Aqueous concentrations of VEGF and soluble VEGF receptor-1 in diabetic retinopathy patients

The aim of this study was to simultaneously measure the concentrations of vascular endothelial growth factor (VEGF) and soluble VEGF receptor-1 (sVEGFR-1, also known as sFlt-1) in the aqueous humor of patients with non-proliferative diabetic retinopathy (NPDR) and to investigate whether aqueous levels of vascular endothelial growth factor (VEGF) and VEGFR-1 are related to diabetic macular edema. Aqueous humor was collected from 27 diabetic patients and 33 age- and sex-matched normoglycemic controls and analyzed for pro-angiogenic VEGF and angiogenic inhibitor VEGFR-1 by enzyme-linked immunosorbent assay (ELISA). The mean foveal thickness was measured by optical coherence tomography (OCT). There was no significant difference in the aqueous levels of VEGF in patients with NPDR compared with control subjects (P > 0.05), while the NPDR patients had significantly lower sVEGFR-1 in their aqueous humor. Furthermore, a significant (P < 0.01) positive correlation was observed between sVEGFR-1 concentration and the mean foveal thickness measured on OCT. The results suggest that decreased chelating effect of sVEGFR-1 may be the preliminary event allowing VEGF to activate the proangiogenic endothelial cell state and to induce permeability. The imbalance between angiogenic agent (VEGF) and the antiangiogenic factors (sFlt-1), which is disturbed in the diabetic state, may determine the fate of diabetic macular edema.