Review of the latest treatments for retinal vein occlusions: emphasis on pharmacologic therapy

Abstract

Retinal vein occlusions (central and branch) are the second most common retinal vascular disorders. Affected patients lose vision due to retinal non-perfusion, vitreous hemorrhage, traction retinal detachments and neovascular glaucoma, but the most common cause of vision loss is macular edema. Animal models and human studies show that breakdown of the blood–retinal barrier results from overexpression of various cytokines and chemokines with upregulation of VEGF being critically important. Laser photocoagulation decreases macular edema due to branch retinal vein occlusion and reduces the overall ischemic drive but resultant improvements in visual acuity are modest (1.5 lines vs 0.3 lines with observation). Laser decreases macular edema in central retinal vein occlusion but does not improve visual acuity better than observation. Numerous surgical treatments have been proposed but none are of proven benefit. Monthly intravitreal injections of drugs that bind diffusible VEGF improve visual acuity and decreases macular edema in most patients. After an initial regimen of intensive monthly therapy, the treatment burden appears to decrease and many patients are ultimately able to discontinue therapy. Corticosteroids (triamcinolone and the dexamethasone delivery system) also restore the blood–retinal barrier but due to high incidences of cataracts and glaucoma, they are generally used as second-line therapy. Ongoing trials are focusing on combination therapy (anti-VEGF, corticosteroids and laser photocoagulation) to optimize visual recovery and decrease treatment burden.