Diabetic retinal neurodegeneration (DRN) is a condition in which the normal function of retinal neurovascular units is impaired due to various factors such as oxidative stress, microvascular damage, metabolic disorders, neurotrophic factor imbalance, and immune damage in hyperglycemia environment. The loss of neurons and glial dysfunction is involved in the destruction of the blood-retinal barrier, impaired vascular response and neurovascular coupling, leading to microvascular disease and neurodegeneration. More and more studies have proved that DRN is associated with microangiopathy and diabetic retinopathy pathogenesis. A deeper understanding of the pathogenesis of neurovascular injury may provide new and more effective prevention strategies for diabetic retinopathy.
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.
ObjectiveTo observe and analyze the correlation between macular microvascular parameters and urinary albumin to creatinine ratio (UACR) in patients with type 2 diabetes mellitus (T2DM). MethodsA cross-sectional study. From October 2017 to April 2018, 100 eyes of 100 patients (T2DM) and 27 eyes of 27 healthy controls (the control group) were enrolled in Xuzhou First People’s Hospital. All subjects underwent anterior segment examination via slit-lamp biomicroscopy, dilated fundus examination, 7-field fundus photographs, OCT angiography (OCTA), the fasting glucose test, glycosylated hemoglobin (HbA1c), urinary albumin, urinary creatinine and UACR levels determination. Height and weight measurement were taken for calculating body mass index (BMI). Diabetic retinopathy was ruled out by fundoscopic examinations and 7-field fundus photographs in T2DM patients. According to the UACR, patients in the T2DM group were subdivided into A1 group (UACR< 30 mg/g), A2 group (UACR 30-300 mg/g), and A3 group (UACR>300 mg/g), with 38 cases and 38 eyes respectively , 40 cases with 40 eyes, 22 cases with 22 eyes. A 6 mm×6 mm scanning area centered on the macular fovea were scanned for right eye using a frequency domain OCTA instrument, which were divided into three concentric circles centered on the macular fovea by the software automatically. The foveal zone was defined as a circular area measuring 1 mm in diameter, the parafoveal zone was described as a middle circle area measuring 1-3 mm in diameter, and the perifoveal zone was an outer circle area measuring 3-6 mm in diameter. The vessel density of superficial capillary plexus (SCP) and deep capillary plexus (DCP), foveal avascular area (FAZ) and perimeter (PERIM), non-circularity index (AI) were measured. The correlation between the macular vessel density, FAZ and UACR was analyzed by Spearman correlation analysis. ResultsA1 group, A2 group, A3 group, and normal control group. The macular area SCP and DCP (F=13.722, 5.644), foveal area (F=4.607, 4.719), parafoveal area (H=23.142, F=2.904), the blood flow density of the area around the fovea (F=12.292, H=10.946), the difference was statistically significant (P＜0.05); with the increase of UACR, the blood flow density of each area of SCP and DCP showed a downward trend. The results of correlation analysis showed that the blood flow density of the whole SCP, parafoveal area, and surrounding area of T2DM patients was negatively correlated with UACR (r=－0.376, －0.240, －0.364, －0.347, P＜0.05). There were no correlation among fasting plasma glucose, HbAlc and UACR (r=0.179, 0.085, P＞0.05). There were no correlation among blood flow density in BMI, SCP foveal area, DCP and UACR (|r|＜0.3, P＞0.05). ConclusionThe whole, parafovea and perifovea vessel density values of SCP in T2DM eyes without DR are negatively correlated with UACR.