Multiple MIGS stents improve IOP reduction

Take-home message: Highlights are presented from what is believed to be the first head-to-head comparison of one, two, and three stents inserted as a stand-alone procedure.

By Fred Gebhart; Reviewed by L. Jay Katz, MD

Philadelphia-Initial findings from a planned 5-year trial show that multiple micro-stents can improve IOP more effectively than a single stent.

An international trial of one, two, or three devices (iStents, Glaukos) implanted as a stand-alone procedure found that two or three stents lowered IOP more effectively than one stent. Multiple stents also lowered the drug burden for patients.

“This is not just exciting for us in glaucoma,” said lead author L. Jay Katz, MD, director, Glaucoma Service, Wills Eye Hospital and professor of ophthalmology, Jefferson Medical College, Philadelphia.

“The comprehensive ophthalmologist is now part of the picture in terms of helping patients with glaucoma,” Dr. Katz said. “MIGS procedures are filling the void between the ‘big guns’ of incisional surgery and less-aggressive approaches, such as medication and laser trabeculoplasty.”

Multiple stent insertions are not unknown, Dr. Katz said, but they are seldom performed in the United States. The FDA approval is for a single stent in conjunction with cataract surgery and multiple stents are not covered by government or private health plans. There have been a few non-U.S. studies of multiple stent insertions, but this is the first head-to-head comparison of one, two, and three stents inserted as a stand-alone procedure.

Dr. Katz is the medical monitor for Glaukos, which sponsored the study. The company’s iStent has been approved for use in the United States as a single device implanted in combination with cataract surgery.

First 18 months

This trial, conducted by the MIGS Study Group in Armenia, is intended to follow a cohort of patients with up to three iStents implanted as stand-alone procedures for 5 years. Findings from the first 18 months of follow up were presented recently.

A total of 120 patients with open-angle glaucoma that remained uncontrolled on up to three medications were enrolled in the study. Of the group, 119 patients had been followed for at least 18 months for this initial report.

Patients were prospectively randomly assigned to receive one, two, or three iStents. Preoperative IOPs ranged from 18 to 30 mm Hg on one to three ocular hypotensive medications, with mean of about 20 mm Hg. After a 30-day medication washout, the mean IOP was about 25 across all three groups.

“Pressures were lowered 12 months after implantation to 13 to 13.5 mm Hg in all three groups and most patients were off-medication,” Dr. Katz said. “After a 30-day medication washout, we re-measured IOP. The group with one stent had an average IOP of 14.8, patients with two stents were 13.6, and those with three stents were down to 12.7.”

All of the patients had an absolute IOP of 18 mm Hg or lower at 12 months. There were clear differences based on the number of stents.

When stratified by IOP at 12 months, 74% of one-stent eyes were at 15 mm Hg or lower regardless of medication compared with 95% of two-stent eyes and 100% of three-stent eyes. When stratified by an IOP reduction of 40% or more without medication versus baseline unmedicated IOP, 57% of one-stent eyes achieved this level compared with 78% of two-stent eyes and 84% of three-stent eyes. Patients with multiple stents were also less likely to be on IOP medication.

At 18 months, the mean unmedicated IOP was 15.6 mm Hg for single-stent eyes, 13.8 mm Hg for two-stent eyes, and 12.1 mm Hg for three-stent eyes.

The initial safety report safety profile was extremely positive, Dr. Katz added.

Most of the patients in the trial had adequate vision and had not had cataract surgery. There was very little change in vision over the first 18 months. Only four patients showed a loss in vision due to progression of pre-existing cataract requiring cataract surgery.

In addition, one eye in each of the one-stent and two-stent groups had best-corrected visual acuity loss of ≥ line. There were no observed problems with corneal swelling, no need for corneal transplantation and no serious complications, such as endophthalmitis.

“What these results are hinting at for companies producing and developing these micro stents is that MIGS is a new surgical arena that represents another choice for patients,” Dr. Katz said.

“Trabeculectomy and tube shunts have been the mainstays in terms of incision surgery,” he said. “They are very effective, but they also create risk, both perioperatively and postoperatively. These minimally invasive procedures are the kinds of procedures that ophthalmologists may feel more comfortable offering to certain patients.”

Medication remains an initial option, he continued, but hypotensive medications are not uniformly successful. Some patients cannot tolerate glaucoma medications. Even if drugs are both effective and tolerable, many patients are unable to maintain an effective regimen of eye drops.

“Where you might have been reluctant to push people toward incisional filtration surgery, the threshold for doing surgery with MIGS may be lower with its better safety profile,” he said.

L. Jay Katz, MD

E: ljkatz@willseye.org

This article was adapted from Dr. Katz’s presentation at the 2015 meeting of the American Society of Cataract and Refractive Surgery. Dr. Katz did not indicate any proprietary interest in the subject matter.