GLAUCOMA 38 EWAP MARCH 2023 be required in the future. “I tend to take the team approach (surgeon and patient) when it comes to decision making, as many patients are reasonably well informed even before our surgical consultation, have often seen several other glaucoma surgeons, and I’m the second, third, or fourth opinion,” he said. “If one performs a MIGS procedure and it fails, the option to go more invasive is available, whereas if one proceeds with more invasive surgery right away, there is no role for most MIGS procedures at that point.” The main reason Dr. Murphy chooses to combine MIGS is additional IOP-lowering power, targeting aqueous production and resistance to conventional outflow simultaneously, for example. “We as glaucoma surgeons know that sometimes a MIGS procedure fails, but if you perform two or three MIGS, it is theoretically less likely for all of them to fail simultaneously,” he said. In terms of which procedures might work best together, Dr. Murphy prefers to combine MIGS procedures that target different aspects of aqueous production and outflow. Reducing resistance to outflow at the level of the trabecular meshwork can be performed in several ways, including canaloplasty, goniotomy, and stenting procedures. “Often I will implant a stent in the nasal quadrant and perform a goniotomy in an adjacent quadrant, as well as perform a 360-degree canaloplasty,” he said. “You’re throwing multiple strategies at the conventional outflow pathway to try to jumpstart the system as much as you can.” Dr. Razeghinejad said with the CyPass (Alcon), which was voluntarily recalled in 2018, it was easy to combine two different mechanisms of MIGS: conventional and uveoscleral pathway. “Currently, we do not have any FDA-approved supraciliary MIGS devices, and procedures aimed at the conventional pathway may be used together or with cyclodestructive procedures,” he said. For example, he said the OMNI Surgical System (Sight Sciences) may be combined with goniotomy to bypass the trabecular meshwork and dilate the distal outflow. Other trabecular meshwork bypassing procedures could also be combined, such as the Hydrus (Ivantis) and the iStent (Glaukos) or goniotomy. These could be done on different parts of the angle, as the collector channels and aqueous veins may not be functioning well in four quadrants. Performing two MIGS procedures on different parts of the conventional pathway may increase the chance of successfully lowering IOP, Dr. Razeghinejad said. Cyclodestructive procedures could also be combined with any of the conventional pathway MIGS, he added. In order to partially mitigate the risk of entering the eye for surgery, Dr. Murphy will perform ab interno MIGS procedures simultaneously. If one is performing a non-incisional procedure or an ab externo procedure, those are very different risk profiles, he said. “But if I’m going to take on the risk of creating an incision and entering the anterior chamber with instrumentation, I am compelled to take as many surgical steps as possible to lower IOP for that patient. “In my mind, the main drawback is the additional cost to the healthcare system because these devices are expensive, and if you use more than one, there’s no discount. There is negligible change to surgical risk, and if anything, OR time utilization is more efficient when combining MIGS,” he continued. “I tend to prefer non-implant MIGS over implant MIGS because while there is good data to support safety and efficacy of implants, they do come with a unique set of risks, and frankly, some patients have an aversion to the word ‘implant,’ especially if they’ve had a bad experience with an unrelated implant in the past. When one is discussing surgery to save a patient’s vision, I find that they are much less concerned with what the surgery costs and very interested in a spare-no-expense approach.” Each MIGS procedure has its own set of risks, Dr. Murphy added. Many of these procedures’ risk profiles overlap, though not entirely. “You can think of it like a Venn diagram; there may be two or three overlapping circles, but there are always additional risks or an increased risk of one particular adverse event when combining procedures. But in my experience, the additive risk is minimal.” If one is performing canaloplasty, for example, there is a fairly low risk of bleeding and hyphema; however, if you add goniotomy to this, as many MIGS devices do, there is a higher risk of bleeding and hyphema, he said. If you perform a stent and goniotomy, there may be a higher risk of implant movement, at the time of surgery or later. If one is using a laser, there are risks associated with additional anesthesia required. While MIGS procedures have a lower risk profile compared to their more invasive counterparts, in Dr. Murphy’s opinion, combining MIGS does marginally increase
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