Pathological changes of the small blood vessels are the main risk for diabetic retinopathy. A distinction is made between proliferative and non-proliferative processes. The diabetic macular edema can manifest itself at any stage of the diabetic retinopathy and poses a serious threat to vision and quality of life. Evidence based therapy primarily focuses on laser coagulation. Laser coagulation suspends progression of the disease and is used particularly for extrafoveolar edema. Especially a pathological swelling, such as the cystoid edema, in this central part of the retina, can cause a rapid deterioration of vision. The treatment of cystoid macular edema with intravitreal application of drugs is a widespread therapeutical approach. Invasive therapeutical drug application into the vitreous cavity has to be sterile in order to prevent infection. The usage of VEGF (Vascular endothelial growth factor) antagonists is an effective treatment for the diabetic macular edema. Several drugs are now available for intravitreal injection. Nevertheless a small number of medical drugs regularly administered to patients still have to be approved by the authorities (off-label use). One can distinguish mainly between VEGF antagonist (growth factor antagonist) like ranibizumab, aflibercept and bevacizumab and steroid therapy which includes dexamethasone, fluocinolone and triamcinolone.