Pathogenesis of macular edema with branch retinal vein occlusion and intraocular levels of vascular endothelial growth factor and interleukin-6

Purpose: To determine whether correlations between vascular endothelial growth factor (VEGF) or interleukin-6 (IL-6) contribute to the pathogenesis of macular edema in eyes of patients with branch retinal vein occlusion (BRVO). Design: Retrospective case-control study. Methods: Nineteen patients with macular edema with BRVO and seven patients with non,ischemic ocular disease (control group) were studied. The degree of retinal ischemia was evaluated in terms of the area of capillary non-perfusion, and the severity of macular edema was examined by optical coherence tomography. Aqueous humor samples were obtained at the time of combined vitrectomy and cataract surgery, and VEGF and IL-6 levels in aqueous humor and plasma were determined by enzyme-linked immunosorbent assay. Results: Aqueous levels of VEGF (351 +/- 273 pg/ml) and IL-6 (7.10 +/- 6.51 pg/ml) were significantly elevated in patients with BRVO compared with the control patients (119 +/- 38.7 pg/ml and 2.27 +/- 1.11 pg/ml, respectively) (P=.0017 and P=.0052, respectively). Aqueous level of VEGF was significantly correlated with that of IL-6 (P=.0396), and aqueous levels of VEGF and IL-6 were correlated with the size of the BRVO non-perfused area (P<.0001 and P=.0331, respectively). Aqueous level of VEGF was correlated with the severity of macular edema (P=.0306). Conclusions: VEGF and IL-6 may be involved in the pathogenesis of macular edema with BRVO. The increase in these cytokines might be used as a unique index of BRVO, through which we can determine the severity of the ischemic condition as being in a quiescent state or an exacerbation of macular edema.