Purpose: To explore the role of vascular endothelial growth factor (VEGF) and interleukin-6 (IL-6) in the aqueous humor in the pathogenesis of diabetic retinopathy (DR).

Methods: Aqueous humor samples were collected in type 2 diabetic patients during cataract surgery. The classification of DR was assigned based on the fundus examination and fluorescein angiography after cataract surgery. The experiment group included non-diabetic retinopathy (NDR, 21 cases), background diabetic retinopathy (BDR, 26 cases), and proliferative diabetic retinopathy (PDR, 19 cases). The control group was the healthy cataract patients (20 cases). The levels of VEGF and IL-6 in the aqueous humor were assessed using the ELISA technique.

Results: The level of VEGF in NDR, BDR, and PDR cases were (240.30 ± 26.15) pg/ml, (292.27 ± 58.91) pg/ml, and (477.41 ± 91.01) pg/ml, respectively. The level of IL-6 in NDR, BDR, and PDR cases were (160.83 ± 33.41) pg/ml, (238.60 ± 62.23) pg/ml, and (389.13 ± 90.35) pg/ml, respectively. The levels of VEGF and IL-6 in the aqueous humor from the control group were (140.58 ± 26.27) pg/ml, (82.72 ± 21.53) pg/ml. The levels of VEGF and IL-6 were significantly different in experiment and control groups (F = 113.67, P < 0.01; F = 106.53, P < 0.01). In the aqueous humor of diabetic patients increased significantly (P < 0.1). The levels of VEGF and IL-6 were significantly correlated with each other in the experiment group (r = 0.995, P < 0.01). The levels of VEGF (r = 0.792, 0.826, 0.841, P < 0.01) and IL-6 ((r = 0.829, 0.817, 0.896, P < 0.01) were also significantly correlated with the duration of DR.

Conclusion: VEGF and IL-6 play important roles in the development of DR. The levels of these two factors are correlated with each other in DR patients.