July 2019

IN FOCUS

MIGS Update
Comparing the COMPARE results to the real world


by Vanessa Caceres EyeWorld Contributing Writer


Hydrus
Source: Ivantis

iStent
Source: Glaukos

 

At a glance

• Results from the recently published COMPARE trial compared the Hydrus Microstent to the use of two iStent Trabecular Micro-Bypass devices in approximately 150 open angle glaucoma patients.
• Both the two iStents and Hydrus lowered IOP and medication use as standalone
procedures. More patients in the Hydrus group had reduced medication use or were medication-free at 12 months.
• The trial did not include phaco, which is part of the current U.S. FDA approval for the two devices.
• A larger number of studies that compare MIGS devices are needed, surgeons think.

Even though the recently published results from the COMPARE trial may not imitate real-life circumstances for cataract and glaucoma surgeons, they still offer clinical pearls and insights.
The COMPARE prospective, multicenter, randomized clinical trial pitted the Hydrus Microstent (Ivantis) head-to-head against the use of two iStent Trabecular Micro- Bypass (Glaukos) devices in 152 eyes from 152 patients, 148 of whom completed the study until its 12-month follow up.1 The goal was to compare the efficacy of the MIGS devices to reduce IOP and medication use among the patients, all of whom had open angle glaucoma. 
Patients were between 45 and 84 years old, had a Shaffer angle grade of III to IV, a best corrected visual acuity (BCVA) of 20/30 or better, and an IOP of 23 to 39 mm Hg after washout of all hypotensive medications. Patients with angle closure glaucoma, exudative age-related macular degeneration, proliferative diabetic retinopathy, secondary glaucoma except pseudoexfoliation or pigmentary glaucoma, and those at significant risk for secondary glaucoma during the washout period were excluded.
Eyes in the study were randomized 1:1 to standalone MIGS with one Hydrus or two iStent devices. However, unlike the “real world,” no phacoemulsification was performed. The U.S. FDA approval for both devices currently requires device use combined with phaco.
The study’s main outcome measures were within-group and between-group differences in IOP and medications at 12 months. Researchers also considered freedom from any repeat glaucoma surgery, an IOP of 18 mm Hg or less, and no use of glaucoma medications. Safety measures were frequency of surgical complications, visual acuity changes, slit lamp findings, and adverse event rates.

The results

Both the two iStents and Hydrus were found to lower IOP and medications. The Hydrus had a greater rate of complete surgical success (P<0.001) at 12 months, according to researchers. Those receiving the Hydrus also used fewer medications after surgery, and more Hydrus subjects were medication-free at 12 months (P=0.0057). 
When researchers analyzed factors that may affect which eyes were medication-free at 12 months, such as age, ethnicity, or number of baseline medications, the strongest factor they found was treatment with the Hydrus. Lower baseline diurnal IOP and milder visual field severity were also significant predictors of zero medication use at 12 months.
Safety was similar in both groups. Two eyes in the Hydrus group and one in the iStent group lost two lines of BCVA. Four cases of IOP elevation greater than 10 mm Hg occurred in the iStent group compared with three cases in the Hydrus group. Device obstruction rates were similar in both groups; obstructions related to iris or tissue adhesions were more common in the iStent group, and peripheral anterior synechiae was the large cause in the Hydrus group. In the iStent group, two eyes had secondary glaucoma surgery performed (3.9%) compared with zero of the Hydrus eyes. No hypotony, device migration, or dislocation occurred in either group.
“This is the first study to directly compare the efficacy of different MIGS devices for use in glaucoma management without concurrent cataract surgery,” the researchers wrote. 

Adding to the MIGS evidence

Beyond the results themselves, the COMPARE study provides yet more evidence to help comprehensive ophthalmologists in their decision-making, surgeons said.
“Having multiple MIGS procedures available to us means that we need better comparative data in order to decide which procedure to use and when,” said COMPARE co-study author David F. Chang, MD. “For canal-based MIGS procedures, all of the FDA clinical trials compared the stent when used concomitantly with phaco to phaco alone. This makes it difficult to compare the relative efficacy of these different devices. The COMPARE trial is therefore important because it is a prospective randomized trial comparing the Hydrus to two ‘generation one’ iStents in eyes without simultaneous phaco. Although so-called standalone implantation of a canal-based stent is off-label, the advantage of this trial design is that any confounding effect of phaco is avoided.”
Although the study’s lack of phaco affects how surgeons may perceive the results, Constance Okeke, MD, said there is still value. “One can still extrapolate a feeling of confidence that there’s efficacy in the MIGS portion of the procedure,” she said. 
The value of head-to-head comparison data from trials like COMPARE and the recently updated HORIZON results are of great use to glaucoma surgeons, said Ike Ahmed, MD, who was involved with both studies. “Unlike other areas of ophthalmology, glaucoma is a chronic condition, and the longer picture is very much a measure of success. It’s valuable information in terms of clinical metrics and also potential events and safety,” he said.
In lieu of the CyPass (Alcon) recall last year, safety data are crucial for any device-related studies, Dr. Ahmed added.

The real-world link and more studies needed

How can surgeons begin to apply study results in the OR if COMPARE does not mimic how they must use the devices—or if the full breadth of studies needed are not yet available? 
Dr. Okeke encourages surgeons to take a hard look at their own data and come up with some conclusions. “Those areas can help us with decision-making when we don’t have clinical trials,” she said. She has reviewed self-driven data and has found that in her hands a certain approach works most effectively in certain patients. For instance, she has reviewed information on her patients and found very good outcomes with the use of goniotomy with the Trabectome (NeoMedix), done in combination with cataract surgery or as a standalone, especially in pseudoexfoliation glaucoma. Other times, based on her self-data review, she has steered away from using a certain procedure that she previously thought was working well, or changed intra- or postoperative procedures to get better outcomes.
Even though the iStent did not have stronger results in COMPARE versus the Hydrus, it still can have its advantages, Dr. Okeke said. She pointed to a fairly easy learning curve and a preference for the iStent in certain eyes. “The Hydrus takes up more space in the canal. If one needs an additional procedure, there may be more room with the iStent than the Hydrus,” she said.
Dr. Okeke also sees a role for goniotomy and canaloplasty, both of which can be used with or without cataract surgery and can be performed on patients with a variety of glaucoma severity. “There’s a little more versatility, and with these procedures, there’s some differences in reimbursement,” she said.
A larger number of head-to-head MIGS comparisons will be important going forward, Dr. Okeke said. A comparison of MIGS devices or procedures that work similarly would be particularly valuable and help target patient selection and glaucoma severity better, she said. 
A broader understanding of which MIGS approaches could help avoid trabeculectomy—even though the latter is still a viable option for many patients—could also help guide surgeons, Dr. Ahmed said. “For example, the HORIZON trial recently showed Hydrus achieving a statistically significant reduction in more major incisional glaucoma surgery at 3 years compared to cataract surgery alone, which is encouraging for a MIGS device,” he said. Additionally, targeting surgical approaches that reduce reliance on medications is often an important outcome to patients, he said.
More data should come out from the COMPARE trial eventually. At the American Glaucoma Society meeting earlier this year, 24-month data from COMPARE showed superior reduction in medication burden with the Hydrus, and fewer patients required additional filtering procedures to obtain adequate IOP control.

Contact information

Ahmed: ikeahmed@mac.com
Chang: dceye@earthlink.net
Okeke: iglaucoma@gmail.com

About the doctors

Ike Ahmed, MD
University of Toronto
Toronto

David F. Chang, MD
Private practice
Los Altos, California 

Constance Okeke, MD
Virginia Eye Consultants
Norfolk, Virginia

Reference

1. Ahmed IIK, et al. A prospective randomized trial comparing Hydrus and iStent micro-invasive glaucoma glaucoma surgery implants for standalone treatment of open-angle glaucoma: The COMPARE Study. Ophthalmology. 2019. Epub ahead of print.

Financial interests

Ahmed: Ivantis, Glaukos
Chang: Ivantis
Okeke: Ellex, Glaukos, NeoMedix, Sight Sciences

Comparing the COMPARE results to the real world Comparing the COMPARE results to the real world
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