Purpose: To investigate the diurnal fluctuations of macular vessel density (VD) in primary open-angle glaucoma (POAG) and healthy subjects using optical coherence tomography angiography.
Methods: A total of 22 POAG eyes and 15 healthy eyes were included in this study. Macular VD, intraocular pressure, and blood pressure were repeatedly measured from 8 AM to 8 PM at a 2-h interval on a single day.
Main outcome measures: the macular VD measurements, their diurnal fluctuations, including the difference between their maximal and minimal value (max-min) and their coefficient of variation (CV) in superficial capillary plexus (SCP) and deep capillary plexus (DCP). The mixed-effects model was performed to compare the fluctuations between groups.
Results: After adjusted age, the diurnal fluctuations of macular VD in SCP and DCP were significantly higher in POAG eyes compared with healthy subjects (max-min: 6.65 ± 3.54%, 3.92 ± 3.63%, respectively; p = 0.037 and CV: 0.06 ± 0.03, 0.04 ± 0.03, respectively; p = 0.003). The fovea VD in DCP of POAG eyes was higher than in healthy subjects (31.52 ± 4.68% and 25.71 ± 3.70%, p = 0.009). However, there was no significant difference between the fovea VD in SCP in two groups (20.97 ± 4.75% and 19.29 ± 4.35%, p = 0.670). The diurnal macular superficial VD measured in most of the participants was lower in the morning.
Conclusions: Whether it is a max-min or a CV assessment method, the POAG eyes had more significant diurnal fluctuations of macular VD than healthy controls, suggesting impaired vascular autoregulation in POAG eyes.
Keywords: Diurnal fluctuations; Healthy subjects; Macular vessel density; Primary open-angle glaucoma.