November 2018


YES connect
Getting on board with MIGS

by Liz Hillman EyeWorld Senior Staff Writer

With the aging U.S. population, both cataracts and glaucoma are increasing in prevalence. Until recently, when patients had both diseases, the option was to perform cataract surgery alone if the glaucoma was mild, or combine cataract surgery with a trabeculectomy or tube shunt if the glaucoma was severe. Patients had nothing beyond the potential IOP improvement with cataract surgery alone, or they were put at risk for the many short- and long-term complications of those procedures. While there is no doubt that many patients still need a full thickness procedure, with the ever-expanding portfolio of microinvasive glaucoma surgery (MIGS) options, we have the potential to improve the control for many patients without many of the risks associated with traditional filtering procedures.
In this month’s “YES connect” column, Michael Greenwood, MD, Richard Lewis, MD, and Manjool Shah, MD, discuss how to incorporate MIGS into your practice. The most crucial aspects of MIGS procedures are good clinical and surgical gonioscopy skills and a solid understanding of angle anatomy and landmarks. These should be honed before proceeding to the full procedure in your patients. Begin with patients with clear corneas and clear landmarks until you are comfortable with the process.

David Crandall, MD,
YES connect co-editor


The iStent inject
Source: Michael Greenwood, MD

Dr. Greenwood demonstrates how he tilts his microscope.
Source: Michael Greenwood, MD


How to get up to snuff with MIGS when you’ve had little exposure in training

I feel like I’m growing up with MIGS.” That’s the perspective of Michael Greenwood, MD, Vance Thompson Vision, Fargo, North Dakota, and it’s likely the sentiment of many others as well.
As a resident from 2012–2015, Dr. Greenwood had minimal exposure to microinvasive glaucoma surgery (MIGS). The iStent (Glaukos, San Clemente, California) had only just received approval from the U.S. Food and Drug Administration, so his exposure to MIGS mostly consisted of this device. He got more exposure during fellowship with John Berdahl, MD, and has since adopted all MIGS devices as they become available on the market.
Established surgeons and those still in training are almost in the same boat with many MIGS options becoming approved within the last few years. Established surgeons are learning about them at ophthalmology meetings, participating in wet labs, observing their colleagues, and working with industry representatives. Likewise, those still in residency are being exposed to them in similar settings, but Dr. Greenwood said there is probably more being taught in training than just a few years ago.
“The momentum is building a little bit. The education had come in PowerPoint form for the last couple of years, and now it’s starting to become more and more of a hands-on thing,” he said.
That said, both Dr. Greenwood and Manjool Shah, MD, clinical assistant professor, Kellogg Eye Center, University of Michigan, Ann Arbor, think training programs still have yet to fully catch up.
“I think the community is recognizing that this class of interventional glaucoma is here to stay,” said Dr. Shah, who received very little exposure to MIGS in residency but had the opportunity to learn more in a fellowship with Iqbal “Ike” Ahmed, MD. He added later that he thinks “we’re going to continue to see more and more exposure for residents, but it’s a slow transition.”
So with those in residency still receiving limited exposure to MIGS, how should one in training or newer in practice step into the MIGS sphere?
In terms of formal training, both Dr. Greenwood and Dr. Shah said wet labs are often held at meetings around the country. Richard Lewis, MD, Sacramento Eye Consultants, Sacramento, California, said interested ophthalmologists should contact companies about resident training.
“They would love to get residents trained and involved,” he said. “After that, consider a mini-fellowship with a glaucoma specialist.”
Dr. Greenwood also encouraged contacting industry representatives for training and said observing a trusted colleague as they perform their procedures is helpful as well.
When you’re ready to get started with any MIGS procedure, you first have to be comfortable with angle anatomy.
“Dust off that goniolens in your pocket, if you have it still, and use it a lot with your patients [in clinic],” Dr. Shah said.
Dr. Greenwood said performing gonioscopy in clinic, which is recommended and is reimbursable for glaucoma patients, allows you to see what is normal and what the different variances are.
After you’re comfortable with that, it’s time to start practicing intraoperative gonioscopy.
“Surgical gonioscopy is a unique skillset. Once you have comfort with the landmarks, in general, then you want to try applying them in the operating room,” Dr. Shah said. “Achieving a good surgical intraoperative gonio view can be challenging. Having seen trainees struggle with some of the MIGS techniques and devices, the struggle is not with the device itself; it’s due to an inability to achieve a good view.
“To get that view, you have to be light with your hands, you have to tilt the head of the patient, you’ve got to tilt the microscope, you’ve got to position your chair. It’s by no means impossible, but it is something that is often a limiting factor when starting off.”
For Dr. Greenwood, turning the patient’s head 30 degrees and tilting the microscope about 30 degrees is a good place to start. Viscoelastic should be placed on the eye before setting the gonioprism, he noted. In addition to the setup of intraoperative gonioscopy being different than in the clinic, Dr. Greenwood said it is direct gonioscopy, whereas in the clinic, it is indirect, giving a slightly different view. Practicing intraoperative gonioscopy also allows you to get comfortable using your nondominant hand to view the angle.
Once you’re comfortable with intraoperative gonioscopy, in general, Dr. Greenwood and Dr. Lewis suggested adding an instrument in your dominant hand.
“Take a straight instrument, a straight Sinskey or a 27-gauge cannula that you’ve straightened out on a [balanced salt solution] syringe, learn how to keep your gonioprism on the eye and go in and out of your cataract incision. Learn how patients behave and what you need to do to get that comfortable view,” Dr. Greenwood said. “Once you’re comfortable with that, you can take that same instrument and you don’t want to touch anything, but go through the motion of moving those instruments within the eye.”
Next comes the task of choosing a MIGS procedure to start with. Both Dr. Greenwood and Dr. Shah said you should pick one to focus on before adding others to your repertoire.
“It’s dependent on your comfort level as a surgeon, your level of comfort managing the broader picture, and what kind of patients you’re hoping to take care of and treat with this sort of growth in your practice,” Dr. Shah said.
Dr. Shah tends to favor Schlemm’s canal-based surgical techniques as a safe introduction to the MIGS family. “There is a physiologic safety net and there are a number of options, either with microstents or microincisions, that allow surgeons to reach a broad segment of patients.”
Dr. Greenwood said MIGS that target the trabecular meshwork are generally a good starting point because of the low risk for hypotony.
“You’ve got your safety net with the backstop of episcleral venous pressure,” he said.
Dr. Greenwood thinks MIGS are good for almost any patient who has uncontrolled glaucoma.
“There are MIGS devices you can use in very advanced, very severe glaucoma that can hopefully eliminate or hold off the need for a tube or trab for a few years,” Dr. Greenwood said, adding that exceptions for MIGS devices include patients with neovascular or pro-inflammatory glaucoma, such as uveitic glaucoma.
Dr. Lewis said he would avoid MIGS in patients on anticoagulants or with vessels in the angle.
After you have experience with various MIGS devices comes what Dr. Greenwood said is the most common question he gets from staff and industry: How do you decide which device to use?
“We have a whole bunch of tools in our toolbox and our job as surgeons is to decide what is the best technology to fit to this patient, rather than forcing them into one certain technology,” he said.
As Dr. Shah put it, “we are blessed now in this time and in this country with a number of devices, a number of options, that we will continue to refine and figure out which patients are best suited for what.”
Some decisions might be based on a patient’s insurance coverage, the patient’s level of disease, and even constraints from one’s practice, Dr. Shah said. In general, Dr. Greenwood said each surgeon has their own internal algorithm for deciding what MIGS to perform with what patient, but, he added, “it boils down to how do you balance the safety and efficacy with what the patient wants.”
In terms of skills, Dr. Shah said once you have the intraoperative gonioscopy skillset, it can be applied broadly to almost all MIGS devices and techniques. Most of the challenges with these procedures, he added, come with aspects of intraoperative gonioscopy, not the MIGS device or insertion procedure itself.
Now is the time, early in one’s practice, to establish this new skillset, Dr. Shah said.
“Glaucoma is everyone’s problem. Whether you are cornea, retina, or comprehensive, you are going to see and manage glaucoma in your practice,” he said. “At the very least, it’s all of our responsibilities as eye care providers to have an awareness. In terms of actual utilization and implementation, I think it’s individual in whether you want to jump in.”
Dr. Greenwood said he thinks MIGS is here to stay, making a huge quality of life impact for patients, and it’s something he thinks cataract surgeons need to know how to do. “If you’re not performing MIGS and a patient has glaucoma, patients should know that MIGS is an option. Your job as a surgeon should be to get these patients to someone who does it. You’d be doing a big disservice not to,” Dr. Greenwood said.

Editors’ note: Dr. Greenwood has financial interests with Alcon (Fort Worth, Texas), Equinox (Sioux Falls, South Dakota), Glaukos, New World Medical (Rancho Cucamonga, California), and Staar (Monrovia, California). Dr. Shah has financial interests with Glaukos and Allergan (Dublin, Ireland). Dr. Lewis has financial interests with Aerie Pharmaceuticals (Durham, North Carolina), Alcon, Allergan, AVS (Goleta, California), Glaukos, Ivantis (Irvine, California), Sight Sciences (Menlo Park, California), Kedallion (Palo Alto, California), and MicroOptx (Maple Grove, Minnesota).

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