Take-home message: In this article, Dr Ianchulev discusses MIGS supraciliary microstenting, a compelling new approach for outflow enhancement that results in sustained reduction of IOP and anti-hypertensive topical medication use in OAG patients.
Conventional glaucoma surgeries (e.g., trabeculectomy and shunts) have provided us with important treatment modalities for advanced glaucoma for many decades, but safety profiles and postoperative complications limit these approaches to the end-stage of the glaucoma disease spectrum. Even then, the trade-offs are significant.1
On the other hand, medical glaucoma treatment is life-long, expensive, and limited by patient compliance. More than 50% of glaucoma patients fail primary topical therapy and require two or more medications, which compounds adverse effects (AEs) and further diminishes compliance. New micro-invasive glaucoma surgical (MIGS) interventions aim to fill the gap and provide effective long-term IOP control while reducing medication use, without the safety concerns of filtering glaucoma surgery.2
One of the emerging MIGS modalities is supraciliary stenting, which creates a permanent conduit at the sclera - ciliary body interface to direct aqueous outflow to the suprachoroidal space. This separate drainage collateral augments the uveoscleral outflow pathway and makes use of the high resorptive capacity of the choroid and its negative colloidal pressure to provide a strong driving force for aqueous drainage.3 And while earlier surgical approaches to increase supraciliary outflow through an artificial fistula caused bleeding, inflammation, and scarring that limited success,4,5 the newer, ab-interno micro-invasive method with the CyPass microstent is able to achieve supraciliary access with minimal tissue trauma and in bleb-less, conjunctiva-sparing approach.6
The CyPass Micro-Stent and implantation procedure
The CyPass® Micro-Stent (Transcend Medical, Inc., Menlo Park, CA) is a 6-mm-long, biocompatible, polymeric, supraciliary implant that creates a new permanent aqueous outflow channel from the anterior chamber (Figure 1A). The device is a fenestrated tube (300 µm-diameter lumen) that is inserted into the supraciliary space through a small corneal incision such as that used for cataract surgery.