The minimally invasive glaucoma surgery (MIGS) space continues to evolve rapidly. These improvements continue to allow MIGS surgeons to provide better, safer, and more efficient care for our glaucoma patients. Recently, there have been several new and innovative additions to the MIGS armamentarium. These include the iStent inject W (Glaukos), the Omni device (Sight Sciences), and the KDB Glide (New World Medical).
The Landscape of New MIGS Innovations
Mark J. Gallardo, MD
The iStent inject W (Figure 1) is an improvement upon the original iStent inject (G2). The outcomes appear to be similar; however, the changes in the implant have allowed for a more efficient and more predictable implantation. Specifically, the flange is a bit wider, increasing from a 230-µm diameter to a 360-µm diameter. The theory behind this increase is to enhance visualization, facilitate predictable stent placement, and prevent overimplantation. Additionally, the injector is slightly different, with 2 windows that allow the surgeon to visualize the 2 stents in the insertion tube. Lastly, the trocar has been slightly redesigned with a tri-beveled tip (theoretically allowing for minimal disruption of the trabecular meshwork) and a few other design changes that will theoretically minimize trocar bias. Overall, this new implant appears to provide similar outcomes to those reported with the iStent inject G2 with slightly more increased ease of use.
The next-generation Omni device (Figure 2) is also a relatively new modification of the original Omni platform that allows for both viscodilation and ab-interno trabeculotomy. The modification of this new platform includes an improved handle that is theoretically more ergonomic, an improved wheel design for deployment and retraction of the microcatheter, as well as an updated Luer lock system. The initial results of 2 trials have been published (the GEMINI prospective study and the ROMEO retrospective study1,2) on outcomes with both canaloplasty and ab-interno trabeculotomy. Both studies report a mild-modest decrease in intraocular pressure (IOP) and glaucoma medication use during the follow-up period.
Lastly, in late 2020, the Kahook Dual Blade (KDB) Glide (Figure 3) was released as a modified version of the original KDB. The new design of the KDB Glide essentially modified the platform of the original KDB; however, the footplate is now more rounded with tapered sides and the overall surface area of the footplate has been decreased. In theory (and in practice) this allows an improved interface with Schlemm’s canal and allows for a more efficient excisional goniotomy. The surgical outcomes with the KDB Glide appear to be similar to those previously published with the KDB; however, the design changes have allowed for a smoother excisional goniotomy.
Glaucoma surgeons continue to enjoy continuous innovation and improvements of newer MIGS surgeries, as well as improvements upon currently available MIGS procedures, all in with goal of improving patient outcomes and the surgeon experience. We are without question in a renaissance period for glaucoma surgery and I look forward to the next several years as more devices and instruments in the pipeline become available for use in the United States.
The MIGS Learning Curve for New Glaucoma Specialists
Matt Porter, MD
As a recent fellow graduate and now a teacher of ophthalmic surgery, I can say it is certainly an exciting time to be treating glaucoma patients. MIGS has given surgeons a variety of treatment options that can be catered to the IOP needs and disease state of each patient. I teach the full spectrum of MIGS to each of my residents, and their enthusiasm for learning these techniques has been fun to watch.
I have found that starting with a goniotomy using a KDB gets learners comfortable working in the angle and seems to be technically easier to perform early in the learning curve. Once successful with goniotomy, trabecular microbypass stents (iStent inject W and Hydrus [Ivantis]) are the next logical step. Stent malposition is common at first, so a great view with the patient head fully rotated and a good viscoelastic fill to avoid corneal striae are critical steps to avoiding this pitfall.
As residents progress with their skill in the angle, I will teach them canaloplasty with the iTrack catheter (Nova Eye Medical) and gonioscopy-assisted transluminal trabeculectomy. I find these procedures take a little more skill but are very safe intraoperatively for learners. Making the initial otomy into the canal can be tricky. It is important to make the opening strike with the cystotome covering both pigmented and nonpigmented trabecular meshwork. A posterior strike over scleral spur will lead to the catheter going into the suprachoroidal space. Using a dispersive ophthalmic viscosurgical device like Viscoat (Alcon) assists with hemostasis and can be used to clear any heme that clouds the surgeon view after otomy creation. I will also teach Xen (Allergan) with an ab-externo technique to interested residents, but I find this to be the most difficult procedure for learners, because successful gel stent placement is very much dependent on proper feel with the injector.
Training residents and fellows to work in the angle and perform MIGS procedures will have increasing importance as these procedures gain further adoption. The future is bright and exciting in glaucoma surgery. GP
References
- Gallardo MJ, Sarkisian SR Jr, Vold SD, et al. Canaloplasty and trabeculotomy combined with phacoemulsification in open-angle glaucoma: interim results from the GEMINI study. Clin Ophthalmol. 2021;15:481-489. Published 2021 Feb 10. doi:10.2147/OPTH.S296740
- Vold SD, Williamson BK, Hirsch L, et al. Canaloplasty and trabeculotomy with the OMNI system in pseudophakic patients with open-angle glaucoma: the ROMEO study. Ophthalmol Glaucoma. 2021;4(2):173-181. doi:10.1016/j.ogla.2020.10.001
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