Positive 2-year data on supraciliary micro-stent

Take-home

Two-year results on the first ab interno micro-stent designed to drain into the suprachoroidal space show good efficacy and safety profiles.

Dr. Ianchulev

By Fred Gebhart; Reviewed by Tsontcho Ianchulev, MD, MPH

Two-year results on the first ab interno micro-stent designed to drain into the suprachoroidal space show good efficacy and safety profiles.

“The CyPass Micro-Stent creates additional outflow from the eye into the suprachoroidal space,” said principal investigator Tsontcho Ianchulev, MD, MPH, associate clinical professor of ophthalmology, University of California-San Francisco and chief medical officer, Transcend Medical, Menlo Park, CA.

“The mechanism of action is very different from other micro-invasive glaucoma surgical (MIGS) devices which stent the trabecular pathway,” Dr. Ianchulev said. “Instead, the CyPass Micro-Stent targets the suprachoroidal space which has a much larger absorptive capacity and a negative oncotic pressure for increased outflow and IOP lowering.”

The most current long-term data on the CyPass Micro-Stent were presented as a poster by Helmut Höh, MD, PhD, head of ophthalmology at Dietrich-Bonhoeffer-Klinikum Neubrandenburg, Ernst Moritz Amdt University, Greifswald, Germany. The device has been approved for use in the European Union and Canada, but remains investigational in the United States.

En Face Cross-Sectional View: En face cross-sectional coherence tomography view of micro-stent (CyPass Mico-Stent, Transcend Medical) in situ in the supraciliary space (image courtesy of Tsontcho Ianchulev, MD, MPH).

Longitudinal View: Longitudinal optical coherence tomography view of the device in situ in the supraciliary space (Image courtesy of Tsontcho Ianchulev, MD, MPH).

CyPass is a biocompatible but nonresorbable polyimide tube 6.3 mm long with a 510-micron external diameter that is implanted ab interno via a 1.5-mm corneal incision into the supraciliary space. The tube has proximal retention features designed for placement in the supraciliary space and distal fenestrations along the lower two-thirds designed to enhance outflow. Implantation ab interno leaves the patients with intact conjunctiva, sclera and trabecular meshwork.

The CyCLE study includes 136 patients who had completed 2-year follow-up from fifteen centers in Europe. All patients had OAG and underwent phaco-cataract surgery and CyPass implantation. Patients were divided into two cohorts based on IOP. Cohort 1, 51 patients, had uncontrolled IOP of 21 mm Hg or greater at baseline. Cohort 2, 85 patients, had controlled IOP of less than 21 mm Hg.

(FIGURE 1) The micro-stent-a biocompatible-but-nonresorbable polymide tube that is 6.3 mm in length with a 510-µm external diameter-is implanted ab interno via a 1.5-mm corneal incision into the supraciliary space (Image courtesy of Transcend Medical).

The mean age of study patients was 74.3 years and 59.6 were female. Overall mean baseline IOP was 19.8 mmHg. In Cohort 1, the mean baseline IOP was 25.5 mm Hg, in Cohort 2 it was 16.4 mmHg. Patients were on a mean of 2.2 medications, 2.2 medications in Cohort 1 and 2.0 medications in Cohort 2. Only 4% of patients were without medications while 26 percent were on one medication and 35%  were on either two medications or three or more medications. Just under 6% of patients had a prior trabeculectomy and 14% had other prior glaucoma interventions.

“We saw safety comparable to other micro-stents and significantly better than conventional glaucoma procedures such as trabeculectomy, which is the goal of MIGS intervention ” Dr. Ianchulev said.

Adverse events included one explanted device, one repositioned device, one case of iritis lasting longer than one month, four patients with an IOP increase lasting longer than one month, two patients with transient hyphema lasting less than one month, five endothelial touches, and 12 cases of peripheral anterior synechia with partial or complete obstruction.

While this was mainly a safety study, we saw significant effect on IOP lowering, Dr. Ianchulev added.

In cohort 1, the mean IOP dropped from 25.5 mm Hg at baseline to between 16.9 and 15.8 mm Hg at 24 months. Medication used dropped from a mean of 2.2 meds to one medication. Cohort 2 showed stable IOP, from 16.4 mm Hg at baseline to a low of 15.2 at six months and 16.1 at 24 months. Medication use in Cohort 2 fell from a mean of 2.0 medications to 1.1.

While trabecular stents have shown diminishing efficacy over 2 years, the sustained IOP effect with a supraciliary stent reflects the large absorptive area and capacity of the suprachoroidal space, Dr. Ianchulev said, as well as the physiology of the oncotic gradient across the stent.

“Transcend Medical has focused aggressively on pursuing the suprachoroidal space because it may offer the best potential for IOP lowering,” he continued. “While this is not a randomized trial and some of the IOP effect can be attributed to the cataract surgery, these are very encouraging results.”

The CyPass device is also easier to use from an operational perspective, he added. Of all the MIGS devices that have been approved or are in trials, this is one of the few than can be done gonio-free.

“Because you don’t need gonioscopy, this is the most phaco-aligned MIGS intervention as you can implant the device using the same surgical setup as your phaco,” he said.

The U.S.-based clinical trial of the CyPass Micro-Stent (COMPASS FDA clinical study), the largest MIGS trial to date, is already fully recruited, randomized, and collecting data, he said. Initial data from 2-year follow up should be available in about 18 months.

Tsontcho Ianchulev, MD, MPH

E: sianchulev@transcendmedical.com.

Dr. Ianchulev is an employee of Transcend Medical.

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