MIGS Device Selection in Practice

Glaucoma is the most common comorbidity I see in my patients with cataracts. On any given operating day, the drug regimen of roughly one in five of the patients on my cataract list includes at least one IOP-lowering topical drop, and I expect the number of patients with comorbid glaucoma to increase as the population ages and screening improves. 

Until a decade ago, lens extraction was performed primarily by cataract surgeons and filtration surgery was performed by glaucoma specialists. MIGS has collapsed those silos. Cataract and glaucoma can be treated with immediately sequential procedures and a single anesthetic, and the refractive impact of combining MIGS and phacoemulsification is small enough not to compromise IOL selection. 

At cataract meetings, I am no longer asked whether to perform MIGS at the time of cataract surgery. Instead, I am asked which MIGS procedure to perform and which patients to refer to a glaucoma colleague. This article draws on real-world data from the International Glaucoma Surgery Registry (IGSR; IGSR.org)—a prospective multicenter registry capturing outcomes from more than 13,000 glaucoma procedures—and recently published multicenter studies^1,2 to provide a framework for cataract surgeons.  

WHO ARE IDEAL CANDIDATES FOR MIGS COMBINED WITH PHACOEMULSIFICATION? 

I look for patients with a visually significant cataract, mild to moderate primary open-angle glaucoma (POAG), and an IOP that is acceptable but not as low as desired on one to three topical medications. The most rewarding subgroup, in my experience, is comprised of patients who have become intolerant of topical therapy because of ocular surface disease, conjunctival hyperemia, reduced tear film stability, lash hypertrichosis, periocular pigmentation, true ocular allergy, and/or adherence concerns. 

Combining phacoemulsification and MIGS can deliver four compelling benefits to this group of patients.

No. 1: A Reduced Medication Burden

Published trials with data extending to 5 years or more have demonstrated a durable reduction of one to two topical IOP-lowering agents after combined surgery, and a meaningful proportion of patients were medication free.³ In a recent IGSR analysis, the mean number of medications required by patients decreased from 2.06 to 1.26 following ab interno canaloplasty (ABiC) using the iTrack Advance (Nova Eye Medical) combined with phacoemulsification, and the proportion of medication-free eyes increased from 7% to 43%.¹

No. 2: A Slower Rate of Visual Field Progression

Five-year data from the randomized HORIZON trial showed that the rate of clinically significant visual field progression was nearly 50% slower in the eyes that received a Hydrus Microstent (Alcon) at the time of cataract surgery compared to those that underwent phacoemulsification alone.⁴

No. 3: A Reduced Reliance on Filtration Surgery

The HORIZON trial also showed that Hydrus implantation combined with phacoemulsification significantly reduced patients’ need for a trabeculectomy later, a trend supported by real-world IGSR data.^1,3

No. 4: A Healthier Ocular Surface and Greater Refractive Accuracy 

Discontinuing topical glaucoma therapy can improve tear film stability and reduce meibomian gland dysfunction, thereby improving patients’ candidacy for and success with toric and presbyopia-correcting IOLs.⁵

CHOOSING A DEVICE: THREE ANATOMIC TARGETS 

Modern MIGS procedures can be categorized based on the outflow pathway being accessed. The evidence base, safety profile, and refractive impact of each anatomic target differ. For the cataract surgeon, a practical question is which target(s) to adopt and which to leave to a glaucoma colleague.

Transtrabecular/Schlemm Canal-Based MIGS

This anatomic target is familiar to cataract surgeons, and these MIGS procedures are supported by the strongest evidence. By targeting the trabecular meshwork, Schlemm canal, and, in some instances, the distal collector system, these procedures can restore conventional outflow without disrupting the conjunctiva. Transtrabecular MIGS is refractively neutral, it is associated with a low incidence of inflammation, and it is generally safe to combine with the implantation of a toric and/or presbyopia-correcting IOL. The category encompasses trabecular bypass stents and canal-based procedures.

The iStent infinite (Glaukos) deploys three preloaded trabecular microbypass stents across approximately 180° of Schlemm canal from a single injector, providing flow arcs of up to 240° of outflow coverage.

The iStent platform is typically indicated for combined phacoemulsification and MIGS in eyes with mild to moderate POAG. As with all these devices, specific indications and approvals vary between countries.   

Randomized controlled trial data support the Hydrus Microstent, including the HORIZON pivotal trial, as mentioned earlier, and the COMPARE trial, which demonstrated higher surgical success and greater medication reduction relative to two first-generation iStent trabecular microbypass stents.^3,6 The Hydrus Microstent’s 8-mm nitinol scaffold spans 3 clock hours of Schlemm canal to dilate its lumen and provide a scaffolded window onto the collector channel system.     

ABiC using the iTrack Advance (Nova Eye Medical) is a MIGS procedure designed to address the three points of resistance in the conventional outflow pathway—the trabecular meshwork, the inner wall of Schlemm canal, and the collector channel ostia—through 360° viscodilation. Its indication allows it to be considered across a range of glaucoma severity, from early to advanced disease. In a recent IGSR multicenter analysis of 318 eyes that underwent ABiC combined with phacoemulsification across 12 sites in five countries, the surgical success rate was 62% overall and 83% in eyes with a baseline IOP greater than 18 mm Hg.¹ In a separate IGSR comparative study, 42% of iTrack eyes and 29% of iStent eyes were medication free at the last follow-up visit (P = .029), and the IOP reduction and overall success rates were comparable between groups.²

The Omni Surgical System (Sight Sciences) combines canaloplasty and trabeculotomy and allows the degree of intervention to be titrated to the individual patient. In the prospective multicenter GEMINI study, Omni combined with phacoemulsification reduced IOP and medication use through 12 months in eyes with mild to moderate open-angle glaucoma.⁷

I choose ABiC when I want a comprehensive canal treatment that does not require an implant. The learning curve for trabecular and canal-based devices is manageable for cataract surgeons who are comfortable with intraoperative gonioscopy.

Suprachoroidal MIGS

The supraciliary space accesses the uveoscleral outflow pathway, an independent route not limited by episcleral venous pressure. Suprachoroidal MIGS is therefore a logical consideration when the conventional pathway may already be compromised, for example, after failed selective laser trabeculoplasty. Currently, the only commercially available suprachoroidal device is the Miniject (iStar Medical). Clinical data have shown a favorable IOP reduction, low reintervention rates, and endothelial cell density loss of approximately 6% at 2 years.⁸

Suprachoroidal MIGS is a natural next step after transtrabecular MIGS for cataract surgeons who are comfortable with gonioscopy.

Minimally Invasive Bleb Surgery

Subconjunctival procedures include the Xen Gel Stent (AbbVie) and Preserflo MicroShunt (Santen). They form a true filtering bleb, behave more like a controlled trabeculectomy than a tissue-sparing MIGS procedure, and are deployed when glaucoma is refractory to maximum tolerated medical therapy. Subconjunctival procedures generally reduce IOP by 30% to 35%, but ongoing bleb management (eg, needling, leak repair, hypotony control, and choroidal effusion management) is an issue.⁹

Bleb care does not slot neatly into high-volume cataract clinics, and most cataract surgeons are likely to refer patients to a glaucoma specialist for these procedures.

A PRACTICAL FRAMEWORK 

When evaluating a patient with cataracts and POAG, I complete five assessment steps before deciding on a MIGS device (see Five Steps to MIGS Device Selection).

For patients with ocular hypertension or stable preperimetric disease, the strongest indication for combining phacoemulsification and MIGS is often the ocular surface. Reducing a patient’s medication burden by even one topical drop may improve tear film stability and reduce meibomian gland dysfunction enough to allow consideration of a toric or presbyopia-correcting IOL. 

Individuals with mild to moderate POAG whose treatment regimen consists of one to three topical drops can often benefit from a transtrabecular device. The iStent platform is well suited to patients with early disease if the primary goals are a meaningful IOP reduction and simplification of the drop regimen. In the pivotal trial of iStent inject combined with cataract surgery, 75.8% of treated eyes achieved at least a 20% reduction in unmedicated diurnal IOP at 24 months.¹⁰ The Hydrus Microstent is a strong choice when there is evidence of glaucomatous progression or a desire to delay filtration surgery.³ ABiC using the iTrack Advance, in contrast, may be considered across a broad range of disease severity and has been associated in observational registry data with a lower postoperative medication burden.² The Omni Surgical System is a closely related canal-based procedure with comparable outcomes in mild to moderate disease.⁷ All four devices have low complication rates when combined with phacoemulsification.  

For select patients with POAG whose conventional outflow route has already been compromised, suprachoroidal MIGS may be a reasonable option. These individuals are typically referred to or comanaged with a glaucoma specialist.

An AI language model (Claude Opus 4.6, Anthropic) was used to assist with outline scaffolding and summarizing IGSR data. All content was reviewed, verified, and revised by the author, who assumes full responsibility for the accuracy and integrity of the manuscript. The AI tool was not used for data analysis, interpretation, or drawing scientific conclusions.