Macular Microvascular Optical Coherence Tomography Angiographic Changes in Different Stages of Primary Open Angle Glaucoma

Background: Globally, primary open-angle glaucoma (POAG) is recognized as a cause of permanent blindness. A novel noninvasive technique called optical coherence tomography angiography (OCTA) can quickly and quantitatively analyze the vascular plexus of the retina and optic disc. Objective: To assess the alterations of macular microvasculature in different stages of POAG and correlate these alterations with retinal nerve fibre layer thickness visual field mean deviation. Subjects and Methods: A cross-sectional study was performed on 60 eyes, including 45 eyes of POAG cases and 15 eyes of normal controls. POAG individuals were classified into mild, moderate, and severe groups according to Hodapp, Parish, and Anderson classification. All subjects underwent Spectralis OCTA to assess macular microvasculature. Results: We found that the superficial and deep macular vessel density (MVD) was significantly reduced in cases with POAG compared to normal controls, which increased as glaucoma severity increased. The mean superficial MVD in the control group and POAG groups (mild, moderate and severe) was 52.8 ± 5.4, 47.6 ± 4.3, 40 ± 3.1 and 32.6 ± 2.9, respectively, while the mean deep MVD in the control group & POAG groups (mild, moderate and severe) was 57.5 ± 4.4, 51.5 ± 4.7, 45.3 ± 2.8 and 37.3 ± 3.2 respectively (p-value < 0.001). Conclusion: POAG patients had a lower MVD than normal controls. The MVD may be a supplementary diagnostic and monitoring tool for glaucoma progression.