MIGS changing surgical glaucoma landscape, approach to procedures

Take-home message: Thomas W. Samuelson, MD, shares his perspective on how microinvasive glaucoma surgery has been integrated into his daily practice.

By Michelle Dalton, ELS; Reviewed by Thomas W. Samuelson, MD

Minneapolis-With overwhelming evidence supporting the belief that cataract surgery lowers IOP in most patients with ocular hypertension and early-to-moderate glaucoma, more and more glaucoma specialists are integrating microinvasive glaucoma surgery (MIGS) into their practices.

“Glaucoma is a very heterogeneous condition,” said Thomas W. Samuelson, MD, founding partner at Minnesota Eye Consultants, Minneapolis.

“The risk of functional impairment from glaucoma varies widely among those with the disease,” he said. “Filtration surgery and aqueous drainage devices are highly efficacious and well suited for patients at significant risk for functional visional impairment from glaucoma, and indeed, is the gold standard for such patients.”

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In Dr. Samuelson’s opinion, cataract surgery should be considered an incremental step in the management of early-to-moderate glaucoma.

The introduction and rapid acceptance among surgeons for MIGS, however, mean that “we now have the luxury of matching the risk of our interventions versus the risk of functional impairment,” Dr. Samuelson said.

Glaucoma specialists now have a more complex management strategy than previously, “where we basically ‘marinated’ the eye with medicines until we did filtration surgery.” He said. “Those days are thankfully long gone.”

While trabeculectomies (“trabs”) and tubes are generally efficacious, glaucoma surgeons have not had a procedure that errs on the side of safety in lieu of efficacy.

“MIGS provides us that option,” he said. “We can triage each patient . . . to the appropriate procedure based on what's the risk of a disease and what's the risk of our recommended treatment.”

He recommends surgeons analyze their own procedures and results to ensure “you don't have to reallocate a little bit based on your outcomes. That is, make sure that your surgical choice doesn’t put your patient at greater risk the disease itself. It's really important to have an option that errs on the side of safety,” he said, but not to misconstrue his statement to mean surgeons should abandon other surgical options.

“When we are faced with cases of advanced glaucoma, trabs and tubes are still a good and viable option,” he said.

NEXT: Bringing MIGS into the fold

MIGS “doesn't have to cure glaucoma to be a great addition to our armamentarium,” Dr. Samuelson said. For example, the introduction of prostaglandin analogues in the 1990s “completely changed” how specialists manage glaucoma.

“But no one expects prostaglandins to cure glaucoma,” he said. “MIGS is one more tool to have that is changing the way we manage glaucoma.”

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For patients with mild or moderate glaucoma who are undergoing other ocular surgery (i.e., cataract), it just makes sense to perform MIGS simultaneously, Dr. Samuelson said. Because of some payer pushback, however, MIGS may not be ready yet as a first-line treatment.

He recalled one payer that wanted to know how many medications a particular patient had failed before undergoing the combined surgery, not taking into account the simultaneous surgery would reduce the number of medications needed and would not introduce additional trauma to the eye.

This is not the first time a treatment other than medication has shown potential to be as efficacious as medication.

“There is plenty of data to suggest that selective laser trabeculectomy (SLT) is as good as latanoprost,” he said. “Yet, the minority of patients receive SLT as first-line therapy, even though SLT is done in the clinic, it's extremely safe, there's no risk of endophthalmitis, and there’s no risk like we have with incisional surgery.”

Dr. Samuelson is, therefore, cautious to predict MIGS will become a first-line treatment “any time soon. It would be difficult to state with authority that MIGS, as safe as it is, is safer than SLT.”

Until glaucoma specialists change the paradigm of reaching for medications first, other treatments are unlikely to become true first-line contenders for patients with mild-to-moderate glaucoma.

“Medications for the majority of our patients with primary open-angle glaucoma are going to remain the standard, but that could change as we get better and better options,” he said.

As long as the patient is compliant and the drop remains well tolerated, “it’s hard to argue with that in terms of performing surgery instead,” Dr. Samuelson said.

Most patients-when given the option between a single, daily topical medication or surgery-will opt for medication, he explained.

But “the days of putting patients on four medications before we try something surgical are over,” he said.

NEXT: MIST + MIGS

Dr. Samuelson has coined the phrase “minimally intrusive sustainable therapy (MIST)-a sustainable and minimally intrusive amount of medication that is one or two bottles, not four bottles,” he said.

“It's not ‘marinating’the eye until it's red and obviously toxic; it's one or two drops a day, so MIST plus MIGS is the formidable approach,” he explained.

In the majority of patients, MIGS plus MIST is applicable and will adequately manage the glaucoma.

In his own practice, Dr. Samuelson uses MIST plus SLT “or whatever I need to” until the patient needs cataract surgery and then he combines phacoemulsification and MIGS. He will do trabeculectomy in phakic eyes, but only when there is significant risk of functional impairment.

The hope is that “only the minority of cases will fail our more conservative, safe measures, and only then should we subject the patient to a more aggressive procedure,” he said.

In the decade since some of the landmark studies on stents in the canal were published, “there’s been a lot of good science on outflow studies and histopathology,” Dr. Samuelson said.

“We've got an evolving glaucoma surgical portfolio that allows us to individualize our care,” he said. “My goal is to provide a measured surgical care for those with the most severe disease, but also for those with mild-to-moderate disease. And that means maximum medical therapy being multiple drugs is going to be a relic.”

Thomas W. Samuelson, MD

P: 612/813-3628.

E: twsamuelson@mneye.com

This article was adapted from Dr. Samuelson’s presentation during Glaucoma Subspecialty Day at the 2014 meeting of the American Academy of Ophthalmology. Dr. Samuelson did not indicate a proprietary interest in the subject matter.