Macular edema is the most important cause of visual impairment in diabetic patients. Intravitreal injections of antiVEGF (vascular endothelial growth factor) agents and laser treatment are two effective therapies for stabilising visual acuity. However, antiVEGF therapy is very expensive and potentially needs to to be repeated for all patients life. Laser treatment, according to modified ETDRS (early treatment diabetic retinopathy study), produces retinal burns with possible negative consequences such as alterations in the visual fields.

With micropulse treatment modality laser energy is delivered in short pulses ("micropulses") rather than as a continuous wave. In this way the amount of energy delivered to the retina and retinal pigment epithelium (RPE) is significantly reduced. This finer control of the photothermal effects should avoid any retinal and RPE damage. At the same time, according to several published reports, the efficacy of treatment appears to be equivalent to conventional laser therapy.

Previous studies investigated the effects of 810nm micropulse laser therapy. Recently, this treatment modality has been made available also with 577nm wavelength, which corresponds to the maximum absorption level for blood. Aim of this study is to assess the safety and efficacy of 577nm micropulse laser treatment compared to conventional modified ETDRS laser therapy.

Inclusion Criteria:

• written informed consent prior to study entry
• male or female patients >= 18 years of age
• patients with diagnosis of diabetes type 1 or 2 and clinically significant macular edema
• visual impairment due to clinically significant diabetic macular edema
• best-corrected visual acuity included between 21 and 74 ETDRS letters
• central retinal thickness greater than 320 micron (Spectralis SD-OCT, Heidelberg Engineering, Germany)
• leakage and/or micro aneurysm in fluorescein angiography images within the area of retinal thickening
• HbA1C ≤10% with well-controlled blood pressure and renal function

Exclusion Criteria:

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