Peripapillary Retinal and Choroidal Vasculature in Patients with Diabetes of Different Durations without Clinical Diabetic Retinopathy

Objective: The aim of this study is to quantitatively assess peripapillary retinal and choroidal vasculature using swept-source optical coherence tomography angiography (SS-OCTA) in patients with diabetes mellitus (DM) across different disease durations but without clinical signs of diabetic retinopathy (DR). Methods: This was a single-center, cross-sectional study conducted at General Hospital of Central Theater Command from April to September 2023. A total of 211 subjects were enrolled and categorized into four groups: non-diabetic controls (88 eyes), DM duration <5 years (135 eyes), 5-10 years (87 eyes), and ≥10 years (92 eyes). SS-OCTA was used to assess peripapillary retinal nerve fiber layer (pRNFL) thickness, ganglion cell-inner plexiform layer (pGCL-IPL) thickness, superficial capillary plexus vascular density (SCP pVD), and choroidal parameters. Linear regression analysis identified factors associated with SCP pVD. Results: Compared with the control group, peripapillary SCP pVD in the diabetic group was significantly lower (33.56 ± 2.87% vs 31.39 ± 3.77%, p < 0.05). This decrease was significantly correlated with diabetes duration (B = -0.205, p < 0.001). A progressive reduction in pRNFL thickness was observed with increasing disease duration, which reached statistical significance. Differences in macular ganglion cell-inner plexiform layer (mGCL-IPL) thickness were identified across the DM groups. Peripapillary choroidal vascularity index (CVI) was significantly lower in all DM groups compared with controls. Furthermore, SCP pVD was independently associated with diabetes duration, pRNFL thickness, peripapillary choroidal thickness, and the presence of hypertension. Conclusion: SS-OCTA can detect early progressive damage to peripapillary microvasculature and choroid in DM patients without clinical DR. These parameters (including SCP pVD, pRNFL thickness, mGCL-IPL thickness, and peripapillary CVI) may serve as early biomarkers for preclinical DR, providing a scientific basis for early screening and targeted intervention to delay the progression of diabetic retinopathy.