Glaucoma Bonus Issue
February 2025

by Ellen Stodola 
Editorial Co-Director

With the variety of MIGS procedures and devices available, and with use both as a standalone option and in conjunction with cataract surgery, there is more interest than ever. Many of these procedures are proving useful and accessible not just to the glaucoma specialist but to comprehensive ophthalmologists as well. Cathleen McCabe, MD, and Rachel Simpson, MD, discussed who should be performing glaucoma surgery, as well as ways to learn and stay fresh with some of these techniques. 

Many patients, an estimated 20% of cataract patients, have a co-diagnosis of glaucoma and are on medication, Dr. McCabe said. Being able to provide microinvasive surgery at the time of cataract surgery doesn’t change the postoperative course, other than allowing them to be potentially free of their glaucoma medication and the negative side effects of that, she said. “I’m a cataract refractive surgeon who got involved with MIGS early on, and I think it’s well within the skillset of anterior segment surgeons,” Dr. McCabe said. She thinks glaucoma treatment in the setting of cataract surgery is part of comprehensive care offered to patients that improves their quality of vision as well as their quality of life. 

“Stay informed because this is a very fast-paced and evolving space right now; it’s exciting to see what’s coming, and there’s good data coming out.”

Cathleen McCabe, MD

“There’s strong agreement among most glaucoma surgeons [that] there’s going to be more glaucoma in the world in 20 years than we are able to treat and that there is a critical role for comprehensive ophthalmologists to be performing MIGS,” Dr. Simpson said. “I even encourage our cornea fellows if they didn’t get a lot of MIGS exposure; I tell them being able to perform MIGS is going to be helpful, especially in private practice.” Dr. Simpson thinks anyone who works in the anterior segment of the eye should feel empowered to be able to perform MIGS. “I think it is incumbent on them to make sure that they are getting the training in residency that allows them to be comfortable working in that space and, maybe even more importantly, to be comfortable making the decision on which procedure is right for each patient.” Understanding the decision-making flow is key, she said.

Dr. McCabe thinks there are certain procedures that everyone should know how to do. “The first step is that everyone, any comprehensive or anterior segment surgeon, should know how to look at the angle. We should know how to do a gonioscopy. We know that it’s important just in the clinical care of our patients, so we should be able to look at the angle and identify structures. That’s the baseline.” It’s what we should be able to do regardless of whether or not we’re going to do MIGS, she said. 

That means being able to position the microscope, the patient’s head, a gonioprism, and the illumination and magnification, and focus in a way that optimizes a view of the angle structures, Dr. McCabe continued. It’s something physicians can practice in the operating room at any time, even without doing a MIGS procedure. 

Dr. McCabe said there are many different gonioprism designs, including those that sit on the eye and one that will attach to the microscope for a hands-free approach with the view managed with the microscope foot pedal. She suggested using something where you can be hands-free or one that you hold in your non-dominant hand, adding it’s important to be comfortable with the viewing technique and find the prism that you like.

Being comfortable in identifying those angle structures, which is the critical part of doing any MIGS procedure, is the biggest hurdle because it’s not a place that we normally look at as an anterior segment or comprehensive surgeon, Dr. McCabe said, and it is a bit of a skill making sure you have good visualization. But once you’re comfortable with that, acquiring the skills to do any of the techniques is much easier.

Dr. McCabe warned against creating folds in the cornea because you’re pushing too hard or a bubble underneath the lens because you’re not holding it steadily in the middle.

Another important thing is to have several different categories of MIGS with which you’re comfortable. “You don’t have to be comfortable with every single trabecular meshwork bypass stent. As time goes on, we’ll have more and more options. You don’t have to master every single option, but you should have one at least that you’re familiar with.”

Dr. McCabe suggested knowing how to do a trabecular meshwork bypass stent, a canaloplasty technique, and a goniotomy device. “I think those three categories are accessible to everyone,” she said, adding that some physicians might want to expand to learning applications for a suprachoroidal stent as well. 

Things become a bit more complicated when a bleb is required in the postop period. “For me, as a cataract and refractive surgeon, I don’t do any procedures that involve bleb formation,” she said. “I think, if you’re interested, it’s an accessible skill, but I don’t want to be involved in the more complicated postoperative care for those.”

Training requirements are continually evolving. Dr. McCabe said when she came out of training, LASIK was just taking off. “It was to the point where as a resident, you could do a few PRKs and maybe a LASIK or two, but it wasn’t routinely part of training. That all changed, and that kind of evolution has happened with MIGS, too, because it is something that training programs realized that their trainees should have exposure to and should have some of those basic skills.”

Dr. Simpson agreed that updated training requirements are reflecting the trends in ophthalmology, particularly the requirement to include more MIGS in training. Trabs and tubes are not happening nearly as often, and you have to do a glaucoma fellowship to get those skills. Dr. Simpson noted that when she was in residency, she was not trained on the iStent (Glaukos). “It’s interesting how much has changed,” she said. 

In terms of other important testing and diagnostic skills for glaucoma, Dr. McCabe said there are some basic skills around anterior segment pathology and glaucoma pathology. She noted being able to grade the severity of the glaucoma. To do that, you need to know how to perform an OCT and get RNFL data so you can look at the health of the optic nerve and be able to interpret a visual field test as well. Many reimbursement schedules are built around reimbursing for certain grades of glaucoma, so you must be able to adequately and accurately grade the severity of the disease.

Because of the nature of the disease, whatever intervention we do at the time of the MIGS procedure won’t be the last invention the patient needs, Dr. McCabe said, and it’s important to leave options available on the journey for the patient. It gives them room to have additional treatments before we go to treatments that we’re trying to avoid that have complications, like trabeculectomies and tubes.

An exciting development, Dr. McCabe said, is the area of sustained drug delivery. She noted Durysta (bimatoprost intracameral implant, AbbVie) and iDose TR (travoprost intracameral implant, Glaukos). There are others in the pipeline that might be easier to access for the general ophthalmologist who doesn’t want to acquire skills to look in the angle, she said, adding these will allow for more treatments that are longer term before surgical intervention needs to happen. She mentioned the SpyGlass Pharma Drug Delivery Platform, which has so far shown significant, long-term, stable IOP reduction. It’s “clipped on at the optic-haptic junction to the IOL,” Dr. McCabe said. “The reason I’m excited is because [it has] nice long-term results so far in terms of pressure lowering. But second, there’s no additional skill needed. It’s an IOL that goes into the eye like any other IOL.”

Dr. Simpson noted that when it comes to diagnostics and testing, what she relies on if she’s trying to decide if a patient needs a MIGS procedure or other glaucoma surgery is OCT to determine if their glaucoma is stable or progressing and preoperative gonioscopy. 

New technology is exciting, she said, but “when you’re talking about glaucoma decision making that’s tried and true, and if I’m trying to decide what type of surgery I’m going to do … it’s what their goal pressure is and how many medications, and I don’t need anything fancy to make those decisions.”

The toolkit starts with a broad understanding of each option that is available, Dr. Simpson said, as well as when to use what. She noted that there are many resources to obtain the necessary skills. Her university had a glaucoma MIGS masterclass designed for surgeons in practice who wanted to develop their angle-based surgical skills. “It was geared for comprehensive doctors who felt like they didn’t get enough in residency and wanted a place that was designated for that. I think people are recognizing the need out there to help people develop these skills,” she said, adding that both ASCRS and AAO offer wet labs in this area.

Dr. McCabe said there are MIGS symposia at all major meetings. “Stay informed because this is a very fast-paced and evolving space right now; it’s exciting to see what’s coming, and there’s good data coming out,” she said. “Sometimes it’s not a new device you’ll learn about, but maybe you’ll get long-term data that’s important in comparing efficacy and different choices, and that’s great to see, too.” If you can go to a skills transfer lab, she said that is a great opportunity. The models for the space, for the angle, are improving, and some of the dry lab models allow you to acquire the exact skills you need for a new technique. 

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About the physicians

Cathleen McCabe, MD
Medical Director
The Eye Associates
Bradenton, Florida

Rachel Simpson, MD
Vice Chair of Education
John A. Moran Eye Center
University of Utah
Salt Lake City, Utah

Relevant disclosures

McCabe: AbbVie, Alcon, Glaukos, Spyglass Pharma 
Simpson: AbbVie, Alcon, Glaukos, Nova Eye Medical 

Contact 

McCabe: cmccabe13@hotmail.com 
Simpson: Rachel.Simpson@hsc.utah.edu