New and Emerging Trabecular Meshwork Bypass Stents

Minimally invasive glaucoma surgery procedures are newly developed surgical modalities for the management of glaucoma. Their target is to lower intraocular pressure with minimal eye trauma and fewer complications. The first-generation iStent® (Glaukos Corp, Laguna Hills, CA, USA) is the first minimally invasive glaucoma surgery device to be approved for the treatment of open-angle glaucoma. It allows aqueous humour to be drained directly from the anterior chamber to Schlemm’s canal, bypassing the trabecular meshwork, which is believed to be the main site of outflow resistance. The second-generation iStent inject® (Glaukos Corp, Laguna Hills, CA, USA) is a smaller implant that allows simultaneous implantation of two stents, which could theoretically result in lower intraocular pressure. The Hydrus® Microstent (Alcon, Geneva, Switzerland) is another trabecular implant that dilates and scaffolds Schlemm’s canal. This articles reviews publications about all trabecular meshwork bypass stents, comparing them in terms of their efficacy and safety.