Optic nerve head, retinal nerve fiber layer and macular thickness analysis in restless legs syndrome

The human retina contains dopaminergic neurons within the inner retinal layer. Several studies demonstrated dopaminergic neuronal loss in Parkinson's disease (PD) using optical coherence tomography (OCT). Hypothetically, restless legs syndrome (RLS) may have an underlying dopaminergic mechanism and a probable relation to PD is assumed. Therefore, we aimed to analyze retinal morphology in RLS patients.

In this cross-sectional study we used spectral domain OCT to measure the features of various retinal layers such as thicknesses of peripapillary retinal nerve fiber layer (RNFL), macular and foveal layers, ganglion cell complex (GCC), and optic nerve head parameters of 36 patients with idiopathic RLS, together with 36 age and sex-matched controls. Differences in the thicknesses of RNFL, macula, GCC and optic disc parameters are statistically compared between patients and controls.

The average peripapillary RNFL thickness, mean macular volume and total retinal thickness were reduced in RLS compared with healthy controls (p = 0.032, p = 0.029, and p = 0.026, respectively). After Bonferroni correction, only the reduction in the inferior inner and outer quadrants of the macula remained significant (p = 0.0040, for both). Optic nerve head parameters (cup volume, cup/disc area ratio, rim area and disc area) and GCC thickness showed no significant difference between patients and healthy controls.

Our study revealed significant retinal thinning in the macula region in RLS. Our results may support the dopaminergic dysfunction in the pathogenesis of RLS. Prospective longitudinal studies with a larger sample are needed to corroborate our results.