Optical coherence tomography angiography is an efficient tool to assess optic nerve perfusion

Abstract

Background Glaucoma is the neuropathy of the optic nerve with accelerated apoptosis of the retinal ganglion cells. Optical coherence tomography angiography provides valuable information about the optic nerve and the retinal circulation as an auxiliary tool for glaucoma diagnosis and optic nerve saving. Purpose To evaluate the performance of optical coherence tomography angiography in distinguishing primary open-angle glaucoma from healthy eyes by measuring the radial peripapillary capillary (RPC) vessel density (VD)% and macular superficial capillary plexus (SCP) VD%. Patients and methods A descriptive prospective cross-sectional case–control study was conducted on 60 participants, who were categorized into two groups: group A (30 patients with primary open-angle glaucoma and group B (30 healthy controls of matched age and sex with group A). Structural (retinal nerve fiber layer and ganglion cell complex thickness), functional (the mean deviation, and pattern standard deviation), and vascular parameters [the VD of RPC in scan 4.5×4.5 mm (in whole image, and the peripapillary region) and macular SCP in scan 6×6 mm] were compared between the two groups. Results Statistically significant decreases of VD of RPC of the whole disk, the peripapillary region, and the macular superficial plexus layer were observed in glaucoma eyes compared with controls (all P<0.001). As for the VD of the RPC of the whole disk, the mean value in the healthy control was (51.83±2.31) and in the glaucoma group was (46.21±2.98). For the VD of the RPC of the peripapillary region, the mean value in the healthy control was (52.56±0.2.61), while it was (46.9±3.1) in glaucoma eyes. Regarding VD of the macular superficial plexus layer, the mean value in healthy controls was 47.53±2.1, while it was 43.91±2.81 in glaucoma eyes. Structural, regarding the comparison of the retinal nerve fiber layer thickness between the two groups, the glaucoma patients had a significant (P=0.0001) lower mean value (81.34±0.11) than healthy controls (103.85±0.6.2). Also, for comparing the ganglion cell complex thickness between the two groups, the glaucoma patients had a significant (P=0.0001) lower mean value (80.72±6.9) than healthy controls (99.67±5.8). Functional, significant statistical differences (P=0.0001) of both, the mean deviation [between healthy control (0.18±0.86) and glaucoma group (−4.2±1.9)] and the mean of pattern deviation (P=0.0001) [between healthy control (1.22±0.91) and glaucoma group (4.6±1.72)] were determined. Conclusion Quantitative assessment of the VD of RPC and superficial macular capillary plexus is a promising tool for glaucoma decision making. As compared with healthy controls, the VD of RPC and SCP in glaucoma patients is reduced.