Abstract
[EN] Background: Retinal microvascular alterations have been previously described in
Parkinson’s disease (PD) patients using optical coherence tomography angiography
(OCT-A). However, an extensive description of retinal vascular morphological features,
their association with PD-related clinical variables and their potential use as diagnostic
biomarkers has not been explored.
Methods: We performed a cross-sectional study including 49 PD patients (87 eyes) and
40 controls (73 eyes). Retinal microvasculature was evaluated with Spectralis OCT-A
and cognitive status with Montreal Cognitive Assessment. Unified PD Rating Scale and
disease duration were recorded in patients. We extracted microvascular parameters
from superficial and deep vascular plexuses of the macula, including the area and
circularity of foveal avascular zone (FAZ), skeleton density, perfusion density, vessel
perimeter index, vessel mean diameter, fractal dimension (FD) and lacunarity using
Python and MATLAB. We compared the microvascular parameters between groups
and explored their association with thickness of macular layers and clinical outcomes.
Data were analyzed with General Estimating Equations (GEE) and adjusted for age, sex,
and hypertension. Logistic regression GEE models were fitted to predict diagnosis of PD
versus controls from microvascular, demographic, and clinical data. The discrimination
ability of models was tested with receiver operating characteristic curves.
Results: FAZ area was significantly smaller in patients compared to controls in
superficial and deep plexuses, whereas perfusion density, skeleton density, FD and
lacunarity of capillaries were increased in the foveal zone of PD. In the parafovea,
microvascular parameters of superficial plexus were associated with ganglion cellinner
plexiform layer thickness, but this was mainly driven by PD with mild cognitive
impairment. No such associations were observed in controls. FAZ area was negatively
associated with cognition in PD (non-adjusted models). Foveal lacunarity, combined
with demographic and clinical confounding factors, yielded an outstanding diagnostic
accuracy for discriminating PD patients from controls.
Conclusion: Parkinson’s disease patients displayed foveal microvascular alterations
causing an enlargement of the vascular bed surrounding FAZ. Parafoveal microvascular
alterations were less pronounced but were related to inner retinal layer thinning. Retinal
microvascular abnormalities helped discriminating PD from controls. All this supports
OCT-A as a potential non-invasive biomarker to reveal vascular pathophysiology and
improve diagnostic accuracy in PD.