Quantitative Analysis of Microvasculature in Macular and Peripapillary Regions in Early Primary Open-Angle Glaucoma

Purpose: To evaluate macular and radial peripapillary capillary vessel densities (RPC VD) across normal, pre-perimetric (PPG), and early perimetric primary open-angle glaucoma (EG) using optical coherence tomography angiography (OCTA).Materials and Methods: Forty-four PPG eyes, 42 EG eyes, and 41 normal eyes were consecutively enrolled. All subjects underwent visual field, OCT, and OCTA examinations. Macular vessel densities were measured in the superficial layer. RPC VD was measured within a 750-μm-wide elliptical annulus extending outward from disc boundary. Diagnostic ability was evaluated with area under the receiver operating curve.Results: Parafoveal vessel densities (ParaVDs) in the PPG group were comparable to the normal group (p > .05), except for temporal quadrant (p = .044), while perifoveal vessel densities (PeriVD) were lower in the PPG group (p < .05). ParaVD and PeriVD were lower in the EG group compared with the normal group (p < .001). Superior-temporal and inferior-temporal retinal nerve fiber layers (RNFLs) were significantly decreased in the EG group compared with the PPG group (p < .05), while only inferior-temporal RPC VD was lower in the EG group (p < .05). RPC VD was comparable to RNFL and ganglion cell complex (GCC) in the diagnosis of PPG (p > .05). Macular whole image vessel density and PeriVD were comparable to RPC VD, RNFL, and GCC in diagnosing EG (p > .05).Conclusions: In early primary open-angle glaucoma, significant microvascular damage was present in both macular and peripapillary areas. The damage of macular microvasculature was more prominent in the peripheral area. Vessel density parameters showed promising diagnostic ability in early glaucoma.Abbreviations: POAG = primary open-angle glaucoma; RGC = retinal ganglion cell; OCTA = optical coherence tomography angiography; RNFL = retinal nerve fiber layer; PPG = pre-perimetric primary open-angle glaucoma; EG = early perimetric primary open-angle glaucoma; IOP = intraocular pressure; PSD = pattern standard deviation; MD = mean deviation; GCC = ganglion cell complex; SBP = systolic blood pressure; DBP = diastolic blood pressure; MAP = mean arterial pressure; MOPP = mean ocular perfusion pressure; wiVD = whole image vessel density; ParaVD = parafoveal vessel density; PeriVD = perifoveal vessel density; RPC VD = radial peripapillary capillary vessel density; AUC = area under the receiver operating curve.