Restless legs syndrome in multiple sclerosis is related to retinal thinning

•Dopaminergic dysfunction has recently been proposed in the restless legs syndrome's (RLS) pathophysiology.•Several studies demonstrated retinal thinning among RLS patients.•Restless legs syndrome is frequently seen in patients with multiple sclerosis (MS).•The thinning of retinal tissue directly indicates axonal loss and neurodegeneration in MS.•The changes in the retinal fiber layer may be remarkable in MS patients presenting with RLS. Restless legs syndrome (RLS) is one of the most frequent comorbidities accompanying multiple sclerosis. Patients with multiple sclerosis (MS) show thinning in the retinal layers throughout the disease. The thinning is related to acute attacks and progression and atrophy of the brain. Optical coherence tomography (OCT) provides relevant information on the pathophysiology of MS. We aimed to evaluate OCT parameters in patients with MS to investigate any changes related to the coexistence of RLS. We consecutively enrolled 75 adults with relapsing-remitting MS. Participants were assessed by using demographic and clinical parameters along with the excessive sleepiness in the daytime (ESS), fatigue severity scale (FSS), and RLS severity scale (IRLSSG). The thickness of the peripapillary retinal nerve fiber layer (pRNFL), macular thickness (MT), and macular ganglion cell – inner plexiform layer (MGCIPL) complex was measured with spectral-domain OCT. Of the 75 participants, 20 were found to have RLS, and 55 did not. Scores of ESS, FSS, and MS disability (EDSS) were worse in patients with RLS. There was no significant difference in retinal nerve fiber layer thickness except for the inferior quadrant(p = 0.029). The mean inferior pRNFL thickness was 104.5 ± 22.6 μm in the RLS (+) group and 114.2 ± 21.6 μm in the RLS (-) group. Patients with RLS had excessive daytime sleepiness, were more fatigued, had higher EDSS scores, and had a thinner retinal layer in the inferior quadrant. Overall, data from the study suggest a possible relationship between retinal volume changes in MS patients with RLS.