Intra-vitreal injections are common in ophthalmology practice and injection numbers are rapidly growing. Pharmacology of Ranibizumab Ranibizumab (LucentisR, Genentech, South San Francisco, USA) is a recombinant humanized monoclonal immunoglobulin G1 (IgG1) -isotype antibody fragment that inhibits human vascular endothelial growth factor (VEGF). It is produced as a 48 kDa antibody fragment, in E. coli, using expression plasmids. It is approved for intravitreal injection for choroidal neovascularization due to age-related macular degeneration, Macular edema due to Diabetic retinopathy and Vein occlusion with its dose 0.5/0.05ml (licensed dose in EU) or 0.3/0.05ml (USA). Intra-ocular pressure changes after intra vitreal injection of Ranibizumab (Lucentis) Intra-Ocular Pressure (IOP) is a result of balance between production of aqueous humor and the drainage of aqueous humor The volume of the vitreous cavity in the human eye is approximately 4 ml, and the volume of medication injected into the vitreous ranges from 0.05 to 0.1 ml. Therefore, depending on the volume infused, the increase in fluid volume within the vitreous cavity is approximately 1.25%–2.5%. In clinical practice this frequently translates into short-term elevation of IOP. Brimonidine Tartarate Mechanism of action It's topical alpha2-adrenergic with its precursor clonidine (nasal decongestant drop) that was discovered by Boehringer Ingelheim and Helmut Stähle in the 1960s which lowering IOP by reducing aqueous humor production and increase uveoscleral out flow which not occur with apraclonidine hydrochloride.