Abstract
Purpose: :
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 12 Long-Evans rats, in order to induce BRVO. The occlusion was performed on the right eye of each animal, while the left eye was used as control. One day after the occlusion, the right eye of each animal was injected intravitreally with either artificial aqueous humor (n=4), bevacizumab (n=4) or triamcinolone (n=4). The animals were sacrificed 24 hours 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 much improved in animals having received treatment post BRVO.
Conclusions: :
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 results are part of an ongoing experiment, which will include the use of combination therapy in the management of BRVO.