Diurnal variations in flow density measured using optical coherence tomography angiography and the impact of heart rate, mean arterial pressure and intraocular pressure on flow density in primary open-angle glaucoma patients.

PURPOSE: To determine the diurnal variations in peripapillary and macular flow density (FD), as measured using optical coherence tomography angiography (OCTA) and to elaborate on the relationship between diurnal FD, circulatory parameters and intraocular pressure (IOP) variations in primary open-angle glaucoma (POAG). METHODS: Forty eyes of 40 POAG patients were drawn into this cross-sectional study. The retinal microvasculature of the macula (superficial and deep layers) and optic nerve [radial peripapillary capillary (RPC)] was examined by OCTA (AngioVue® , Optovue). Optical coherence tomography angiography (OCTA) measurements were conducted at 08:00, 11:00, 15:00 and 20:00 over the course of two consecutive days. Intraocular pressure (IOP) and circulatory parameters were assessed accordingly. Diurnal variations in FD were analysed using linear mixed models. RESULTS: While superficial macular FD and RPC FD revealed not to be affected by diurnal variations (p = 0.492, p = 0.319), FD in the deep layer of the macula increased throughout the day (p < 0.001). Superficial macular FD was influenced significantly by mean arterial pressure (MAP) (p = 0.006) and heart rate (HR) (p = 0.033), whereas FD in the RPC layer was significantly affected by HR (p = 0.010). No statistically significant effect of IOP fluctuations on FD was observed. CONCLUSION: This study shows diurnal fluctuations of deep macular FD measured by OCTA and outlines the relationship between FD and hemodynamic parameters (MAP/HR) in POAG patients.