Optical coherence tomography findings in multiple sclerosis and comparison with Primary Sjögren’s syndrome

Background Primary Sjögren’s syndrome (PSS) with central nervous system (CNS) involvement can mimic multiple sclerosis (MS). Optical coherence tomography (OCT) quantifies retinal neuroaxonal damage and may assist differential diagnosis. Methods In this case–control study, 170 eyes (60 from participants with MS, 56 from PSS, and 54 from healthy controls [HCs]) were examined with OCT. Peripapillary retinal nerve fiber layer (RNFL), ganglion cell complex (GCC), and foveal, parafoveal and perifoveal retinal thicknesses and foveal volume were measured. Group comparisons, including subgroup analyses of MS with and without previous optic neuritis (ON) and PSS with CNS involvement, used parametric or non-parametric tests (significance p < 0.05). Results Whole RNFL and GCC thickness were significantly lower in MS than in PSS and HCs, with RNFL thinning in all quadrants except nasal. MS showed lower parafoveal and perifoveal retinal thickness and reduced foveal volume compared to PSS and HCs. When MS was compared with PSS with CNS involvement, parafoveal thickness remained significantly lower in MS, whereas other OCT parameters were similar. In three-group analyses, MS with prior ON showed the most pronounced parafoveal and perifoveal thinning versus MS without ON and PSS with CNS involvement, while MS without ON did not differ from PSS with CNS involvement. Conclusions OCT demonstrates more extensive retinal neuroaxonal damage in MS than in PSS and HCs, especially in peripapillary RNFL and parafoveal/perifoveal macula. These findings support the potential role of OCT in differentiating MS from PSS with CNS involvement and in identifying MS patients with more severe neuroaxonal injury.