Critical appraisal of ranibizumab in the treatment of diabetic macular edema

Diabetic retinopathy is the leading cause of blindness among individuals of working age in industrialized nations, with most of the vision loss resulting from diabetic macular edema (DME). The formation of DME depends on the action of several growth factors and inflammatory mediators, but vascular endothelial growth factor (VEGF) appears to be critical for breaking down the blood-retinal barrier and promoting the accumulation of macular edema. Laser photocoagulation has been the standard-of-care for three decades, and although it stabilizes vision, significant gains in visual acuity after treatment are unusual. Several VEGF inhibitors (pegaptanib, aflibercept, and ranibizumab) have been initially developed and tested for the treatment of age-related macular degeneration and subsequently for DME. In Phase I, II, and III trials for DME, ranibizumab has been shown to be superior to macular laser photocoagulation and intraocular triamcinolone acetonide injections for improving visual acuity and drying the macula. As a result, ranibizumab is the only anti-VEGF drug that has been approved by the United States Food and Drug Administration for the treatment of DME. Most experts now consider intravitreal anti-VEGF therapy to be standard-of-care for DME involving the fovea.