To investigate the relationship between the concentration of aqueous humor cytokines and the severity of diabetic retinopathy.

Thirty-six subjects were included in the control, non-proliferative diabetic retinopathy (NPDR), and proliferative diabetic retinopathy (PDR) groups, each group has 12 patients. Aqueous levels of cytokines (interleukin (IL)-1α, IL-1β, IL-2, IL-4, IL-6, IL-8, IL-10, vascular endothelial growth factor (VEGF), monocyte chemoattractant protein (MCP)-1, interferon (IFN)-γ, tumor necrosis factor (TNF)-α) were investigated according to the severity of diabetic retinopathy.

When the control group was compared with the PDR and NPDR groups, aqueous levels of IL-6 were significantly higher in PDR patients than in those of both the control and NPDR groups ( p = 0.016 and p = 0.003, respectively). The aqueous levels of VEGF were significantly higher in the eyes of PDR patients than in those of the control group ( p = 0.003). There were no statistically significant differences between the 3 groups with regard to other cytokines.

Aqueous levels of IL-6 and VEGF were higher in the eyes of PDR patients than in those of healthy controls.