Retinal nerve fiber layer thickness and thalamus pathology in multiple sclerosis patients

Background and purpose Visual impairments are frequent in multiple sclerosis (MS). Optic neuritis can directly reduce retinal nerve fiber layer (RNFL) thickness. Our objectives were to evaluate associations of the RNFL thickness (RNFLT) of MS patients with magnetic resonance imaging (MRI) measures of regional brain atrophy and tissue injury in the post-chiasmatic deep gray matter (GM) section of the visual pathway. Methods Retinal nerve fiber layer thickness was measured using optical coherence tomography (OCT) in 96 relapsing−remitting MS (RR-MS) patients and 46 controls. MRI was obtained within ±3 months of OCT. RNFLT associations with MRI measures from diffusion tensor imaging and regional and tissue specific atrophy were assessed. Results In RR-MS, lower RNFLT was associated with lower white matter volume and lower whole brain volume. Lower RNFLT was associated with lower total deep gray matter volume and lower thalamus volume. Lower RNFLT was associated with greater mean diffusivity (MD) in normal appearing (NA) brain tissue and NA gray matter. Trends were found for lower RNFLT with greater MD in NA white matter and thalamus. RNFLT in controls was not associated with MD. Conclusions Lower RNFLT is associated with microscopic tissue injury in NA regions of the brain and with neurodegeneration of the deep gray matter and thalamus in RR-MS.