Mitigating the MIGS Fear Factor

First-generation MIGS devices completely changed the way we think about glaucoma and brought about an entirely new market. Admittedly, as good as the first generation was, there was room for improvement in terms of outcome consistency and ease of insertion. Nevertheless, the MIGS concept itself gave rise to a new era in glaucoma and sparked development that continues to this day.

With several years of clinical application – and many more in development and trials – we now have yet another generation of options that demonstrate remarkable predictability that we would not have thought possible when this technology was in its infancy. What’s more, new designs offer opportunities for confidence in terms of proper placement. Indeed, second-generation MIGS represent an evolution in technology that promises better patient outcomes and greater surgical confidence that will likely translate into increased adoption.

According to a survey by the ASCRS, only 30 percent of respondents have actively adopted MIGS, yet many say they are interested and considering it (1).

Early on, a primary goal for MIGS surgeons was building confidence in their ability to place the stent properly in Schlemm’s canal. Not only was proper canal placement required, but also one had to consider where along the canal the stent should be placed: ideally in proximity to a collector channel to achieve the required effect. Some surgeons learned the nuance of positioning over time and achieved outstanding outcomes on a regular basis.

If all was well aligned, one could rely on a great result. But there were some inconsistencies involved – from surgeon to surgeon, and from one procedure to the next. Relying on everything correctly “lining up” posed a challenge. And if one didn’t place the stent properly inside of the canal, efficacy was bound to suffer.  There have been cases cases where the stent was placed over a collector channel, but not planted properly in the canal. With the need for such precision in canal placement and location, it is understandable why results might vary.

When the Hydrus Microstent was introduced, it helped overcome these concerns. By allowing the surgeon to know when the placement is both properly located inside the canal, and correctly aligned with the collector channels, both of which shortens the learning curve and helps with surgeon confidence.

When you first see the second-generation MIGS device, it can appear imposing, and the initial assumption is that it will have a longer learning curve, but it doesn’t. Size does not equate to a more challenging implantation. On the contrary, size is a benefit, not an obstacle, and it can help surgeons to learn the surgery more quickly.

My personal second-gen experience is with the Hydrus Microstent, and I’ve found it to be very intuitive from a design perspective — it makes sense. It looks like a large device that must go into a very small space. But because the Hydrus is a full 8 mm, it’s quite obvious if it is – or is not – in Schlemm’s canal. You don’t have to wait to see if it is efficacious, nor will you wonder if a lack of efficacy is related to imperfect placement. You can visualize the entire implantation process. Think back to your internship years; how challenging was it to draw arterial blood with a tiny needle? And how much easier it was to place a cannulated IV line? That’s what it’s like learning to use the Hydrus compared with first-generation MIGS devices.

The Hydrus has three mechanisms of action: it bypasses the trabecular meshwork;  dilates and scaffolds the canal; and spans 90 degrees to support collector channel access. Furthermore, the scaffolding keeps Schlemm’s canal dilated, whereas viscoelastic dissipates. Data from the HORIZON trial support that these features add efficacy while maintaining safety (3). It is also comfortable for patients, which helps prevent movement.

Hydrus is a strong front-line solution for patients with mild to moderate glaucoma and, in my experience, the pressure drops just as you would expect it to, based on the clinical study data. HORIZON was a global trial and it was the largest MIGS trial to date, with 556 patients enrolled. It compared the efficacy of the Hydrus Microstent plus cataract surgery versus cataract surgery alone in mild to moderate glaucoma, and provided two-year data. Even at two years, cataract surgery is shown to lower IOP; but over time, adding the stent lowers IOP further and decreases the burden of using medications.

Unlike other MIGS data that showed either stability or a decline over two years, the HORIZON trial demonstrated an increase in comparative effectiveness versus phaco alone from year one to two years in both the 20 percent reduction primary endpoint and the unmedicated diurnal pressures (3).

Although many ophthalmologists have spent a long time investigating their options, we all recognize that MIGS is here to stay – despite a history of low penetration. We also have likely reached a tipping point as second generation technology is more forgiving, requires less specialization and is intuitive, providing intra-operative clues regarding accurate placement. We should all expect adoption to ramp up significantly in the near term.