Longitudinal Analysis of Retinal Microvascular and Choroidal Imaging Parameters in Parkinson's Disease Compared with Controls

Purpose: To quantify rate of change of retinal microvascular and choroidal structural parameters in subjects with Parkinson's disease (PD) compared with controls using OCT and OCT angiography (OCTA).Design: Prospective longitudinal study.Participants: Seventy-four eyes of 40 participants with PD and 149 eyes of 78 control individuals from the Eye Multimodal Imaging in Neurodegenerative Disease database.Methods: Subjects underwent OCT and OCTA imaging at 2 time points approximately 12 months apart.Main Outcome Measures: Imaging parameters included central subfield thickness, ganglion cell-inner plexiform layer (GC-IPL) thickness, peripapillary retinal nerve fiber layer thickness, choroidal vascularity index, superficial capillary plexus perfusion density (PFD), vessel density (VD), and foveal avascular zone area.Results: Participants with PD had greater rate of yearly decrease in GC-IPL (PD = -0.403mm, control = + 0.128 mm; P = 0.01), greater yearly decline in PFD in the 3 x 3 mm ETDRS circle (PD = -0.016, control = + 0.002; P < 0.001) and ring (PD = -0.016, control = + 0.002; P < 0.001); 6 x 6 mm ETDRS circle (PD = -0.021, control = 0.00; P = 0.001), and outer ring (PD = -0.022, control = 0.00; P = 0.001). Participants with PD had greater rate of yearly decline in VD in 3 x 3 mm circle (PD = -0.939/mm, control = + 0.006/mm; P < 0.001) and ring (PD = -0.942/ mm, control = + 0.013/mm; P < 0.001); 6 x 6 mm circle (PD = -0.72/mm, control = -0.054/mm; P = 0.006), and outer ring (PD = -0.746/mm, control = -0.054/mm; P = 0.005). When stratified by PD severity based on Hoehn and Yahr stage, faster rates of decline were seen in Hoehn and Yahr stages 3 to 4 in the 3 x 3 mm circle PFD and VD as well as 3 x 3 mm ring VD.Conclusions: Individuals with PD experience more rapid loss of retinal microvasculature quantified on OCTA and more rapid thinning of the GC-IPL than controls. There may be more rapid loss in patients with greater disease severity.