Diagnostic value of optical coherence tomography angiography in evaluating parameters of foveal avascular zone in early diabetic retinopathy

AIM: To analyze the diagnostic value of optical coherence tomography angiography(OCTA)in evaluating the parameters of foveal avascular zone(FAZ)in early diabetic retinopathy(DR).METHODS: Retrospective study. A total of 209 cases(209 eyes)of type 2 diabetes mellitus(T2DM)with DR admitted to our hospital from June 2019 to December 2022 were selected as DR group. The DR group was divided into three groups, with 115 cases(115 eyes)in mild group, 54 cases(54 eyes)in moderate group, and 40 cases(40 eyes)in severe group according to stage. Another 100 cases(100 eyes)of T2DM patients without DR were selected as No-DR group, and 70 cases(70 eyes)of healthy people were selected as control group for physical examination at the same time, all of whom underwent OCTA examination. The DR group was enrolled according to the disease degree, one eye was randomly taken for the study if the degree in both eyes was the same, while the control group and the No-DR group were randomly selected for one eye to be included in the study. The perimeter of the foveal avascular area(PERIM), FAZ transverse diameter, FAZ vertical diameter, FAZ area, macular fovea retinal thickness(MFRT), acircularity index(AI), full layer retinal blood flow density within a range of 300 μm around the FAZ(FD-300), and changes in FAZ vascular density(VD)levels among different groups of subjects were compared. Furthermore, Pearson correlation analysis was used to determine the correlation between general data and FAZ related indicators, and receiver operating characteristic(ROC)curve was used to evaluate the diagnostic value of macular FAZ indicators for DR.RESULTS: The levels of FBG, MFRT, FAZ area, and PERIM in patients with mild, moderate, and severe DR were significantly higher than those in the No-DR group and the control group, while the levels of AI and VD were significantly lower than those in the No-DR group(all P<0.05); patients in the No-DR group, mild DR group, moderate DR group, and severe DR group had significantly higher cystatin C, FAZ transverse diameter, and FAZ vertical diameter than the control group, while FD-300 vascular density was significantly lower than the control group(all P<0.05); the MFRT was positively correlated with age(r=0.295, P=0.001); The AI and VD was negatively correlated with age(r=-0.296, -0.235, all P<0.05); the area under the curve(AUC)of MFRT, FAZ area, PERIM, AI, and VD for the diagnosis of DR were 0.745, 0.738, 0.696, 0.792, and 0.847, respectively.CONCLUSION:The structure and microcirculation of FAZ can be changed in DM patients, and the related parameters of FAZ have certain value in the diagnosis of early DR.