Progressive Changes in the Retinal Structure of Patients with Parkinson's Disease

Background: Many optical coherence tomography (OCT) studies have reported alterations in the retinal nerve fiber layer (RNFL) in Parkinson's disease (PD) and other neurodegenerative diseases. However, whether retinal alterations are a biomarker for PD is still controversial. Objective: To investigate potential correlations between PD and morphological changes in retina using OCT and to determine its usefulness as a biomarker of disease progression in PD. Methods: We performed a cross-sectional study on patients with PD (N = 37) and age-matched controls (N = 42), followed by a longitudinal study of the PD patients (N = 22) over approximately 2.5 years. Results: The average retinal nerve fiber layer (RNFL) thickness (p < 0.001), total macular thickness (p = 0.001), and macular volume (p = 0.001) were decreased in PD patients compared to controls and had further decreased at the follow-up visit (p < 0.05 for all). The average RNFL thickness and the total thickness of macular were negatively correlated with age in PD patients at baseline. Linear regression analysis revealed that age (p = 0.002, p = 0.003, respectively) and LEDD (p = 0.011, p = 0.013, respectively) were correlated to total thickness and volume of macular in 22 PD patients in the follow-up study. However, no correlation was found between RNFL and other parameters. Conclusions: PD progression is associated with pronounced retinal structure changes, which can be quantified by OCT. Patterns of RNFL and macular damage detected by the noninvasive technology of OCT can be a useful biomarker for evaluating the progression of PD.