| Objective:To investigate the morphological and structural changes of microcirculation under different scan mode by means of optical coherence tomography angiography(OCTA)in different stages of diabetic retinopathy(DR).Methods:52 diabetic patients(70 eyes)with different stage of DR(graded according to the International Clinical Severity Scale for DR)and 9 healthy subjects(18 eyes)underwent different scan mode(3 mm × 3 mm and 6 mm × 6 mm)using OCTA,get the capillary network images of superficial capillary plexuses(SCP),deep capillary plexuses(DCP)and choriocapillary.The measurements of foveal avascular zone(FAZ)area of SCP,parafoveal vessel densitis of different plexuses under 3 mm × 3 mm and 6 mm × 6 mm scan mode were also calculated using Imagej software,acircularity index(AI)of FAZ was also calculated.T-test(comparison between two groups)was used to compare the FAZ area,vessel density,AI and other indicators of the subjects in different groups.Results:1 FAZ area: The area of SCP in no-DR group is 0.331±0.088.The area of SCP in mild NPDR group is 0.419±0.108.The area of SCP in moderate and severe NPDR group is 0.417±0.105.The area of SCP in PDR group is 0.604±0.192.In the control group,the FAZ area of SCP is 0.276±0.072.The FAZ area of mild NPDR group,moderate and severe NPDR group and PDR group is higher than that of the control group(P<0.05).But there was no statistical difference between the no-DR group and the control group(P>0.05),there was also no statistical difference between the no-DR group and the mild NPDR group,moderate and severe NPDR group(P>0.05),there was a statistical difference between the no-DR group and the PDR group(P<0.05),there was no statistical difference between the NPDR groups,.but there has statistical differences between the NPDR groups and PDR group(P<0.05).2 Vessel density2.1 The vessel density under 3 mm × 3 mm scan mode:The vessel density of SCP,DCP and choriocapillary layer in the no-DR group are 0.464±0.045,0.505±0.053 and 0.616±0.051 respectively.The vessel density of SCP,DCP and choriocapillary layer in the mild NPDR group are 0.433±0.050,0.462±0.039 and 0.587±0.060 respectively.The vessel density of SCP,DCP and choriocapillary layer in the moderate and severe NPDR group are 0.406±0.047,0.432±0.044 and 0.598±0.059 respectively.The vessel density of SCP,DCP and choriocapillary layer in the PDR group are 0.367±0.053,0.391±0.006 and 0.489±0.036 respectively.For the control group,the vessel density of SCP,DCP and choriocapillary layer are 0.476±0.072,0.512±0.122 and 0.623±0.381 respectively.There was no statistical difference between the no-DR group and the control group in SCP,DCP and choriocapillary layer(P>0.05).There was no statistical difference between the mild NPDR group and the control group in SCP and choriocapillary layer(P>0.05),but there has a statistical difference between the mild NPDR group and the control group in DCP(P<0.05).There was also has statistical differences between the moderate and severe NPDR group,PDR group and the control group in SCP,DCP and choriocapillary layer(P<0.05,P<0.001).There was a statistical difference between the no-DR group and mild NPDR group in DCP(P<0.05).There was also has statistical differences between the moderate and severe NPDR group,PDR group and the no-DR group in SCP,DCP and choriocapillary layer(P<0.001).There was a statistical difference between the mild NPDR group,moderate and severe NPDR group and PDR group in DCP(P<0.05,P<0.001).There was a statistical difference between the moderate and severe NPDR group and PDR group in SCP,DCP and choriocapillary layer(P<0.05,P<0.001,P<0.001)2.2 The vessel density under 6 mm × 6 mm scan mode: The vessel density of SCP,DCP and choriocapillary layer in the no-DR group are 0.499±0.043,0.508±0.049 and 0.617±0.044 respectively.The vessel density of SCP,DCP and choriocapillary layer in the mild NPDR group are 0.457±0.044,0.492±0.040 and 0.562±0.065 respectively.The vessel density of SCP,DCP and choriocapillary layer in the moderate and severe NPDR group are 0.440±0.029,0.485±0.035 and 0.585±0.056 respectively.The vessel density of SCP,DCP and choriocapillary layer in the PDR group are 0.421±0.075,0.373±0.066 and 0.483±0.051 respectively.For the control group,the vessel density of SCP,DCP and choriocapillary layer are 0.525±0.053,0.593±0.048 and 0.618±0.049 respectively.There was no statistical difference between the no-DR group and the control group in SCP(P>0.05),but here has a statistical difference between the no-DR group and the control group in DCP and choriocapillary layer(P<0.05).There was also has statistical differences between the mild NPDR group,moderate and severe NPDR group,PDR group and the control group in SCP,DCP and choriocapillary layer(P<0.05).There was a statistical difference between the mild NPDR group and the no-DR group in SCP and choriocapillary layer(P<0.05),but there was no statistical difference in DCP(P>0.05).There was also has statistical differences between the no-DR group and PDR group in SCP,DCP and choriocapillary layer(P<0.05).There was no statistical difference between the NPDR groups in SCP,DCP and choriocapillary layer(P>0.05).But there has statistical differences between the NPDR groups and PDR group(P<0.001).2.3 The vessel density of outer ring:The vessel density of SCP,DCP in the no-DR group are 0.511±0.059 and 0.509±0.064 respectively.The vessel density of SCP,DCP in the mild NPDR group are 0.485±0.539 and 0.498±0.049 respectively.The vessel density of SCP,DCP in the moderate and severe NPDR group are 0.454±0.099 and 0.501±0.047 respectively.The vessel density of SCP,DCP in the PDR group are 0.444±0.038 and 0.392±0.086 respectively.For the control group,the vessel density of SCP,DCP are 0.527±0.068 and 0.522±0.062 respectively.There was a statistical difference between the no-DR group and the control group only in DCP(P<0.05),and there was a statistical difference between the DR groups and the control group in DCP(P<0.05).There was also has statistical differences between the moderate and severe NPDR group,PDR group and the no-DR group in DCP(P<0.05).There was a statistical difference between the NPDR groups and the PDR group in DCP(P<0.05).3 Acircularity index(AI) The acircularity index of no-DR group,mild NPDR group,moderate and severe NPDR group and PDR group are 1.163±0.052,1.199±0.070,1.224±0.067 and 1.539±0.093 respectively,For the control group,the acircularity index is 1.106±0.033.There was no statistical difference between the no-DR group and control group(P>0.05),but there has statistical differences between the mild NPDR group,moderate and severe NPDR group,PDR group and the control group(P<0.05;P<0.001;P<0.001).There was no statistical difference between the no-DR group and mild NPDR group(P>0.05),but there has statistical differences between the moderate and severe NPDR group,PDR group and the no-DR group(P<0.05;P<0.001).There was no statistical difference between the mild NPDR group and moderate and severe NPDR group(P>0.05),but there has statistical differences between the mild NPDR group and PDR group(P<0.001).There was a statistical differences between the moderate and severe NPDR group and PDR group(P<0.001).Conclusion: FAZ area of DR patients was larger than that of healthy people,and increased with the aggravation of DR and the increase of lesion grade.In patients with diabetes,the parafoveal vessel density decreased with the increase of lesion severity and lesion grade,especially in the DCP layer.The AI of FAZ increases with the progression of DR,and AI can be used as a marker to measure the change of FAZ,which is an effective biological image parameter for monitoring the progress of DR. |
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