Preparation for the Future: Delivering Extensive MIGS Training in Fellowship
By Manjool Shah, MD
As a glaucoma fellowship director, I’m always helping the program evolve along with emerging therapies. In addition to teaching clinical management and conventional surgeries for glaucoma, we continually add new minimally invasive glaucoma surgeries (MIGS) as they emerge, and we strive to help our fellows learn the nuanced decision-making skills required to select the right therapies and manage glaucoma effectively.
While the list of treatments increases, fellowship training is still just one year, which makes the process more challenging for both fellows and educators. MIGS training, unlike the conventional glaucoma toolkit of trabeculectomy and tube shunt procedures, has no standardized level of expectation or approach to teaching. As a result, fellowship programs are highly variable in which MIGS they teach, and programs may teach only a few techniques and procedures. It’s my philosophy that to prepare glaucoma specialists for the future, we need to teach the fundamentals that link all of the currently available MIGS approaches together, as well as to build fellows’ proficiencies in a range of different MIGS procedures.
Why Teach a Broad Range of MIGS?
As an educator, I want to make sure that my trainees have the maximum awareness and preparation for current procedures. The MIGS landscape will change. What we’re doing in five or ten years may look nothing like what we’re doing today, so we need to give surgeons a breadth of experiences that best equip them to evaluate and integrate next-generation technologies as they emerge.
Surgery tends to change in evolutionary steps, building on the fundamentals we’ve developed, so today’s MIGS prepare doctors to evolve their skills along with the next evolutionary steps. With in-depth preparation, fellows become critical observers, participants, and evaluators of currently available techniques, which will enable them to do the same with emerging technologies. And by seeing the whole range of treatment options and nuances between various approaches and techniques, they can select the right surgery for each patient, even in complex cases.
In-depth knowledge and capabilities are particularly essential for MIGS because the space is still so new. We’re approaching a decade with iStent (Glaukos) in the U.S., but we still don’t have much meaningful, high-quality comparative data to inform our decisions for various types of cases. Until we have that data, we have to use our experience to guide us—and gaining the widest set of experiences in fellowship is the best way to succeed from the start.
Fundamental Skill Sets for MIGS Preparation
In our clinic, surgeons use essentially all of the MIGS procedures and devices available in the U.S., and we gradually integrate all of them into the fellows’ toolkit. While I don’t necessarily expect fellows to gain expertise in all of the procedures, many are built on the same fundamentals. Once surgeons can do one, they will often be able to do another one by filling in a small knowledge gap on their own. The fundamental skills fall into four basic categories.
1. Intraoperative gonioscopy. The first skill surgeons need to master before doing any glaucoma procedure is intraoperative gonioscopy. Visualization is often a weak point for anyone learning MIGS procedures, but it’s essential to see clearly and consistently for safety, so we focus on gonioscopy first. Practice often starts with doing intraoperative gonioscopy at the start or at the end of regular cataract surgery, or after a preceptor has already performed a MIGS procedure. Gradually, the trainee moves towards performing gonioscopy while also using an instrument in their other hand. Once these competencies have been demonstrated, they are able to attempt to perform the actual MIGS procedure.
2. Schlemm’s canal procedure skills. We typically start fellows learning the skill set required for Schlemm’s canal MIGS, such as goniotomy, GATT, iStent, Hydrus Microstent (Ivantis), ab interno canaloplasty, and the OMNI Surgical System (Sight Sciences). Like any new surgeries fellows learn, they go from observing MIGS procedures and practicing in the wet lab, to doing them under guidance, and we adjust based on the surgeon’s experience and needs.
There are some nuances between these procedures, and troubleshooting varies a bit depending on the situation, but they require the same basic skills. As mentioned earlier, gonioscopy and visualization are paramount, and different procedures sometimes require subtle differences in gonioscopic technique. When focusing on specific surgical techniques, we pay a lot of attention to hand position and grip, wrist motion, and general ergonomics. Most MIGS procedures are done at the time of cataract surgery, typically at the start of the case. As such, we devote special attention to safe navigation of the anterior chamber to prevent damage to the phakic lens or corneal endothelium.
Once fellows master these skills, they have the framework to explore the nuances that are specific to each procedure. For example, excision goniotomy techniques require a broad view and the ability to maintain the view while engaging the angle and turning the wrist in either internal rotation or flexion. Hand and wrist position can vary between these directions. Similar forehand and backhand skills may be required to advance a micro catheter or suture in the canal clockwise or counterclockwise for canaloplasty or GATT techniques. Microstenting also benefits from an understanding of dynamic hand and wrist positions for placement as well as potential recapture and repositioning. An understanding of appropriate use of ophthalmic viscosurgical devices (OVD) to create space, manipulate devices, and clear heme is also a common theme with variations based on specific technique.
3. Subconjunctival MIGS skill set. Fellows gain another skill set when we introduce them to subconjunctival MIGS, which for now is only XEN (Allergan). The technique is similar in difficulty to Schlemm’s procedures, but it requires different skills; there simply is no other procedure that we do that is similar to ab interno XEN placement. Aside from the ab interno technique, other approaches to placing this stent are similar to a trabeculectomy or placing a tube shunt, so I focus my time and attention on teaching ab interno placement, knowing that off-label ab-externo techniques often require skills that are already being developed (tissue handling, hemostasis, etc). Ultimately, we want our trainees to have maximum flexibility with subconjunctival microstenting so they can tailor their technique to unique patient needs.
4. Postoperative care. Postoperative care varies widely depending on the MIGS procedure we choose. For example, for a patient who has a Schlemm’s canal microstent during cataract surgery, recovery is virtually the same as cataract surgery alone. However, we have to be aware of the relatively high rate of steroid response and manage our postoperative therapy accordingly. Decisions about withdrawing or continuing previously used glaucoma medications also factor into the conversation and vary from patient to patient and technique to technique. In patients with Schlemm’s canal incisional procedures like goniotomy and GATT, we must give extra attention to mitigating postoperative blood reflux, which can delay visual rehabilitation and risk IOP elevation. For a patient who has a XEN procedure, the low, diffuse bleb that is generated is fundamentally different from a trabeculectomy bleb, requiring different anti-inflammatory and antifibrotic regimens and potential postoperative adjustment in some cases.
Teaching MIGS Decision-Making
While fellows are training in MIGS surgical techniques, they are handling case after case and learning the nuances of MIGS decision-making. They see some straightforward cases where patients require an initial MIGS intervention. For example, a pseudophakic patient with mild or moderate glaucoma and slightly elevated pressures a poor tolerance for topical medications is often a good candidate for a Schlemm’s canal procedure such as a goniotomy or a canaloplasty. Patients with more recalcitrant disease who need a greater IOP or medication reduction may be a good candidate for XEN. We also have to recognize that not all eyes are good MIGS candidates – sometimes the disease severity and patient history move us towards trabeculectomy or tube shunts.
In our tertiary care clinic, fellows also see many patients who have failed previous surgical interventions. They need to learn the complex process of understanding what the past procedures were and visualizing the problem. For example, was a procedure performed well or not? Can the previous approach be salvaged, or do we need to move forward with a new procedure? How will the previous surgery affect the choice and outcomes of a new procedure? In hundreds of cases over the course of a year-long fellowship, surgeons learn MIGS decision-making based on many complex factors. For example, a patient who has failed Schlemm’s canal microstenting will often require us to move towards subconjunctival surgery such as a XEN. However, patients who have had previous subconjunctival surgeries, including strabismus surgery, prior glaucoma surgery, pars plana vitrectomy, and even older extracapsular cataract extractions may have too much scarring to succeed with subconjunctival microstenting. These patients may be better candidates for tube shunts.
The patients who come to our clinic play a big role in shaping the journey of fellowship training. Thus, there is no linear organization to teaching MIGS skill sets—we don’t spend a few months on Schlemm’s canal procedures and then switch to subconjunctival MIGS. Because we do a mix of procedures on any given surgery day, fellows will spend time both observing and performing all of the above until they master the necessary techniques.
On the days before surgery, I spend a few minutes reviewing upcoming cases with the fellow who will be joining me. We discuss why we chose each procedure, what approach we will be taking, and what sort of techniques we’ll be utilizing. I demonstrate techniques using a pen and paper, surgical videos, and even holding something like a chopstick to demonstrate correct wrist and hand action. I want fellows to prepare as if they’ll be performing every case. In time, they’ll be rigorously prepared to make well-informed decisions and perform MIGS procedures for their own patients, as well as to integrate the next generation of MIGS technologies down the road.
Manjool Shah, MD, is a Clinical Assistant Professor of Ophthalmology and Visual Sciences and Medical Director of the Glaucoma, Cataract, and Anterior Segment Disease Clinic at Kellogg Eye Center, University of Michigan, Ann Arbor.
Disclosures: Dr. Shah is a consultant to Allergan/Abbvie, Glaukos, Katena, Ivantis, and ONL Therapeutics.