577nm Micropulse Laser Versus 532nm Subthreshold Laser Photocoagulation for Diabetic Macular Edema

Inclusion Criteria: * Aged \>18 years * Patients with diabetes mellitus type 2 * Diagnosed as diabetic retinopathy with Clinical Significant Macular Edema * Central retinal thickness(CRT) of more than 250μm as measured by optical coherence tomography (OCT) * ETDRS visual acuity \>19 letters (Snellen equivalent of 20/400 or better) * No macular laser coagulation or surgery or medicine therapy of macular edema within the last 6 months * Blood glucose was controlled steadily(HbA1c≤10%) Exclusion Criteria: * Taking part in other clinical trial within 3 months * Planning panretinal photocoagulation(PRP) within 3 months * Performed cataract surgery in the last 3 months * Accompanied with other retinal vascular disease that can lead to macular edema, for example branch retinal vein occlusion(BRVO),central retinal vein occlusion(CRVO) * Accompanied with severe opacity of refractive media that maybe impact therapy and observation * Accompanied with nystagmus * Accompanied with some history that maybe interfere with result or increase the risk of patients