| Objective: In order to investigate the macular microvascular changes in diabetic patients without diabetic retinopathy(DR),it is important to explore the clinical significance by using optical coherence tomography angiography.Methods: Totally 89 patients with type 2 diabetic were enrolled in The Second Hospital of Hebei Medical University from March to June in 2017.According to the international clinical grading criteria of diabetic retinopathy,114 eyes(66 patients)with non-proliferative diabetic retinopathy are classified as the NPDR group,and 37 eyes(23 patients)without diabetic retinopathy are classified as zero stage group.A total of 61(39 subjects)normal eyes with matched age are enrolled in the control group.All the subjects have underwent the 3mm×3mm scanning of macular retina by optical coherence tomography angiography,and get two layers of the foveal avascular zone(FAZ)and four layers of macular blood flow density map.Meanwhile,it has measured the percentage of the FAZ area of superficial capillary plexuses(SCP)and deep capillary plexuses(DCP),the macular blood flow density and macular blood flow density,including SCP,DCP and choroid capillary plexuses.T test(two groups comparison)or the single factor analysis of variance(multi-group comparison)were used to compare FAZ area,macular blood flow density and macular blood flow density percentage on different gender,age,the duration of using duration,grouping stage(NPDR,0 stage,and control group).Results:1.FAZ area: The area of SCP and DCP group in zero stage group is 0.39±0.14,0.69±0.20 respectively.The area of SCP and DCP in NPDR group is 0.44±0.16,0.80±0.32 respectively.In the controlled group,the FAZ area of SCP,DCP were 0.38±0.12,0.64±0.21 respectively.The area of FAZ in each layer of group is higher than that of the controlled group(t=2.89,P=0.013< 0.05;t=3.66,P=0.001<0.05).But there was no statistical difference between the NPDR group and the 0 stage group(t=1.89,P=0.179>0.05;t=2.13,P= 0.103>0.05),also between the control group and the 0 stage group(t=0.48,P=0.179>0.05;t=-0.87,P=0.103>0.05).2.The macular blood flow density : The macular blood flow density of SCP,DCP and choroidal capillaries layer in the zero stage group are respectively 1.71±0.23,1.80±0.26 and 3.21±0.22.The macular blood flow density of the 3 layer in NPDR group are respectively 1.63±0.21,1.76±0.42 and 3.19±0.26.For the control group,the macular blood flow density of the 3 layer are 1.70±0.36,2.09±0.34 and 3.19±0.22.The macular blood flow density in DCP layer of the zero stage and NPDR group are lower than that of the controlled group(t=3.726,P<0.001;t=5.535,P<0.001).But there was no statistical difference between the NPDR group and the 0 stage group(t=-0.545,P=0.587>0.05).3.The percentage of the macular blood flow density: The macular blood flow density percentage of SCP,DCP and choroidal capillaries layer in the zero stage group are respectively 14.06±2.74,15.33±2.95 and 35.42±6.00.The macular blood flow density of the 3 layer in NPDR group are 13.41±2.56,14.35±4.21 and 35.40±6.97 respectively.For the controlled group,The percentage of macular blood flow density percentage of the 3 layer are respectively 13.33±3.71,17.98±4.24 and 35.18±6.21.The macular blood flow density percentage in DCP layer of the zero stage and NPDR group are lower than that of the control group(t=-3.76,P=0.001<0.05;t=-5.46,P=0.000 <0.05).But there was no statistical difference between the NPDR group and the 0 stage group(t=-0.47,P=1.000>0.05).4.The area of FAZ in diabetic patients is not related to age,but it is associated with diabetes duration.The FAZ area of SCP layer in patients whose symptom is between five and ten years or over10 years diabetic duration is higher than that in diabetic duration within five years(t=-2.93,P=0.012<0.05;t=-2.41,p=0.017<0.05).Conclusion: The patient of diabetic have decreased their macular blood flow density and the percentage of the flow density in diabetics without diabetic retinopathy.As the duration of the diabetes disease increased,the area of FAZ is obviously enlarged.It is suggested that micro vascular damage has existed in the retina before diabetic retinopathy.OCTA quantification of FAZ area and DCP layer macular blood flow density and the percentage of blood flow density can be used as an effective way to monitor the progression of diabetes and predict the occurrence of diabetic retinopathy. |
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