A drainage apparatus is disclosed to reduce intraocular pressure in an eyeball that includes an anterior chamber having aqueous humor disposed therein, a cornea and a surrounding marginal limbus by which the cornea is continuous with a scleral layer and a conjunctival layer disposed on an exposed surface of the eyeball and under eyelids, the apparatus comprising an inlet assembly configured to be disposed at the anterior chamber of the eyeball, an outlet assembly configured to be disposed at the external surface of the eyeball, the assembly having a central chamber, a tube extending between the inlet and outlet assemblies and configured to promote fluid communication between the inlet and outlet assemblies, and control means disposed within the outlet assembly for controlling a flow of aqueous humor through the tube from the anterior chamber of the eyeball to the external surface of the eyeball, the control means further comprising a replaceable filter disposed within the central chamber of the outer member to prevent intraocular infection, the filter having a medicinal agent applied thereto for preventing occlusion of the filter or bacterial contamination by inhibiting at least one of the formation of fibrotic membranes, inflammatory membrane, or bacterial adhesions or biofilms, thereby preventing increased of intraocular pressure or infection.
