Exploring the Interventional Mindset

Sponsored by Glaukos

Expanding Our Options

We don’t need to think too hard about the reasons why the MIGS category keeps expanding. We need only to look at the need, the evidence, and the impact.

Steven R. Sarkisian Jr., MD

Let’s start with an obvious question: with a plethora of MIGS devices available in the clinic offering a variety of mechanisms, including canal dilating, stenting, tissue stripping, trabecular bypass stenting, and subconjunctival-based procedures, ‘why do we need continued innovation in the MIGS category?’

Despite the array of procedural options, there are still some patients for whom an ideal MIGS option does not exist. The entire impetus behind MIGS is the idea that we can do better by and for our patients by addressing glaucoma surgically (or with laser) to spare, reduce, or eliminate the need for medications that they don’t like, don’t take, might cause side effects, don’t offer 24-hour control, and might not work as expected (or at all). So, really, the question should be: Why stop the innovation cycle in MIGS?

Look at the Need

If glaucoma is highly variable in appearance, and progression risk is highly individualized, then having more options improves the ability to personalize management—which is inherent to the interventional mindset.

Perhaps the question is whether there is need for another generation of the iStent (Glaukos)? Each of the MIGS options has demonstrated some degree of success in studies, but only a few have stood the test of rigorous clinical trials—and only iStent has the longest-term data in the class. If we believe that the evolution in MIGS is predicated on refining and improving personalized outcomes, then the recently FDA-cleared iStent infinite (Glaukos) is simply following that same trajectory.

Look at the Evidence

At 12 months of follow-up, the pivotal iStent infinite study demonstrated that 76.1% of patients achieved ≥ 20% mean diurnal intraocular pressure (MDIOP) reduction from baseline on the same or fewer topical medication classes.¹ By the end of the study MDIOP was reduced 5.9 mm Hg from baseline (23.4 mm Hg at baseline) and 93% of patients reduced or maintained medication burden (only 5 of 72 increased medication burden).

But looking at the study population makes those numbers jump off the page: Most patients failed at least 2 prior surgeries and were on an average of 3 medications at the time of treatment, and all procedures were performed in a standalone setting. Previously, the options for patients with true refractory glaucoma who had failed incisional surgery were another trabeculectomy, revise the old one, or do a tube. We’ve gathered evidence on tube versus trab after a failed trab, or as primary surgery, but we don’t have much evidence on the outcomes after the second outflow procedure fails. To have an option like iStent infinite that is proven and demonstrated in this patient population, that lowers pressure significantly down into the mid-teens and with patients on fewer medications, is a major game changer, especially if you compare the safety profile of a second tube or a cyclodestructive procedure.

Look at the Impact

What does it really mean to get patients off drops?

Friends don’t let friends be on four bottles of glaucoma drops. The complex milieu of compliance, cost, convenience, safety, and access issues associated with topical medications is well known. We also know that compliance goes down as the regimen expands and gets more complex.

Relieving those stresses is one aspect, but you can also approach the question strictly on the basis of the pathology. What is maximally tolerated medical therapy anymore? The viability and safety of MIGS allows us to rethink the answer, and the iStent infinite only extends that possibility. In my mind, it’s reasonable to start with SLT, followed by prostaglandin monotherapy, and possibly a combination drop, but after that, iStent infinite, either with or without cataract surgery, and having failed medical and incisional intervention, would be the next conservative procedure in the paradigm. In the future, I could see adding long-term sustained release mechanisms to maximize responder rates. The paradigm just keeps expanding. And returning to the original question: Why do we need continual innovation in the MIGS category? Because it improves what we can do for patients.

1. Sarkisian SR Jr, Grover DS, Gallardo MJ, et al; iStent infinite Study Group. Effectiveness and safety of iStent infinite trabecular micro-bypass for uncontrolled glaucoma. J Glaucoma. 2023;32(1):9-18.

Maybe We Ought to be Asking ‘Why Not?’

If we know certain MIGS devices are effective for refractory glaucoma, and we are confident in their safety, are we missing an opportunity if we don’t introduce them earlier in the continuum?

Valerie Trubnik, MD, FACS

I imagine my thinking around trabeculectomy and glaucoma drainage devices is pretty similar to how most glaucoma surgeons approach them: I do them because patients need them, because there isn’t really another great option, and not necessarily because they are the best option. And I do them knowing the array of complications that may occur, as well as the probability for failure.

The pivotal study of the iStent infinite (Glaukos) shows us there is perhaps another way to address a broad range of glaucoma,¹ although that option is also applicable much earlier in the glaucoma continuum. Let’s take a look at why that is the case.

Flexibility and Performance

Evaluating my own patient results postoperatively has led me to conclude that using more iStents leads to greater IOP reduction and less postoperative IOP fluctuation without compromising safety.

We know from past studies that the iStent is safe and effective in mild to moderate glaucoma, we know that more is better with regard to stents (likely in part because of an increase in the facility of outflow and different and greater access to downstream channels), and we know from experience that lower and more sustained IOP reduction slows the rate of glaucoma progression.²

Why Not?

I started using iStent infinite in glaucoma patients who had exhausted all other options, where the most likely next step would be another shunt. But as I gained more experience in real-world practice, I started to wonder if ‘why iStent infinite?’ is perhaps the wrong question. We can consider the patient’s perspective. As much as I’m grateful to have drops in my armamentarium, I think that they can have significant short- and long-term consequences that can lead to noncompliance, subsequent glaucoma progression, and even future surgical failures. If we’re able to reduce the medication burden by even one drop, it’ll be incredibly beneficial for that patient in the future and significantly improve their quality of life.³

1. Sarkisian SR Jr, Grover DS, Gallardo MJ, et al; iStent infinite Study Group. Effectiveness and safety of iStent infinite trabecular micro-bypass for uncontrolled glaucoma. J Glaucoma. 2023;32(1):9-18.

2. Katz LJ, Erb C, Carceller Guillamet A, et al. Long-term titrated IOP control with one, two, or three trabecular micro-bypass stents in open-angle glaucoma subjects on topical hypotensive medication: 42-month outcomes. Clin Ophthalmol. 2018;12:255-262.

3. Samuelson TW, Singh IP, Williamson BK, et al. Quality of Life in Primary Open-Angle Glaucoma and Cataract: An Analysis of VFQ-25 and OSDI From the iStent inject® Pivotal Trial. Am J Ophthalmol. 2021;229:220-229.