Glaukos completes enrollment in pivotal trial of PRESERFLO MicroShunt for treatment-resistant glaucoma

Glaukos Corporation (NYSE: GKOS) has completed patient enrollment in its US 510(k) pivotal study of the PRESERFLO MicroShunt.¹

The trial enrolled its target of at least 110 adult patients across sites in the United States and Canada, each of whom had already undergone unsuccessful incisional or cilioablative glaucoma surgery and remained inadequately controlled on IOP-lowering medications.¹ That patient profile is notable: this is not a first-line device study but one aimed squarely at the population glaucoma specialists find hardest to help, patients who have already failed trabeculectomy, tube shunt surgery, or laser cilioablation and have few remaining surgical avenues.

The PRESERFLO MicroShunt itself is a small, flexible device, just 8.5 mm long, constructed from SIBS [poly(styrene-block-isobutylene-block-styrene)], a biocompatible material also used in Glaukos' iStent line. Planar fins along the shunt are designed to facilitate tissue fixation during a minimally invasive procedure, helping the device stay positioned and limiting leakage after implantation. The design philosophy echoes the broader MIGS ethos that Glaukos pioneered more than a decade ago, favoring smaller incisions and gentler tissue disruption over the more invasive dissection required by conventional filtration surgery, but PRESERFLO's target IOP reductions and patient population place it closer to trabeculectomy-level efficacy than to earlier-generation MIGS devices.

"The completion of patient enrollment in our U.S. pivotal study represents an important milestone toward potentially bringing the PRESERFLO MicroShunt to US patients with advanced glaucoma who are at risk for significant vision loss," said Thomas Burns, Glaukos chairman and CEO, in a news release. "We believe the PRESERFLO MicroShunt has the potential to address an important unmet clinical need by providing glaucoma specialists with an elegant, ab-externo surgical alternative to conventional filtration procedures such as trabeculectomy and tube shunt surgery."1

The study's primary effectiveness endpoint is a 20% or greater reduction in mean diurnal IOP from baseline at 12 months postoperatively, without an increase in the number of IOP-lowering medication classes patients require.¹ Glaukos intends to use the results to support a future FDA marketing submission. Enrollment completion starts the clock on that 12-month follow-up window, meaning topline data are unlikely to be reported before mid-2027 at the earliest.

Glaukos holds exclusive development and commercialization rights to PRESERFLO in the United States, Australia, New Zealand, Canada, Brazil, and Mexico under a license agreement with Santen Pharmaceutical Co., Ltd. The device is already approved and commercially available in several of those markets, including Canada and Australia, and has built a substantial track record in Europe under Santen's stewardship. Long-term data from Santen's ongoing Open-Label Extension Study, reported by Ophthalmology Times Europe, found that endothelial cell density loss at 4 years post-implantation was similar between PRESERFLO and trabeculectomy patients, an important reassurance given early concerns about corneal endothelial safety with ab-externo shunts.² Ophthalmology Times Europe has also covered how MIGS devices broadly, including PRESERFLO, are reshaping surgeons' ability to personalize glaucoma treatment by matching device to disease severity rather than defaulting to trabeculectomy.³

The pivotal study also arrives as Glaukos continues to build out what it calls a "comprehensive, best-in-class portfolio" spanning the full continuum of glaucoma care. That portfolio already includes iDose TR, the travoprost intracameral implant that began its US commercial launch in 2024 after FDA approval, and which Ophthalmology Times has reported continues to show durable IOP control and strong medication-free rates through 36 months in Glaukos' Phase 3 program.⁴ Where iDose TR targets patients earlier in the disease course who need a dropless alternative to daily drops, PRESERFLO is positioned at the opposite end of the spectrum, for patients who have already cycled through incisional surgery and have IOP that medications alone cannot manage. Together, the 2 technologies illustrate Glaukos' stated strategy of building distinct tools for distinct points along the glaucoma treatment pathway, rather than a single device meant to serve every patient.

For now, the completion of enrollment is a procedural milestone rather than a clinical one. But for a segment of POAG patients who have run out of good options, and for the glaucoma specialists treating them, it marks tangible progress toward a domestic alternative that has already earned adoption abroad.

References:

1. Glaukos Corporation Completes Enrollment in U.S. Pivotal Study of PRESERFLO MicroShunt. Press release. Business Wire.

2. Santen releases long-term data on PRESERFLO MicroShunt and Endothelial Cell Density loss. Ophthalmology Times Europe. https://europe.ophthalmologytimes.com/view/santen-data-preserflo-microshunt-endothelial-cell-density-loss

3. MIGS helping to personalize glaucoma surgery options. Ophthalmology Times. https://www.ophthalmologytimes.com/view/migs-helping-to-personalize-glaucoma-surgery-options

4. Glaukos announces several positive clinical updates for its iDose platform. Ophthalmology Times. https://www.ophthalmologytimes.com/view/glaukos-announces-several-positive-clinical-updates-for-its-idose-platform