November 2016

 

COVER FEATURE

 

Complicated glaucoma surgery management

Cataract surgery and glaucoma management


by Liz Hillman EyeWorld Staff Writer

 
   
MIGS procedure
Trab360 is a MIGS procedure that can perform an ab interno trabeculotomy up to 360 degrees.

Source: Arsham Sheybani, MD

Inserting iStent
Inserting iStent into the canal has a bit of a learning curve.

Readjusting the iStent
Readjusting the iStent in Schlemm’s canal Source: Arsham Sheybani, MD

Pearls, preferences, and the future of MIGS

Cataract surgery in glaucoma patients has changed dramatically within the last decade. “I think the femtosecond laser has changed things. I think the MIGS procedures have changed things. I think the patient expectation level is much higher. They expect good vision no matter how badly they start off. They all expect perfect results,” said Richard Lewis, MD, Sacramento Eye Consultants, Sacramento, California. “I think the bar is a lot higher for everything.” Jason Bacharach, MD, North Bay Eye Associates, Petaluma, California, said there has been a “paradigm shift in how I manage the disease concomitantly.” Dr. Bacharach said he will generally advise people with mild to moderate glaucoma who also have at least a moderate cataract to have microinvasive glaucoma surgery (MIGS) at the time of cataract surgery in an effort to avoid trabeculectomy in the future.

“In many patients I can avoid a procedure that brings along with it life-long risks, potentially reduced visual acuity, and, if you don’t deal with the cataract up front, can cause cataract progression, making a patient subsequently at risk for an additional surgery to remove a progressive cataract,” Dr. Bacharach continued. “In that situation, for example with trabeculectomy, having to go back and remove a cataract, the cataract surgery itself induces risk that the initial glaucoma surgery could fail.” Though cataract surgery alone has been shown to have an IOP-lowering effect,1 Steven Sarkisian, MD, clinical professor of ophthalmology, and director of the glaucoma fellowship, Dean McGee Eye Institute, Oklahoma City, said it is not long lasting. “I think that if a patient is on medication and has a coexisting cataract, failing to do something to address the glaucoma at the time of cataract surgery, given our multiple options now, is a lost opportunity,” Dr. Sarkisian said. “You’re doing patients a real disservice if you don’t at least make them aware of the option.”

iStent: Four years later

Both Drs. Bacharach and Lewis have been implanting the iStent (Glaukos, San Clemente, California), the first U.S. Food and Drug Administration-approved MIGS device designed to bypass the trabecular meshwork, for upward of 10 years, being involved in its clinical trials. Dr. Sarkisian has been using the iStent since its 2012 FDA approval. Research has shown the iStent to have a strong safety profile and IOP-lowering effect compared to cataract surgery alone, and Dr. Bacharach said his clinical experience has demonstrated the same. Dr. Lewis said he likes the iStent but noted that it’s not for everyone. Patients with narrow or closed-angle glaucoma are not good candidates for the procedure, he said. “I need to have good visibility of the angle and I need to be able to position them well,” Dr. Lewis explained. Surgeons face a learning curve with the iStent as well. “The key to success with the iStent is to get over the learning curve as fast as possible, which means that on the first day you perform the iStent, you should consider doing three to five surgeries,” Dr. Sarkisian said. “The second day you do the iStent, make sure it’s about a week or two later and you do the same thing. You need to do a high volume of cases up front in order to get over the learning curve.” As for surgical pearls, Dr. Sarkisian said having an even hand with the gonioprism, not pushing too hard or too lightly is important to avoid striae in the cornea and air bubbles. He said the incision should not be made too posteriorly, so as to avoid hitting blood vessels, because blood under the gonioprism could obscure the view. The anterior chamber should not be over or under inflated, and positioning the patient’s head and the microscope to give a direct view of the angle are important. “You need to see well and do whatever it takes to get there,” Dr. Sarkisian said. Dr. Lewis recalled a patient with arthritis, which made it difficult to administer glaucoma drops and thus made her a good candidate for a MIGS procedure at the time of cataract surgery. Severe spine and back issues, however, meant a lot of manipulation to get this woman in the appropriate position for iStent surgery. Arsham Sheybani, MD, assistant professor, Washington University School of Medicine, St. Louis, said he coaches residents and fellows to relax their hand, pulling back toward themselves slightly just before releasing the stent. “It almost looks like you’re out of the canal, but you have released all tension so you’re not turning the eye away from you,” he said. “You’re sliding it into the canal instead of hitting the outer wall. ... More often than not though, you see people trying to push the stent in instead of guiding it in nicely.” Dr. Lewis said taking a video of some of your first iStent procedures can help you learn from your mistakes and enhance your skill. When to implant iStent—before or after cataract surgery—is also a consideration. Dr. Bacharach said the decision is situational for him. Before cataract surgery, the cornea is clear and unclouded, plus you might not have to open another viscoelastic tube, he said. Implanting after cataract surgery can be useful in eyes where the angle is a bit narrower at the start. “The suggestion I have if you’re going to implant it before you do the cataract surgery is to implant it after doing the capsulorhexis. The potential pitfall of doing the MIGS first is that if you get a little bleeding, it can make the capsulorhexis more challenging,” Dr. Bacharach said. A patient failed to tell Dr. Lewis he was on tamsulosin, which resulted in floppy iris syndrome as he put the stent in with eventual iris prolapse. After that case, Dr. Lewis said he prefers to place the iStent after cataract surgery. Dr. Sarkisian also said he prefers to place the iStent after cataract surgery when the eye is soft and because any blood in Schlemm’s canal can help identify collector channels, and targeting these could improve IOP reduction. Constance Okeke, MD, MSCE, Virginia Eye Consultants, Norfolk, Virginia, recommends placing the iStent before cataract surgery because it allows for a better view. She uses a 15-degree blade with a 1.5-mm incision at its widest diameter because it minimizes egress out of the wound, and allows you to maintain a well-formed chamber with reduced chance of corneal folds, which could impede visualization of angle structures.

New kid in the MIGS market

A new stent—the CyPass Micro-Stent (Alcon, Fort Worth, Texas)—recently received FDA approval. CyPass, like the iStent, is meant to improve outflow through the eye’s natural drainage system, but unlike the iStent, it is inserted into the suprachoroidal space. Will the two stents be in competition with each other? The physicians interviewed don’t think about it that way, but rather view the addition of CyPass as giving specialists another tool to better treat a broad spectrum of glaucoma patients. “I think CyPass will be a nice addition, and I think it’s going to broaden the indication for MIGS and glaucoma surgery in general,” Dr. Lewis said. Dr. Bacharach said he doesn’t consider the iStent and suprachoroidal stents mutually exclusive. “I think it will expand the opportunity and marketplace for surgeons to use the devices in a greater patient platform,” he said. “For example, in people with more significant IOP reduction needs, it might be that a CyPass is beneficial. For those patients in whom you’ve placed an iStent and need additional IOP reduction, you can surely place a suprachoroidal stent, and there have been some early studies that demonstrate that they might work well together.” Dr. Sarkisian said the CyPass might be attractive to surgeons who don’t feel comfortable with the iStent. “There are surgeons for whom implanting the iStent can be somewhat difficult,” Dr. Sarkisian said. “For some surgeons it has been a struggle for them to convert to canal surgery.” Dr. Sheybani also thinks the CyPass is one of the technically easier MIGS procedures. He thinks it has the potential to lower pressure more than the devices targeting the trabecular meshwork because the suprachoroidal space has less resistance to outflow than the episcleral venous pathway. “The other interesting thing will be if you have a tube or [trabeculectomy] patient who is now failed,” Dr. Sheybani said. “I don’t think it would be reasonable to go back and in that case do an iStent or angle surgery because a lot of the collector system, just from surgery alone, might be damaged. But CyPass would give an alternative pathway. It might have a place in refractory glaucomas, whereas before we might have been doing diode [cyclophotocoagulation].”

Other options and combination therapies

Dr. Sarkisian said the waters have become “a little bit muddier”—in a good way—in that there are a variety of MIGS procedures surgeons can perform in combination with cataract surgery. “I’ll combine iStent with [endoscopic cyclophotocoagulation] in a lot of cases,” Dr. Sarkisian said. Ab interno canaloplasty or an ab interno trabeculotomy or goniotomy can be combined with cataract surgery or performed as standalone procedures. He named the Trab360 (Sight Sciences, Menlo Park, California), iTRACK Microcatheter (Ellex, Adelaide, Australia), Trabectome (NeoMedix, Tustin, California), Kahook Dual Blade (New World Medical, Rancho Cucamonga, California), and GATT (gonioscopy-assisted transluminal trabeculotomy) as examples of devices that could perform these procedures. In his hands, however, Dr. Sarkisian said he performs iStent, endoscopic cyclophotocoagulation, and Trab360, doing a combination of these procedures depending on the desired outcome with cataract surgery. “I think that all of these have positions in our arsenal, but my go-to right now is an iStent,” Dr. Bacharach said of his current preferred MIGS procedure. Dr. Okeke said her predominant MIGS procedure is Trabectome. “It was the first MIGS procedure I trained to do, and I continue to utilize it because I think it’s useful for all stages of glaucoma from mild to moderate to even severe disease,” she said, adding that she will also perform goniotomy procedures with Trabectome and has used the Kahook Dual Blade and Trab360. “I have used the Kahook more frequently as the next procedure and then the Trab360 … but I have found that my Trabectome outcomes are better.” Dr. Sheybani said he doesn’t perform one MIGS procedure more than the others, considering them spread pretty evenly. Different MIGS procedures suit different patients. “So much of it depends on their comorbidities,” he said, explaining that being on blood thinners, for example, can be a contraindication for some MIGS procedures because of the risk for hyphema. The physicians interviewed said they think each of the MIGS options—those that stent, ablate, or otherwise improve aqueous outflow —have a role. “Having been in glaucoma for more than 30 years, I think it’s nice that we have a broader base of procedures to attack this problem,” Dr. Lewis said.

“There is a lot of glaucoma, and there will be a need for interesting and innovative ways to treat the aging population that will have glaucoma as the number … is going to increase dramatically over the next few decades,” Dr. Okeke said.

Reference
Cataract surgery article summary

1. Berdahl JP. Cataract surgery to lower intraocular pressure. Middle East Afr J Ophthalmol. 2009;16:119–122.

Editors’ note: Dr. Bacharach has financial interests with Alcon, Allergan (Dublin), and Glaukos. Dr. Lewis has financial interests with Aerie Pharmaceuticals (Irvine, California), Alcon, Allergan, CenterVue (Fremont, California), Glaukos, and Ivantis (Irvine, California). Dr. Okeke has financial interests with Glaukos, NeoMedix, and New World Medical. Dr. Sarkisian has financial interests with Aeon Astron (Leiden, Netherlands), Alcon, Allergan, Beaver-Visitec International (Waltham, Massachusetts), Glaukos, InnFocus (Miami), Katena (Denville, New Jersey), New World Medical, and Sight Sciences. Dr. Sheybani has financial interests with Allergan.

Contact information

Bacharach
: jbacharach@northbayeye.com
Lewis: rlewiseyemd@icloud.com
Okeke: iglaucoma@gmail.com
Sarkisian: Steven-Sarkisian@dmei.org
Sheybani: sheybaniar@wustl.edu 

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