April 2018

COVER FEATURE

Intersection of refractive surgery and MIGS
Making MIGS choices


by Vanessa Caceres EyeWorld Contributing Writer


 


A GATT performed with a 5-0 prolene suture; the suture has passed nearly 360 degrees around Schlemm’s canal and the distal end of the suture can be retrieved prior to creating a 360 degree trabeculotomy
Source: Davinder Grover, MD

How surgeons match glaucoma patients with MIGS treatment options

Glaucoma surgeons and comprehensive ophthalmologists continue to better understand how to effectively match patients with microinvasive glaucoma surgery (MIGS) options.
“We are still trying to figure out which MIGS is best for which patient and determine the best way to tailor the surgery to the patient,” said Davinder Grover, MD, attending surgeon and clinician, Glaucoma Associates of Texas, Dallas.
The explosive growth within MIGS creates more options, but it also involves further analysis of the factors needed to match MIGS procedures with each patient. Here are the factors that several surgeons currently use to help with their decision and where they think the need for MIGS is still underserved.

Glaucoma severity, IOP goals

A great starting point is to think about glaucoma severity and whether the MIGS in question uses or bypasses trabecular outflow, said Arsham Sheybani, MD, assistant professor of ophthalmology and visual science, Washington University School of Medicine, St. Louis. “In general, in patients with advanced disease who need lower pressures than where they are at or who need to reduce medications, we typically won’t start with the trabecular outflow pathway,” Dr. Sheybani said.
“I think traditionally, most types of MIGS procedures are better for patients with mild or moderate primary open angle glaucoma [POAG],” Dr. Grover said. “The advanced stages of POAG likely need a new drainage either with the XEN [Allergan, Dublin, Ireland], InnFocus MicroShunt [not yet approved in the U.S.; Santen, Osaka, Japan], or a trab or tube.”
Like many surgeons, for Jacob Brubaker, MD, Sacramento Eye Consultants, Sacramento, California, there’s a constant evaluation of a patient’s glaucoma severity, current IOP and IOP goal, and medication use. He shared a typical example and how that has changed.
“Until recently when there was only the iStent [Glaukos, San Clemente, California], it was a matter of what their IOP is right now. If someone came in with an IOP of 15 on three medications and they had a cataract, even with severe glaucoma, I’d feel comfortable using the iStent to get a little lower IOP,” he said.
“Now, with the CyPass [Alcon, Fort Worth, Texas], the XEN, and goniotomy, that opens up the spectrum. My algorithm is that patients who are ideal for the iStent are on one or two medications, have mild glaucoma, their IOP is well controlled, and I am confident that I can get them off one drop and get their IOP down to 15,” Dr. Brubaker explained.
However, if Dr. Brubaker has a patient with a cataract, an IOP in the upper teens or low 20s, and who is on many drops, he will lean toward the CyPass. “There’s a higher likelihood of getting them off their medications and getting their pressure a little lower than with the iStent, but there’s a higher risk for myopic shifts and hypotony,” he said.
The level of IOP change needed or the need to come off a certain number of drops can affect what MIGS choice can be used—or if it can be used at all, Dr. Sheybani said. He is also cautious about not getting the IOP too low. “We can always get pressure lower, but it’s hard to go low and come back up,” he said.
For advanced glaucoma, there may not be sufficient IOP lowering or medication reduction with the iStent, as U.S. surgeons are limited to implanting one iStent at a time, said Dana Wallace, MD, Thomas Eye Group, Atlanta. She will let patients know this in advance to keep their expectations in check.
Another consideration is whether the patient has a cataract. The iStent and CyPass can be performed only at the time of cataract surgery, so that affects procedure and device choices, Dr. Wallace said. Although that can be limiting, she cited several standalone MIGS procedures such as gonioscopy-assisted transluminal trabeculectomy (GATT), ab interno canaloplasty, and the Kahook Dual Blade (KDB, New World Medical, Rancho Cucamonga, California) as possible choices.

Risk profile

With safety concerns always at the forefront, risk profile is an important consideration for patient selection. “Many of the MIGS procedures seem to be associated with a higher risk of steroid response, so I would be more cautious in a known steroid responder and choose weaker steroids and shorter courses of therapy,” Dr. Wallace said. She is also cautious in patients under consideration for GATT who are on blood thinners that can’t be discontinued.
“For a patient in whom I am planning a GATT, and to a lesser extent an ab externo canaloplasty, I discuss postop hyphema and the need for head up positioning so they have appropriate expectations for vision recovery after surgery,” she said.
The risks or side effects associated with certain MIGS procedures are also part of the decision-making process. For example, the CyPass can be associated with a myopic shift, choroidal effusions, and anterior chamber shallowing, although rarely, Dr. Grover said. Angle-opening MIGS such as the KDB, Trabectome (NeoMedix, Tustin, California), and GATT have a slightly higher risk of transient hyphema but are still relatively safe, he added.

Insurance

Selecting the right medical option for a patient doesn’t always square with a patient’s insurance coverage. “It gets to be challenging,” Dr. Brubaker said. The iStent is well covered through insurance, and the CyPass has some good coverage as well depending on the glaucoma severity, he added. If the best option is not covered by their insurance, Dr. Brubaker will let patients know that they would have to pay out of pocket and that the choice may be off-label. “Some patients are concerned about filtering devices, and they’re willing to try anything to avoid that step. In that case, it’s a good option. But not everyone can afford to pay for an off-label device,” he said.
“Unfortunately, [insurance] is a harsh reality,” Dr. Grover said. “Without insurance coverage, it is hard for patients to afford the costs of surgery. This must be in one’s mind when discussing surgical options.” However, the availability of trabeculotomy and goniotomy reimbursement codes come in handy in those situations, he added.

Lifestyle

A patient’s work and hobbies also play a role in selecting MIGS options. For example, if a patient is a scuba diver, Dr. Grover is concerned about the rare potential of blood reflux into the anterior chamber with the negative pressure induced by the scuba mask. “This could, theoretically, result in recurrent hyphemas, especially when diving,” he said. Additionally, if patients must hold their head in positions below the heart for prolonged time periods, Dr. Grover tries to avoid angle surgery because of the concern for blood reflux, a phenomenon he has seen in yoga instructors. “For these active patients, I may consider either a CyPass, XEN, or a traditional trab or tube shunt,” Dr. Grover said.

Looking forward

Although MIGS offers a multitude of treatment options, surgeons look forward to additional future uses for underserved patients.
“I think the biggest underserved area is low tension glaucoma,” Dr. Brubaker said. “There are no MIGS options right now that are designed to achieve an IOP in the high single digits.”
The idea of using more than one MIGS device at a time—for instance, three iStents instead of one—and using certain MIGS as a standalone procedure without cataract surgery would open up treatment options for many patients, Dr. Brubaker added.
Dr. Wallace also sees a need for MIGS without cataract surgery. “In particular, it would be nice to offer the CyPass to patients who have had multiple retinal surgeries in the past and thus have significant scarring, which makes any filtering procedure quite difficult. Because many of these patients are pseudophakic, this device is currently not available,” she said.
Recently, Dr. Grover has been using Cypass in refractory glaucoma patients with prior tubes, secondary glaucoma patients with conjunctival scarring, and in patients who have failed angle surgery with relatively good results. “I think this will be a great potential use for Cypass although currently off-label,” he said.

Editors’ note: The physicians have no financial interests related to their comments.

Contact information

Brubaker
: jbrubaker@saceye.com
Grover: dgrover@glaucomaassociates.com
Sheybani: sheybaniar@wustl.edu
Wallace: danajwallace@gmail.com

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