Aqueous humor levels of vascular endothelial growth factor and adiponectin in patients with proliferative diabetic retinopathy before and after intravitreal bevacizumab injection

To determine the levels of vascular endothelial growth factor (VEGF) and adiponectin (APN) in the aqueous humor of patients with diabetic proliferative retinopathy (PDR) before and after injection of bevacizumab (IVB). Twenty eyes of twenty consecutive type 2 diabetic patients with PDR were enrolled in this study. Aqueous samples were collected at baseline and one month after IVB to evaluate VEGF and APN levels. 20 age-matched patients undergoing cataract surgery were used as control. Best-corrected visual acuity (BCVA) and foveal thickness (FT) changes after IVB were also measured. Safety was assessed by recording the incidence of ocular and non-ocular adverse events. At baseline APN and VEGF levels were significantly lower in controls than in PDR patients (APN: 3.6±1.1 vs 18.7±4.5 ng/ml; VEGF: 39.5±25.5 vs 146.2±38.71 pg/ml). After IVB, both compounds significantly decreased in PDR patients. FT and BCVA at baseline were significantly different between controls and patients (FT: 215.6 ± 34.8 vs 532.7 ± 112.4 μm; BCVA: 23.6 ±4.2 vs 18.4 ± 7.3 letters). After IVB a significant decrease of FT with a concomitant improvement of BCVA occurred. Neither ocular nor systemic adverse events were reported. Our findings demonstrate that PDR patients show VEGF and APN levels in aqueous humor higher than those found in control subjects. IVB significantly reduced the levels of both compounds, which remain always at concentrations higher than those recorded in control subjects. The inhibition of VEGF is not associated with total regression of retinal neovascularization secondary to PDR, hence other angiogenic factors might play a role in the pathogenesis of PDR. Thus, future approach to PDR must be multifactorial, acting towards molecules like APN in combination with the currently used anti- VEGF drugs