Objective To observe the changes of blood flow density in the macular area of normal eyes,and to analyze its correlation with age.Methods A cross-sectional study.Two hundred and fifty normal healthy subjects (125 males and 125 females,aged 44.76± 14.77) in routine ophthalmologic examination at the Department of Ophtalmology of Guangdong Provincial People's Hospital during June 2017 to June 2018 were enrolled.Among them,20 to 29,30 to 39,40 to 49,50 to 59,and ≥ 60 years old were 50 subjects (50 eyes) in each.BCVA,slit lamp microscope,indirect ophthalmoscope,OCT angiography (OCTA) examinations were conducted for all eyes.The subjects were examined by both eyes,and the data of 1 eye was selected by EXCEL to generate random numbers,including 126 right eyes and 124 left eyes.The range of 6 mm × 6 mm in the macular area was scanned using a frequency domain OCTA instrument.The software automatically divides it into three concentric circles centered on the macular fovea,which were foveal area with a diameter of 1 mm,parafoveal area of 1 to 3 mm,and foveal peripheral area of 3 to 6 mm.The blood flow density of superficial capillary vessel,deep capillary vessel and foveal avascular area (FAZ) within a 300 μm width (FD-300),FAZ area,perimeter (PERIM),non-circularity index,center retinal thickness (CRT) were measured.The relationship between the blood flow density in macula,CRT,FAZ and age was analyzed by Pearson correlation analysis.Results The mean blood flow density of superficial capillary vessel and deep capillary vessel were (51.61 ± 2.54)％ and (54.04± 5.46)％,respectively.The average FD-300,CRT,PERIM and non-circularity index were (285.55 ± 12.13) μm,(2.150 ± 0.367) mm,1.10 ± 0.04,respectively.The relevance of the results showed that the age was negatively correlated with the blood flow density of whole area (r=-0.335,-0.279;P＜0.01),parafoveal area (r=-0.255,-0.368;P＜0.01),foveal peripheral area (r=-0.330,-0.269;P＜0.01) in superficial capillary vessel and deep capillary vessel as well as FD-300 (r=-0.311,P＜0.01),but not correlated with the blood flow density of foveal area (r=-0.071,-0.118;P=0.264,0.064).There was no relationship between the age and the FAZ area,PERIM,non-circularity index (r=-0.070,-0.055,0.074;P=-0.267,0.385,0.142).The age was negatively correlated with the average CRT (r=-0.217,P＜0.01),but not correlated with the CRT in foveal area (r=0.115,P=0.068).The CRT was positively correlated with the blood flow density of superficial capillary vessel and deep capillary vessel in foveal area (r=0.715,0.653;P＜0.01),but negatively correlated with the FAZ area (r=-0.669,P＜0.01).Conclusion The capillary blood flow density ofmacular area in the normal eyes decreases with age.

Objective:To investigate the characteristics of macular perfusion and structures in patients with early stages of diabetic retinopathy (DR) using optical coherence tomography angiography (OCTA).Methods: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).Results: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)mm 2, 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). Conclusions: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.

Diabetic macular edema (DME) is the main cause of vision loss and even blindness in patients with diabetic retinopathy. Intravitreal anti-vascular endothelial factor therapy has become the gold standard management of DME. However, not all eyes response optimally to common management of DME, which could be due to the differences of individual factors. Increasing age could be the predictive factors for poor outcome. The influence of glycemic control, hypertension, dyslipidemia, chronic kidney disease and relative factors on treatment response require further investigation. Identifying the systemic factors that influence the treatment response of DME can provide the evidence to predict the prognosis of DME, and improve the efficacy of clinical treatment.