Outcomes analysis of trabecular meshwork bypass devices

Introduction: Recent innovations in glaucoma surgery have led to new alternatives for glaucoma patients requiring surgery. We investigate the intraocular pressure (IOP) outcomes following the placement of trabecular bypass devices. Areas covered: The aim of this paper is to analyze the current literature on trabecular bypass devices. The first and second generation iStents (Glaukos Corporation, Laguna Hills, CA, USA) act as a snorkel to increase delivery of aqueous through the trabecular meshwork and into Schlemm’s canal. The Hydrus (Ivantis Inc., Irvine, CA) is a larger device that in addition to acting as a snorkel, maintains Schlemm’s canal patency over several clock hours. The literature reviewed was found by searching Pubmed for iStent, micro-bypass, Schlemm’s canal scaffold, and individual references were followed. Expert commentary: Safer alternatives in Minimally Invasive Glaucoma Surgery (MIGS) procedures continue to be developed, and have a more favorable safety profile compared to traditional penetrating surgeries. However, the IOP reduction associated with these procedures is not as reliably low. There is significant heterogeneity in reported results, particularly with first generation stents. Early data with multiple stent insertion suggests that it is possible to achieve target IOPs in the mid-teens or below in a significant number of patients while still on medication.