Topographic Differences in Superficial Macular Vessel Density in Eyes with Early Primary Open-Angle Glaucoma and Normal Tension Glaucoma

Introduction: To compare macular vascular microcirculation in early primary open-angle glaucoma (POAG), normal tension glaucoma (NTG), and normal subjects. Methods: 99 patients with early glaucoma (99 eyes: 60 POAG and 39 NTG) and 78 normal subjects were included. All subjects underwent optical coherence tomography angiography (OCTA) scan at 6×6 mm macular area. Macular vessel density (VD) and perfusion density (PD) and 9 sectors were compared between the controls, POAG and NTG groups. Linear regression analysis was used to investigate the relationship between VD and other variables including macular PD, signal strength (SS) and mean macular ganglion cell-inner plexiform layer (mGCIPL) thickness. Results. Significant losses in total area of VD and PD were detected in POAG and NTG groups compared to the controls (all P < 0.01). There were no significant differences in all inner sectors of macular VD and PD between POAG and controls (all P >0.05). Except for outer-nasal sector, all other outer sectors of macular VD and PD were significant lower in POAG than in the controls (all P < 0.01). The inferior-inner sector and all outer sectors of VD and PD were significant lower in NTG than in the controls (all P < 0.01). Macular VD was significantly correlated with macular PD (r = 0.99, P < 0.001), SS (r = 0.60, P < 0.001) and mGCIPL thickness (r=0.51, P < 0.001). Conclusions: Macular microcirculation declined significantly in early POAG and NTG patients. Macular microcirculation loss in the NTG group was more central and nasal compared with that in the POAG group. A decrease in macular VD was correlated with lower macular PD, lower SS and thinner mGCIPL thickness.