Retinal vascular indexes and renal function in hypertensive patients: relationship between different microvascular networks

Purpose: Aim of the paper is to present preliminary data on the correlation between the level of renal damage expressed through laboratory and retino-choroidal vascular parameter in non-diabetic hypertensive patients. Methods: Retrospective observational study included patients affected by Chronic Kidney Disease (CKD) or not evaluated by OCT and OCT-A. Clinical and laboratory parameters included blood pressure and renal function assessment. Results: Statistically significant differences were observed between the two subgroups as far as mean office blood pressure (BP) (p=0.013) and office systolic BP (p=0.011). OCT parameters showed no statistically significant differences. In OCT-A FAZ area was larger in no CKD patients in both capillary plexus (63.2±2.37% vs. 61.2±1.64%, p=0.004; and 63.1±2.73% vs. 61.2±2.01%, p=0.019, respectively), Vessel Density was lower in CKD group (in inner ring 36.8±2.7% vs. 38.8±1.64%, p=0.004; and 36.7±2.9% vs. 38.8±2.1%, p=0.002, respectively, and in outer ring 40.2±1.8% vs. 41.5±1.1%, p=0.012 and 40.4±1.8% vs. 42.0±1 %, p<0.001). No significant differences were observed with respect to Fractal Dimension, Vessel Tortuosity, or Vessel Length Density, but Capillary Density Index (CDI) was significant lower in CKD patients (p<0.001). Correlation between CDI and urinary albumin excretion (UAE) levels was significant negative (r= –0.49, p=0.0001). ROC curve analysis demonstrated discriminative ability of CDI in identifying UAE levels (AUC=0.777, p<0.0001). Conclusion: UAE association with reduction in CDI suggests a possible coexistence of endothelial damage at the retinal and renal levels.Retinal microvascular alterations are indicative of CKD, and OCTA can provide new biomarkers for early evaluation of the related damage.