Diabetic retinopathy is one of the main causes of blindness in industrialized nations. Following 20 years of the disease almost 90% of patients develop diabetic retinopathy. Diabetes may further cause dry eye, cataract, glaucoma or a neuropathy of the optic nerve, amongst others. 90% of visual impairment in patients with diabetes is caused by diabetic retinopathy. Non proliferative diabetic retinopathy is distinguished from proliferative diabetic retinopathy. Patients commonly do not experience any symptoms for a long period of time. In later stages vision deteriorates when the macular area is affected and vitreous bleeding has occurred. Diabetic retinopathy is diagnosed using slitlamp biomicroscopy, optical coherence tomography (OCT) and angiography (FA). Microaneurysms or intraretinal bleeding are common findings in non proliferative diabetic retinopathy, newly formed vessels (neovascularization) occur in proliferative diabetic retinopathy, soon leading to blindness of the affected eye if left untreated. If treatment becomes necessary an FA examination is performed in order to determine the indication and type of treatment. OCT commonly reveals retinal edema that requires treatment. Treatment strategies include laser and intravitreally applied substances acting against the vascular endothelial growth factor (VEGF). Patients must be made aware that regular internal checkups regarding long-term blood sugar levels (HbA1C), intraretinal lipids and blood pressure levels have to be carefully monitored and managed if necessary. Regular ophthalmological examinations are fundamental for patients with type 1 or type 2 diabetes in order to avoid visual deterioration or blindness.