Vitreous and aqueous concentrations of proangiogenic, antiangiogenic factors and other cytokines in diabetic retinopathy patients with macular edema: Implications for structural differences in macular profiles

The aim of the study was to determine anatomical and growth factor profiles in patients with clinically significant macular oedema (CSMO) undergoing pars plana vitrectomy (PPV). Twenty patients with moderate nonproliferative diabetic retinopathy (NPDR) with persistent CSMO underwent PPV. Patients had baseline and postoperative clinical assessment including Ocular Coherence Tomography (OCT). Baseline vitreous and aqueous and serial postoperative aqueous samples were analysed for vascular endothelial growth factor-A (VEGF-A), pigment epithelium derived Factor (PEDF) and other factors (pg/ml) including hepatocyte growth factor, MMP 9, soluble flt-1 Receptor, and TGF β1 by ELISA. Vitreous from patients with full thickness macular holes (8) and proliferative diabetic retinopathy (22) were collected for comparison as controls. Vitreous VEGF-A concentration in the NPDR group was 957 pg/ml compared to 239 pg/ml in the macula hole (FTMH) control (p<0.0001) and 596 pg/ml compared to PDR (p=0.006). The median diabetic vitreous PEDF concentration was 1.36 μg/ml (FTMH 2.6 μg/ml p=0.05). In NPDR, it was higher (1.59 μg/ml) than PDR (1.27 μg/ml) p=0.02. There were changes to the HGF, soluble flt-1 Receptor and TGF b1 concentrations in the NPDR compared to either PDR or the normal state. In CSMO, two OCT profiles were identified: dome-shaped macular elevation (Group 1) (n=4) and diffuse-low elevation profile (Group 2) (n=16) which also showed differences in the postoperative median aqueous VEGF concentrations despite macular volume decreasing for both. The results suggest that there is an up-regulation of VEGF in the vitreous of the diabetic eye with a reciprocal decrease in PEDF. The structural and molecular differences between the two OCT macular profiles may explain the varying response to PPV in patients with diffuse CSMO.