Ability of Swept-source OCT and OCT-angiography to detect neuroretinal and vasculature changes in patients with Parkinson disease and essential tremor

Background/Objectives To evaluate the ability of swept-source optical coherence tomography (SS-OCT) implemented with angiography analysis (SS-OCTA) to detect neuro-retinal and vasculature changes in patients with Parkinson’s disease (PD) and essential tremor (ET), and to distinguish between both pathologies. Subjects/Methods A total 42 PD and 26 ET patients and 146 controls underwent retinal evaluation using SS-OCT plus OCT-Angio™. The macular (m) and peripapillary (p) retinal nerve fiber layer (RNFL) and ganglion cell layer (GCL), and macular vasculature were assessed. A Linear discriminant function (LDF) was calculated to evaluate the diagnostic ability of SS-OCTA in both PD and ET. Results PD patients presented a reduction in mRNFL ( p < 0.005), mGCL (all sectors, p < 0.05) and pRNFL ( p < 0.005) vs healthy controls, and in mRNFL and pRNFL vs ET patients ( p < 0.001). ET patients showed a significant reduction in mGCL vs controls ( p < 0.001). No differences were observed in the macular vasculature between groups. Predictive diagnostic variables were significant only for PD and a LDF was obtained with an area under the ROC curve of 0.796. Conclusions Neuro-retinal thinning is present in both diseases, being greater in PD. While SS-OCT could be useful in diagnosing ET and PD, the diagnostic potential for SS-OCTA based on an LDF applies only to PD, not ET.