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Paramjit K Bhullar, Emma Pead, Atalie C. Thompson, Stephen Paul Yoon, Dilraj S Grewal, Bryce Polascik, Tom MacGillivray, Emanuele Trucco, Sharon Fekrat; Evaluation of potential biomarkers in multimodal retinal images for diagnosis of Parkinson's disease: a pilot study. Invest. Ophthalmol. Vis. Sci. 2019;60(9):4565. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Prospective pilot cross-sectional study (NCT03233646) to assess for differences in retinal architecture and vasculature in Parkinson’s disease patients compared to age- and sex-matched cognitively-intact controls
Optical coherence tomography (OCT), OCT angiography (OCT-A, Zeiss Cirrus HD-5000 AngioPlex), and ultra-widefield (Optos California UWF-SLO) images of both eyes were obtained for nine Parkinson’s and nine age- and sex-matched control subjects without diabetes, glaucoma, vitreoretinal disease, or vision <20/40. OCT was used to compare the central macular thickness (CMT), ganglion cell layer (GCL), and retinal nerve fiber layer (RNFL). OCT-A was used to compare foveal avascular zone (FAZ) size and vessel density (VD) and perfusion density (PD) of the 6x6 superficial capillary plexus (SCP). Ultra-widefield images were used to perform fractal (branching complexity) analysis via bespoke VAMPIRE software (Centre for Clinical Brain Sciences, The University of Edinburgh, UK) for UWF-SLO. The retinal vasculature was first segmented and used to obtain global branching complexity of arteries and veins. Wilcoxon rank sum test was performed to compare groups.
Parkinson’s eyes had a thinner GCL (73.0±6.9 vs 75.7±12.2, p=0.02) and RNFL (82.9±8.3 vs 89.7±6.9, p=0.01) compared to controls, but there was no difference in mean CMT (264.6±25.2 vs 267.6±24.4, p=0.55). OCT-A comparison of Parkinson’s to controls showed no difference in FAZ (0.208±0.1 vs 0.26+0.2, p=0.36), but a borderline-significant difference in the PD of the inner circle of the 6x6mm (0.416±0.044 vs 0.440.7±0.034, p=0.062) and 3x3mm SCP (20.9±1.42 vs 21.7±0.022, p=0.08), a borderline significantly thinner VD of the 3x3 inner circle (20.8±1.42 vs 21.7±1.60, p=0.07), and a significantly thinner inner circle of the 6x6 VD (17.4±1.72 vs 18.3±1.43, p=0.04). UWF fractal analysis of Parkinson’s to controls demonstrated a significant increase in the branching complexity of vessels for right (1.37±0.06 vs 1.45±0.03, p=0.0018) but not left (1.34±0.07 vs 1.40±0.04, p=0.1359) eyes.
In this pilot study, we identify potential biomarkers in Parkinson's disease in both the macula and the retinal periphery. Further validation of these biomarkers both for diagnostic utility and ability to detect disease progression through future larger longitudinal studies is needed.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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