Abstract
BACKGROUND: Recent studies have suggested that retinal changes measured with optical coherence tomography are detectable in early Parkinson's disease (PD), highlighting the potential of ophthalmic biomarkers for diagnosis and monitoring. OBJECTIVE: We set out to investigate the relationship between optic disc pallor measured in fundoscopy images and both prevalent and incident PD. METHODS: We analyzed color fundus photographs from 787 UK Biobank participants: 89 with prevalent PD, 317 with incident PD, and 381 age- and sex-matched controls. Optic disc pallor in several zones was quantified using semi-automated software. We used logistic and linear regression, adjusted for relevant covariates, to test for associations between disc pallor and PD status and duration. RESULTS: Participants with prevalent PD had significantly paler optic discs globally (OR per standard deviation [SD] increase = 1.39 [CI: 1.08-1.81], P = 0.012) and across several zones compared to controls. Each year since PD diagnosis was associated with a 1.37 SD increase in global pallor (standardized β = 1.37 [SE = 0.61], P = 0.029), and a similar increase across several zones, however, this finding was sensitive to outliers with long disease duration. No significant associations were observed for the incident PD group. CONCLUSIONS: Optic disc pallor is significantly associated with PD and may become more pronounced with disease duration. This suggests that optic disc pallor, measured in routinely taken color fundus photographs, may serve as a biomarker for PD-related neurodegeneration. © 2025 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.