Effect of anti‐VEGF drugs and steroids on the inner blood‐retinal barrier, after experimental BRVO in rats: preliminary results

Abstract

AbstractPurpose To evaluate the effect of anti‐VEGF drugs and steroids on the inner blood‐retinal barrier (BRB) function after experimental branch retinal vein occlusion (BRVO) in rats. The integrity of the barrier is related to the expression of occludins by retinal endothelial cells.Methods Laser photocoagulation was applied to retinal veins of the right eye of 4 Long‐Evans rats, to induce BRVO. The left eye was used as control. One day after the occlusion, the right eye of each animal was injected intravitreally with either bevacizumab (n=2) or triamcinolone (n=2). The animals were sacrificed 7 days later; all retinas were harvested and prepared for indirect immunohistochemistry, using an anti‐ occluding primary antibody. The specimens were examined using a confocal microscope and images were acquired.Results In normal retinas, occludins appeared as a dense, well‐organised, fluorescent reticulum along the vascular wall. In eyes with BRVO, the structure of occludins was disrupted; irregular linear fluorescence appeared along occluded veins, while absence of fluorescence suggested down‐regulation of occludin expression. Occludin distribution was improved in animals having received treatment post BRVO.Conclusion The administration of bevacizumab and triamcinolone post BRVO seems to improve the function of the inner BRB. This could explain macular edema reduction after the use of these drugs. These preliminary results are part of an ongoing experiment, which will include the use of combination therapy in the management of BRVO.