Suprachoroidal MIGS Devices

Abstract

The suprachoroidal outflow pathway has the potential to reduce intraocular pressure (IOP) significantly but has been associated with sight-threatening complications including severe and prolonged hypotony. Historically, suprachoroidal devices have been implanted ab externo requiring a conjunctival peritomy and scleral flap dissection. Additionally, the long-term efficacy of previous attempts to harness this space has been disappointing due to occlusion of implanted devices by fibrosis in the suprachoroidal space. More recently, there have been a number of suprachoroidal devices that are injected ab interno., including the CyPass Micro-Stent (Alcon Laboratories Inc., Fortworth, Texas, USA), the iStent Supra (Glaukos Corporation, San Clemente, CA, USA) and the MINIject (iSTAR Medical Isnes, Belgium). These have utilized a clear corneal entry, thereby sparing the conjunctiva. Early results with these ab-interno devices showed safety and efficacy in IOP-lowering that is similar to Schlemm’s canal minimally invasive glaucoma surgery devices and procedures. Despite the ab-interno approach, their long-term efficacy also seems to be limited by fibrosis. In addition, the first commercially available ab-interno suprachoroidal device, the CyPass Micro-Stent, has been voluntarily withdrawn globally by the manufacturer in August 2018, after 5-year follow-up data demonstrated a higher level of endothelial cell loss with the device than in controls. The iStent Supra and MINIject are not yet available commercially.