Progressive loss of retinal ganglion cells and RNFL in non-optic neuritis eyes of multiple sclerosis patients – a longitudinal study

Abstract

Purpose : The aim of this study was to determine the rate of retinal ganglion cell layer (GCL) and retinal nerve fibre layer (RNFL) loss in non-optic neuritis (NON) eyes of relapsing remitting MS (RRMS) patients followed annually over 3 yrs. Secondly, to find which specific ocular parameters had enough sensitivity to both identify changes at baseline and monitor progression accurately.

Methods : 45 RRMS patients were recruited and 20 age, race, and sex-matched healthy subjects served as controls. All underwent annual spectral domain optical coherence tomography (OCT) scans and clinical review for 3 years. One eye was randomly selected for patients without a history of ON; the non-optic neuritis eye was used in patients with a history of previous ON. For controls one eye was chosen at random.

Results : GCL+inner plexiform layer (GCL/IPL) and temporal sector RNFL (tRNFL) both demonstrated highly significant thinning at baseline (p=0.004, p=0.005) while temporal inferior and temporal superior sectors just reached significance. All nasal segments as well as global (gRNFL) were not significantly different from controls. tRNFL was reduced by 11.8% vs only 7.2% for RGC/IPL. Sensitivity analysis revealed an advantage of RGC/IPL over tRNFL with thinning > 95th percentile of controls in 21 patients (47%) based on RGC/IPL and in only 17 patients (38%) measured by tRNFL while gRNFL was abnormal in only 8 (18%). This is probably related to small inter-subject variability of RGC/IPL thickness. In follow up there was significant reduction of RGC/IPL layer, tRNFL and gRNFL. The largest reduction was observed in tRNFL (4.8%), followed by gRNFL (2.3%) and RGC/IPL (1.4%). Annual change was -1.01μ, -0.73μ and -0.32μ respectively. Sensitivity analysis showed a significant rate of thinning in 24 patients (53%) based on tRNFL, 10(22%) on gRNFL and 12(27%) on RGC/IPL. Reduction of RGC layer thickness was relatively uniform across the perimacular region at around 1-1.5 m, corresponding to about 2 % of thinning (0.5mm samples). Fellow eyes of ON patients showed slightly higher rate of progression compared to patients who had never had ON, but this was not significant(p>0.05).

Conclusions : While both GCL/IPL and temporal tRNFL are useful parameters for identification of disease at baseline, tRNFL showed the greatest thinning longitudinally and therefore has potential application for monitoring.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.