Intravitreal Avastin as a Treatment of Diffuse Diabetic Macular Edema

Background: Macular edema, defined as retinal thickening within 2 disc diameters of the center of the macula, results fromretinal microvascular changes that compromise the blood-retinal barrier, causing leakage of plasma constituents into thesurrounding retina and, consequently, retinal edema. Focal edema is associated with hard exudate rings caused by leakagefrom micro aneurysms. Diffuse edema is caused by leakage from micro aneurysms, retinal capillaries, and arterioles.Avastin (Bevacizumab) is a recombinant humanized monoclonal IgG1 antibody that binds to and inhibits the biologic activityof human vascular endothelial growth factor (VEGF). It contains human framework regions and the complementaritydetermining regions of a murine antibody that binds to VEGF. Avastin produced in a Chinese Hamster Ovary mammalian cellexpression system in a nutrient medium containing the antibiotic gentamicin and has a molecular weight of approximately149 kilo Daltons.Purpose: To assess the anatomic effect and visual acuity response after intravitreal (Avastin) in patients with diffuse diabeticmacular edema.Patients and Methods: This study included 15 eyes of15 Patients with stable diabetes mellitus with diffuse diabetic macularedema. All eyes had received some form of argon laser photocoagulation (pan retinal photocoagulation (PRP), Focal orGrid of duration not less than 6 months. Mean age of 59 years treated with two intravitreal injections of Avastin 1.25 mgin 0.05 ml six weeks apart. Patients were examined by experienced ophthalmologist visual acuity, evaluation of diabeticretinopathy, central macular thickness by optical coherence tomography each was evaluated at the begging of study(baseline) and follow-up visits.Results: 15 eyes of 15 diabetic patients with persistent diffuse macular edema with no improvement in visual acuity.All the patients received two injections of A vastin six weeks apart. No complications were observed in any patient. Themean baseline visual acuity was (log Mar=1.338±0.455) and the mean visual acuity at three months following the secondintravitreal injection was (log Mar=1.094±0.254), the mean central macular thickness at baseline was 492 µm decreasedto 369 µm at the end of three months.Conclusions: A vastin resulted in a significant decrease in macular thickness and improvement in visual acuity at threemonths after the second injection.