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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 â , 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.Key words: blood pressure -diurnal variations -flow density -heart rate -intraocular pressure -open-angle glaucoma -optical coherence tomography angiography †These authors contributed equally to this study.

PurposeTo evaluate the effect of topical mydriatic eye drops on optical coherence tomography angiography (OCTA) parameters in patients with age-related macular degeneration (AMD).Methods27 eyes of 27 patients suffering from AMD were included in this cross-sectional study. Patients with ≥-4.5 diopters spherical equivalent, corneal opacities or dense cataract preventing high-quality imaging were excluded. Whole-en-face scans of the superficial capillary plexus (SCP) and deep capillary plexus (DCP) in the central 3x3mm foveal region as well as whole-en-face and peripapillary scans of the radial peripapillary capillaries (RPC) were generated using OCTA (AngioVue®, Optovue). Imaging was first conducted with patients’ eyes in miosis, then in mydriasis after instillation of a dilating eye drop (0.5% tropicamide, 2.5% phenylephrine-HCl). Main outcome measures were flow density (FD), foveal avascular zone (FAZ), signal strength index (SSI) and motion artifact score (MAS).ResultsOur results reveal that in AMD patients there is no significant difference between FD measurements taken in miosis and those taken in mydriasis around the SCP (p = 0.198), DCP (p = 0.458), RPC whole-en-face (p = 0.275) and RPC peripapillary (p = 0.503). Measurements taken in these two states appear to be equivalent for assessment of FD (90%CI within ± 0.05). No significant difference was found either in the area of the FAZ (p = 0.338) or in the SSI (p = 0.371) before and after the instillation of tropicamide/phenylephrine. MAS was significantly lower after the application of mydriatic eye drops (p = 0.003).ConclusionsOur findings reveal that neither measurements of FD nor measurements of the FAZ area changed significantly in AMD patients after the application of tropicamide/phenylephrine. Since MAS improved significantly in dilation, mydriatic examination is recommended. Nevertheless, a comparison of OCTA metrics from images taken with different pupil states (miosis versus mydriasis) is valid for clinical trials.

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Hemodialysis (HD) is known to affect ocular blood flow. This case-control study aims to evaluate macular and peripapillary vasculature in patients with end-stage renal disease (ESRD) receiving HD in comparison to matched controls. A total of 24 eyes of 24 ESRD patients receiving HD and 24 eyes of 24 healthy, age- and gender-matched control subjects were prospectively included in this study. Optical coherence tomography angiography was used to image the superficial (SCP), deep (DCP), and choriocapillary (CC) macular vascular plexus, as well as the radial peripapillary capillaries (RPC) of the optic disc. In addition, retinal thickness (RT) and retinal volume (RV) were compared between both groups. Flow density (FD) values of each retinal layer and data of parameters related to the foveal avascular zone (FAZ), as well as RT and RV, were analyzed using Mann–Whitney U tests. There was no significant difference in FAZ parameters between the two groups. Whole en face FD of the SCP and CC was noticeably reduced in the HD group in comparison to the control group. FD was negatively correlated with the duration of HD treatment. RT and RV were significantly smaller in the study group than in controls. Retinal microcirculation appears altered in patients with ESRD undergoing HD. Concurrently, the DCP appears more resilient towards hemodynamic changes in comparison to the other microvascular retinal layers. OCTA is a useful, non-invasive tool to investigate retinal microcirculation in ESRD patients.