ObjectiveTo observe the changes in the structure and function of the retina in diabetic patients, and preliminarily explore the changes in the characteristics of neuropathy and microvascular damage in different degrees of diabetic retinopathy (DR). MethodsA prospective controlled study. From May to December 2020, 63 eyes of 63 patients with type 2 diabetes who were recruited from the Department of Ophthalmology of Shandong Provincial Hospital and 40 healthy volunteers with age and sex matching in the same period (control group) were included in the study. All subjects underwent optical coherence tomography angiography (OCTA) and portable non-mydriatic visual electrophysiological diagnosis system RETeval. OCTA was used to measure the thickness of the retinal nerve fiber layer (pRNFL) around the optic disc, the blood flow density of theradial peripapillary capillary (RPC) around the optic disc, and the thickness of the macular ganglion cell complex (GCC). The "DR evaluation plan" mode of the RETeval device was used to perform flash electroretinogram examination, and the "DR evaluation score" measured by the system was recorded. According to the DR grading standard established in the early treatment of DR research, DR was classified. Diabetic patients were divided into non-DR (non-DR) group, mild to moderate non-proliferative DR (mNPDR) group, and severe non-proliferative DR (sNPDR) group , Proliferative DR (PDR) group, with 12, 16, 18, and 17 eyes respectively. The comparison of pRNFL thickness, GCC thickness, RPC blood flow density and "DR assessment score" between groups was performed by one-way analysis of variance; the correlation between pRNFL thickness and RPC blood flow density was analyzed by Pearson correlation analysis. ResultsCompared with the control group, the overall, upper and lower thickness of the macular GCC of the affected eyes in different degrees of DR groups were significantly thinner, and the difference was statistically significant (F=13.560, 15.840, 5.480; P<0.05). Compared with the control group, the overall pRNFL (F=6.120), upper part (F=6.310), lower part (F=5.330), upper nose (F=7.350), lower nose (F=2.690), the upper nasal side (F=4.780), the upper temporal side (F=3.710), and the lower temporal side (F=3.750) became thinner, the difference was statistically significant (P<0.05). Correlation analysis results showed that the whole optic disc, upper part, lower part, upper nose, upper nasal side, lower nasal side, and lower temporal RPC blood flow density were positively correlated with pRNFL thickness (r=0.260, 0.256, 0.275, 0.489, 0.444, 0.542, 0.261; P<0.01). The "DR evaluation scores" of the eyes in the control group, non-DR group, mNPDR group, sNPDR group, and PDR group were 12.71±5.62, 22.18±3.77, 24.68±2.41, 24.98±2.78, 29.17±7.98 points; the DR lesions were more severe, the evaluation score were higher, and the difference was statistically significant (F=1.535, P<0.01). ConclusionCompared with the control group, the macular GCC, pRNFL thickness and RPC blood flow density of diabetic patients are significantly reduced; the "DR evaluation score" is increased, and it is related to the severity of DR.
Diabetic retinopathy (DR) is the main cause of blindness in diabetic patients. Early diagnosis and intervention are essential to improve the quality of life of patients with DR. Choroidal vascularity index (CVI) is the ratio of choroidal luminal area to total area, which can reflect the structure and blood flow of the choroid, and has been used to evaluate the choroidal condition in various eye diseases. CVI has shown great potential in the prediction, early intervention, disease assessment, and prognosis of DR. The relationship between CVI and photoreceptors needs more research, and CVI may be used as a predictive indicator of photoreceptor health and visual prognosis. In addition, the study of CVI at different layers of the choroid is limited by the accuracy of stratification and the repeatability of measurement. Artificial intelligence and other technologies may provide solutions for this. In the future, through more comprehensive study and the help of artificial intelligence, the value of CVI will be further enriched, which is of great significance for the elucidation of the pathogenesis of DR and serving the clinic.