Neurodegeneration plays an important role in permanent disability in multiple sclerosis (MS).

The objective of this paper is to determine whether progressive neurodegeneration occurs in MS eyes without clinically evident inflammation.

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.

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.

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.