Retinal Vessel Density and Retinal Nerve Fiber Layer Thickness: A Prospective Study of One-Year Follow-Up of Patients with Parkinson's Disease

Objective: This study aims to compare the superficial vascular density from the macular region and the retinal nerve fiber layer (RNFL) thickness from the optic disc region between Parkinson's disease (PD) patients and controls. Methods: We enrolled 56 idiopathic PD patients, totaling 86 eyes (PD group), and 45 sex- and age-matched healthy individuals, amounting to 90 eyes (control group). All subjects underwent examination using Zeiss wide-field vascular optical coherence tomography (OCT) (Cirrus HD-OCT 5000 Carl Zeiss, Germany), with a scanning range of 3 mm x 3 mm. We divided the images into two concentric circles with diameters of 1 mm and 3 mm at the macular fovea's center. Patients with PD were evaluated during their off phase using the Unified Parkinson's Disease Rating Scale III (UPDRS-III) and the Hoehn-Yahr scale (H-Y scale) to assess disease severity. Results: The PD group exhibited significantly lower RNFL thickness (106.13 +/- 12.36 mu m) compared to the control group (115.95 +/- 11.37 mu m, P < 0.05). Similarly, the superficial retinal vessel length density was significantly lower in the PD group (20.7 [19.62, 22.17] mm(-1)) than in the control group (21.79 +/- 1.16 mm(-1), P < 0.05). Correlation analysis revealed a negative correlation between RNFL thickness and UPDRS III score (r(s)=-0.036, P=0.037), and RNFL thickness tended to decrease with increasing severity of movement disorders. However, during the 6 and 12-month follow-up of some PD patients, we observed no progressive thinning of the RNFL or decreased superficial vascular density. Conclusion: PD patients show retinal structural damage characterized by RNFL thinning and reduced retinal vessel length density. However, RNFL thickness did not correlate with vascular density nor did it decrease with the disease's progression.

Automated summary

This study aimed to compare the superficial vascular density and RNFL thickness between PD patients and controls. The results showed that the PD group had lower RNFL thickness and retinal vessel length density than the control group. However, there was no correlation between RNFL thickness and vascular density, and no progressive thinning of the RNFL or decreased vascular density with disease progression.