Optical coherence tomography measurements as potential imaging biomarkers for Parkinson's disease: A systematic review and meta-analysis

Background and purpose Retinal pathological changes may precede or accompany the deterioration of brain tissue in Parkinson's disease (PD). The purpose of this meta-analysis was to assess the usefulness of optical coherence tomography (OCT) measurements as potential imaging biomarkers for PD. Methods PubMed, Embase, Web of Science and Cochrane Library databases were systematically searched for observational studies (published prior to 30 May 2020) comparing the OCT measurements between PD patients and healthy controls (HCs). Our main end-points were peripapillary retinal nerve fiber layer (pRNFL) thickness, macular ganglion cell complex thickness, macular thickness and macular volume. Pooled data were assessed by use of a random-effects model. Results A total of 36 observational studies were identified that included 1712 patients with PD (2548 eyes) and 1778 HCs (2646 eyes). Compared with the HC group, the PD group showed a significant reduction in mean pRNFL thickness (weighted mean difference [WMD] -3.51 mu m, 95% confidence interval [CI] -4.84, -2.18; p = 0.000), all quadrants at the pRNFL (WMD range -7.65 to -2.44 mu m, all p < 0.05), macular fovea thickness (WMD -5.62 mu m, 95% CI -7.37, -3.87; p = 0.000), all outer sector thicknesses at the macula (WMD range -4.68 to -4.10 mu m, all p < 0.05), macular volume (WMD -0.21 mm(3), 95% CI -0.36, -0.06; p < 0.05) and macular ganglion cell complex thickness (WMD -4.18 mu m, 95% CI -6.07, -2.29; p < 0.05). Conclusions Our pooled data confirmed robust associations between retinal OCT measurements and PD, highlighting the usefulness of OCT measurements as potential imaging biomarkers for PD.

Automated summary

This meta-analysis reviewed 36 observational studies and found significant reductions in pRNFL thickness, macular fovea thickness, macular volume, and other OCT measurements in PD patients compared to healthy controls.