MIGS Gains A First

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Drs. Brandon J. Baartman, Vance Thompson Vision, Omaha, Nebraska and Eva Liang, Center for Sight, Las Vegas discuss one of the newest MIGS devices and a soon-to-be available dropless medication option.

Dr. Baartman
The microinvasive glaucoma surgery (MIGS) space has evolved over the past decade, with the number of devices available today being quite broad. Each of the options, from devices that are used to create goniotomies of various sizes, to delivering viscoelastic to expand Schlemm’s canal and collector channels, to trabecular microbypass stents, represent different ways of reaching the same goal: to increase aqueous outflow through the natural pathway of the eye.

There have been two main hurdles, however, for more widespread adoption of MIGS technologies. One is that the devices have been labeled for use in conjunction with cataract surgery, making the options somewhat limited for standalone procedures. Another is the everchanging insurance coverage and reimbursement schedules, creating a fluid situation of feasible procedures for every patient.

The iStent infinite Trabecular Micro-Bypass System Model iS3 (glaucoma) is FDA approved for exactly what glaucoma surgeons needed—a stand-alone minimally invasive low-risk glaucoma procedure that we can employ after a patient has had stand-alone cataract surgery and failed prior medical and surgical intervention that also has a clear pathway to reimbursement. This device has the potential to change the course of patients’ disease without subjecting them to the additional risks of what used to be the classic secondary surgical intervention of a tube or a trab.

Angle-based procedures have changed the way we look at interventional glaucoma care. MIGS has shifted the surgical treatment earlier in the disease pathway of glaucoma. Recent studies have shown for the first time that intervention with MIGS reduces the rate of visual field loss, supporting earlier intervention’s ability to change the course of the disease.1 The 3-stent iStent infinite is the least invasive trabecular path available for pseudophakic patients, and it is also the least invasive way to access collector channels in a broad range of the angle, one of the hallmarks of its success in clinical trials.

Adoption of the iStent infinite will come easily to those who are already using previous generations of stents. The procedure is comfortable for many comprehensive ophthalmologists as well as glaucoma physicians. The more ophthalmologists performing the procedure, the more patients can be treated earlier in the disease process.

Dr. Liang
When treating patients with glaucoma, concern regarding patient’s adherence to their medication regimens in always top of mind. Not only is it difficult for these often elderly patients to reliably adhere to complex dosing regimens, drops often have unwanted side effects and take a toll on the ocular surface. Earlier intervention with approaches that take some of the medication burden out of the patient’s hands like MIGS and sustained drug-delivery can slow vision loss and have a dramatic impact on our patients’ quality of life.

The iDose TR (Glaukos) is a micro-invasive intraocular titanium implant that continuously delivers a proprietary formulation of travoprost. The company has submitted an NDA based on data from two pivotal Phase 3 trials with 1,150 subjects.2-4 The pivotal investigations compared the safety and efficacy of a single administration of slow or fast iDose TR to topical timolol twice a day in reducing IOP in subjects with open-angle glaucoma or ocular hypertension. Both the fast- and slow-release iDose TR arms achieved the pre-specified primary efficacy endpoint of non-inferiority to timolol through 3 months, with the implant demonstrating excellent tolerability and a favorable safety profile through 12 months. 2-4

In the first trial, IOP reductions from baseline over the first 3 months were 6.6 to 8.5 mm Hg in the slow-release iDose TR arm versus 6.6 to 7.7 mm Hg in the timolol arm. For the second trial, those measures were 6.7 to 8.4 mm Hg in slow-release iDose TR arm versus 6.8 to 7.2 mm Hg in the timolol arm. More than 90% of slow-release subjects remained well-controlled on the same or fewer IOP-lowering topical medications at 12 months compared to screening after a single administration versus 67% of timolol subjects in both trials. Additionally, 81% of slow-release iDose TR subjects were completely free of IOP-lowering topical medications at 12 months across both trials. Conjunctival hyperemia was a very low 3% for device subjects with the most frequent adverse event in those subjects being mild transient iritis at 6%.2-4

The iDose TR will be an obvious choice for pseudophakic patients who have not had a prior MIGS device and medication compliance issues. For phakic patients, I would be sure that the angles are open and deep enough to support the device. Once the iDose TR is approved, we will have a better understanding of labeling and insurance coverage which will help clarify how it will be implemented in practice. The clinical data definitely supports the iDose TR’s usage in the real world.

For ophthalmologists who are already doing MIGS and are comfortable working in the angle, inserting the iDose TR with its loader is a very straightforward procedure to learn. In the iDose TR exchange trial, it was shown that the device can be safely exchanged for a new one after 4 to 5 years.5

With MIGS ever expanding, we may soon be combining the procedures with other techniques to find a way to address the outflow pathway and reduce the influx of fluid in tandem. Future technologies may further challenge the way we think about lowering IOP.


Disclosure: Dr. Baartman is a consultant to Allergan and Equinxo, a speaker for Glaukos, and has received research fees from Glaukos. Contact: [email protected] 

Disclosure: Dr. Liang is a consultant to Glaukos. Contact:  [email protected]; Twitter @evaeye


  1. Montesano G, Ometto G, Ahmed IIK, et al. Five-Year Visual Field Outcomes of the HORIZON Trial. Am J Ophthalmol. 2023;251:143-155. doi: 10.1016/j.ajo.2023.02.008.
  2. Glaukos. Glaukos announces positive results for iDose TR exchange trial, highlighting favorable safety and tolerability. 2023. Available at: https://investors.glaukos.com/investors/news/news-details/2023/Glaukos-Announces-Positive-Results-for-iDose-TR-Exchange-Trial-Highlighting-Favorable-Safety-and-Tolerability/default.aspx. Accessed July 10, 2023.
  3. Business Wire. Glaukos announces positive topline outcomes for both phase 3 pivotal trials of iDose TR, achieving primary efficacy endpoints and demonstrating favorable tolerabilityand safety profiles. 2022. Available at: www.businesswire.com/ news/home/20220907005394/en/Glaukos-Announces-Positive-Topline-Outcomes-for-Both-Phase-3-Pivotal-Trials-of-iDose-TR-Achieving-Primary-Efficacy-Endpoints-and-Demonstrating-Favorable-Tolerability-and-Safety-Profiles. Accessed July 20, 2023.
  4. Business Wire. Glaukos’ iDose® TR demonstrates sustained IOP reduction and favorable safety profile over 36 months in phase 2b study. 2022. Available at: www.businesswire.com/news/home/20220111005492/en/Glaukos%E2%80%99-iDose%C2%AE-TR-Demonstrates-Sustained-IOP-Reduction-and-Favorable-Safety-Profile-Over-36-Months-in-Phase-2b-Study (Date last accessed: 30 May 2023).
  5. Berdahl JP, Katz LJ, Navratil T. Outcomes of the prospective randomized controlled multicentre phase III trials of iDose TR versus topical timolol. Poster presented at the ASCRS Annual Meeting; May 5-8, 2023; San Diego, CA.