Vascular complexity and severity of diabetic retinopathy by using swept-source optical coherence tomographic angiography

Objectives: To evaluate the associations of retinal vascular complexity features with the severity of diabetic retinopathy (DR) by using non-invasive optical coherence tomographic angiography (OCTA). Methods: This prospective cross-sectional study recruited ocular-treatment-naive patients with type 2 diabetes mellitus registered in the community of Guangzhou, China. The OCTA was used to obtain the measurements of fractal dimension (FD) and blood vessel tortuosity (BVT) in superficial capillary plexus (SCP) and the deep capillary plexus (DCP). The univariate and multivariate linear regression was used to analyze the correlation of FD and BVT in different layers with DR severity. Results: A total of 1282 patients (1282 eyes) were included, with a mean age of 64.2 (7.8) years, 60.81% of male. The FD in DCP decreased and BVT in DCP increased in DR patients compared to non-DR patients, even after adjusting for confounding factors (P< 0.05). Trend analysis showed a significant decrease in FD values as DR progresses, while the BVT progressively increased with worsening DR severity (P< 0.01). Conclusion: The FD and BVT determined using OCTA might be useful parameters for objectively distinguishing DR from non-DR, and indicating the DR progression.