Peripapillary retinal nerve fibre layer (pRNFL) and macular ganglion cell plus inner plexiform layer (mGCIPL) thinning are markers of neuroaxonal degeneration in relapsing multiple sclerosis (RMS). pRNFL and mGCIPL thinning is more pronounced in patients with physical or cognitive disability progression, while it is reduced by disease-modifying treatment (DMT).
The objective of this study was to investigate the potential of retinal layer thinning for prediction of treatment response in RMS.
In this 4-year prospective observational study on 113 RMS patients, pRNFL and GCIPL were measured at DMT initiation and after 12 (M12) and 24 months (M24) of follow-up by spectral-domain optical coherence tomography (OCT). Inclusion criteria included adherence to DMT for at least 2 years. Patients suffering optic neuritis between baseline and M24 were excluded. Treatment response was defined as absence of 6 month confirmed EDSS progression and Symbol Digit Modalities Test (SDMT) worsening during the observation period. Best possible cut-off values of retinal thinning for predicting treatment response were determined by receiver-operating characteristics (ROC) analyses. Odds ratios (OR) for treatment response were calculated by multivariate logistic regression models correcting for age, sex, disease duration and EDSS/SDMT at baseline.
Thinning of mGCIPL <0.5mm at M24 displayed superior prediction of treatment response (odds ratio [OR] 4.5; 95% confidence interval [CI]: 1.8 – 7.6; p<0.001; specificity 91%, sensitivity 81%) followed by mGCIPL <0.3mm at M12 (OR 3.9; 95% CI: 1.4 – 6.9; p<0.001; specificity 85%, sensitivity 78%) and pRNFL <2mm at M24 (OR 3.7; 95% CI: 1.1 – 6.5; p=0.023; specificity 84%, sensitivity 69%), while pRNFL at M12 was not significantly predictive.
mGCIPL – and to a lesser degree pRNFL – thinning predict physical and cognitive disability progression upon DMT initiation. Pending validation, retinal layer thinning may be a useful and easily accessible biomarker of treatment response in RMS.