AIM: To investigate the value of optical coherence tomography angiography(OCTA)parameters and serum caspase-1 for assessing the severity of diabetic retinopathy(DR).METHODS:Patients diagnosed with DR in our hospital from June 2024 to December 2025 were retrospectively enrolled and were divided into early non-proliferative DR(NPDR)and advanced proliferative DR(PDR)groups according to fundus fluorescein angiography(FFA)findings. Patients with diabetes mellitus but without DR were selected as the control group. OCTA parameters included macular vascular density, the perimeter and area of the foveal avascular zone(FAZ), mean retinal thickness, hyperreflective foci(HRF), and internal limiting membrane abnormalities. Blood biochemical indicators contained fasting blood glucose, glycated hemoglobin(HbA1c), systemic immune-inflammation index(SII), triglyceride/high-density lipoprotein(TG/HDL)ratio, urinary albumin/creatinine ratio(UACR), and caspase-1.RESULTS: Totally 128 DR patients(151 eyes)were enrolled in this study, including 75 patients(90 eyes)in the NPDR group(40 males and 35 females, mean age: 74.3±5.6 y)and 53 patients(61 eyes)in the PDR group(27 males and 26 females, mean age: 75.9±5.8 y). Meanwhile, 60 diabetic patients(120 eyes)without DR were recruited as the control group(33 males and 27 females, mean age: 72.6±5.4 y).The macular vascular density gradually decreased in the control, NPDR and PDR groups, while perimeter and area of FAZ, and mean retinal thickness gradually increased, and the incidence of HRF and internal limiting membrane abnormalities gradually increased(all PSymbol|@@0.001). The levels of SII, UACR and caspase-1 gradually increased(all PSymbol|@@0.001). The duration of diabetes mellitus was longer in the NPDR and PDR groups than in the control group(all PSymbol|@@0.001).Multivariate logistic regression analysis demonstrated that diabetic duration, HRF, and caspase-1 were risk factors for the occurrence of DR, while macular vascular density served as a protective factor(all P<0.001). Moreover, caspase-1 was identified as a risk factor for the progression of DR to PDR, and macular vascular density was a protective factor against DR progression(all P<0.001). Receiver operating characteristic(ROC)curve analysis showed that the area under the curve(AUC)of caspase-1 combined with macular vascular density for predicting DR occurrence and PDR was 0.864 and 0.890, respectively, both higher than those of single indicators(all PSymbol|@@0.05).CONCLUSION: The combination of macular vascular density from OCTA parameters and serum caspase-1 has important clinical value in assessing severity of DR.