Enzymatic vitreolysis by plasmin injection, is the newest method of treatment, inducing posterior Vitreous detachment, by its enzymatic action, that affects on laminin and fibronectin, located between posterior vitreous, and internal limiting membrane, and releases the traction of posterior cortex, which plays a major role in the increase, and chronification of macular edema, and finally aids in edema resolution, Specially if there is some evidence of diffuse diabetic macular edema or, posterior hyaloid traction. In this study we will try to evaluate the effect of autolog plasmin injection produced by urokinase, without vitrectomy, as a primary treatment of diffuse diabetic macular edema. Inclusion criteria contain diabetic patients, which suffer from diffuse diabetic macular edema. Exclusion criteria contain uncontrolled hypertension, unstable blood sugar level, renal failure, history of ocular hypertension, glaucoma, ischemic macular or peripheral retina, history of ocular surgery in the last 6month, posterior vitreous detachment, and proliferative diabetic retinopathy. Study will be performed by one time injection of intravitreal plasmin in case group, without any intervention in control group, in totally 20 eyes with diffuse diabetic macular edema, and the effect on macular edema will evaluate by measurement of the changes in visual acuity and central macular thickness before, 1 month, and 2 month after injection.