A New Chapter in MIGS Innovation

Dr. Thomas Siempis, MD, FRCOphth, FEBO

Dr. Siempis is a specialist in Glaucoma and Advanced Anterior Segment Surgery, based in Thessaloniki, Greece, with a particular focus on Microinvasive Glaucoma Surgery. He serves as the Glaucoma Lead at both St. Luke’s Hospital and the Ophthalmica Institute in Thessaloniki and holds the position of Honorary Clinical Lecturer at the University of Glasgow. He completed his fellowship in Glaucoma and Advanced Anterior Segment Surgery at the University of Toronto, Canada.

Dr. Siempis is a paid consultant of Glaukos.

Over the past few years, significant advancements have transformed the management of glaucoma, a chronic and potentially blinding disease. Among these innovations, Microinvasive Glaucoma Surgery (MIGS) has emerged as a game-changer, providing glaucoma specialists with more tools than ever before to intervene earlier and more effectively.

At the forefront of this evolution is the concept of Interventional Glaucoma—a proactive approach that contrasts with traditional treatment paradigms, which often rely on long-term topical medications and reserve surgical intervention, typically in the form of bleb-based procedures, for more advanced or uncontrolled disease stages. MIGS enables earlier intervention with a lower risk profile, helping to preserve vision while enhancing patients' quality of life.

The Role of Trabecular Meshwork Bypass Procedures

Among MIGS options, Trabecular Bypass procedures have become the most widely adopted, thanks to their favourable safety profile, efficacy, and ability to bridge the gap between pharmacologic therapy and more invasive surgeries like trabeculectomy.

The iStent® implant, approved by the FDA in 2012, was the first ab-interno Trabecular Micro-Bypass implant indicated for patients with mild to moderate primary open-angle glaucoma (POAG). Since then, the platform has evolved, with the iStent inject® and now the iStent infinite®, each offering new levels of precision, efficiency, and effectiveness.

The iStent infinite®—currently available in Canada, Australia and the United States, and recently granted Medical Device Regulation (MDR) approval in Europe—represents a significant leap forward. FDA approval was based on pivotal clinical data showing that iStent infinite® used as a stand-alone procedure achieved clinically significant intraocular pressure (IOP) reduction in patients with open-angle glaucoma (OAG) that was uncontrolled by previous therapy1.

Clinical Experience with the iStent infinite® Platform

Having used all three generations of the iStent® implant, I’ve found that each iteration offers unique advantages. With respect to the first-generation iStent®, even though it has a steeper learning curve, it is versatile, allowing repositioning and combination with other MIGS procedures such as extension goniotomy or canaloplasty. 

The iStent inject® (and iStent inject® W) on the other hand, came with a redesigned stent and improved injector and simplified implantation thereby significantly broadening access to MIGS. It has become the workhorse for Trabecular Micro-Bypass procedures and is supported by the largest body of long-term clinical evidence among MIGS devices to date.

As far as the iStent infinite® is concerned, my first experience with it came during my Glaucoma and Advanced Anterior Segment (GAASS) fellowship at the University of Toronto under the mentorship of Professor Ike Ahmed.

From the outset, it was clear that iStent infinite® was more than just a redesign of the second-generation device. One key enhancement is the inclusion of three preloaded stents, allowing for a much wider treatment area of collector channels that can span up to 8 clock hours. Clinical studies have shown that implanting three iStents leads to lower mean IOP at 36 months post-implantation, particularly after washout of IOP-lowering medications2.

In my opinion, one of its most important improvements lies in the fact that the injector provides an infinite number of ‘clicks’. This gave me the confidence that all three stents could be optimally implanted without having to worry about running out of clicks. Optimally placed iStents are paramount to the success of the surgery and achieving the best possible IOP lowering. The second-generation injector has four clicks available for use which essentially gives the surgeon two extra opportunities to reposition a misaligned or underimplanted stent.

The infinite injector allows the surgeon to easily rethread the iStent and then re-implant it if necessary. The stent delivery button can be pushed as many times as required before moving onto the second stent. This process is facilitated by a separate button, called the “singulator” that prepares the next stent for deployment.

Additionally, the injector allows for a very smooth and controlled deployment of each stent which reduces the chances of misaligning the stent during the removal of the trocar from the trabecular meshwork (TM). The insertion tube has a subtle 8-degree angle, which helps to approach the TM in a perpendicular way without applying excessive pressure to the posterior aspect of the main corneal incision. The fact that trocar is visible at all times, further allows for more precise implantation of the stents.

The auto-introducer is another new feature on the iStent infinite injector which means that the surgeon does not need to retract the sleeve once inside the eye, removing thus a step from the implantation process. The auto introducer ‘plugs’ the incision stopping egress of OVD providing a more stable anterior chamber.

While it is technically feasible to implant all three stents in a single maneuver, I found it advantageous to implant two stents initially (ideally two clock hours apart), refill the anterior chamber with a heavy cohesive viscoelastic, and then place the third stent—aiming as far superonasally or inferonasally as possible.

Preliminary Real World Clinical Outcomes 

Earlier this year, I had the opportunity to present early clinical outcomes of combined phacoemulsification and iStent infinite® implantation at the ESCRS Winter Meeting in Athens3. In this retrospective case series, we evaluated consecutive patients treated between March 15, 2023, and April 31, 2024, at an academic ophthalmology center in the Greater Toronto Area.

Among 56 eyes from 43 patients (mean age: 73.4 years), 40% had advanced glaucoma. Our primary outcome was the proportion of eyes achieving either medication reduction with stable IOP, or ≥20% IOP reduction with the same or fewer medications. Notably, 87.7% of eyes met the primary endpoint. Mean preoperative IOP was 15.9 mmHg on 1.7 medications and mean postoperative IOP at month 12 was 13.4 mmHg on 1.2 medications (p < 0.05). No serious adverse events were reported. While a 2.5 mmHg reduction may seem modest, this is clinically meaningful, especially in patients with advanced disease or limited therapeutic options.

Looking Ahead

The European launch of the iStent infinite® marks an exciting new chapter in MIGS innovation. With its user-friendly design and promising clinical performance, this device represents a welcome addition to our surgical toolkit. I look forward to incorporating it into my practice and further exploring its potential to improve outcomes for glaucoma patients across Europe. 

iStent infinite(R) IMPORTANT SAFETY INFORMATION

INDICATION FOR USE. The iStent infinite System is intended to reduce intraocular pressure safely and effectively in adult patients diagnosed with primary open-angle glaucoma, pseudo-exfoliative glaucoma or pigmentary glaucoma. The device is safe and effective when implanted in combination with or without cataract surgery in those subjects who require intraocular pressure reduction and/or would benefit from glaucoma medication reduction. The device may also be implanted in patients who continue to have elevated intraocular pressure despite prior treatment with glaucoma medications and/or conventional glaucoma surgery. CONTRAINDICATIONS: The iStent infinite System is contraindicated under the following circumstances or conditions: •In eyes with primary angle closure glaucoma, or secondary angle-closure glaucoma, including neovascular glaucoma, because the device would not be expected to work in such situations.• In patients with retrobulbar tumor, thyroid eye disease, Sturge-Weber Syndrome or any other type of condition that may cause elevated episcleral venous pressure WARNINGS/PRECAUTIONS: • For prescription use only. •Intended users are trained ophthalmologists only. • This device has not been studied inpatients with uveitic glaucoma. • Do not use the device if the Tyvek® lid has been opened orthe packaging appears damaged. In such cases, the sterility of the device may becompromised. • Due to the sharpness of certain injector components (i.e., the insertionsleeve and trocar), care should be exercised to grasp the injector body. Dispose of device in asharps container. • iStent infinite is MR-Conditional • Physician training is required prior touse of the iStent infinite System. • Do not re-use the stent(s) or injector, as this may result ininfection and/or intraocular inflammation, as well as occurrence of potential postoperativeadverse events • There are no known compatibility issues with theiStent infinite and otherintraoperative devices (e.g., viscoelastics) or glaucoma medications. • Unused product &packaging may be disposed of in accordance with facility procedures. Implanted medicaldevices and contaminated products must be disposed of as medical waste. • The surgeonshould monitor the patient postoperatively for proper maintenance of intraocular pressure.If intraocular pressure is not adequately maintained after surgery, the surgeon shouldconsider an appropriate treatment regimen to reduce intraocular pressure. • Patients shouldbe informed that placement of the stents, without concomitant cataract surgery in phakicpatients can enhance the formation or progression of cataract. ADVERSE EVENTS: The mostcommon postoperative adverse events reported in the iStent infinite pivotal trial includedIOP increase ≥ 10 mmHg vs. baseline IOP (8.2%), loss of BSCVA ≥ 2 lines (11.5%), ocularsurface disease (11.5%), perioperative inflammation (6.6%) and visual field loss ≥ 2.5 dB(6.6%). CAUTION: Please see DFU for a complete list of contraindications, warnings,precautions, and adverse events.

For additional safety information on iStent products, see here: www.glaukos.com

Glaukos® and iStent infinite® are registered trademarks of Glaukos Corporation. All rights reserved. ©2025. PM-EU-0367