Increased levels of vascular endothelial growth factor and interleukin-6 in the aqueous humor of diabetics with macular edema

PURPOSE: To investigate the relationship between diabetic macular edema and the levels of vascular endo. thelial growth factor VEGF) and interleukin 6 (IL-6) in aqueous humor and plasma. DESIGN: Comparative cross-sectional study. METHODS: Fifty,four eyes from 54 diabetic patients were used. The concentrations of VEGF and IL-6 in undiluted aqueous specimens (obtained from the eyes during cataract surgery) and in plasma were measured by an enzyme-linked immunosorbent assay. To assess bloods aqueous barrier function, the aqueous flare intensity was measured by a laser flare,cell meter as an estimate of the aqueous protein level. RESULTS: The aqueous levels of VEGF and IL-6 were significantly correlated with the severity of macular edema (P = 0.628, P <.001 and p = 0.517, P <.01 respectively), as well as with the aqueous protein concentration (p = 0.618, P <.001 and p = 0.588, P <.001, respectively). Aqueous levels of VEGF and IL-6 were significantly higher than their respective plasma levels (both P <.001). In addition, the aqueous level of VEGF was significantly correlated with that of IL-6 (p = 0.537, P <.01). Furthermore, the status of the posterior vitreous significantly correlated with the severity of macular edema (1) = 0.618, P <.000 1). CONCLUSIONS: These results suggest that both VEGF and IL-6 are produced together in the intraocular tissues, and are involved in the pathogenesis of macular edema.