Around the world there is an increasing incidence of diabetes mellitus, with millions of people affected. In this population, diabetic macular edema (DME) is the most common cause of visual impairment. While the visual impairment caused by EMD is variable, its early treatment can improve visual acuity and quality of life. The objective of this project is to use the new OCT-angiography technology, which evaluates macular capillary network without the need of intravenous injection of contrast, to assess macular microcirculatory network in its response to intravitreal pharmacological treatment of EMD. The resulting qualitative evaluation can be helpful in understanding the pathophysiology of visual loss associated with DME and in determining prognosis.

Patients who participate in this study will be selected among adults treated at the Retina Clinic and Ocular Oftalmologia clinics and will be aware of all stages of the research, formalizing the approval of their participation by informed consent term. The tests will be performed after pupillary dilation with 2 eye drops of tropicamide 1% (Mydriacyl, Alcon Laboratories), in Cirrus 5000 HD-OCT devices (Carl Zeiss Meditec - Dublin USA). Image acquisition protocols Optic Disc Cube 200x200 and 512x128 Macular Cube will be used, with analysis by RNFL protocols and NGO Analysis Report and Macular Cube Analysis Report, respectively. Subjective analysis of the examinations will be performed by the three authors of this project independently and then compared between them.

Inclusion Criteria:

• Previous diagnosis of diabetes mellitus type 1 or 2;
• Age equal or greater than 18 years;
• At least one eye with diabetic macular edema and central thickness greater than or equal to 290 microns (female patients) or 305 microns (males) measured by OCT and subjected to intravitreal pharmacotherapy.

Exclusion Criteria:

• Aphakic patients;
• History of major eye surgeries (vitrectomy, cataract surgery, scleral buckle, other intraocular surgery) in the last 4 months;
• Tractional retinal detachment involving the macula, vitreomacular traction syndrome or other concurrent macular diseases;
• Advanced or uncontrolled glaucoma (according to the investigator's judgment); Evidence of angle neovascularization;
• Presence of an eye condition (besides diabetic retinopathy) which, in the opinion of the investigator, may alter the visual acuity during the study course (e.g. venous or arterial retinal occlusions, uveitis or other ocular inflammatory diseases, neovascular glaucoma, etc.);
• Significative cataract which, in the opinion of the investigator, may be decreasing visual acuity in 3 lines or more;
• History of YAG Laser capsulotomy in the last 2 months;
• Severe renal disease, defined as chronic renal failure requiring dialysis or a kidney transplant;
• Blood pressure higher than 180/110 mmHg, acute myocardial infarction, other acute cardiac events requiring hospitalisation, stroke, transient ischemic attack or treatment for congestive heart failure;
• Systemic treatment with anti-VEGF or pro-VEGF in the last 4 months.

Patients with diabetic macular edema.