Macular edema in diabetes, defined as retinal thickening within two disc diameters of the center of the macula, results from retinal microvascular changes that compromise the blood-retinal barrier, causing leakage of plasma constituents into the surrounding retina and consequently retinal edema. Thickening of the basement membrane and reduction in the number of pericytes are believed to lead to increased permeability and incompetence of the retinal vasculature. This compromise of the blood-retinal barrier leads to the leakage of plasma constituents into the surrounding retina with subsequent retinal edema. Hypoxia produced by this mechanism can also stimulate the production of vascular endothelial growth factor (VEGF). Vascular endothelial growth factor (VEGF) increases retinal vascular permeability, causes breakdown of the blood-retina barrier and results in retinal edema. Diabetic macular edema (DME) is the most common cause of visual reduction in patients with Diabetes Mellitus. The prevalence of DME globally is around 6.8 %. Diabetic Retinopathy (DR) is the most common microvascular complication of diabetes and the leading cause of blindness worldwide. DME is a complication of diabetic retinopathy that affects the macula, which is located at the center of the retina and responsible for central vision. Bangladesh is the 10th country in the world for the number of adults living with diabetes with some 7.1 million (5.3-12.0). In Bangladesh, it is therefore expected that diabetic secondary complications, like DR, will increase along with the rising trend of diabetes mellitus. The use of therapeutic monoclonal antibodies has revolutionized in the treatment of many diseases. In recent years, millions of patients have been successfully treated with these biological agents. Ranibizumab is one such therapeutic monoclonal antibody for intraocular use. Ranibizumab is a humanized, recombinant, immunoglobulin G1 monoclonal antibody fragment against vascular endothelial growth factor A (VEGF-A) and thus prevents choroidal neovascularization. The small size of ranibizumab allows for enhanced diffusion into the retina and choroid.