The pathophysiology of blebs, in relation to glaucoma implant surgery, and the reasons for success or failure of the blebs will be presented. The importance of intraocular pressure on the success of the bleb will be emphasized.The presentation will discuss the mechanisms whereby blebs, formed by glaucoma surgical tube implants, fail. The audience will understand the significance of the preoperative intra-ocular pressure , and thereby, the cytokine levels in the aqueous forming the bleb. Lowering the pressure prior to allowing aqueous to reach the plate surface will demonstrate how the deleterious effects of pressure on bleb failure can be avoided. The choice of implant, valved or non-valved, will be shown to be important in relation to the effectiveness of bleb survival. Thus the presentation, will present why the immediate preoperative intraocular pressure needs to be decreased , why choice of implant can effect outcome, and how modifications in respect to implant use, can be utilized to make the effect of the implant more successful. The presentation does not suggest further improvement in design of the implant, as a number of iterations of the original Molteno implant are already available. The pathophysiology of the bleb thereby remains the most important aspect of success or failure of the bleb.