MIGS evolution augurs earlier intervention, stand-alone procedures
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The volume of minimally invasive glaucoma surgery has increased significantly in recent years, providing an alternative to traditional glaucoma surgeries.
Data from various studies demonstrate that MIGS is associated with low risk for adverse events and has beneficial effects on visual field preservation, quality of life and cost-effectiveness among patients with mild to moderate glaucoma.
Source: Shari Fleming Photography
The FDA 510(k) clearance of the iStent infinite (Glaukos) trabecular micro-bypass system in August 2022 helped change the paradigm of glaucoma care.
“The most notable change in the stand-alone approach to MIGS has been the approval of iStent infinite,” OSN Glaucoma Section Editor Thomas W. Samuelson, MD, said.
“The procedure achieved better results in clinical trial than many of us anticipated and has caused many of us to take a fresh look at MIGS as stand-alone procedures,” he said. “When utilized as a combined procedure, such as with cataract surgery, MIGS is well established and has not changed much in recent years. However, when used as a stand-alone intervention, the procedures have changed significantly. Exactly when iStent infinite is going to be utilized is still being assessed, at least in my hands. While we have had excellent stand-alone options to use with progressive disease not controlled with medications, we may be entering an era whereby we can use minimally invasive procedures as an alternative to medications. We now have even newer MIGS coming in the pipeline and a lot of really good clinicians and bioengineers working to try and find new strategies in the glaucoma surgery space.”
Promising paradigm
The MIGS paradigm has evolved in recent years and consists of a group of interventions that involve ab interno microincision, minimal tissue trauma, modest IOP-lowering efficacy, high safety profile and rapid recovery.
These procedures have come a long way, according to Ahmad A. Aref, MD, MBA, associate professor of ophthalmology and attending physician in the glaucoma and cataract consultation service at University of Illinois College of Medicine.
“MIGS has completely changed my and many of my colleagues’ practices,” Aref said. “Increasing evidence suggests that we should consider intervention earlier on in a patient’s disease stage because that may give us the best chance of preserving the drainage functionality of the eye. We often start treating patients with glaucoma with medications, but that may not be ideal over the long term because the effect from medications fluctuates over time. As the medication is instilled, it eventually wears off, and then eye pressure goes up, whereas something surgical, such as a MIGS, has a more sustained duration effect and prevents those fluctuations in eye pressure that may be associated with progressive vision loss.”
In a 2022 review published in Current Opinion in Ophthalmology, Aref and colleagues summarized published data from three randomized controlled clinical trials that assessed the safety and efficacy of MIGS, including iStent, CyPass (Alcon) and Hydrus (Alcon), with cataract surgery vs. cataract surgery alone.
Results across all three trials showed the combined MIGS procedures achieved at least 20% IOP lowering vs. cataract surgery alone. Moreover, other than CyPass, which was voluntarily withdrawn from the market, MIGS appeared safe, with adverse events consistent and acceptable with routine intraocular surgeries.
“We have data that shows that with some of our MIGS procedures, especially the Hydrus implant, not only are we able to lower eye pressure and decrease medication burden, which has been shown in prior studies, but the newest finding is that these procedures are capable of decreasing the risk for visual field loss after a 5-year time span,” Aref said. “This is a huge deal for those of us who treat glaucoma. Many of these studies are so focused on lowering eye pressure, but at the end of the day, our management of glaucoma is more about preserving vision.”
HORIZON trial
The 5-year findings from the HORIZON trial had a profound impact on the realm of MIGS.
As Healio/OSN reported in 2021, researchers randomly assigned 556 eyes with mild to moderate glaucoma to cataract surgery alone or in combination with the Hydrus microstent.
At 5 years, eyes treated with Hydrus required fewer medications and surgeries compared with eyes that underwent cataract surgery alone. Additionally, eyes treated with the microstent were less likely to require incisional glaucoma surgery, with 2.5% of microstent eyes requiring surgery compared with 6.4% of eyes that underwent cataract surgery alone (P = .022).
“Safety is something that is important for all MIGS procedures, and perhaps even more so after the CyPass withdrawal,” Ike K. Ahmed, MD, said at the American Academy of Ophthalmology meeting in 2021. “I think we can say, over 5 years, this is a very safe device, and we have zero concerns over endothelial cell loss.”
“We have been talking about the HORIZON trial for a few years now based on some poster and presentation data, but we now have the manuscript in print showing visual field preservation in microstent patients compared with cataract surgery alone,” Sarah H. Van Tassel, MD, director of the glaucoma service and glaucoma fellowship at Weill Cornell Medicine, said.
“The manufacturers should be applauded for what was a very costly and rigorous analysis of the data,” Van Tassel said. “Both patients and payers, and the remaining MIGS skeptics, should all now see that MIGS plays an incredibly essential role in the glaucoma space. Hopefully, people will be inspired by this 5-year data and want to demonstrate not just by proxy the IOP lowering and medication reduction, which are important surrogate indicators, but also that MIGS preserves structure and function because that is a real previously unmet need. Additional high-quality head-to-head data in terms of the different MIGS techniques and devices would serve the field well.”
Other advancements
Other exciting advancements in MIGS are on the horizon, according to Healio/OSN Board Member Nathan M. Radcliffe, MD.
“In the short term, excimer laser trabeculectomy will be arriving, which allows a very small trabecular meshwork opening to be created ab interno with a precise excimer laser,” Radcliffe said. “There is long-term data on this approach from Europe, and it looks as if this may be commercially available in the U.S. within the coming years.”
Slightly further down the road, experts anticipate the approval of femtosecond laser trabeculotomy (FLT) with the ViaLase laser system.
“This FLT procedure is expected to be remarkable because we will be able to perform goniotomy through a nonincisional approach using a femtosecond laser,” Radcliffe said.
Samuelson agreed.
“We can definitely anticipate better lasers coming in the pipeline, including hybrid lasers that offer incisional outcomes,” Samuelson said. “I am on the medical monitoring side of the FLT technology that uses a laser to create a 200 µm × 400 µm trabeculostomy. It is not yet FDA approved and is still investigational, but I am very encouraged by how it is progressing. Briefly, it creates a trabeculotomy without an incision, and there is no risk for infection, there’s little or no risk for hyphema, and it can be done in an office setting. It is promising.”
Another upcoming strategy is the iDose TR. In February, Glaukos submitted a new drug application to the FDA for the microinvasive intraocular implant designed to continuously deliver a travoprost formulation.
As Healio/OSN previously reported, the new drug application stems from positive findings from two phase 3 trials that “achieved the prespecified primary efficacy endpoints through 3 months and demonstrated a favorable tolerability and safety profile through 12 months.”
“Many of procedures in the pipeline will be bolstered by the anticipated approval of iDose, which will provide another level of pressure-reducing durability because the payload is larger and we anticipate a longer effect,” Samuelson said. “However, a con of iDose is that it will likely require being given in a procedure room as it requires a small incision and instilling viscoelastic within the anterior chamber.”
Many glaucoma specialists are using Durysta (bimatoprost implant, Allergan) more often because it ensures that the medication is delivered directly into the eye by the surgeon and is not dependent on compliance, Samuelson said.
“What will make this interventional mindset more effective is if we can intervene with our lasers and MIGS procedures and enhance their efficacy by giving intracameral long-acting drug delivery,” he said. “There are pros and cons to all of these approaches, but really the take-home is that we are making great progress and will have more options than ever in the glaucoma surgical space.”
Reimbursement concerns
Concerns about reimbursement accompany the success of MIGS procedures.
“Reimbursement remains a challenging and important issue,” Van Tassel said. “It is crushing to see payers whittle away at this space, but hopefully continued data will demonstrate the critical value of MIGS for our patients and the training, skill and time that is required to manage these patients, which is definitely more than standard cataract surgery.”
Radcliffe agreed.
“The biggest challenge that the field of glaucoma needs to overcome is the current reimbursement-challenged environment,” Radcliffe said. “Procedures that save the health care system money and allow patients to keep their vision longer and have a better quality of life are dramatically undervalued by Medicare and other insurance payers.”
For example, a laser procedure that could save thousands of dollars in pharmaceutical costs may only be reimbursed a few hundred dollars and require prior authorization and documentation for use, he said.
“Our field needs to continue to speak together with one voice to remind insurance companies that the remarkable scientific advancements that are being performed on a daily basis in the field of glaucoma deserve fair reimbursement so that we may continue to invest in the future of our patients with glaucoma,” Radcliffe said.
Decreased reimbursement will lead to less incentive for capital investors to help fund the development of MIGS technologies, according to Samuelson.
“We must find a way to continue to adequately reimburse for these procedures,” Samuelson said. “Glaucoma is a huge problem in our society, and my hope is that we continue to invest in MIGS and other strategies to find better and safer interventions. Reimbursement is one of the significant threats in this space. There’s only so much capital to go around, and if reimbursement continues to decrease, innovators and investors will take their resources elsewhere, which is my biggest concern.”
Striking a balance
As advancements in the glaucoma surgery space continue to grow, the trick will be to consolidate the available procedures and those in the pipeline.
“We always need prospective randomized trials in the MIGS space. However, with the almost 10 different types of MIGS procedures available to clinicians, it becomes mathematically impossible to study all of the different devices in a comparative manner,” Radcliffe said. “Therefore, longitudinal prospective studies are very helpful. Many companies in this space are studying their approach in a prospective manner, but not in comparison or in combination with other approaches.”
Van Tassel said it will be exciting to see the continued innovation and disruption in MIGS, but consolidation could be meaningful, as many players have entered the space.
“It will be helpful to have a better sense of which devices and approaches are best and in what scenarios,” she said. “It will be a balance because there is some truth to the fact that one particular device may be easier or safer for one particular surgeon, but there has to be a right answer to which devices are best in which circumstances, and it would benefit the field to see perhaps some consolidation balanced with continued innovation.”
Samuelson encouraged glaucoma surgeons to continue to maintain their trabeculectomy and tube shunt skills. While less invasive procedures are much needed and important, severe glaucoma that needs more aggressive treatment still exists.
“There are still going to be patients who will fail on these less invasive approaches,” he said. “I still see people who are hanging by a thread and are a few axons away from losing their independence and function. Those patients will still need aggressive pressure reduction, in some cases sub-physiologic. We have to be ready to offer more aggressive procedures that can get single-digit pressures and maintain pressure in vision longer term.”
But overall, the hope is to sustain the momentum in the MIGS space.
“While we are going to continue to advance the interventionist mindset, it is unrealistic to think that drug therapy is going away,” Samuelson said. “It’s going to change, and we are not going to tolerate the toxicity issues that we have seen in the past, especially with regard to surface toxicity and redness. We’re going to get better at intracameral delivery, and we will see a combination of intelligent drug design and delivery combined with safer surgical procedures. We have certainly made great strides in that direction, but we can definitely do better.”
- References:
- Ahmed IIK, et al. Ophthalmology. 2022;doi:10.1016/j.ophtha.2022.02.021.
- Ahmed IK. 5-year results from the HORIZON trial: Long-term safety and effectiveness of combined phacoemulsification and minimally invasive glaucoma surgery with the Hydrus microstent. Presented at: American Academy of Ophthalmology meeting; Nov. 12-15, 2021; New Orleans.
- Aref AA, et al. Curr Opin Ophthalmol. 2022;doi:10.1097/ICU.0000000000000923.
- Eyes that received Hydrus microstent less likely to require medications after 5 years. https://www.healio.com/news/ophthalmology/20211116/eyes-that-received-hydrus-microstent-less-likely-to-require-medications-after-5-years. Published Nov. 16, 2021. Accessed April 18, 2023.
- Ibach M. Interim results of a prospective phase II study of travoprost intraocular implants. Presented at: American Academy of Optometry meeting; Nov. 9, 2018; San Antonio, Texas.
- Glaukos announces positive results for iDose TR Exchange trial, highlighting favorable safety and tolerability. https://investors.glaukos.com/investors/news/news-details/2023/Glaukos-Announces-Positive-Results-for-iDose-TR-Exchange-Trial-Highlighting-Favorable-Safety-and-Tolerability/default.aspx. Published Jan. 10, 2023. Accessed April 15, 2023.
- Glaukos submits new drug application to U.S. FDA for iDose TR. https://investors.glaukos.com/investors/news/news-details/2023/Glaukos-Submits-New-Drug-Application-to-U.S.-FDA-for-iDose-TR/default.aspx. Published Feb. 27, 2023. Accessed April 15, 2023.
- Glaukos submits new drug application for iDose TR. https://www.healio.com/news/ophthalmology/20230227/glaukos-submits-new-drug-application-for-idose-tr. Published Feb. 27, 2023. Accessed April 18, 2023.
- Sarkisian SR Jr, et al. J Glaucoma. 2023;doi:10.1097/IJG.0000000000002141.
- For more information:
- Ahmad A. Aref, MD, MBA, of University of Illinois College of Medicine, can be reached at aaref@uic.edu.
- Nathan M. Radcliffe, MD, of New York Eye Surgery Center, can be reached at drradcliffe@gmail.com.
- Thomas W. Samuelson, MD, of Minnesota Eye Consultants, can be reached at twsamuelson@mneye.com.
- Sarah H. Van Tassel, MD, of Weill Cornell Medicine, can be reached at shvantassel@gmail.com.
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