Microinvasive Glaucoma Surgery (MIGS)

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Article initiated by:

Babak Eliassi-Rad, MD, Vikas Singh, MD

All contributors:

Nathaniel P. Skillin, MD, PhD, Ahmad A. Aref, MD, MBA, Koushik Tripathy, MD (AIIMS), Faisal Ridha, MD, Monica K. Ertel, MD, PhD, Stephen Vincent Lau, MBChB, Babak Eliassi-Rad, MD, Leonard K. Seibold, MD, Hongan Chen, M.D., Nathaniel P. Skillin, MD, PhD

Assigned editor:

Leonard K. Seibold, MD

Review:

Assigned status Update Pending

 by Leonard K. Seibold, MD on October 31, 2025.

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Contributing Editors:	add

Introduction

Glaucoma is the leading cause of irreversible blindness worldwide and is estimated to affect 76 million people, a number expected to increase to 111.8 million in 2040. About 3 million people in the United States have glaucoma; this is estimated to have a direct medical cost of $2.9 billion.  Initial therapy for glaucoma typically consists of topical eye drops or laser trabeculoplasty, both of which aim to lower intraocular pressure (IOP) and have similar efficacy. Historically though, when pharmacologic and/or laser treatment fails to control IOP, incisional surgery such as trabeculectomy or glaucoma drainage device implantation is required.  Despite their efficacy, these surgical interventions result in labile postoperative IOPs, require frequent follow-up, have a prolonged recovery time, and offer a risk of serious early and late complications. Therefore, these procedures are often delayed in mild to moderate disease and are reserved for patients with more severe disease who warrant aggressive intervention. For decades, this left clinicians and patients with a treatment gap of limited options for patients with mild to moderate disease who had uncontrolled IOP despite medical and laser therapy.  Even in patients who respond to medical therapy, there are several barriers to adequate therapy that may limit its long-term utility.  These barriers include noncompliance with the prescribed regimen, intolerance of medication side effects, financial burden limiting access to medications, or physical inability to reliably self-administer eye drops. However, since the early 2000s, the field of glaucoma has seen the advent of microinvasive glaucoma surgery (MIGS), which has sought to fulfill the unmet need for improved treatment options and close this treatment gap.  The term "MIGS" was coined by Dr. Iqbal Ike K. Ahmed in 2009.

Patients generally are good candidates for MIGS if they have mild to moderate glaucoma, are intolerant or noncompliant with drops, or if their IOP is not controlled with topical eye drops or laser trabeculoplasty.  MIGS procedures can also be used to reduce drop dependence at the time of traditional phacoemulsification surgery in patients whose disease may be well controlled.  MIGS are often not sufficient treatment for patients with more advanced disease who require a low IOP goal.  For these patients, traditional incisional surgeries, such as glaucoma drainage implants or trabeculectomy, are often still indicated.  

MIGS Definition

MIGS procedures constitute a group of surgical interventions that share 5 characteristics.

1.     High safety profile: Compared to traditional incisional surgeries, MIGS carry a much lower risk of serious complications such as hypotony, choroidal effusions, or choroidal hemorrhages. 
2.     Minimal disruption of normal anatomy: MIGS allow for enhancement of physiological outflow mechanisms avoiding major alterations in normal ocular anatomy.
3.     Ab interno approach: MIGS are typically performed ab interno through a traditional clear corneal wound with direct visualization of the anatomical target. 
4.     Efficacy: MIGS should offer meaningful IOP-lowering effect. The level of IOP reduction is often inferior to traditional filtering surgery but should be at least 20%.  Alternatively, patients who do not experience an IOP decrease should attain the reduction of at least 1 medication.
5.     Ease of use for patients and physicians: MIGS should allow for a rapid recovery with minimal additional downtime for patients.  They should also be easily incorporated into traditional phacoemulsification surgery. 

MIGS Approaches 

MIGS offer IOP lowering by targeting various aspects of normal aqueous dynamics.  The first approaches involve enhancing outflow across the trabecular meshwork and through the Schlemm canal.  The juxtacanalicular trabecular meshwork has traditionally been identified as the site of greatest resistance to aqueous outflow.  This resistance can be overcome through bypassing or removing this tissue to lower IOP through increased outflow. Bypass can be achieved by placing a trabecular meshwork bypass stent, which allows aqueous to flow directly through the stent from the anterior chamber into the Schlemm canal.  Another approach to bypass the resistance of the trabecular meshwork is goniotomy or trabeculotomy, which involves surgical incision and/or excision of this tissue and allows for improved aqueous outflow into the Schlemm canal. Dilation of the Schlemm canal through cannulation and expansion with viscoelastic is yet another approach to improve outflow through the normal physiologic aqueous outflow system. 

A second group of MIGS approaches seeks to increase outflow via alternate pathways. The uveoscleral outflow pathway can be augmented by accessing the suprachoroidal space with microstent placement.  Alternatively, if traditional outflow pathways are unlikely to be improved, aqueous can be shunted into the subconjunctival space through an ab interno, small-incision approach.

A third MIGS approach involves decreasing aqueous production by ablation of the ciliary body.  This approach is employed during endocyclophotocoagulation, in which an endoscopic laser probe is inserted through a clear corneal incision and used to directly visualize and ablate the ciliary body. 

MIGS Devices and Outcomes

Trabecular meshwork bypass by stent placement

As previously mentioned, trabecular meshwork bypass can be achieved either through the placement of stents or through surgical incision/excision of the trabecular meshwork tissue.  MIGs utilizing stent placement are discussed below, with additional details in the article about Trabecular Meshwork Bypass by Stent.

iStent

Device Design

The iStent Trabecular Micro-Bypass Stent (Glaukos, Laguna Hills, CA) received FDA approval in 2012 as the first MIGS implant. The device is a heparin-coated, non-ferromagnetic titanium stent. The device measures 0.3 mm in height and 1 mm in length. There is a snorkel that is 0.25 mm in height with a central lumen of 120 µm, which projects into the anterior chamber. The body of the device, which is implanted into the Schlemm canal, contains 3 retention arches to ensure that the device will remain in place.  The iStent is preloaded into a single-use sterile injector.

Indications

The device is indicated for the treatment of mild to moderate glaucoma and is approved for implantation at the time of phacoemulsification.

Pivotal trial 

The pivotal trial for approval of the iStent compared the effectiveness of phacoemulsification alone to phacoemulsification with iStent placement.  It was a prospective, randomized trial that included 240 eyes with mild to moderate glaucoma and IOP less than or equal to 24 mm Hg on one to three drops.  Patients were randomized to either phacoemulsification alone or phacoemulsification with iStent placement: 111 patients received iStent placement at the time of phacoemulsification. Patients were followed out to 12 months, and the primary endpoint was an IOP ≤21 mm Hg without ocular hypotensive medications.  At 12 months, 72% of eyes that underwent iStent placement with phacoemulsification had reached the primary endpoint, versus 50% of eyes undergoing phacoemulsification alone. Furthermore, 66% of iStent eyes had achieved an IOP reduction greater or equal to 20%, compared to only 48% of eyes in the control (phacoemulsification only) group. Of note, both groups experienced statistically significant IOP lowering at one year, and there was no difference in adverse events between the two groups. 

iStent inject

Device Design

The iStent inject is the second-generation trabecular meshwork bypass stent, which received FDA approval in June 2018 (Glaukos, Laguna Hills, CA). The iStent inject is the smallest device to be implanted in the human body and, like the first generation iStent, is composed of heparin-coated, non-ferromagnetic titanium. Each stent is 360 µm in height by 230 µm in diameter, consisting of a tapered head with a recessed thorax and a terminal flange. The head resides in the Schlemm canal, the thorax straddles the trabecular meshwork, and the flange resides in the anterior chamber.  The central lumen of each stent is 80 µm in diameter. The iStent inject consists of a single-use injector that comes pre-loaded with two devices, which are to be placed 2–3 clock hours apart in the nasal angle at the time of cataract surgery. 

Indications

The device is indicated for the treatment of mild to moderate glaucoma and is approved for implantation at the time of phacoemulsification.

Pivotal Study 

The pivotal trial for approval of the stent compared iStent inject with phacoemulsification to phacoemulsification alone. It was a prospective, single-masked, multi-center study with 505 eyes randomized 3:1 to iStent plus phacoemulsification (n=387) or phacoemulsification alone (n=118).  Included patients had a diagnosis of mild to moderate primary open-angle glaucoma, were on up to three pressure-lowering drops, had a preoperative IOP of less than or equal to 24 mm Hg, and required cataract surgery. Primary endpoints examined were number of patients with 20% or greater reduction in IOP at 24 months and the change in unmedicated IOP at 24 months. At 24 months, 75.8% of patients who received iStent inject at the time of cataract surgery had experienced at least a 20% reduction in IOP compared to 61.9% in the phacoemulsification-alone group.  Patients who received iStent at the time of phacoemulsification also had a mean IOP reduction of 7.0 ± 4.0 mm Hg compared to 5.4 ± 3.7 mm Hg in the patients who underwent phacoemulsification alone. Furthermore, 84% of eyes that underwent iStent/phacoemulsification were medication-free at 23 months, compared to 67% of eye that underwent phacoemulsification alone.

iStent inject W with Infinite Injector; iStent infinite

Device Design

The iStent inject W is the third-generation trabecular meshwork bypass stent which received FDA approval in July 2020 (Glaukos, Laguna Hills, CA) as a Premarket Approval Supplement to the second-generation iStent inject.  iStent inject W is a heparin-coated, non-ferromagnetic titanium stent that is functionally equivalent to the second-generation iStent inject but has a wider flange (360 µm) to improve placement and visualization in the trabecular meshwork. The Infinite Injector is a single-use injector that comes preloaded with two or three iStent inject W stents and allows for re-threading and unlimited delivery attempts in cases of under implantation. Stents are placed 2-3 clock hours apart in the nasal angle.

Indications

iStent inject W with Infinite Injector Technology (2 stents) is indicated for the treatment of mild to moderate glaucoma and is approved for implantation at the time of phacoemulsification. iStent infinite (3 stents) received FDA approval in August 2022 and is indicated for use as a standalone procedure for the treatment of uncontrolled glaucoma in whom previous medical and surgical treatment has failed. Glaukos is currently conducting a clinical trial for the standalone use of iStent infinite in patients with glaucoma who have not failed conventional medical and surgical treatment (NCT06057051).

Pivotal Study (iStent infinite)

The pivotal trial for approval of iStent infinite as a standalone procedure evaluated the safety and effectiveness of implanting three iStent inject W devices in patients with open angle glaucoma uncontrolled by prior surgical or medical therapy. It was a prospective, multi-center, single-arm study with 72 eyes. Included patients had a diagnosis of open angle glaucoma with a pre-operative IOP ≥20 mm Hg and ≤35 mm Hg and had either failed 1 or more incisional glaucoma surgeries or cilioablative procedures (n=61, Failed-Surgery subgroup), or were on maximum tolerated medical therapy (MTMT) defined as ≥4 classes of topical IOP-lowering medications or fewer in cases of intolerance or contraindications (n=11, MTMT subgroup). Six patients were phakic and 66 were pseudophakic. Primary endpoints examined were the proportion of patients with ≥20% reduction in IOP at 12 months on the same or fewer IOP-lowering medications and the mean change in IOP at 12 months. 76.1% of patients who received iStent infinite had experienced at least a 20% reduction in IOP on the same or fewer IOP-lowering medications (Failed-Surgery subgroup: 73.4%; MTMT subgroup: 90.9%). Lens status had no effect on treatment response.  Patients had a mean IOP reduction of 5.9 ± 0.6 mm Hg (Failed-Surgery subgroup: 5.5 ± 0.7 mm Hg; MTMT subgroup: 8.1 ± 0.9 mm Hg).  The mean number of IOP-lowering medications decreased from 3.1 ± 0.89 at baseline to 2.70 ± 1.03 at 12 months. 43.7% of patients used fewer IOP-lowering medications at 12 months.

Hydrus Microstent

Device Design 

The Hydrus Microstent, developed by Ivantis Inc., received FDA approval in August 2018 and was acquired by Alcon (Fort Worth, TX) in 2022. The microstent is 8 mm in length and 290 µm in diameter with 3 windows and an inlet that sits in the anterior chamber. It is made of nitinol, which is a flexible, biocompatible titanium and nickel alloy that has been used in cardiac stents. The device spans 90 degrees of the trabecular meshwork. It functions to lower IOP through 2 mechanisms: trabecular meshwork bypass stent and scaffold for the Schlemm canal to maintain patency.

Indications

The device is indicated for the treatment of mild to moderate glaucoma and is approved for implantation at the time of phacoemulsification.

Pivotal Study 

The HORIZON study compared phacoemulsification alone to phacoemulsification with Hydrus Microstent implantation. A total of 546 patients with primary open-angle glaucoma who had visually significant cataracts, IOP between 22 mm Hg and 34 mm Hg, and who were on between 1–4 hypotensive eye drops were enrolled. Three hundred sixty-nine (369) eyes underwent phacoemulsification with Hydrus Microstent implantation and 187 eyes underwent phacoemulsification alone. The primary endpoint was the proportion of eyes with unmedicated IOP reduction of greater than or equal to 20% at 24 months after surgery. Other secondary endpoints included mean change in IOP from baseline to 24 months and number of hypotensive medications. At 24 months, 77.3% of eyes in the Hydrus group experienced at least a 20% reduction in IOP compared to 57.8% of eyes in the phacoemulsification group alone. Mean change in unmedicated IOP at 24 months postsurgery was -7.6 ± 4.1 mm Hg in the Hydrus group compared to -5.3 ± 3.9 mm Hg in the phacoemulsification alone group. There was also a significantly greater reduction in hypotensive eye drops in the Hydrus group compared to the phacoemulsification-alone groups. Hydrus plus phacoemulsification group went from 1.7 ± 0.9 drops to 0.3 ± 0.8 drops at 24 months after surgery while the phacoemulsification alone group went from 1.7 ± 0.9 drops to 0.7 ± 0.9 drops at 24 months. 

Trabecular meshwork bypass by tissue excision 

In addition to the above-mentioned stents, trabecular meshwork (TM) bypass can also be achieved through surgical incision/excision of the trabecular meshwork tissue. General advantages of these MIGS procedures are the ability to bypass the trabecular meshwork and form a direct pathway to the Schlemm canal for 3 or more clock hours. Importantly, no implant is required, and these goniotomy/trabeculotomy procedures can be performed as a standalone procedure or combined with simultaneous cataract surgery. General disadvantages are the risk of cleft closure from residual TM leaflets, and IOP reduction is limited by episcleral venous pressure and resistance from the Schlemm canal. MIGS utilizing this technique are described below, with additional details in the article about Ab Interno Trabeculectomy and Trabeculotomy.

Kahook Dual Blade / KBD GLIDE

Device Design

The Kahook Dual Blade (KDB; New World Medical, Rancho Cucamonga, CA) is a specialized goniotomy blade that was introduced in the United States in 2015. It was designed for improved excision of the trabecular meshwork during goniotomy. The blade is a single-use disposable blade with a sharp tip that is used to pierce the trabecular meshwork, a ramp that stretches the trabecular meshwork, and dual parallel blades that create paired parallel incisions in the trabecular meshwork. This design allows for complete excision of the trabecular meshwork and reduces the potential for scarring from residual tissue leaflets. Surgical technique involves an ab interno approach through clear corneal incisions with visualization of the angle using direct gonioscopy and a perpendicular approach to the TM. Treatment ranges between 3–5 clock hours.

The second-generation KDB GLIDE has been available since October 2020. While the parallel dual blade and ramp design remains the same, new features include a rounded heel, tapered sides, and a smaller footplate. These changes improve ease of use and optimize fit within the canal.

Indications  

Kahook Dual Blade goniotomy can be performed in patients with open-angle glaucoma, ocular hypertension, and in certain patients with angle-closure glaucoma. KDB goniotomy can be performed either at the time of cataract surgery or as a stand-alone procedure in phakic, aphakic, or pseudophakic patients. 

Pivotal Studies

Several studies have demonstrated the clinical efficacy of Kahook Dual Blade goniotomy for IOP reduction in patients with glaucoma. One such study by Greenwood and colleagues looked at 1-year outcomes of KDB with phacoemulsification. The study included 71 eyes from a mixed population of patients with mild to severe glaucoma of various types, including primary open angle glaucoma, pigmentary glaucoma, pseudoexfoliation, normal tension glaucoma and angle-closure glaucoma. Primary outcome measures were reduction in IOP and proportion of patients achieving a reduction in IOP of more than 20% from baseline. Secondary outcome measures included reduction in hypotensive eye drops. At 6 months, mean IOP decreased from 17.4 ± 5.2 mm Hg to 12.8 ± 2.6 mm Hg, and 58.3% of patients had an IOP reduction of ≥20% from baseline.  The number of hypotensive eye drops decreased from 1.6 ± 1.3 to 0.9 ± 1.0 eye drops. Another study included 52 eyes of patients with open-angle glaucoma and visually significant cataracts who underwent phacoemulsification with KDB goniotomy. Outcome measures were mean reduction in IOP, proportion of patients with ≥20% reduction in IOP and reduction in IOP-lowering eye drops. At 1 year postoperatively, eyes that underwent phacoemulsification with KDB goniotomy experienced a significant reduction in mean IOP from 16.8 ± 0.6 mm Hg at baseline to 12.4 ± 0.3 mm Hg; 57.7% of eyes experienced a 20% reduction in IOP, and the number of medications decreased from 1.6 ± 0.2 to 0.8 ± 0.1 eye drops. Another study evaluated 12-month outcomes of phaco-KDB versus KDB alone. Success was defined as ≥20% IOP reduction and/or reduction of at least 1 glaucoma medication. Phaco-KDB had a success rate of 71.8% and KDB alone of 68.8%.

TrabEx / TrabEx Pro

Device Design

TrabEx is a specialized goniotomy blade developed by NeoMedix and subsequently acquired by MicroSurgical Technology (Redmond, WA). Similar to KDB goniotomy, TrabEx works by removing a strip of trabecular meshwork and the inner wall of the Schlemm canal in order to create a path for the drainage of aqueous humor. TrabEx is a single-use, disposable instrument with serrated dual blades in a trapezoidal configuration. TrabEx Pro was FDA approved in June, 2022 and integrates the TrabEx blade into a handpiece with active irrigation and aspiration (I/A) to stabilize the anterior chamber without the need for viscoelastic during goniotomy. Active I/A also removes tissue and debris generated during goniotomy to improve visibility during surgery. Surgical technique is the same as that of KDB GLIDE, involving an ab interno approach through clear corneal incisions with visualization of the angle using direct gonioscopy and a perpendicular approach to the TM with goniotomy of three to six clock hours.

Indications

TrabEx and TrabEx Pro are FDA cleared (2022) ophthalmic surgical instruments but do not yet have formal indications to lower IOP in patients with glaucoma.

Clinical Outcomes (TrabEx Pro)

Gosling et al. evaluated the safety and efficacy of TrabEx Pro in a retrospective case series of 73 eyes in 64 patients. Patients with open angle glaucoma were treated with TrabEx Pro as a standalone procedure or TrabEx Pro combined with phacoemulsification. Primary outcomes were the mean IOP and medication burden after surgery. 73% of eyes achieved an IOP reduction of >20% with IOP <21 mmHg and no reoperation or increased medication burden at their latest follow-up (up to 24 months). Mean IOP decreased from 31.3 ± 7.3 to 20.9 ± 10.4 mmHg, while mean medications decreased from 2.9 ± 1.2 to 1.9 ± 1.3. The most common complication was hyphema in 12 patients, of which 4 eyes had an IOP spike >10 mmHg. Other complications included hypotony (n=1), postoperative uveitis (n=2), and postoperative cystoid macular edema (n=1).

SION

Device Design

SION is a specialized goniotomy instrument developed by Sight Sciences (Menlo Park, CA). Similar to KDB goniotomy, SION works by removing a strip of trabecular meshwork and the inner wall of the Schlemm canal in order to create a path for the drainage of aqueous humor. SION is a single-use, disposable instrument with a bladeless design that excises tissue without cutting to improve safety and ease of use. Surgical technique involves an ab interno approach through clear corneal incisions with visualization of the angle using direct gonioscopy and a perpendicular approach to the TM with goniotomy of three to six clock hours.

Indications

SION is an FDA cleared (2022) ophthalmic surgical instrument but does not yet have formal indications to lower IOP in patients with glaucoma.

Clinical Outcomes

Clinical data regarding SION remain limited. A recent conference abstract reported a small series of 38 eyes undergoing SION goniotomy combined with cataract surgery, mean IOP decreased from 16.0 mm Hg preoperatively to 13.9 mm Hg at 3 months, while mean glaucoma medication use decreased from 2.8 to 2.4 medications. Additional prospective studies are needed to characterize its long-term efficacy and comparative effectiveness.

Trabectome

Device Design

Trabectome is a surgical system developed by NeoMedix and subsequently acquired by MicroSurgical Technology (Redmond, WA). It was FDA approved in 2004 and is used to perform an ab interno trabeculotomy. The system works by removing a strip of trabecular meshwork and the inner wall of the Schlemm canal in order to create a path for the drainage of aqueous humor. The device consists of a single-use, disposable hand piece that performs electrocautery, irrigation, and aspiration. It is connected to a generator with a frequency of 550 kHz that allows adjustments in 0.1 Watt increments and is controlled via a 3-stage foot pedal control that initiates irrigation, aspiration and electrocautery in sequence. Continuous I/A allows for removal of debris and regulation of temperature. Additionally, the tip of the Trabectome is bent at a 90° angle to create a protective triangular footplate and allow for easier insertion into the Schlemm canal and is coated to facilitate smooth movement within the canal. Ablation may be applied for 60–120° of trabecular meshwork to allow for re-establishment of the drainage pathway.

Indications

Trabectome is indicated for patients with various types of open angle glaucoma, ocular hypertension and can be used in some patients with angle closure glaucoma. Trabectome can be performed in conjunction with cataract surgery or as a stand-alone procedure. It can be performed in patients who are phakic, pseudophakic, or aphakic.

Clinical Outcomes 

Maeda and colleagues evaluated the outcomes of stand-alone Trabectome in 80 eyes of 69 patients with or without previous intraocular surgery or laser. A mean preoperative IOP of 26.6 ± 8.1 mm Hg was reduced to a mean of 17.4 ± 3.4 mm Hg at 6 months postoperatively. Average number of medications also decreased from 4.0 ± 1.4 to 2.3 ± 1.2 drops at 6 months. The study reported no serious complications, including choroidal effusion, choroidal hemorrhage, or infection. Thirteen eyes required subsequent surgeries due to uncontrolled IOP, with 10 patients receiving trabeculectomy and 3 patients receiving repeat Trabectome. In a study completed in 2008 involving 304 eyes in patients with open-angle glaucoma, similar results were found with combined phacoemulsification and Trabectome.  Mean IOP was found to have decreased from 20.0 ± 6.3 mm Hg to 15.5 ± 2.9 mm Hg at 1 year postoperatively and the average number of topical medications was reduced from 2.65 ± 1.13 to 1.44 ± 1.29 drops. Complications included iris injury in 4 patients and IOP spike in 26 patients.

Gonioscopy-Assisted Transluminal Trabeculotomy (GATT)

Surgical approach

GATT is a form of ab interno trabeculotomy that was initially described by Grover and colleagues in 2014. Under direct visualization with a gonioscopy lens, a goniotomy is made in the nasal trabecular meshwork, which serves as the entry point for the iTrack microcatheter (Nova Eye Medical, Fremont, CA) or a suture. Subsequent modifications described the use of a thermally blunted, marked 5-0 polypropylene (Prolene) suture as a less costly alternative to the iTrack microcatheter. The iTrack microcatheter, described in more detail in the following section, is 250 µm in diameter and has an illuminated distal tip to allow for visualization during advancement of the catheter through the Schlemm canal. Microsurgical forceps are used to advance the microcatheter or suture into the Schlemm canal circumferentially 360 degrees. Once it has been passed through the entire canal, the distal end of the catheter or suture is grasped and the proximal end is retracted out of the eye, shearing the trabecular meshwork to create a 360-degree trabeculotomy. The TRAB360 system (Sight Sciences, Menlo Park, California) was developed to facilitate greater control during GATT but has since been superseded by the OMNI Surgical System, which is detailed in the following section.

GATT Procedure Gonioscopy-Assisted Transluminal Trabeculotomy

Source: YouTube, Ophthalmology Times, GATT, DSG RLF labelled. https://youtu.be/VXPOZtIhpnk Accessed September 16, 2025.

Surgical Video Demonstrating a suture GATT with a 5-0 Prolene Suture

Source: YouTube, Davinder Grover, MD, MPH https://youtu.be/1laohyDLi2A Accessed September 16, 2025.

Indications  

GATT can be performed in adult or pediatric patients with open-angle glaucoma and a clear cornea. It can be performed as a stand-alone procedure or in combination with cataract surgery. Patients can be phakic, pseudophakic, or aphakic. 

Clinical outcomes    

In their original review, Grover and colleagues reported on the 6 and 12 month outcomes of GATT performed in adult patients with open-angle glaucoma either in combination with phacoemulsification or as a stand-alone procedure. There were 85 eyes of 85 patients included: 57 patients with primary open-angle glaucoma showed an average IOP decrease of 11.1 ± 6.1 mm Hg, and patients required 1.1 fewer drops at 1 year postoperatively.  For the 28 patients with other forms of open-angle glaucoma, IOP decreased an average of 19.9 ± 10.2 mm Hg, and patients required 1.9 fewer IOP-lowering medications at 1 year postoperatively. Treatment failure occurred in 8/85 patients (9%) due to the need for subsequent glaucoma surgery. The most common complication was a transient hyphema reported at follow-up in 30% of patients at 1 week postoperatively that resolved within month. Since the original publication, Grover and colleagues have reported the successful use of the GATT technique in primary congenital glaucoma, juvenile open-angle glaucoma, and even in eyes with prior incisional glaucoma surgery.  These early results represent a promising conjunctival sparing technique that can be used in conjunction with, or independently of, cataract surgery. 

C-Rex

Device Design

C-Rex (IanTrek Inc., White Plains, NY) is a single use, disposable handpiece with a sharp, angled probe containing a retractable nitinol memory-shaped filament with a distal tissue disruptor having cutting edges on both sides. Nitinol is used to keep the filament rigid for effective cutting as it is advanced circumferentially along Schlemm’s canal. Once the probe pierces Schlemm’s canal, the disruptor cuts the trabecular meshwork and inner wall of Schlemm’s canal as it is advanced up to 180˚ using a slider on the handpiece. As the shaft is retracted, the other side of the disruptor cuts the outer wall of Schlemm’s canal to fully expose collector channels. The process can be repeated on the other side of the eye for a complete 360˚ dual-wall canalotomy.

Indications

C-Rex is an FDA cleared (2021) ophthalmic surgical instrument but does not yet have formal indications to lower IOP in patients with glaucoma.

Clinical Outcomes

A prospective cohort study (CIRCLE) assessing the efficacy of standalone C-Rex and C-Rex combined with phacoemulsification in adults with open angle glaucoma is currently underway (NCT06615661).

Enhancing aqueous outflow through the Schlemm canal 

In addition to the above-mentioned techniques for bypassing resistance at the level of the trabecular meshwork, other MIGS procedures aim to improve the conventional outflow pathway at the level of the Schlemm canal and its downstream collector channels. These procedures work through cannulation and dilation of the Schlemm canal and the distal outflow system to reduce outflow resistance. These are mentioned below.

iTrack / iTrack Advance

Device Design

The iTrack microcatheter system (Nova Eye Medical, Fremont, CA) was originally designed for ab externo canaloplasty but was later used for ab interno canaloplasty (ABiC) and GATT. The 250 µm diameter microcatheter has an internal guidewire to push through adhesions and herniations of the Schlemm canal and an internal fiber optic that allows for easy visualization of the distal catheter tip during the procedure. After making a nasal goniotomy, the catheter is advanced 360 degrees into the Schlemm canal and slowly withdrawn while performing viscodilation of the canal and the distal outflow system.  This approach allows for enhancement of the natural outflow system without tissue destruction.  Furthermore, it is believed to decrease herniation of the inner wall of the Schlemm canal into the distal collector channels to improve outflow and create small fractures in trabecular beams to expand the effective filtration area and create new areas for filtration.

The iTrack Advance is the newest generation device from Nova Eye Medical and received FDA approval on March 30, 2023. It consists of a single use, disposable handpiece with a stainless steel cannula to pierce the trabecular meshwork and a similar composite microcatheter as the original iTrack with an outer diameter of 220 µm having a hydrophilic, lubricious coating and an internal guidewire and fiber optic. The handpiece connects to the company’s proprietary iLumin endoilluminator light source and the ViscoInjector which holds >100 µL of viscoelastic. Rotation of the ViscoInjector knob delivers 2.25 µL of viscoelastic per click.

Indications

ABiC with iTrack and iTrack Advance can be performed either in conjunction with cataract extraction or as a standalone procedure.  It is FDA approved for the treatment of mild-moderate glaucoma in addition to more advanced and refractory glaucoma.

Clinical Outcomes

Gallardo et al. evaluated the efficacy of ABiC using the iTrack microcatheter in a single-site 12 month study.  75 eyes of 68 patients with POAG underwent ABiC: 41 eyes underwent stand-alone ABiC and 34 eyes underwent combined ABiC/phacoemulsification.  Average pre-operative IOP in both groups was 20.4 ± 4.7 mm Hg, which decreased to 13.3 ± 1.9 mm Hg at 12 months post-operatively.  There was no significant difference between IOP reduction in eyes that underwent stand-alone ABiC versus eyes that underwent combined ABiC/phacoemulsification.  Average IOP reduction at 12 months post-op was 32.3% in both groups; 32.8% in the stand-alone ABiC group and 31.7% in the ABiC/phacoemulsification group.  84.9% of eyes experienced an IOP reduction of greater than 20% from baseline.  Furthermore, the average number of IOP lowering drops decreased from 2.8 ± 0.9 drops to 1.1 ± 1.1 drops, which represents a 60.0% reduction on average.  At 1 year post-operative follow-up, 40% of eyes were off all IOP lowering drops.

OMNI Surgical System

Device Design

The OMNI Surgical System (Sight Sciences, Menlo Park, CA) combines the earlier devices of VISCO360 (designed for ABiC) and TRAB360 (designed for GATT) into a single surgical platform and launched in 2017 under a general 510(k) FDA clearance for general ophthalmic surgical use. The cannula tip is used to pierce the trabecular meshwork and the microcatheter is advanced 180˚ through the Schlemm canal. ABiC is performed by delivering viscoelastic into the canal as the catheter is retracted, the procedure is then repeated on the other side. After ABiC, the microcatheter is again introduced into Schlemm’s canal and a 180˚ trabeculotomy is performed on both sides. By combining ABiC and trabeculotomy in one procedure, this approach targets all three conventional outflow resistance points (trabecular meshwork, the Schlemm canal, and outer collector channels). The OMNI Ergo series debuted in 2023 with upgraded ergonomics, a new cannula tip profile, and TruSync technology that matches the rate of viscoelastic delivery with the rate of catheter retraction. The OMNI Edge debuted in 2025 with a larger viscoelastic reservoir of 21 µL compared to 11 µL in the OMNI Ergo.

Indication

The OMNI Surgical System received an expanded 510(k) clearance on March 1, 2021 for ABiC followed by trabeculotomy to reduce intraocular pressure in adult patients with primary open-angle glaucoma. It can be performed as a standalone procedure or combined with phacoemulsification and has shown efficacy in treating mild, moderate, and advanced glaucoma.

Pivotal Study

GEMINI was the pivotal clinical trial for approval of combination canaloplasty and trabeculotomy using the OMNI surgical system. GEMINI evaluated the efficacy of 360˚ canaloplasty and 180˚ trabeculotomy combined with phacoemulsification in patients with mild to moderate open angle glaucoma. The primary outcomes were the change in mean unmedicated IOP from baseline to 12 months as well as the reduction in mean number of IOP-lowering medications from screening to 12 months. Gallardo et al. reported the 12 month results of this prospective, multi-center, interventional trial that enrolled 149 patients, of which 120 were included in the final effectiveness analysis. Mean IOP decreased from 23.9 ± 3.0 to 15.6 ± 4.0 mm Hg and 80% of patients were unmedicated at 12 months. Mean number of IOP lowering medications decreased from 1.8 ± 0.9 to 0.3 ± 0.9 at 12 months. Complications were mild and included hyphema (n=9), transient IOP elevation (n=3), anterior uveitis (n=2), peripheral anterior synechiae (n=2), clinically significant cystoid macular edema (n=1) and blepharitis (n=3). An extension study evaluated long-term efficacy at 36 months in 66 patients. Mean IOP decreased from 23.1 ± 2.7 to 16.3 ± 3.3 mm Hg and mean IOP-lowering medications decreased from 1.7 to 0.3. 74% of patients remained medication free at 36 months.

STREAMLINE Surgical System

The outer sleeve of the STREAMLINE surgical system is positioned on the trabecular meshwork (inset). When the device is actuated, the sleeve retracts allowing the inner cannula to pierce the trabecular meshwork and deliver 7 µL of viscoelastic bidirectionally.

Device Design

The STREAMLINE Surgical System (New World Medical, Rancho Cucamonga, CA) received FDA clearance on October 8, 2021. The device is single-use and disposable, consisting of a stainless-steel cutting inner cannula with a polymer outer sleeve. When the actuator button on the handset is fully depressed, the outer cannula retracts from the inner cannula tip, which pierces the TM to create a 150 µm diameter goniotomy while simultaneously delivering approximately 7 µL of viscoelastic for dilation of the Schlemm canal and distal collector channels. The device is primed and loaded with enough OVD to perform the procedure approximately eight times. The precision goniotomies can be extended to create larger goniotomies over several clock hours as needed.

Indication

STREAMLINE can be used to treat ocular hypertension and open-angle glaucoma. The procedure can be performed with cataract surgery or as a standalone procedure, and can thus be used in both phakic and pseudophakic eyes.

Clinical Outcomes

Lazcano-Gomez et al. reported the safety and efficacy of the STREAMLINE surgical system in a prospective, multi-center, single-arm clinical trial involving 45 Hispanic patients with mild to moderate open angle glaucoma undergoing concurrent phacoemulsification. The primary outcome was the proportion of unmedicated eyes with IOP reduction of ≥20% from baseline at 12 months. At this timepoint, 67.5% of patients were medication-free with an IOP reduction of ≥20% from baseline. 90% of eyes at 12 months achieved a mean IOP reduction of ≥20%. Mean IOP decreased from 23.0 ± 1.8 to 15.3 ± 2.8 mm Hg and the mean number of IOP-lowering medications decreased from 1.95 ± 0.82 to 0.63 ± 1.19. The most common complications after surgery were transient and included corneal striae (n=3), IOP elevation (n=3), and hyphema (n=2).

The VENICE study is an ongoing randomized controlled trial comparing the efficacy of canaloplasty using STREAMLINE to stent-based MIGS using two iStent inject W devices in patients with mild-to-moderate POAG undergoing phacoemulsification. The primary outcome is the change in unmedicated IOP over time. 6 month interim results of 72 eyes suggest comparable IOP and medication reduction between the two groups. In medication free eyes (81.8% in the STREAMLINE group and 78.4% in the iStent group), mean IOP decreased from 24.80 ± 2.79 to 16.00 ± 3.40 mmHg in the STREAMLINE group compared to a decrease from 24.60 ± 3.18 to 15.80 ± 2.21 mmHg in the iStent group. Mean number of IOP lowering medications decreased from 1.90 ± 0.81 to 0.20 ± 0.48 in the STREAMLINE group compared to a decrease from 1.70 ± 0.90 to 0.40 ± 0.79 in the iStent group.

VIA360 Surgical System

Device Design

The VIA360 Surgical System (New World Medical, Rancho Cucamonga, CA) received FDA clearance February 14, 2025 and is functionally similar to the OMNI Surgical System. The device is single-use and disposable, consisting of a handpiece with a viscoelastic reservoir, pump, stainless steel cannula and nylon microcatheter with 7 distal ports. The cannula tip is reversible in direction and is advanced into the angle through a clear corneal incision under gonioscopic visualization and pierces the trabecular meshwork and inner wall of the Schlemm canal. As the scroll wheel on the handpiece is rotated, the 40 mm long catheter advances through the canal. When the scroll wheel is depressed, 2–3 µL of viscoelastic is dispensed through the distal tip and six distal side ports, thereby dilating the Schlemm canal and the outer collector channels. This process is repeated up to 50 times for a full 360˚ viscodilation with delivery of >100 µL of viscoelastic. With the microcatheter fully advanced, pulling back on the instrument can facilitate a trabeculotomy spanning up to 360˚. The microcatheter is then retracted back into the handpiece.

Indications

VIA360 is an FDA cleared (2025) ophthalmic surgical instrument and viscoelastic delivery device but does not yet have formal indications to lower IOP in patients with glaucoma.

Clinical Outcomes

There are no published reports on the safety or efficacy of the VIA360 Surgical System at this time.

Enhancing aqueous outflow through the suprachoroidal space

While the above MIGS approaches augment the conventional outflow pathway, another MIGS approach is to target outflow through the unconventional, uveoscleral pathway.  While the first FDA-approved device that targeted this mechanism of IOP reduction has been withdrawn from the market (CyPass Micro-Stent), this alternative approach is drawing renewed industry attention.

CyPass Micro-Stent

Device Design

The CyPass Micro-Stent (Alcon, Fort Worth, TX) is a polyimide, supraciliary device for ab interno implantation. The goal of the device is to create a controlled cyclodialysis cleft with stented outflow to the suprachoroidal space. The stent is 6.35 mm long with an outer diameter of 430 µm, an inner diameter of 300 µm, and with 76 µm fenestrations along the length of the device. The flexible implant is loaded onto a retractable guidewire that conforms to the scleral curvature. The device is inserted through the initial phacoemulsification incision and advanced toward the sclera spur. The guide wire is used to perform blunt dissection of the ciliary body in order to allow passage into the supraciliary space where the stent can be placed. The proximal end of the stent has three retention rings to allow for improved stability of the device in the angle.

Indications  

CyPass received FDA approval in July 2016 for use in conjunction with cataract surgery in patients with mild to moderate primary open-angle glaucoma. The device was withdrawn from the market in August 2018, based on results of the 5-year COMPASS-XT trial, which demonstrated a significant decrease in corneal endothelial cell counts in patients undergoing CyPass with phacoemulsification compared to patients undergoing phacoemulsification alone.  

Clinical Outcomes 

The COMPASS trial reported on the two-year safety and efficacy outcomes of Cypass.  The study enrolled 505 subjects randomized to phacoemulsification alone (131 patients) or phacoemulsification with Cypass (374 patients). Baseline IOP of patients in the phacoemulsification/Cypass group was 24.2±2.8 mm Hg with an average of 1.4±0.9 medications. Baseline IOP in patients in the phacoemulsification-only group was 24.5±3.0 mm Hg with an average of 1.3±1.0 medications. There was significant reduction in IOP in both groups at the 2 year follow-up; however, IOP reduction was significantly greater in the Cypass group compared to phacoemulsification alone; IOP decreased 7.4 mm Hg from baseline in the stent group, compared to a decrease of 5.4 mm Hg in the phacoemulsification-only group. Additionally, 77% of patients in the stent group had ≥20% reduction in IOP. compared to 60% in the phacoemulsification-only group. Average number of medications decreased from 1.3±1.0 at baseline to 0.6±0.8 at 2 years in the phacoemulsification-only group, and from 1.4±0.9 drops at baseline to 0.2±0.6 at 2 years in the Cypass group. Further, 85% of eyes in the Cypass group were drop free at 2 years.  

CylcoPen with AlloFlo

Device Design

The CycloPen (Iantrek Inc., White Plains, NY) is a single-use, disposable instrument designed for the creation of a controlled cyclodialysis and insertion of a microtrephined scleral allograft (AlloFlo) into the cyclodialysis cleft as a structural reinforcement to prevent restenosis. The instrument consists of a handpiece and allograft carrier. AlloFlo is a decellularized scleral allograft with dimensions of 0.5 x 0.5 x 5 mm. AlloFlo is highly porous and water permeable, with minimal mechanical mismatch to surrounding native tissue to minimize the foreign body response and resulting fibrosis. The surgical procedure begins with formation of a cyclodialysis cleft by dissecting and separating the ciliary body from the scleral wall across one to two clock hours using a cyclodialysis spatula. Viscoelastic is then injected into the cleft to maintain patency for AlloFlo implantation. The CycloPen is positioned in the angle under gonioscopic visualization and advanced under the scleral spur into the newly formed cleft. As the surgeon pulls back on the handpiece actuator, the AlloFlo tissue graft is released into the cyclodialysis cleft such that the proximal end of the tissue is flush with the iris root. AlloFlo can be implanted as a single central reinforcement or as two lateral reinforcements of the cleft.

Indications

CycloPen is an FDA cleared (2021) ophthalmic surgical instrument and AlloFlo is regulated as a human cell/tissue product, meaning the device and tissue combination do not yet have formal indications to lower IOP in patients with glaucoma.

Clinical Outcomes

The CREST trial is a multicenter, prospective cohort study evaluating the safety and effectiveness of microinterventional cyclodialysis and allograft scleral reinforcement with and without concurrent phacoemulsification. The primary outcome of the study is a ≥20% decrease in IOP without additional IOP-lowering medications or secondary glaucoma surgery. Ianchulev et al. reported a one-year interim analysis of 117 eyes (89 patients) in the cohort in which this procedure is combined with phacoemulsification. Mean IOP decreased from 20.2 ± 6.0 to 13.9 ± 3.9 mmHg and mean IOP lowering medications decreased from 1.4 ± 1.3 to 0.8 ± 0.9 at 12 months. 81.9% of eyes with 12 month follow up achieved a medicated IOP ≤18 mmHg on the same or fewer medications. There were no serious adverse events or post-operative complications and there were no instances of AlloFlo migration. Mild complications included transient IOP elevation (n=9), hyphema (n=3), and hypotony (n=1). 4 patients experienced transient macular edema attributed to phacoemulsification. Notably, the authors reported only a 6.5% mean reduction in endothelial cell count in 59 eyes with available preoperative and 12 month postoperative data, which is similar to standalone phacoemulsification.

Shunting aqueous outflow into the subconjunctival space

Similar to traditional filtering surgery, another MIGS surgical approach to decreasing IOP is to shunt aqueous from the anterior chamber to the subconjunctival space. The Xen gel stent implant is currently the only the FDA approved device that utilizes this approach. Because this approach results in the formation of a filtering bleb, there is debate as to whether this approach can truly be classified in the MIGS category. 

XEN Gel Stent

Device

The XEN Gel Stent (AbbVie, North Chicago, IL) is a 6 mm tube composed of porcine-derived gelatin crosslinked with glutaraldehyde. The inner lumen of the tube is 45 µm in diameter and the outer diameter of the gel stent is 150 µm.  After implantation, the gelatin in the stent hydrates slightly, causing expansion of the device to ensure improved stability. The gel stent is loaded in a single-use, single-handed disposable injector with a 27-gauge needle.  The injector is inserted into the anterior chamber through a clear corneal incision and the tip of the injector is used to pierce through TM and the sclera into the subconjunctival space. The slider of the injector is advanced to deploy the stent into place and create an outflow from the anterior chamber to the subconjunctival space.  Mitomycin C is typically injected subconjunctivally before or after stent placement to limit bleb fibrosis.

In 2019, the XEN Gel Stent 63 was announced. The new design features the same 6 mm length but has a larger inner diameter (63 µm) and outer diameter (170 µm) and is deployed using the same 27-gauge XEN Injector. The larger inner diameter is intended to further decrease IOP compared to the XEN 45. The device is marketed in several countries outside the US but has not yet received FDA approval.

Indications  

The Xen Gel Stent is FDA approved (2016) for the treatment of patients with refractory glaucoma in whom maximal medical therapy is insufficient or in patients who have failed previous surgical treatment, and pseudoexfoliative or pigmentary glaucoma with open angles that are unresponsive to maximum tolerated medical therapy.  It can be performed in phakic or pseudophakic patients.

Clinical Outcomes   

The initial study with the Xen Gel Stent included 65 patients with refractory glaucoma, which was defined as poorly controlled IOP on maximally tolerated medical therapy or a failed previous filtering surgery or cilioablative procedure. Surgical technique utilized in this study included conjunctival cut-down, pretreatment with mitomycin C-soaked sponges followed by ab interno implantation of the Xen Gel Stent, and then conjunctival closure. At 12 months postoperatively, mean IOP decreased from baseline by 9.1 mm Hg and 75.4% of patients had ≥20% reduction in IOP. The average number of IOP-lowering medications decreased from 3.5 drops at baseline to 1.7 at 1 year postoperatively.  Most adverse events were mild, and the most common included the need for needling, transient decrease in visual acuity, and transient hypotony. 

Reducing aqueous production by ciliary body ablation

Another mechanism to achieve IOP reduction in MIGS is the decrease of aqueous production through ablation of the ciliary body. This approach is employed in endocyclophotocoagulation (ECP), during which a laser endoscopic probe is inserted through a clear corneal incision and used to directly visualize and ablate the ciliary body.   

Endocyclophotocoagulation (ECP)

Device Design

ECP is performed with an endoscopic probe attached to a laser unit (BVI, Waltham, MA) that includes a diode laser (810 nm), a Xenon light source, a helium-neon aiming beam, and fiber optic imaging. The connected video monitor provides for endoscopic viewing by the surgeon, and a foot pedal allows for surgeon control of the laser. The probe comes in a 19-, 20-, or 23-gauge size that is either straight or curved and is inserted into the anterior chamber through a clear corneal incision. Laser settings start at 0.25 Watts; continuous cycle and power is titrated to achieve both blanching and contraction of the ciliary processes. Treatment typically consists of 200–360 degrees of the angle. 

BVI received FDA approval for an updated ECP system called Leos (Laser Endoscopy Ophthalmic System) in April 2025. This new ECP system is optimized for ab interno access with improved ergonomics, a high-resolution camera, and customized LED illumination. Leos also automates parameters such as image focus, illumination, and orientation that previously required manual adjustment.

Indications

ECP was first approved by the FDA in 1991 and is indicated for the treatment of glaucoma in patients who have failed with conventional topical and systemic medications, or previous laser photocoagulation, or trabeculectomy and other filtering procedures, or cyclocryotherapy or other cyclodestructive procedures.  ECP is most commonly used in open-angle glaucoma but also has a particularly advantageous role in the treatment of angle closure or plateau iris, where it can function to deepen the angle. It can be performed in conjunction with phacoemulsification or as a stand-alone procedure in phakic or pseudophakic patients.  ECP can also be performed in conjunction with other angle-based procedures mentioned above to provide additional IOP lowering. 

Clinical Outcomes

The technique of ECP was first described by Uram in 1995. In 1997, Chen and colleagues evaluated the safety and efficacy of ECP in refractory glaucoma of multiple subtypes. The study included 68 patients with refractory glaucoma who had either failed maximal medical therapy or had previous failed filtration surgery or transscleral cyclodestructive procedure. ECP treatment was performed on 180-360 degrees of the ciliary body. In these patients, mean IOP decreased from 27.7±10.3 mm Hg preoperatively to 17.0±6.7 mm Hg at final postoperative time point (average 12.9 months). By final follow-up, 90% of eyes achieved an IOP of £21 mm Hg. Furthermore, mean number of medications decreased from 3.0±1.3 to 2.0±1.3 drops postoperatively. There were no cases of hypotony or phthisis and only 4 eyes lost 2 or more lines of Snellen visual acuity.

ECP is commonly combined with phacoemulsification, and the addition of ECP offers both a significant IOP and medication reduction, compared to phacoemulsification alone.  Francis and colleagues (2014) compared IOP reduction with phacoemulsification alone to ECP with phacoemulsification. The study included 80 patients that underwent phacoemulsification (control group) and 80 eyes that underwent phacoemulsification with ECP (study group); baseline IOP was 18.1 ± 3.0 mm Hg in both groups. At 2 years' postoperative follow-up, IOP in the study group had decreased to 16.0 ± 3.3 mm Hg compared to 17.3 ± 3.2 mm Hg in the control group with a significantly greater decrease in the study group. The mean number of glaucoma medications decreased from 1.5 ± 0.8 to 0.4 ± 0.7 drops at 2 years in the study group and from 2.4 ± 1.0 to 2.2 ± 1.1 in the control group. This represents a significantly greater reduction in number of glaucoma medications at 2 years with the addition of ECP at the time of cataract surgery.

The CONCEPT study is an ongoing prospective, multicenter, parallel group randomized controlled trial comparing phacoemulsification alone to phacoemulsification with ECP in patients with mild to moderate open angle glaucoma. This will be the first RCT to assess the efficacy of ECP and plans to follow 160 patients (n=80 for each arm) over 2 years.

Finally, a recent study of Leos in human cadaveric eyes demonstrated similar tissue effects to standard ECP while offering greater spatial control over tissue destruction compared to transscleral cyclophotocoagulation.

Standalone MIGS

Although commonly performed and studied with concurrent phacoemulsification, several MIGS devices and procedures have been investigated for use as standalone procedures.

Trabecular Meshwork Bypass Stents

Salient results of standalone iStent inject and Hydrus Microstent studies are shown in the chart below. For more information on device design and clinical indications, please refer to the "MIGS Devices and Outcomes" section earlier in the article. *Indicates IOP after wash-out.

Device	Study Design	IOP Reduction	Medication Reduction	Post-op Adverse Events > 1% or additional glaucoma surgery
iStent inject (Glaukos)	iStent inject (n = 94) vs. latanoprost/timolol (n = 98) (Fea et al., 2014) Randomized controlled trial	iStent mean IOP reduced from 25.2* to 13.0 mm Hg at POM12 iStent 92.6% had IOP < 18 mm Hg at POM12	4/94 iStent patients were taking medications at POM12	One stent obstruction treated with Nd:YAG laser
	iStent inject only (n = 66) (Voskanyan et al., 2014) Prospective cohort	Mean IOP reduced from 26.3* to 15.7 mm Hg at POM12 81% achieved IOP ≤18 mm Hg at POM 12	71.7% had reduction of 2 or more medications at POM12 15.2% had reduction of 1 medication at POM12	Elevated IOP (10%) Elevated IOP treated with additional surgery (3%) Stent obstruction treated with laser surgery (3%) Stent not visible on postoperative gonioscopy (13%)
	iStent inject on 2 medications (n = 53) (Berdahl et al., 2017) Prospective cohort	Mean IOP reduced from 24.9* to 16.6* mmHg at POM13 and 12.9 at POM18 100%  had IOP ≤ 18 mmHg at POM 12 87% had IOP ≤ 15 mmHg at POM 12	Mean  medications decreased from 2 to 1 at POM 18	None
	iStent inject  on 1 medication (n = 57) (Lindstrom et al. 2016, 2020) Prospective cohort	Mean IOP reduced from 24.4* to 14.4* at POM18 and 13.2* mm Hg at POM48 100% had IOP ≤18 mm Hg at POM 12 and 95% at POM48 67% had IOP ≤15 mm Hg at POM 12 and 82% at POM48	100% were medication free at POM18 and 95% at POM48	Elevated IOP (1.7%) BCVA loss > 1 line (3.5%) Additional glaucoma surgery required in 1 eye
	iStent inject only (n = 33) (Hengerer et al., 2019) Prospective cohort	Mean IOP reduced from 25.3 to 14.6 at POM36 97% had IOP ≤ 18 mm Hg at POM36 70.0% had IOP ≤ 15 mm Hg at POM36	Mean medication reduced from 3.0 to 0.5 at POM36	Additional glaucoma surgery required (6%) Cataract progression (6%) Uveitis (3%)
	iStent inject only in POAG (n = 17), PEX (n = 15), and PG (n = 3) (Klamann et al., 2015) Retrospective case series	POAG: mean IOP decreased from 21.2 to 14.2 mm Hg at POM6 PEX: mean IOP decreased from 23.8 to 15.3 mm Hg at POM6 PG: mean IOP decreased from 28.3 to 12.3 mm Hg at POD1 but increased to > 30 mm Hg in all within 1 month	POAG: mean medications decreased from 2.2 to 0.9 at POM6 PEX: mean medications decreased from 2.3 to 1.0 at POM6	Additional glaucoma surgery in all PG eyes
	iStent inject only in previously failed trabeculectomy (n = 22) (Davids et al., 2018) Retrospective case series	Mean IOP decreased from 22.5 to 15.5  mm Hg at POM 12	Mean medications decreased from 2.6 to 2.2 at POM12	Additional glaucoma surgery in 6 eyes (27.3%)
	iStent inject after at least 1 failed filtration surgery (n = 42) (Macher et al., 2018) Retrospective case series	Mean IOP decreased from 23.8 to 15.2  mm Hg at POM 12 > 1 filtration surgery: mean IOP decreased from 26.1 to 16.3 mm Hg at POM12	Mean medications decreased from 2.7 to 2.0 at POM12	Additional glaucoma surgery in 15 eyes (36%)
	iStent inject standalone (n = 57) or combined phaco (n = 214); 5-year outcomes (Guedes et al., 2025) Retrospective case series	Standalone: Mean IOP decreased from 17.8 to 14.3 mm Hg at POY5 (n = 29) Combined: Mean IOP decreased from 16.0 to 14.0 mm Hg at POY5 (n = 73)	Standalone: Mean medications decreased from 2.60 to 1.72 (n = 29) Combined: Mean medications decreased from 2.14 to 0.38 (n = 73)	Intraoperative bleeding (1.1%), PAS (0.4%) 4 eyes underwent secondary procedure due to IOP above target
iStent infinite (Glaukos)	iStent infinite after failed glaucoma surgery or maximum tolerated medical treatment (MTMT) (n = 71) (Sarkisian et al., 2023) Prospective cohort	Mean IOP decreased from 23.4 to 17.5 mm Hg at POM12 Failed surgery: mean IOP decreased from 23.5 to 18 mm Hg at POM12 MTMT group: mean IOP decreased from 22.8 to 14.7 mm Hg at POM12 74.2%  had IOP of ≤18 mm Hg by POM 12 36.4% had IOP ≤ 15 mm Hg by POM12	Mean medications decreased from 3.1 to 2.7 at POM12	IOP increase ≥ 10 mm Hg vs. baseline IOP (3%) Loss of BSCVA > 2 lines (10%) Additional glaucoma surgery required (4%) Significant > 10% of AC Hyphema (5%) Stent migration (3%) Stent obstruction (3%) Blepharitis (5%) Hyperemia (3.3%)
	iStent infinite (n = 91) vs. Hydrus (n = 89) (Ahmed et al., 2025) Prospective, randomized controlled trial	iStent infinite: Mean IOP decrease of 6.8* mm Hg Hydrus: Mean IOP decrease of 5.7* mm Hg Significant difference in unmedicated IOP at 6 months	iStent infinite: 96.7% of patients were medication free at 6 months Hydrus: 96.6% of patients were medication free at 6 months	iStent infinite: PAS > 1 mm (1.1%), hyphema (1.1%) Hydrus: PAS > 1 mm (4.5%), hyphema (4.5%), improper anatomical placement (7.9%) Significant difference in surgical complication rate at 6 months
Hydrus Microstent (Alcon)	2 iStents (n = 75) vs. Hydrus microstent (n = 73) (Ahmed et al., 2020) Randomized controlled trial	Hydrus group: Mean IOP decreased from 19.0 to 17.3 mm Hg at POM12; 30.1% had IOP < 18 mm Hg at POM 12 iStent group: Mean IOP decreased from 19.1 to 18.1 mm Hg at POM12; 9.3% had IOP < 18 mm Hg at POM 12 No significant difference between groups at POM12	Hydrus group: mean medication decreased from 2.5 to 0.9 at POM12; 46.6% were medication free at POM12 iStent group: mean medication decreased from 2.7 to 1.7 at POM12; 24% were medication free at POM12 Significant difference between groups at POM12	Hydrus: BCVA loss > 2 lines (2.7%), IOP spike > 10 mm Hg (4.1%), new cataract (2.6%), device obstruction (12.2%) iStent group: BCVA loss > 2 lines (1.3%), IOP spike > 10 mm Hg (5.2%), device obstruction (13.2%), secondary surgery (3.9%)
	Hydrus (n = 31) vs. selective laser trabeculoplasty (n = 25) (SLT) (Fea et al., 2017) Prospective cohort	Hydrus group: mean IOP decreased from 23.1 to 16.5  by POM 12 SLT group: mean IOP decreased from 23.2 to 15.9  by POM 12 No significant difference between groups at POM12	Hydrus group: mean medication decreased from 2.3 to 0.9 at POM12; 47% were medication free by POM 12 SLT group: Mean medication decreased from 2.5 to 2.0 at POM12; 4% were medication free by POM 12 Significant difference between groups at POM12	Hydrus group: transient IOP spikes (6.5%), temporary decrease in BCVA > 2 lines (9.7%) SLT group: none
	Hydrus only (n = 406) (Agar et al., 2022) Retrospective case series	Mean IOP was reduced by 29.1% at POM 12 and 22.3% POM 60	Reductions of 0.7-1.5 medications per eye through POM 60	Elevated IOP >10 mmHg above baseline (4.2%) Peripheral anterior synechiae formation (3.7%)
	Hydrus (n = 21) vs. Canaloplasty (n = 24) (Gandolfi et al., 2016) Retrospective case series	HM group: Mean IOP decreased from 24 to 15 at POM 24 CP group: Mean IOP decreased from 26 to 16 at POM 24 No significant difference between groups through POM 24	HM group: mean medications 0.9 at POM24 CP group: mean medications 0.7 at POM24 No significant difference between groups at baseline or at POM24	CP group: transient hyphema (29%), YAG laser goniopuncture in 6 eyes HM group: transient hyphema (19%), YAG laser synechiolysis in 4 eyes

Goniotomy, Trabeculotomy, and Canaloplasty

The chart below summarizes salient results from standalone studies of goniotomy, trabeculotomy, and canaloplasty using the KDB, TrabEx Pro, Trabectome , iTrack , OMNI Surgical System, and GATT. *Indicates IOP after washout.

Device and Procedure	Premise and Study Type	IOP Reduction	Medication Reduction	Post-op adverse events > 1% or additional glaucoma surgery
KDB Goniotomy (New World Medical)	KDB only (n = 53) (Berdahl et al., 2018) Retrospective case series	Mean IOP decreased from 23.5  to 15.0 mm Hg at POM6 88.7% had IOP ≤ 18 mm Hg at POM6	Mean medications decreased from 2.5 to 1.5 at POM6	IOP spike (6%) Descemet membrane tear (4%) Corneal edema (2%) Posterior vitreous detachment (2%)
	KDB only (n = 42) (ElMallah et al., 2020)Retrospective case series (same cohort as Berdahl et al. study)	Mean IOP decreased from 21.6 to 16.5 mm Hg at POM12 59.5% had IOP ≤ 18 mm Hg at POM12	Mean medications decreased from 2.5 to 2.2 at POM12	See above Additional glaucoma surgery required (14%)
	KDB only (n = 53) (Salinas et al., 2018) Retrospective case series	Mean IOP decreased from 18.4 to 13.9 mm Hg at POM6 92.3% had IOP ≤ 18 mm Hg  at POM6 63.5% had IOP ≤ 14 mm Hg at POM6	Mean medication decreased from 2.5 to 1.4 at POM6	Hyphema (34.9%) Additional glaucoma surgery required in 1 eye
	KDB only (n = 40) (Bravetti et al., 2023) Retrospective case series	Mean IOP decreased from 18.1 to 14.8 mm Hg at POM12 67.5% had IOP ≤ 16 mm Hg at POM12 82.5% had IOP ≤ 18 mm Hg at POM12	Mean medication decreased from 2.5 to 1.7 at POM12	Refectory IOP elevation above 18 mm Hg (17.5%) IOP spike above 21 mm Hg at POM2 (5.0%)
Trabectome Goniotomy (MicroSurgical Technology)	Trabectome only (n = 21) vs. combined with phacoemulsification (n = 28) (Akil et al., 2017) Prospective cohort	Mean IOP decreased from 37.6  to 16.9  mm Hg  at POM12	Mean medication decreased from 3.4  to 1.8 at POM12	Additional glaucoma surgery required in 8 eyes (28.6%)
	Trabectome only (n = 235) vs. combined with phacoemulsification (n = 352)(Neiweem et al., 2016) Retrospective case series (to develop predictive surgical calculator)	Mean IOP decreased from 22.6 to 16.9 mm Hg at POM12	Mean medications decreased from 2.8 to 2.3	Not reported
iTrack ABiC (Nova Eye Medical)	iTrack ABiC only (n = 11) vs. combined with phacoemulsification (n = 34) (Khaimi, 2021) Retrospective case series	Mean IOP decreased from 15.4 to 15.3 mm Hg at POM36	Mean medications decreased from 2.2 to 0.8 at POM36 33% were medication free at POM36	Transient hyphema (percentage not reported)
	iTrack ABiC only (n = 4) vs. combined with phacoemulsification (n = 23) (Koerber & Ondrejka, 2022) Retrospective case series	Mean IOP decreased from 23.5 to 17.7 mm Hg at POM48	Mean medications decreased from 2 to 1 at POM48	None
	iTrack ABiC only (n = 21) vs. combined with phacoemulsification (n = 23) (Gallardo 2021, 2022) Retrospective case series	Mean IOP decreased from 20.9  to 13.2 by POM36 95.7% had IOP ≤17 mm Hg at POM36 87% had IOP ≤ 15 mm Hg at POM36	Mean medications decreased from 3.0  to 1.6 at POM36 26% were medication free at POM36	BCVA loss of 2 lines or more (14.2%) Microhyphema (14.2%) Layered hyphema (4.7%) IOP spike greater than 10 mm Hg (4.7%)
OMNI ABiC and Trabeculotomy (Sight Sciences)	OMNI only (n = 9) vs. combined with phacoemulsification (Grabska-Liberek, et al., 2022) Prospective cohort	Mean IOP decreased from 22.1 to 13.3 at POM12	Mean medications decreased from 2.6 to 0.7 at POM12	Hyphema (44%) Elevated IOP (44%)
	OMNI only (canaloplasty only) (n = 50) vs. Combined with phacoemulsification (Toneatto et al., 2022) Prospective cohort	Mean IOP decreased from 23.0 to 15.6 mm Hg at POM12 66.0% had IOP < 18 mm Hg at POM12	Mean medications decreased from 3.0 to 2.0 at POM12	Standalone and combined cases reported together Moderate and severe hyphema (2.5%) Transient hypotony (4–5 mm Hg) within the first month (5.0%) Additional glaucoma surgery required in 15%
	OMNI only; split into groups > 18 (n = 159) or ≤ 18 mm Hg (n = 71) at baseline (Radcliffe et al., 2024) Retrospective case series (IRIS registry) Note: n = 44 at POM36	Baseline IOP > 18 mm Hg. Mean IOP decreased from 25.1 to 16.2 mm Hg at POM36 Baseline IOP ≤ 18 mm Hg: Mean IOP decreased from 15.5 to 12.4 mm Hg at POM36	Baseline IOP > 18 mm Hg: Mean medications decreased from 2.1 to 1.2 at POM36 Baseilne IOP ≤ 18 mm Hg: Mean medications decreased from 2.3 to 0.8 at POM36 Overall 59.1% were medication-free at POM36	Baseline IOP > 18 mm Hg: Additional glaucoma surgery required in 45.9% (13 SLT, 24 MIGS, 7 Trabeculectomy, 15 GDI, 13 CPC) Baseline IOP ≤ 18 mm Hg: Additional glaucoma surgery required in 18.3% (4 SLT, 2 MIGS, 5 GDI)
	OMNI only; split into groups > 18 (n = 24) or ≤ 18 mmHg (n = 24) at baseline (Vold et al., 2021) Retrospective case series Note: IOP > 18 (n = 24) and IOP ≤ 18 (n = 19) at POM12	Baseline IOP > 18 mm Hg: Mean IOP decreased from 21.8 to 15.6 mm Hg at POM12 Baseline IOP ≤ 18 mm Hg: Mean IOP decreased from 15.4 to 13.9 mm Hg at POM12	Baseline IOP > 18 mm Hg: Mean medications decreased from 1.7  to 1.2  at POM12; 37.5% were medication free at POM12 Baseline IOP  ≤ 18 mm Hg: Mean medications decreased from 2.0 to 1.3 at POM12; 31.6% were medication free at POM12	Mild anterior chamber inflammation > 30 days postoperatively (12.5%) Posterior capsular opacity (10.4%) IOP >10 mm Hg above baseline >30 days postoperatively (6.3%) Cystoid macular edema (6.3%) Corneal edema (4.2%) Secondary glaucoma surgery required in 10%
	OMNI only; split into groups > 18 (n = 17) or ≤ 18 mmHg (n = 12) at baseline (Williamson et al., 2023) Retrospective case series (Same cohort as Vold et al. study)	Baseline IOP > 18 mm Hg: Mean IOP decreased from 22.1 to 14.7 mm Hg at POM24; IOP < 18 mm Hg in 82.4% at POM24 Baseline IOP ≤ 18 mm Hg: Mean IOP decreased from 15.6 to 13.3 mm Hg at POM24; IOP ≤ 18 mm Hg in 75% at POM24	Baseline IOP > 18 mm Hg. Mean medications decreased from 1.9  to 1.6  at POM24; 37.5% were medication free at POM12 Baseline IOP  ≤ 18 mm Hg. Mean medications decreased from 2.2  to 1.3 at POM24; 31.6% were medication free at POM12	See above Unclear for standalone
	OMNI only (n = 38) (Klabe & Kaymak, 2021) Retrospective case series	Mean IOP decreased from 24.6 to 14.9 mm Hg at POM24 88.5%  had IOP < 18 mm Hg at POM24	Mean medications decreased from 1.9 to 0.5at POM24 57.7% were medication free at POM24	Transient hyphema (44.7%) Choroidal effusion (7.9%) Anterior synechiae (5.3%) Transient lens-cornea touch associated with shallow anterior chamber (2.6%) Additional glaucoma surgery required in 2 patients
	OMNI only (n = 67) (Bleeker et al., 2022) Retrospective case series	Mean IOP decreased from 22.1 to 15.2 mm Hg at POM6 IOP . 18 mm Hg in 79% at POM6 IOP ≤ 15 mm Hg in 40% at POM6	Mean medications decreased from 2.3 to 0.7 at POM6 37.2% were medication-free at POM6	Transient hyphema (39%) IOP ≥10 mm Hg above baseline 1-month after surgery (5.1%) Additional glaucoma surgery in 2% (2 Trabeculectomy)
Gonioscopy-Assisted Transluminal Trabeculotomy (GATT)	GATT only in failed glaucoma surgery (n = 44) (Wang et al., 2023) Retrospective case series	Mean IOP decreased from 27.4 to 15.3 mm Hg at POM24 82.1% had IOP ≤ 18 mm Hg at POM 24 56.4% had IOP ≤ 15 mm Hg at POM24	Mean medications decreased from 3.6 to 0.5 at POM24 66.7% were medication free at POM 24	IOP of ≥ 30 mm Hg within one month (43.1%) Additional glaucoma surgery required (11.4%) Ciliochoroidal detachment (9.0%)
	GATT only in failed trabeculectomy (n = 26) (Cubuk et al., 2020) Retrospective case series	Mean IOP decreased from 25.3 to 15.2 mm Hg by POM12	Mean medications  decreased from 3.8  to 1.1 at POM12	Hyphema (91.3%) IOP spikes (8.7%) Hypotony (4.3%) Long term posterior capsule staining with hemorrhage (4.3%)
	Standalone GATT (n = 40) vs. combined with phacoemulsification (n = 68) in POAG and PEX (Bozkurt et al., 2021) Retrospective case series	Mean IOP decreased from 27.7 mm Hg to 14.7 mm Hg at POM12	Mean medications decreased from 3.6 to 0.9 at POM12	Additional glaucoma surgery required in 4 patients
TrabEx Pro Goniotomy (MicroSurgical Technology)	Standalone TrabEx Pro (n = 28) vs. combined with phacoemulsification (n = 45) (Gosling et al., 2022)	TrabEx: Main IOP decreased from 32.9 to 21.2 mm Hg at POM12 TrabEx/Phaco: Mean IOP decreased from 30.4 to 15.6 mm Hg at POM12	TrabEx: Mean medications decreased from 3.0 to 2.0 at LFU TrabEx/Phaco: Mean medications decreased from 2.8 to 1.8 at LFU	Hyphema (n = 12), of which 4 had IOP spike >10 mm Hg Hypotony (n = 1), postoperative uveitis (n = 2), postoperative CME (n = 1)

Combined MIGS

There is increasing interest in the value of combining MIGS procedures to further lower IOP and medication burden. While data is currently limited and mostly generated by retrospective, nonrandomized studies, reports suggest that combined MIGS result in a higher proportion of patients being medication free at 12 months compared to single MIGS.

Phaco + iStent + VISCO360 vs. Phaco + iStent

Heersink and Dovich reported 6-month outcomes in POAG eyes receiving phaco-iStent-VISCO360 (n = 86) compared to phaco-iStent (n = 100). A greater proportion of the former group achieved ≥20% reduction in IOP and an IOP <18 mm Hg on the same or few medications. Specifically, the mean IOP reduction was 2.9 ± 3.6 mm Hg and 46% achieved IOP <18 mm Hg on same or fewer medications in the phaco-iStent-VISCO360 cohort, compared to 1.7 ± 3.1 mm Hg and 35% achieving IOP <18 on same or fewer medications in the phaco-iStent cohort.

iStent + cataract extraction + ECP (ICE-1) vs. iStent + cataract extraction

A retrospective study published in 2017 compared 12-month outcomes of the first generation iStent + cataract extraction + ECP (ICE-1; study group) compared to phaco + iStent (control group) in OAG. Included patients ranged from mild to severe OAG. Mean preoperative IOP was 21.49 ± 9.56 mm Hg in the study group (51 eyes) and 20.66 ± 3.23 mm Hg in the control group (50 eyes). At 12 months, the study group had both a greater mean IOP reduction (7.14 vs. 4.48 mm Hg) as well as medication reduction (63% vs. 38%).

iStent inject (x2) + cataract extraction + ECP (ICE-2) vs. iStent inject (x2) + cataract extraction

A retrospective study by Pantalon et al. in 2020 evaluated the combination of the second generation iStent inject (two stents), cataract excision, and ECP (ICE-2, n=63) compared to iStent inject (two stents) and cataract excision (control, n=46) in patients with OAG. The ICE-2 procedure resulted in a decrease in mean IOP of 6.92 mm Hg compared to 3.54 mm Hg for the control group. However, the ICE-2 group had a statistically significant higher mean IOP at baseline compared to the control group. Impressively, 31.7% of eyes in the ICE-2 group did not require any medications to control IOP compared to 19.6% in the control group despite a similar number of baseline medications and higher mean baseline IOP in the ICE-2 group.

Phaco + ECP + KDB (PEcK) vs. Phaco + ECP

Izquierdo et al. published a report in 2021 detailing the results of a randomized, prospective study comparing the efficacy of combined phacoemulsification, ECP, and KDB goniotomy (PEcK, n=27) to phacoemulsification and ECP (n=22) in patients with OAG. Baseline IOP was similar in both groups, yet PEcK resulted in a statistically significant decrease in mean IOP (5.52 mmHg; 33%) compared to control (3.19 mmHg; 20%) after 12 months. Furthermore, 59% of patients were medication free in the PEcK group compared to 44.1% in the control group at this timepoint.

ECP + KDB vs. KDB / PEcK vs. Phaco + KDB

Mayeda et al. performed a retrospective study of 723 eyes comparing the efficacy of combined MIGS to single MIGS both with and without concurrent phacoemulsification in patients with OAG up to 24 months post-op. Between the standalone groups of KDB only (N=79) and KDB with ECP (N=44), there were no significant differences in mean IOP or mean number of IOP-lowering medications at any timepoint. Similarly, there were no significant differences between PEcK (N=178) and Phacoemulsification with KDB (N=422) in mean IOP or mean number of IOP-lowering medications. However, only the KDB + ECP and PEcK groups maintained a significant decrease in mean IOP-lowering medications at the 24-month follow-up.

OMNI + Hydrus + Phaco vs. OMNI + Phaco

A retrospective study of 80 eyes compared the outcomes of phacoemulsification with OMNI canaloplasty and Hydrus Microstent placement to phacoemulsification with OMNI alone. Patients in the OMNI + Hydrus group had a mean baseline IOP of 17.0 ± 4.9 mm Hg on an average of 2.9 ± 1.2 IOP-lowering medications compared to 16.0 ± 4.6 mm Hg and 1.9 ± 1.1 in the OMNI group. At 12 months, mean IOP in the OMNI + Hydrus group was 15.3 ± 3.5 mm Hg compared to 13.6 ± 3.9 mm Hg in the OMNI group. Mean number of IOP lowering medications at 12 months were 2.2 ± 1.4 (OMNI + Hydrus) and 1.2 ± 1.0 (OMNI). Many patients were lost to follow up at the 24-month timepoint making comparisons difficult, but there were no significant differences between the two groups at any timepoint.

OMNI + Hydrus + Phaco vs. Hydrus + Phaco

Dickinson et al. reported a retrospective cohort study of 84 patients who underwent phacoemulsification combined with Hydrus Microstent with (n=42) and without (n=42) OMNI canaloplasty. Mean IOP decreased from 16.2 ± 3.7 to 14.1 ± 3.5 mmHg in the Hydrus group compared to a decrease from 16.4 ± 4.2 to 13.6 ± 3.1 mm Hg in the Hydrus/OMNI group. Mean IOP lowering medications decreased from 2.13 ± 0.8 to 0.57 ± 0.9 in the Hydrus group compared to a decrease from 2.3 ± 1.3 to 0.16 ± 0.4 in the OMNI + Hydrus group (P < 0.05). A significantly greater proportion of patients in the OMNI + Hydrus group (87.3%) were medication free at 6 months compared to Hydrus group (64.3%). This data was collected at the 6 month post-operative timepoint, and no longer term data has been reported.

Hydrus + iTrack ABiC + Phaco

A retrospective case series of 51 eyes with POAG evaluated the efficacy of phacoemulsification combined with iTrack ABiC and Hydrus Microstent. Notably, there was no control group in this report. Overall, mean IOP decreased from 19.1 ± 4.0 to 13.9 ± 2.6 mm Hg and IOP lowering medications decreased from 2.25 ± 1.2 to 1.2 ± 1.4 at 12 months. Patients were further stratified based on IOP control: >18 mm Hg on maximal glaucoma medical therapy (Uncontrolled) and ≤18 mm Hg (Controlled). In the controlled IOP group, mean IOP decreased from 15.9 ± 2.1 to 14.3 ± 2.7 mm Hg at 12 months and 13.5 ± 2.3 mm Hg at 24 months, while IOP lowering medications decreased from 2.7 ± 0.9 to 1.4 ± 1.5 at 12 months and 1.7 ± 1.5 at 24 months. In the uncontrolled IOP group, mean IOP decreased from 21.9 ± 3.1 to 13.6 ± 2.5 mm Hg at 12 months and 13.9 ± 1.8 mm Hg at 24 months, while IOP lowering medications decreased from 1.9 ± 1.3 to 0.9 ± 1.3 at 12 months and 1.3 ± 1.5 at 24 months. Additional subgroups stratified by glaucoma severity showed a similar trend of increased efficacy with increasing disease severity.

PEcK vs. ICE-1

A retrospective case series compared outcomes between PEcK (53 eyes) and ICE-1 (23 eyes). Of note, none of the ICE-1 cohort had moderate-to-severe or severe glaucoma compared to the PEcK cohort. Baseline IOP for PEcK was 18.3 ± 5.9 mm Hg on 3.3 ± 1.3 IOP-lowering medications and 14.7 ± 4.3 mm Hg on 1.7 ± 0.93 IOP-lowering medications for ICE-1.  At 12 months, the mean PEcK IOP reduction was 5.1 ± 4.4 mm Hg and the mean ICE-1 reduction was 2.3 ± 4.0 mm Hg. Mean medication reduction at 12 months was 1.6 ± 1.5 for PEcK and 0.97 ± 0.66 for ICE-1. Neither results were statistically significant at 12 months, but PEcK demonstrated significantly greater IOP reduction at the 6 month timepoint.

Conclusion

The advent of microinvasive glaucoma surgery has allowed for improved management of patients with mild to moderate glaucoma.  As surgeon experience expands and the number of MIGS approaches grows, these procedures may even be utilized in more severe cases and across a wide range of clinical scenarios. MIGS procedures are an especially useful treatment option in patients with poor medication tolerance, or poor compliance, or whose IOP requires more lowering than drops or laser trabeculoplasty can provide. MIGS can be easily incorporated into routine phacoemulsification surgery and can be used in patients whose IOP is well-controlled on drops but who desire drop independence. The field of MIGS has expanded rapidly in the last decade, adding to the glaucoma surgeons’ armamentarium and their ability to tailor surgical approaches to each specific patient. Current areas of clinical investigation and debate include the relative benefits of tissue-sparing MIGS (e.g., canaloplasty) versus tissue-destructive MIGS (e.g., goniotomy), the identification of patient populations most likely to respond to specific MIGS approaches, and the use of combined MIGS procedures to target multiple outflow pathways and achieve multimodal IOP reduction in treatment-resistant glaucoma. Future devices and surgical approaches will continue to be developed in the coming years.