At 89 clinical sites , we randomly assigned 660 adults ( mean age , 6110 years ) with diabetic macular edema involving the macular center to receive intravitreous aflibercept at a dose of 2.0 mg ( 224 participants ) , bevacizumab at a dose of 1.25 mg ( 218 participants ) , or ranibizumab at a dose of 0.3 mg ( 218 participants ) .