OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY IN PARKINSON’S DISEASE: A SYSTEMATIC REVIEW AND META-ANALYSIS

We performed a systematic review and meta-analysis of the literature up to date and summarized eligible studies on the differences of optical coherence tomography angiography (OCTA) retinal measurements in Parkinson’s disease (PD) patients and controls and performed bias analysis to assess the robustness of the association estimates to unobserved confounding.

We performed a literature search for eligible studies on MEDLINE and EMBASE from database inception up to October 13,2021 and adopted a two-step screening process.

We used the Hartung-Knapp-Sidik-Jonkman random-effects method (1) to combine study-specific SMD in pooled effect estimates and a meta-analytic extension of the E-value metric (2) to quantify the confounding bias capable of nullifying the pooled estimates.

We identified nine eligible cross-sectional studies, involving 475 eyes from PD patients and 781 eyes from healthy controls. The pooled standardized mean differences (SMD) of retinal vessels density (VD) in the whole superficial vascular plexus (SVP), foveal SVP, parafoveal SVP and foveal avascular zone (FAZ) was -0.57 [95% CI: -1.08 to -0.05, p-value=0.04], -0.14 [95% CI: -0.88 to 0.59, p-value=0.62], -0.59 [95% CI: -1.41 to 0.23, p-value=0.12] and -0.20 [95% CI: -0.79 to 0.38, p-value=0.39], respectively. In order for the SMDs estimates of VD in whole SVP, foveal SVP, parafoveal SVP and FAZ to be nullified, an unmeasured confounder would have to be associated with a risk ratio of 2.74, 1.54, 2.81 and 1.70, respectively, with the risk of PD or the corresponding OCTA measures. 

Our results support associations between OCTA retinal measurements and PD, suggesting that OCTA may be a potential useful tool in the diagnosis of PD.