Advancements in microinvasive glaucoma surgery (MIGS) have altered the trajectory of glaucoma management and treatment for many patients, as surgeons are considering these interventions, including novel combinations, earlier in the course of the disease.
“The interventional mindset is a new philosophy for many glaucoma specialists and even general eyecare providers,” says I. Paul Singh, MD, Eye Centers of Racine & Kenosha, WI. “We know compliance is not very good with topical medications, and it goes down precipitously when we add medications to a patient’s regimen. It’s difficult for patients to continue using drops consistently for the rest of their lives, and noncompliance results in fluctuating pressures, which can potentially worsen their glaucoma. More and more data—from the LiGHT study and the HORIZON study, for example—are showing that even if pressures are similar after a procedure, the need for incisional surgery down the road lessens when we relieve patients of the medication burden.1,2
“In the last 5 years, we have seen a proliferation of technology in the glaucoma space, enabling us to tailor different procedures to individual patients and to intervene much earlier,” Dr. Singh says. “Now, the decision and the motivation to perform surgery is not based solely on reducing pressures but also on reducing the medication burden for patients.”
MIGS Bypass Devices
The first trabecular meshwork bypass implants—the iStent Trabecular Micro-Bypass (Glaukos), the iStent inject Trabecular Micro-Bypass (Glaukos), and the Hydrus Microstent (Ivantis)—are approved for use in patients with mild-to-moderate glaucoma who are undergoing cataract surgery.
“The MIGS procedures that are combined with cataract surgery are increasingly being accepted,” says Christine L. Larsen, MD, who practices at Minnesota Eye Consultants in Bloomington, MN. “I would imagine that many cataract surgeons are utilizing MIGS procedures universally in their patients with at least mild glaucoma.”
The Xen Gel Stent (Allergan), approved in 2016 to treat refractory glaucoma, does not have to be combined with cataract surgery. “Similar to trabeculectomy, the Xen creates a new drainage mechanism by diverting fluid from the anterior chamber to the subconjunctival space,” says Carlos Buznego, MD, who practices at the Center for Excellence in Eye Care in Miami. “Although the Xen was approved for ab interno implantation, some surgeons adopted a novel external technique, inserting the device through the conjunctiva. Regardless of the approach, the Xen enables surgeons to perform a filtering-style procedure with much less operative time and use of facility resources when compared with trabeculectomy and tube surgery. I would add, however, that there is still a place for trabeculectomy and tube surgeries for more advanced cases or cases where the Xen stent fails.”
Dr. Larsen notes a new device, the PreserFlo shunt (Santen), is expected to become available soon. “Both the Xen and the PreserFlo were developed to reduce or minimize some of the postoperative risks, particularly hypotony, that we often see with trabeculectomy,” she says.
Same-Day Post-Ops, MIGS, and COVID-19
From discussions with colleagues, I know we’re all trying to minimize the time patients spend in our ASCs and our offices during the coronavirus pandemic. To that end, many of us are checking IOPs in the ASC an hour or two after a MIGS procedure, and then seeing the patient in the office 1 week later. We know a pressure spike, if it happens at all, likely will occur in the first 8 hours after surgery, and infection won’t present in one day. By performing same-day post-op examinations and eliminating the next-day post-op visit, not only are we relieving patients of the inconvenience of an office visit the day after surgery, we are also minimizing everyone’s risk of exposure to COVID-19.
Efficiency and flow are big parts of the new discussion during this pandemic, and that discussion will likely continue post pandemic. I think one of the benefits we will see is improved efficiency.
— I. Paul Singh, MD
RESOURCES:
Hildebrand GD, Wickremasinghe SS, Tranos PG, et al. Efficacy of anterior chamber decompression in controlling early intraocular pressure spikes after uneventful phacoemulsification. J Cataract Refract Surg. 2003;29:1087-1092.
Endophthalmitis Vitrectomy Study Group. Results of the Endophthalmitis Vitrectomy Study. A randomized trial of immediate vitrectomy and of intravenous antibiotics for the treatment of postoperative bacterial endophthalmitis. Arch Ophthalmol. 1995;113:1479-1496.
Solo MIGS and Novel Combinations
Safely lowering IOP is the bedrock of glaucoma therapy, and the various MIGS devices accomplish that goal, but not necessarily to the extent desired, as some patients must continue topical medications after surgery. Trabeculectomy, which has been the gold standard in glaucoma therapy for years, reduces IOPs significantly but carries risks for serious complications.3 Given this conundrum, surgeons are taking advantage of the MIGS safety profile and combining standalone procedures in innovative ways to further reduce pressures while avoiding the more invasive filtering surgeries.
“Originally, MIGS wasn’t felt to be useful in patients with more advanced disease,” Dr. Larsen says, “but we have found we can mitigate some of the higher risks for these patients by using, for example, iStent or Hydrus and combining them with an Omni (Sight Sciences) goniotomy with viscodilation or a Kahook Dual Blade (KDB, New World Medical) goniotomy. By mixing and matching these types of procedures, we can often lower pressures as much as filtering surgery would while avoiding some of the risks associated with those surgeries.”
According to Dr. Singh, the list of possible MIGS combinations is expanding quickly.
“Combining MIGS mechanisms to complement each other at the time of a single surgery is generating excitement among surgeons,” he says. “Not only can we combine a trabecular meshwork bypass stent with cataract surgery, we can also perform viscodilation of the outflow system or decrease inflow at the same time. We can implant a stent after canaloplasty or endocyclophotocoagulation (ECP). Viscodilation, trabecular meshwork removal, and ECP are also standalone procedures that are usually well-covered by most insurance carriers.”
Adjunctive Therapies
“It takes confidence to go back into the ASC specifically to perform a glaucoma procedure,” Dr. Singh says. “You must have confidence in the product and your skill set. What’s helping our outcomes, and the reason why I feel more comfortable offering standalone MIGS, is because we have other technologies, such as selective laser trabeculoplasty, that we can use after a MIGS if the pressure is not quite low enough. And now we have a drug delivery option as a potential adjunct.”
Earlier this year, the FDA approved Durysta (bimatoprost implant; Allergan), the first intracameral, sustained-release implant indicated to reduce IOP in patients with open-angle glaucoma or ocular hypertension (Figure 1).3
“Durysta consists of a small biodegradable pellet that releases 10 mcg of bimatoprost into the eye over about 4 months,” Dr. Singh explains. “In some studies, up to 25% of patients achieved two years of efficacy with just one implant.4 Being able to implant a sustained-release antiglaucoma medication at the time of or after a standalone MIGS increases our chances of reducing the number of topical medications a patient may need.”
A New Age of Earlier Intervention
The potential to individualize therapies for glaucoma patients, whether they have early, moderate, or late-stage disease, is an advantage of MIGS.
“We now have many more options available that enable us to tailor a surgical approach to an individual patient,” says Dr. Larsen. “We can do a much better job of minimizing risk and maximizing efficacy.”
Coding Insights
Coding for MIGS devices and procedures continues to evolve, and I urge you to check for the latest updates from Medicare and other third-party payers. Here, I’ll cover briefly several coding issues I have observed.
The first-generation iStent Trabecular Micro-Bypass and the Hydrus Microstent are assigned a temporary CPT code, 0191T. The iStent inject, which deploys two stents, was assigned 0191T for the first stent and 0376T for the second stent. Although many Medicare carriers were initially paying surgeons for both codes, the vast majority of payers now honor only the 0191T for payment. Fortunately, from a surgery center’s point of view, reimbursement for procedures using the 0191T code more than covers the cost of the iStent inject, making this a worthwhile service to provide.
The bundling of canaloplasty (66174) with goniotomy (65820) when performed together in the same setting is another significant change. Until recently, surgeons and surgery centers were billing for both of these procedures; however, in July 2020, the Centers for Medicare & Medicaid Services ruled that the two procedures will be “mutually exclusive,” meaning the codes cannot reasonably be billed for the same eye in the same surgical session.
The Xen Gel Stent, originally approved for ab interno implantation, was assigned the temporary code 0449T; however, upon approval, Medicare carriers and other payers did not recognize this as an approved procedure, and obtaining approval and payment was difficult. When surgeons adopted an ab externo technique, a pre-existing permanent code, 66183 (insertion of an anterior segment drainage device utilizing an external surgical approach without reservoir), could be utilized. From a billing and coding point of view, that “old school” permanent code has been recognized, approved, and reimbursed by Medicare and third-party payers.
— Carlos Buznego, MD
Dr. Singh predicts a new era in glaucoma management. “Earlier intervention for our glaucoma patients is the wave of the future,” he says. “I think we’re entering an age in which glaucoma is a surgical management or procedure-based subspecialty. Topical medications are wonderful when we need them, but they’re not ideal for long-term IOP control. I’m excited about the innovations we’re seeing now, and I look forward to those currently under development. I believe they will give us a better chance a drop-free world for patients to better manage their glaucoma and maintain a high quality of life.” ■
REFERENCES:
- Gazzard G, Konstantakopoulou E, Garway-Heath D, et al. Laser in Glaucoma and Ocular Hypertension (LiGHT) trial. A multicentre, randomised controlled trial: design and methodology. Br J Ophthalmol. 2018;102(5):593-598.
- Samuelson TW, Chang DF, Marquis R, et al. A Schlemm Canal Microstent for Intraocular Pressure Reduction in Primary Open-Angle Glaucoma and Cataract: The HORIZON Study. Ophthalmology. 2019;126(1):29-37.
- Durysta (bimatoprost implant) for intracameral administration [package insert]. Madison, NJ: Allergan USA, Inc.; 2020. https://www.accessdata.fda.gov/drugsatfda_docs/label/2020/211911s000lbl.pdf . Last accessed August 16, 2020.
- Craven ER, Walters T, Christie WC, et al. 24-Month Phase I/II Clinical Trial of Bimatoprost Sustained-Release Implant (Bimatoprost SR) in Glaucoma Patients. Drugs. 2020;80(2):167-179.
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