The Retinal Blood Flow Density Is Related to the Pathological Severity of Diabetic Kidney Disease

This study aimed to investigate the correlation between fundus blood flow parameters and the severity of pathological biopsy in patients with diabetic kidney disease (DKD).

Data of patients with type 2 diabetes mellitus who completed renal pathology biopsies and optical coherence tomography angiography (OCTA) examinations, including renal function, 24-h urine protein quantification, and macular flow imaging, were collected. DKD pathology biopsies were graded as stages 1-4, and differences and correlations of the parameters were compared between groups. The grading was transformed into early (stage 1) and late (stages 2-4), and regression analyses were conducted to develop a model, draw a nomogram, and test efficacy.

This study included 157 eyes from 157 individuals in total. Urinary microalbumin and to urinary creatinine ratio (mALB/NCR) increased with pathological grading, whereas while glomerular filtration rate was decreased (p < 0.01). Corresponding retinal blood flow in superficial, deep, and full paracentral rings was decreased, which correlated with pathological grading (p < 0.01), with the highest blood flow density in the whole layer (r2 = -0.707). Meaningfully, in the early DKD model (area under the curve = 0.929 [0.889-0.970], p < 0.01), whole-layer blood flow density, mALB/NCR, and diabetes duration were statistically significant.

The decrease in macular retinal blood flow density detected by OCTA is closely associated with the increase in pathological grading of DKD and can be used as a noninvasive parameter for monitoring early changes in DKD.