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To investigate the characteristics of macular perfusion and structures in patients with early stages of diabetic retinopathy (DR) using optical coherence tomography angiography (OCTA).
A cross-sectional study was performed.Forty eyes of 27 diabetic patients without diabetic retinopathy (NDR), forty eyes of 24 patients with mild non-proliferative diabetic retinopathy (NPDR) and forty eyes of 28 patients with moderate NPDR were recruited in Guangdong Provincial People’s Hospital from June 2017 to August 2018.RTVue-XR OCTA was used to scan a 6 mm×6 mm area centered in the fovea and the superficial vascular complex (SVC) and deep vascular complex (DVC) vessel density, fovea avascular zone (FAZ) area, FAZ perimeter, acircularity index (AI), and vessel density of a 300 μm wide ring area around FAZ (FD300) were quantified.The associations among stages of DR and macular vessel density, structures were analyzed.This study was approved by the Ethics Committee of the Guangdong Provincial People’s Hospital (No.2016232A).
The vessel density of SVC and DVC tended to decrease as the progression of DR.The vessel density of SVC was (51.25±3.27)%, (48.81±3.99)%, (47.00±3.49)%, (45.73±3.35)%, and the vessel density of DVC was (53.89±6.30)%, (49.94±6.05)%, (46.69±4.87)% and (44.78±4.30)% in the control group, NDR group, mild NPDR group, and moderate NPDR group, respectively.The vessel densities of SVC and DVC were statistically different among the four groups (F=18.33, 21.53; both at P<0.01). The vessel density of SVC and DVC in the NDR group, mild NPDR group, moderate NPDR group was significantly lower than that in the control group (all at P<0.01). The vessel densities of FD300 in the mild NPDR group and moderate NPDR group were significantly lower than that in the control group (all at P<0.01). The FAZ area of the control group, NDR group, mild NPDR group, and moderate NPDR group was (0.31±0.11), (0.32±0.09), (0.34±0.13), and (0.37±0.10)mm2, respectively.There was no significant difference in the FAZ area among the four groups (F=2.18, P=0.09). The FAZ perimeter and AI were significantly higher in the moderate NPDR group than those in the control group (both at P<0.05).
OCTA is able to detect the decrease of vessel density in diabetic patients before the occurrence of visible fundus lesions.The vessel density of SVC and DVC in patients with early stages of DR is decreased.DVC vessel density may be a sensitive marker to indicate DR.FD300 is not significantly decreased until mild NPDR, FAZ area and perimeter are significantly increased in moderate NPDR, indicating a more irregular FAZ.