What advent of MIGS means for earlier glaucoma intervention

Ophthalmologists should consider treating glaucoma earlier and more aggressively than called for in current guidelines, according to Iqbal Ike K. Ahmed, MD.

"It's a time for change, partly because the current treatment paradigm is not working well," said Dr. Ahmed, medical director, Prism Eye Institute; associate professor of ophthalmology, University of Toronto, and clinical professor of ophthalmology, University of Utah.

The advent of microinvasive glaucoma surgery (MIGS) has opened up new opportunities to control primary open-angle glaucoma with earlier intervention, he said.

Dr. Ahmed made his case for "interventional glaucoma" in the Drs. Henry and Frederick Sutro Memorial Lecture at the 7th annual Glaucoma 360 New Horizons Forum, hosted by the Glaucoma Research Foundation.

In addition to making use of MIGS, interventional glaucoma might utilize other novel drainage devices and sustained drug-delivery devices and be combined with cataract surgery, he said. This approach is more proactive, aims at lower IOP, lowers risk and addresses adherence, he said.

Glaucoma treatment is ripe for disruption because it is failing so many patients, he said. Open-angle glaucoma progresses in 89% of people diagnosed with the disease, he said citing a 2013 study by Heiji et al. in Acta Ophthalmologica.

As a result, glaucoma remains a leading cause of blindness, Dr. Ahmed noted. A 2013 study of 592 people with open-angle glaucoma found that 26.5% were blind in at least one eye after 10 years after diagnosis, he said citing a 2013 study by Peters et al. in AJO. At the time of their last visit, 42.2% were blind in at least one eye and 16.4% were blind in both eyes.

In addition, nearly 50% of patients with glaucoma experience complications within 3 years of initiating treatment, he said, citing Market Scope. That compares with less than 10% for retinal, oculoplasty, cataract, and refractive treatments.

The reasons aren't hard to find. Glaucoma is often undiagnosed or improperly treated, with widespread lack of compliance, he said, citing a 2015 article by Remo et al. in Trans Vis Sci Tech. The severity of damage is underestimated, IOP is insufficiently reduced, IOP peaks and means are not adequately assessed, and it is difficult to evaluate the rate of progression, these researchers found.

Even when patients are treated carefully in trials, they still progress, Dr. Ahmed said. For example, 20% of those treated progressed over 24 months, compared with 34% of those untreated in the 2016 United Kingdom Glaucoma Treatment Study (Garway-Heath et al. Lancet).

But that study found that the risk of progressing was 19% lower per mmHg reduction in IOP. In similar trials, the reduction in risk ranged from 10% to 19%. Such reductions in risk with reductions in IOP have been documented since at least 1987, he added.

In the advanced glaucoma intervention study (Am J Ophthalmol. 2000), those patients who maintained an IOP less than 18 mm Hg at all visits did not progress at all for 8 years.

He cautioned that these findings apply to "real manifest glaucoma" and not ocular hypertension or early glaucoma.

The findings in glaucoma recall the results of trials in diabetes and blood pressure in which patients fared much better when their disease levels were managed more intensively, with fluctuations as well as levels kept under control, Dr. Ahmed said.

Conventional guidelines call for a step-wise approach with modest IOP targets and clinicians watching and waiting to see if glaucoma progresses or IOP increases before intensifying therapy. For example, the European Glaucoma Society says a target IOP of less than 18 mm Hg with a reduction of at least 30% "may be sufficient" in moderate glaucoma.

Instead, Dr. Ahmed proposed aggressively treating glaucoma from the start, aiming for a lower IOP while taking into account compliance and risks.

Adding a third or fourth medication may not be effective in achieving a lower IOP, he said, citing a 2004 study by Neelakantan et al. in J Glaucoma.

One reason may be compliance. Across 34 studies, non-adherence ranged from 4.6% to 80%, and non-persistence ranged from 50% to 75% over 12 months.

On the other hand, compared with medical treatment, the patients treated with surgery showed lower mean diurnal IOP, lower peak IOP, and less IOP fluctuation with fewer spikes, Sit et al. reported in 2008 in Surv Ophthalmol. Similar findings emerged even when surgery was the primary therapy, Musch et al reported in 2009 in Ophthalmology.

Yet, out of more than 3 million people with glaucoma in the United States, 500,000 are being treated with lasers and 120,000 with trabeculectomy and tube shunts, Dr. Ahmed said, citing Market Scope. The use of trabeculectomy is in decline, and while tube shunt use is rising, the numbers are still low, he added, citing a 2015 study by Arora et al. in Ophthalmology.

That sets the stage for MIGS, which are minimally traumatic with high safety and rapid recovery, said Dr. Ahmed.

The interventional glaucoma approach could combine MIGS with cataract surgery, he said. About 15% to 20% of the 3.7 million patients undergoing cataract surgery in the United States every year have glaucoma, he pointed out, citing the Centers for Medicare and Medicaid Services as well as a 2012 study by Tseng et al. in JAMA.

"MIGS is to phaco as toric lenses are to IOLs," he said.

In addition, interventional glaucoma could make use of sustained-release drug delivery to lower IOPs while modulating wound healing. It. And it could take advantage of microstenting bleb surgery, said Dr. Ahmed.

"We're changing our attitude," he concluded. "We're enabled by what's available to us and what's coming in the future."