Parallel work aims to develop the VEGF dual dAb in a compatible slow-release delivery system and to evaluate its efficacy in vivo,3 the ultimate aim being to extend the treatment interval of VEGF driven ocular angiogenic disorders that show vascular leak such as wet age-related macular degeneration, diabetic macular edema, retinal vein occlusion and potentially cancers such as glioblastoma with a high vascular dependence (2, 4). Here, VEGFA is linked to retinal vein occlusion.