Differences in rate of change of retinal structural and microvasculature parameters in parkinson’s disease compared to controls

Abstract Background Prior cross‐sectional studies have revealed decreased macular perfusion density (PFD) and increased peripapillary PFD in Parkinson’s disease (PD). We assess longitudinal rate of change of retinal microvascular and structural parameters in PD vs controls with normal cognition. Method Subjects were imaged using Zeiss Cirrus HD‐5000 AngioPlex. Those with confounding medical or ocular comorbidities were excluded. Superficial capillary plexus (SCP) PFD and vessel density (VD) were assessed within ETDRS 6×6 circle, inner ring, outer ring and 3×3 circle and inner ring. SCP foveal avascular zone (FAZ) area was assessed. PFD, VD, FAZ, peripapillary retinal nerve fiber layer (RNFL), ganglion cell‐inner plexiform layer (GCIPL), and central subfield thickness (CST) were measured at 2 time points 1 year apart. Rate of change per year was calculated. Generalized estimating equations analyzed associations between rate of change of imaging parameters and PD. Result 74 eyes of 40 patients with PD (60% male, mean age 67.47.9 years) & 149 eyes of 78 controls (28% male, mean age 70.35.8 years) were included. No demographic differences were observed between groups except higher proportion of females in controls (p = 0.001). PD had a greater decline in PFD in 6×6 circle (mean change per year = 0.021, control = 0.00, p = 0.001), 6×6 inner ring (PD = 0.018, control = 0.001, p = .007), 6×6 outer ring (PD = 0.022, control = 0.00, p = 0.001), 3×3 circle (PD = 0.016, control = 0.002, p<.001), 3×3 inner ring (PD = 0.016, control = 0.002, p<0.001). PD had greater decline in VD in 6×6 circle (mean change per year in PD = 0.72/mm, control = 0.054/mm, p = 0.006), 6×6 inner ring (PD = 0.636/mm, control = 0.048/mm, p = 0.03), 6×6 outer ring (PD = 0.746/mm, control = 0.054/mm, p = 0.005), 3×3 circle (PD = 0.939/mm, control = 0.006/mm, p<0.001), 3×3 inner ring (PD = ‐0.942/mm, control = 0.013/mm, p<0.001). PD had greater decrease in GCIPL (mean change per year in PD = 0.403µm, control = 0.128µm control, p = 0.01). There were no significant differences in rate of change in FAZ area, RNFL thickness, CST, and no significant differences in rate of change when stratified by PD severity. Conclusion PD may be associated with more rapid loss of retinal microvascular perfusion and vessel densities and more rapid thinning of GCIPL compared to normal aging in controls with normal cognition.