The investigator is clinically not convinced about vitrectomy being indicated or the possible side effects outweigh the possible positive effects of vitrectomy<br/>- - - Diabetes mellitus type 1<br/>- - - Visual acuity of the study eye (decimal) > 0,3 (LogMar < 0,5)<br/>- - - Visual acuity of the study eye (decimal) < 0,05 (LogMar > 1,3)<br/>- - - Central retinal thickness stated by SD-OCT < 250 µm<br/>- - - Any clouding of optical media influencing the evaluation of the retina<br/>- - - Previous focal laser coagulation of the macula in the study eye within 3 months prior to baseline<br/>- - - Previous treatment of diabetic macular edema involving intravitreal steroids or VEGF blockers within 3 months prior to baseline<br/>- - - Previous vitrectomy in the study eye<br/>- - - Previous cataract surgery in the study eye within 3 months prior to baseline<br/>- - - Pseudophakia with opening of the posterior capsule by surgery or YAG laser capsulotomy within 3 months prior to baseline<br/>- - - History of glaucoma (including or excluding local or systemic therapy) in either eye<br/>- - - Uveitis or extraocular inflammation in either eye<br/>- - - Pseudoexfoliative syndrome<br/>- - -  Known ocular ischemia syndrome in either eye (occlusion of extraocular arteries, influencing the vascularisation of the study eye)<br/>- - - Retinal venous occlusion in the study eye<br/>- - - History of retinal detachment (including or excluding any therapy) in either eye<br/>- - - Tractive retinal detachment due to diabetic epiretinal proliferation in the study eye<br/>- - - Intravitreal hemorrhage interfering with the assessment of the posterior pole in the study eye prior to baseline<br/>- - - Active malignancies (history of successful treated malignancies is not an exclusion criterion)<br/>- - - History of cerebral vascular accident or myocardial infarction within 12 months prior to baseline<br/>- - - Diabetes mellitus with HbA1c > 10 % or if it can be expected that the patient’s diabetes cannot be controlled adequately during the trial <br/>- - - Uncontrolled arterial Hypertension defined as a systolic value of > 180 mmHg and/or a diastolic value of > 110 mmHg<br/>- - - Systemic therapy with steroids or anticoagulative therapy with coumarin derivatives or heparin (Aspirin or Clopidogrel is allowed)<br/>- - - History of allergy to fluorescein or ranibizumab<br/>- - - Women who are pregnant or planning a pregnancy<br/>- - - Women who are breast feeding<br/>- - - Inability to comply with study or follow-up procedures<br/><br/>