Assessment of retinal blood flow changes in early Parkinson's disease: An optical coherence tomography angiography study

Background: To evaluate retinal microvasculature and choroidal thickness in patients with Parkinson's disease (PD) with optical coherence tomography angiography (OCTA). Materials and Methods: Forty-one eyes from 41 patients diagnosed with PD and 41 eyes of 41 healthy subjects underwent retinal and choroidal assessment using swept source DRI Triton OCT (Topcon, Tokyo, Japan). Macular perfusion parameters, including superficial and deep foveal avascular zones (FAZs and FAZd, respectively), superficial capillary plexus (vascular density [VDs]), deep capillary plexus (VDd), and choriocapillaris (VDc), were compared with healthy controls. Results: The central sectors of the VDs, VDd, and VDc measurements (P = 0.001; P = 0.001; P = 0.001, respectively) and the superior sectors of VDs and VDc (P = 0.001; P = 0.001, respectively) were found to be significantly higher in the study group compared to the control group. FAZs and FAZd values were found to be decreased significantly in PD patients (P = 0.001 and P = 0.001, respectively). Choroidal thickness was significantly reduced (P = 0.007). Central macular thickness measurement did not differ between the groups (P > 0.05). In the multivariate regression model, VDs superior, FAZs, and choroidal thickness variables were determined to have a significant and independent effect in differentiating patients with PD from the individuals in the control group. Conclusion: PD seems to affect macular and choroidal microcirculation. The reduced choroidal thickness and increased central sectors of the VDs, VDd, and VDc measurements may provide disease activity information. However, more comprehensive studies on OCTA demonstrating clinical utility in PD are needed to support our findings.