Application of optical coherence tomography angiography in fundus screening in newly diagnosed patients with type 2 diabetes

Objective To explore the diagnostic value of optical coherence tomography angiography(OCTA) in fundus screening in newly diagnosed type 2 diabetic patients.

Methods Forty patients with newly diagnosed type 2 diabetes from November 2019 to March 2021 were included in this study. Experienced physicians performed fundus examination for them. According to diabetic retinopathy (DR) conditions, non-DR patients were included in NDR group (n=20), those with mild non-proliferative diabetic retinopathy (NPDR) were included in early DR group (n=20). At the same time, 20 healthy subjects matched with age were included in control group. OCTA was used to scan and quantitatively analyze the macular region of the study subjects, and macular blood flow density(MVD) of superficial vascular capillary(SVC), deep vascular capillary (DVC) and choroidal capillaries layer (CC) and the area of the macular fovea without blood vessels (FAZ) were obtained. The difference of different indicators in each group and the value of screening and diagnosis for early DR were compared.

Results The blood flow density of SVC, DVC and CC were (0.52±0.09), (0.54±0.13) and (0.51±0.07), respectively in the NDR group, were (0.45±0.09), (0.43±0.09) and (0.45±0.06), respectively in the early DR group, and were (0.54±0.01), (0.57±0.01) and (0.52±0.02), respectively in the control group. Compared with the control group, blood flow density of SVC, DVC and CC decreased in the NDR group and early DR group. The FAZ area was (0.39±0.06) mm² in the NDR group, (0.43±0.05) mm² in the early DR group, and (0.29±0.01) mm² in the control group. The FAZ area of the NDR group and the early DR group was larger than that of the control group, and the early DR group had the most obvious expansion of FAZ area. Multivariate Logistic analysis showed that DVC blood flow density and FAZ area both affected the diagnosis.

Conclusion Early changes of macular vascular density and enlargement of FAZ can be observed in early diabetic retinopathy by OCTA. Patients with early diabetic retinopathy have reduced MVD and enlarged FAZ area. Both blood flow density and FAZ area of DVC can affect the diagnosis of early DR, and FAZ area has higher diagnostic value for early DR.