| Objective:OCTA was used to detect the morphological changes of macular fovea,blood flow density and their correlation with cystatin C and fasting blood glucose in early diabetic retinopathy.To evaluate the diagnostic value of macular foveal avascular zone（FAZ）parameters in early diabetic retinopathy.Methods:A total of 24 eyes of diabetic patients were collected from the outpatient department of Ophthalmology,endocrinology and inpatient department of the Affiliated Hospital of Youjiang Medical College for Nationalities from October 2021 to January 23rd.DWR group 17 eyes,NPDR group 7 eyes;18 eyes of healthy control group were examined by OCTA.According to subjects’age,sex,course of disease,best corrected vision（Log MARBCVA）,cystatin C,fasting blood glucose and OCTA,foveal thickness,superficial FAZ area and circumference,proximity index,parafoveal 300μm blood vessel density（FD-300）,superficial FAZ blood flow density and other relevant parameters were obtained.The analysis and comparison between groups were carried out.Results:（1）The mean value of cystatin C in healthy group,DWR group and NPDR group was 0.97±0.06 mg/L,1.18±0.12 mg/L and 1.42±0.34 mg/L,respectively,and there was no statistical significance in cystatin level among the three groups（P>0.05）.The mean values of fasting blood glucose in the healthy group,DWR group and NPDR group were 5.00±0.13mmol/L,8.60±1.14 mmol/L and 7.30±0.13 mmol/L,and the differences of fasting blood glucose between DWR group and NPDR group were statistically significant（P=0.030,P<0.05）.（2）The mean thickness of macular fovea in the healthy group,DWR group and NPDR group was 262.22±24.14μm,247.29±16.36μm and 248.43±21.72μm,respectively.The comparison of macular foveal thickness among the healthy group,DWR group and NPDR group showed that there was no statistical significance in this index at different stages of DR（F=2.580,P=0.089,P>0.05）.The average area of shallow FAZ in the healthy group,DWR group and NPDR group was 0.20±0.01 mm2,0.27±0.09 mm2 and 0.40±0.08 mm2,respectively.With the increase of disease severity,the area of shallow FAZ gradually increased,and the difference was statistically significant（F=18.542,P=0.000,P<0.05）;Pairwise comparison results showed that the differences among health group,DWR group and NPDR group were statistically significant（P<0.05）.The average perimeter of shallow FAZ in the healthy group,DWR group and NPDR group was 1.86±0.08 mm,2.20±0.10 mm and2.76±0.15 mm,respectively.With the progression of the disease,the perimeter of shallow FAZ gradually increased,and the difference was statistically significant（F=14.588,P=0.000,F=14.588,P=0.000,P<0.05）;Pairwise comparison results showed that there was statistical significance between healthy group and DWR group and NPDR group respectively（P<0.05）.The mean value of shallow FAZ near circle index in the healthy group,DWR group and NPDR group was 0.72±0.02,0.64±0.02 and 0.57±0.06,respectively,and the mean value of shallow FAZ near circle index decreased gradually,with statistical significance（F=7.129,P=0.002,P<0.05）.Pairwise comparison results showed that there was statistical significance between healthy group and DWR group and NPDR group respectively（P<0.05）.The mean blood vessel density of shallow FD-300 in healthy group,DWR group and NPDR group was37.11±0.69,35.00±0.81 and 28.43±2.44,respectively,and there were statistically significant differences among the three groups（F=12.954,P=0.000,P<0.05）.Pairwise comparison showed that there was a statistically significant difference in shallow FD-300vascular density between healthy group and NPDR group（P<0.05）.There was no significant difference in shallow FD-300 vascular density between healthy group and DWR group,DWR group and NPDR group.The mean value of superficial FAZ blood perfusion density in the healthy group,DWR group and NPDR group was 41.00±0.58 mm-1,44.00±0.43 mm-1and44.66±2.51 mm-1,respectively.The mean value of superficial FAZ blood perfusion density decreased with the progression of the disease,and the difference was statistically significant（F=3.025,P=0.051,P>0.05）;Pairwise comparison showed that NPDR was significantly different from healthy group and DWR group（P<0.05）.There was no significant difference between healthy group and DWR group（P>0.05）.（3）The analysis results of this study showed that the age of patients in the healthy control group,DWR group and NPDR group was not correlated with the superficial FAZ area（r=-0.105 P=0.595）,the proximal circle index（r=-0.194 P=0.322）and the thickness of macular fovea（r=-0.163 P=0.446）.Age was negatively correlated with superficial FAZ perfusion density（r=-0.430 P=0.023）.The optimal corrected visual acuity BCVA in DWR group and NPDR group was not correlated with superficial FAZ area（r=0.381 P=0.142）,superficial FAZ blood perfusion density（r=-0.155 P=0.471）,and macular fovea thickness（r=0.143 P=0.505）.The FAZ circle index was negatively correlated with the best corrected visual acuity BCVA（r=-0.475*P=0.019）.Fasting blood glucose in DWR group and NPDR group was not correlated with superficial FAZ area（r=-0.345 P=0.098）,proximity index（r=-0.019 P=0.929）,superficial FAZ perfusion density（r=-0.019 P=0.929）and macular fovea thickness（r=0.185）P=0.386)were not correlated.Cystatin c and its superficial FAZ area（r=0.293 P=0.164）,proximity index（r=-0.227 P=0.285）,superficial FAZ perfusion density（r=-0.010 P=0.964）,and macular fovea thickness（r=0.359）were measured in DWR and NPDR groups P=0.085)were not correlated.（4）The shallow FAZ index had the greatest diagnostic value in diabetic retinopathy.The diagnostic efficiency,confidence interval,best diagnostic threshold and sensitivity and specificity of the threshold were AUC=0.734,P=0.010,95%CI,0.549-0.877,respectively.The best diagnostic threshold was 0.3889,the sensitivity was 0.556,and the specificity was0.8333.Conclusion:1.This study suggests that the retinal microcirculation and structure of early diabetic retinopathy in OCTA are manifested as decreased blood density,increased area and circumference of superficial FAZ,decreased thickness of macular fovea and decreased proximity index.2.The study found that visual acuity changes in early diabetic patients were correlated with changes in near circle index,which may be a new indicator of morphological changes in early diabetic retinopathy,providing new ideas for further research on diabetic retinopathy. |
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