A network of NEI supported researchers, who are a part of the Diabetic Retinopathy Clinical Research Network completed a two years study in 2015 that found the drug Lucentis can be an effective treatment for people with advanced stage diabetic retinopathy, called proliferative diabetic retinopathy. Proliferative diabetic retinopathy is the growth of abnormal blood vessels that leak blood. This can distort vision and damage the retina. Lucentis is one of several drugs called vascular endothelial growth factor (VEGF) inhibitors that can block the growth of abnormal blood vessels. This is also commonly used to treat age-related macular degeneration. This study suggests that using VEGF inhibitors may help prevent macular edema.