The aim is to present, along with a brief literature review, the results of OCT scan in eyes with diabetic macular edema (DME), as well as examples of the utility of OCT for different therapeutic approaches. One-hundred and thirty-six eyes with diabetic retinopathy were analyzed with OCT to explore the different patterns of DME. Some eyes with DME were studied with OCT pre and postoperatively to determine the efficacy of photocoagulation and vitrectomy to restore a normal macular profile. Sixty-eight eyes with a central foveal thickness of 200 mu or more were considered "edematous". Three different patterns of DME were recognized and analyzed: macular thickening, cystoid macular edema and shallow retinal detachment. The change in macular profile and internal retinal structure after laser or surgical treatment are well visible with OCT. OCT contributes in understanding the anatomy of DME and the intraretinal damage and seems to be the technique of choice for the follow-up of macular edema. We think that this tool should always be used in monitoring the effect of therapies in future studies.