In vivo assessment of retinal vessel pathology in amyotrophic lateral sclerosis

Changes in skin and muscle small blood vessels (SBVs) and microvascular structures of the brain have been reported in patients with amyotrophic lateral sclerosis (ALS). A direct assessment of brain SBVs in vivo is currently not feasible. Retinal vessels are considered a mirror of brain SBVs. In this study, we used optic coherence tomography (OCT)-based measurements to detect changes in retinal blood vessels of ALS patients compared to those of healthy controls. We analysed Spectralis-OCT images of 34 ALS patients and 20 HCs. The inner wall thickness (IWT), outer wall thickness (OWT), and lumen diameter (LD) of retinal vessels were assessed using intensity-based measurements. In addition, the different retinal layers were analysed using automated segmentation software. The correlations between the various retinal layers and clinical parameters [e.g., disease duration and revised ALS functional rating scale (ALS-FRS-R)] were examined. The OWT of retinal vessels was higher in ALS patients than in HCs (p = 0.04). There were no differences in the IWT, LD. ALS patients showed a thinning of the outer nuclear layer (ONL) compared to HCs (median 1.63 vs. 1.77, p = 0.002). The whole retinal thickness negatively correlated with the ALS-FRS scale (r = 0.3, p = 0.03). Our study reports retinal vessel pathology in ALS patients. These changes may be related to those observed in SBVs in skin and muscle biopsies. Furthermore, we report a thinning of the ONL in ALS, revealing a possible affection of rods and cones function in ALS.