON. Conclusions: In RRMS eyes without clinically evident inflammation, progressive loss of RNFLT and GCIPT occurred, supporting the need for neuroprotection in addition to suppression of autoimmune responses and inflammation.