Retinal nerve fiber layer thickness measured by optical coherence tomography correlates with Expanded Disability Status Scale (EDSS) in multiple sclerosis (MS)

Purpose To determinate if retinal nerve fiber layer (RNFL) thickness was correlated with Expanded Disability Status Scale (EDSS) score in patients with definite multiple sclerosis (MS) Methods 74 consecutive patients (extracted from the prospective Lorraine Multiple Sclerosis Registry) were included. A neurological examination with determination of the EDSS score and an ophthalmological examination with visual acuity, visual field testing, and RNFL measurements with optical coherence tomography (OCT3-Carl Zeiss Meditec, Dublin California USA) were performed. Results Mean age was 44,5 years and 66% were women. EDSS average score was 3. Prior optic neuritis was present in 83% OD and 41% OS. EDSS score was negatively correlated with RNFL thickness (-0,28 p=0.04 OD and -0.2 p<0,1 OS). There were no correlation between RNFL thickness and MS subtype or any of other ophthalmological tests. At the opposite, RNLF thickness was significantly lower among eyes with prior optic neuritis (74 vs 90 OD and 76.8 vs 90.3 micrometers, p<0.01). In addition we did not find any correlation between EDSS and other ophthalmological tests. Conclusion Our study demonstrates that RNFL thickness is statistically correlated with EDSS score. RNFL thickness measured by OCT appears to be an interesting structural biomarker to detect global axonal loss in MS patients. Larger studies are warranted to confirm if RNFL thickness could serve as a surrogate of EDSS score.