Prospective Trial of Treat and Extend Aflibercept for Macular Edema Secondary to Branch Retinal Vein Occlusion

Retinal vein occlusion (RVO) includes central RVO (CRVO) and branch RVO (BRVO). A highly prevalent retinal vascular disease, RVO is second only to diabetic retinopathy. In CRVO, hemorrhages and edema develop throughout the retina, whereas in BRVO the pathology is more sectoral, involving the portions of the retina drained by the obstructed branch vein. This suggests that increased intraluminal pressure behind the obstruction may lead to transudation of blood cells and plasma into the retina. However, recent studies have demonstrated that although increased venous pressure may be the precipitating event for hemorrhages and edema, increased production of vascular endothelial growth factor (VEGF) occurs early in RVO and is a major contributor to their evolution and persistence. In addition, the high levels of VEGF contribute to progression of retinal nonperfusion and hence retinal ischemia, which may in turn increase production of VEGF, and may explain why some eyes enter a vicious cycle of worsening disease often referred to as conversion to an ischemic RVO. Treat-and-extend intravitreal anti-VEGF with age related macular degeneration and diabetic macular edema has been reported to offer the opportunity to individual management while minimizing treatment burden and similar visual and anatomical outcomes to those with fixed montly dosing. Also, small retrospective treat-and-extend intravitreal bevacizumab injection for treatment of BRVO associated macular edema demonstrated similar visual outcomes and number of intravitreal injections as did pro-re-nata treatment with ranibizumab conducted in phase 3 trials but with fewer visits and lower annual medical costs. The effects of afilbercept have been reported to persist for over 8 weeks in DME and AMD studies. In addition, VIBRANT study also demonstrated that bi-monthly injection of aflibercept showed significant visual improvement in BRVO patients. In the treat-and-extend studies of RVO, ranibizumab has been extended for up to 4 months at intervals of 2 weeks. But, to our knowledge, there was no prospective study of treat-and-extend regiments with intravitreal aflibercept in treatment naïve patients in BRVO.