Commentary: the CyPass, a novel supraciliary implant for openangle glaucoma
Traditional glaucoma surgeries are effective at lowering the intraocular pressure (IOP) but with a relatively high incidence of complications, that can amount to 77% (early and late) (1). In contrast, micro incisional glaucoma surgeries (MIGS) have a complication rate that is 10 to 20 fold lower (2) but were only in less advanced glaucoma until recently (3-5). Although often advertised as new, procedures that qualify as MIGS have been performed for more than a century: for instance, Tailor performed angle surgery in 1891 and Heine introduced suprachoroidal drainage procedures in 1900 (6). Many more MIGS types are now available, including trabecular meshwork (TM) bypass stents (iStent G1 and iStent G2 Inject, Glaukos, Laguna Hills, CA; Hydrus, Ivantis, Irvine, CA, USA), TM ablation (Kahook Dual Blade, New World Medical, Rancho Cucamonga, CA, USA; Trabectome, Neomedix Inc, Tustin, CA, USA) or disruption (Trab360, Sight Sciences, Menlo Park, CA, USA) devices. There are subconjunctival (XEN, AqueSys, Irvine, CA, USA) or suprachoroidal shunts (Gold Shunt, SOLX, Waltham, MA, USA; CyPass, Transcend Medical, Menlo Park, CA, USA; iStent G3 Supra, Glaukos, Laguna Hills, CA, USA), and endocyclophotocoagulation (Endo Optiks, Little Silver, NJ, USA). The CyPass is implanted via an interno approach which is less invasive than ab externo as necessary with the older SOLX Gold Shunt or the Aquashunt (Opko Health, Miami, FL, USA) (7). Although both used inert and biocompatible materials (gold and polypropylene), a high rate of fibrosis can be seen even when combined with antifibrotics (8-10). This is not surprising as the same fibroblasts are present in the suprachoroidal space as in the sub-tenon space that epibulbar devices face.