A comparative optical coherence tomography study in neuromyelitis optica spectrum disorder and multiple sclerosis

The aim of this study was to find, using spectral domain-optical coherence tomography (SD-OCT), retinal imaging biomarkers differentiating neuromyelitis optica spectrum disorder (NMOSD), multiple sclerosis (MS) and healthy controls (HCs).

The population was composed of patients with NMOSD (n=23) or MS (n=110) and of HCs (n=75). Evaluation criteria were retinal thickness/volume, visual acuity, low contrast vision acuity and Expanded Disability Status Scale score.

Considering all eyes and after statistical adjustments including the number of optic neuritis (ON) episodes, we found that NMOSD patients did not have significantly more retinal atrophy than MS patients; whereas MS non-optic neuritis (NON) eyes had thinner temporal (p=0.032) and temporo-superior peripapillary retinal nerve fibre layer (pRNFL; p=0.011) thicknesses than NMOSD NON eyes; in addition, NMOSD NON eyes presented significant naso-inferior pRNFL (p=0.024), temporal pRNFL (p=0.039), macular ganglion cell complex (p=0.004) and ganglion cell layer (p=0.002) atrophy vs HC eyes. We identified significant correlations between visual and clinical disability and retinal thicknesses in both diseases.

OCT may help to differentiate NMOSD and MS by focusing on the NON eyes (temporal pRNFL atrophy more severe in MS). Moreover, we discuss the possibility of a retinal degenerative process independent of ON in NMOSD.