April 2018


Intersection of refractive surgery and MIGS
Adopting MIGS into practice

by Ellen Stodola EyeWorld Senior Staff Writer


“There is a spectrum of MIGS, and refractive surgeons should take into account postoperative care when deciding what devices they are comfortable implanting.”
—Linda Huang, MD

Kahook Dual Blade goniotomy

CyPass insertion

iStent insertion
Source (all): Michael Patterson, DO


Surgeons offer information on the MIGS learning curve, barriers to adoption, and how comprehensive and refractive surgeons can use MIGS

With the approval of many new MIGS devices in the past several years, surgeons choosing to incorporate them into practice must consider the learning curve that comes with each device and the skillsets needed to develop expertise with these procedures. Linda Huang, MD, Glaucoma Institute of Northern New Jersey, Rochelle Park, New Jersey, Thomas Samuelson, MD, Minnesota Eye Consultants, Minneapolis, Jacob Brubaker, MD, Sacramento Eye Consultants, Sacramento, California, and Michael Patterson, DO, Eye Centers of Tennessee, Crossville, Tennessee, shared their views on the MIGS learning curve and highlighted considerations for comprehensive and refractive surgeons wanting to use these devices. Some MIGS procedures include the iStent (Glaukos, San Clemente, California), the XEN Gel Stent (Allergan, Dublin, Ireland), and the CyPass Micro-Stent (Alcon, Fort Worth, Texas).

MIGS learning curve

There is a learning curve for adopting MIGS, Dr. Huang said. “Many procedures involve the angle, and intraoperative gonioscopy is a skill that is not commonly used in the operating room,” she said. “Recognizing and identifying angle anatomy intraoperatively is also a skill to develop.” Dr. Huang added that once these two are mastered, they can be applied to many MIGS devices. “Then there are specific skills unique to individual devices, but mastery of one device usually translates to other devices.”
Dr. Patterson agreed that there is a learning curve, particularly in making sure that physicians are capable of understanding the angle and are proficient at doing intraoperative gonioscopy. “That is a totally different animal for MIGS surgery than it is in the clinic,” he said, adding that if you can understand placement and anatomy of the angle, you’re pretty much set.
Dr. Patterson is a big proponent for doing preoperative gonioscopy. A lot of ophthalmologists rely on optometrists or outside providers to do the preoperative exam, he said, but then you don’t know what you’re looking at when you get into the OR.
The biggest learning curve with MIGS is using the gonioprism for good visualization of the angle structures, Dr. Brubaker said. “The other challenge that can be difficult initially is that the surgeon is restricted to using only one hand in the eye while the other hand is occupied holding the gonioprism,” he said. Most surgeons learning MIGS begin with trabecular meshwork-targeted procedures like the iStent, Dr. Brubaker said. “Although the iStent has a slightly longer learning curve than some of the other MIGS, I think this is a good place to start,” he said. “This procedure has a lower risk profile than other MIGS.” He noted that the “trick” with iStent placement is ensuring that the stent is well seated in the canal and not placed too superficially. “I think this takes 10–15 cases to get a complete feel for proper placement,” he said.
Dr. Brubaker added that from a placement standpoint, he thinks the CyPass has the shortest learning curve. “The gonioscopic challenge with the CyPass is that the surgeon has to make sure to not press down on the lip of the corneal wound during placement,” he said. “Because the CyPass is inserted in the more posteriorly located supraciliary space, the surgeon needs to raise the wrist and the handle of the inserter to prevent downward force on the corneal lip.” Dr. Brubaker said that this helps to avoid distortion of the cornea, making visualization difficult. “Another challenge with the CyPass is recognizing differences in iris root appearances among patients,” he said. “Rather than focusing on the apparent insertion of the iris at the more posterior root, it is crucial to target insertion of the CyPass just below the scleral spur.” This is a constant anatomic feature that can reliably direct CyPass placement in every case, he said.
With the other trabecular meshwork targeted MIGS such as gonioscopy-assisted transluminal trabeculotomy (GATT) and Kahook Dual Blade (KDB, New World Medical, Rancho Cucamonga, California), one can rely on the techniques used in learning the iStent, Dr. Brubaker said. “A good feel for the location and depth of the meshwork and canal are particularly helpful during one’s progression toward these more advanced MIGS,” he said. “Both of these procedures require the use of interocular microincision forceps under gonioscopic visualization.” He added that this is a technique that can be helpful in these procedures but also if repositioning is necessary with the CyPass or iStent.  
Finally, Dr. Brubaker said that the use of the XEN Gel Stent is on a different spectrum when compared to internal MIGS. “The (indirect) gonioprism is only used to guide initial targeting of the needle,” he said. “The stent is injected with direct visualization.” He added that the learning curve with the XEN is making sure the stent is well placed. Advanced placement just under the conjunctiva is a technique that usually requires more than a handful of cases before this can be mastered, Dr. Brubaker said.

Skills needed to implant vs. skills needed to manage

According to Dr. Huang, the skills to manage postoperatively are different than the skills needed for implantation. “The benefit of MIGS procedures is they often have lower rates of complications compared to traditional filtering surgery, such as hypotony, which can be difficult and time consuming to manage,” she said. “However, MIGS procedures are not free of complications.”
Less invasive MIGS procedures such as trabecular meshwork bypass stents (iStent) may be easier to manage than procedures that resemble traditional surgery, Dr. Huang said, such as gel stents (XEN), which may even require postoperative bleb needling and injections of anti-fibrotics. Significant postoperative care can be a barrier to adoption of MIGS procedures, she said. “There is a spectrum of MIGS, and refractive surgeons should take into account postoperative care when deciding what devices they are comfortable implanting,” Dr. Huang said.
Dr. Patterson said that in these cases it’s important for the surgeon to be comfortable managing hyphema, shallow chamber, choroidal folds, and other issues that may arise. He added that he has no problems with the majority of his MIGS patients, but you do need more chair time with certain patients.
Dr. Brubaker said that most surgeons initially focus on performing the procedure itself, but once these techniques are learned, postoperative management becomes more crucial. With the iStent, success resolves around appropriate glaucoma medication management in the postoperative period to avoid IOP spikes, he said. With the CyPass it is crucial to prepare the patient for the likely delayed visual recovery due to early hypotony and myopic shifts. With trabecular meshwork ablating procedures, Dr. Brubaker said, the surgeon needs to be prepared to deal with postoperative hyphema. “While this usually self clears, it is important to prepare patients for this possibility and have a clear understanding when these need to be surgically washed out.” Finally, with the XEN, the postoperative management is crucial for success, he said. “Having a firm comprehension of bleb management is critical for success.”
“I think the bigger barrier to adoption varies by procedure,” Dr. Brubaker said. “With internal MIGS, I think the challenge pendulum swings toward the technical procedure itself, while the more aggressive MIGS such as GATT and XEN have a potentially more difficult postoperative course.” 
“It is important for surgeons to understand that the follow-up care is as important, and possibly more important, than the actual procedure,” Dr. Samuelson said. “Glaucoma cannot be cured, it can only be managed.” He said that adequate surveillance postoperatively is mandatory for this reason.
“I would discourage surgeons from adopting MIGS if they are unwilling to be accountable for appropriate postoperative surveillance,” he said. “While it is true that many patients are co-managed in today’s medical environment, proper co-management still requires careful correspondence with the referring doctor and coordination of care, to be certain that steroids are discontinued in a timely fashion and those patients developing a steroid response are adequately monitored and treated.”
Dr. Samuelson added that it’s important to move on to more aggressive procedures if the MIGS procedure fails to adequately control the disease process.

Intraoperative gonioscopy

Dr. Brubaker said that there is a learning curve with gonioscopy. “This can be practiced on non-MIGS patients initially,” he said. “It is crucial to tilt the head and microscope enough to obtain an enface view of the angle.” A challenge that he often sees with beginning MIGS surgeons is they don’t get the right angle and the TM or ciliary body is viewed at an oblique angle. “This makes visualization and treatment much more difficult than it needs to be,” he said. “In addition to this the dominant hand that is holding the intraoperative devices and instruments needs to have adequate support to prevent posterior or anterior wound stretch, which can also cause corneal distortions.”
Dr. Brubaker said that he will use a standard Swan-Jacob lens for most of his cases. It is nice if it has a cutout at the apex of the prism to allow for a free insertion of the intraocular instruments, he said. “The single use iPrism in conjunction with the iClip from Glaukos has an enhanced viewing angle,” Dr. Brubaker said. “The clip helps to move and stabilize the eye if necessary.” He finds this prism especially useful for procedures that treat a wider portion of the angle such as KDB, GATT, or if placing multiple stents. 
Dr. Huang noted that intraoperative gonioscopy can be a barrier, as good visualization is needed for implantation of devices. “However, once intraoperative gonioscopy is learned and mastered, it can be a skill that is useful in many different types of MIGS procedures,” she said. “I recommend a direct gonio lens to visualize the angle, such as a Swan-Jacob lens.” She added that certain direct lenses have a ring that contacts the limbus, which allows for stabilization and control of the globe. The ring also allows the gonio lens to float over the cornea, Dr. Huang said, minimizing pressure and distortion of the cornea and thus allowing a clear view. “Intraoperative gonioscopy, however, is easy to practice at the end of cataract surgery,” she said. “For surgeons who wish to master the skill, I recommend that at the end of a cataract case, they rotate the patient’s head and microscope and use the gonio lens to view the angle.” Then, she said to use a cannula to gently touch the TM and mimic the motion of device implantation.

How refractive cataract surgery patients resemble MIGS candidates

Dr. Samuelson said that one aspect of MIGS surgery that will appeal to refractive cataract surgeons is that MIGS surgery by definition is microinvasive. “For example, canal- based surgery does not influence the postoperative refractive result,” he said. “Moreover, for the canal device surgery, such as the iStent or Hydrus [Ivantis, Irvine, California], the intraoperative and perioperative adverse event and complication rate in the pivotal trials was not statistically different from cataract surgery alone.” Therefore, Dr. Samuelson said that adding MIGS surgery to refractive cataract surgery follows a similar, premium visual outcomes mindset and strategy. “That said, I am cautious about the use of multifocal implants in patients with manifest glaucoma and visual field loss, primarily due to loss of contrast sensitivity as well as the possibility that the glaucoma could progress in years to come, which could further compromise the visual function,” Dr. Samuelson said.
Many MIGS procedures are for patients with mild to moderate glaucoma and are often coupled with cataract surgery, Dr. Huang said. “Often MIGS procedures do not require an additional incision and are easily performed after the cataract is removed,” she said. “MIGS procedures have been shown to decrease intraocular pressures and may also decrease medication burden.”

Standalone MIGS surgeries with refractive patients

“Some MIGS procedures are performed in conjunction with cataract surgery,” Dr. Huang said. If done as a standalone, the patient’s insurance may not cover the procedure, she noted. In those instances, Dr. Huang usually offers a self-pay option or may offer a MIGS procedure that is approved as a standalone procedure.
MIGS procedures may be useful in patients who are pseudophakic or post-refractive surgery as they often involve small corneal incisions and are sutureless, she said. “Compared to traditional filtering surgery, MIGS procedures will likely cause less astigmatism and also affect the tear film less.”
Dr. Samuelson thinks that standalone MIGS surgeries will play a more important role in the future. “Currently, both the iStent and CyPass are approved only in conjunction with cataract surgery,” he said. “Other procedures such as the Kahook Dual Blade, Trabectome [NeoMedix, Tustin, California], ab interno canaloplasty, and GATT can be performed as standalone procedures.” Hopefully, as more evidence-based information becomes available, MIGS devices will be available for standalone surgery as well, he said, adding that patients may sometimes be willing to pay out of pocket for some of the procedures that are currently not covered by insurance or Medicare.

Reimbursement for MIGS

Dr. Patterson thinks that some of the biggest barriers are insurance and reimbursement patterns. Surgeons will have to reassess if it’s worth their time to continue putting in these devices, he said.
He noted that in his area, the prices of the stents and devices remain the same, but reimbursement has decreased to just a few hundred dollars. This change happened just this year, Dr. Patterson said, and he noted it will have a particular impact on his practice, where he does 300–400 MIGS procedures in a year.
Reimbursement for MIGS procedures utilizing devices remains a significant barrier for adoption, according to Dr. Samuelson. “CyPass coverage is still difficult in my area, and XEN coverage is even more of a challenge,” he said. “Fortunately, our Schlemm’s canal-based surgery, such as the iStent, is now routinely covered.” He said the CyPass recently received a favorable ruling in his region, so coverage for supraciliary surgery should improve. The XEN remains uncovered in Dr. Samuelson’s area.
Initially all MIGS procedures have had this challenge, Dr. Brubaker said. “After an initial battle, the iStent has developed great coverage,” he said. “The CyPass and XEN Gel Stent have had their challenges as well.” He added that the coverage for the CyPass has improved greatly in his area, and the XEN has also improved as of late. “Reimbursement will always be a challenge with early adopters,” he said. “If I think a particular device is the best treatment for my patient, I usually have a detailed discussion about the benefits of the procedure and how it compares to the older, typically riskier but covered procedure. I give my patients a detailed cost breakdown for the new procedure and let them decide what they would like to do. It is surprising how often my patients elect to pay out of pocket for the newer procedure.”  
Dr. Brubaker think it is important to give patients all their options and let them decide what they would like to have done.
“I think it is important to have multiple treatment options for one’s patients,” he said. “If the only MIGS you know how to do is not covered by the patient’s particular carrier and they can’t afford to pay out of pocket, having an alternative MIGS option that is covered can greatly improve the care of patients.”

Editors’ note: Dr. Brubaker has financial interests with Alcon, Allergan, Glaukos, and New World Medical. Dr. Patterson has financial interests with Allergan and New World Medical. Dr. Samuelson has financial interests with Alcon, Allergan, Glaukos, Ivantis, MicroOptx (Maple Grove, Minnesota), New World Medical, and Sight Sciences (Menlo Park, California). Dr. Huang has no financial interests related to her comments.

Contact information

: jacobbrubaker@me.com
Huang: physicians@glaucomainstitute.com
Patterson: michaelp@ecotn.com
Samuelson: twsamuelson@mneye.com

Adopting MIGS into practice Adopting MIGS into practice
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