Bleb-forming MIGS procedures offer low complication rates
In addition, the procedures do not jeopardize possible future surgeries.
Presenting glaucoma patients with a minimally invasive approach to lower their IOP with a bleb-forming MIGS procedure can be an appropriate alternative to traditional trabeculectomy or tube surgery.
The Xen gel stent (Allergan) and the not-yet approved PreserFlo microshunt (Santen) can result in improved outcomes and minimized complication profiles for patients early in their disease process, OSN Technology Board Member Carlos Buznego, MD, said.
“We’re able to offer this to patients early in the disease process, but we have to be aware that success rates may not be as high as we hope. However, if we can minimize complication rates and not jeopardize future surgeries, then I feel that offering these MIGS bleb type procedures makes a lot of sense,” Buznego said.
More therapies available
Traditional glaucoma treatments, such as topical medication or laser trabeculoplasty, may not be sufficient for many patients. Patients are living longer with their disease and are not as compliant with topical medication as they claim, Buznego said.
MIGS has offered these patients an alternative to traditional glaucoma therapies. There are many effective devices that utilize the trabecular meshwork or Schlemm’s canal, such as the Glaukos iStent or iStent inject, and several procedures that open up Schlemm’s canal or the trabecular meshwork, Buznego said.
“However, more and more we realize there are patients who don’t respond to this therapy, and the traditional aqueous pathway is no longer working. ... We need to find a different pathway to divert fluid,” he said.
MIGS procedures are less invasive and potentially safer, and they have an almost similar efficacy profile as traditional therapies, such as trabeculectomy or a tube shunt, Davinder S. Grover, MD, MPH, told Ocular Surgery News.
The Xen gel stent creates a “predictable and effective” standardized outflow pathway in a minimally invasive method and can be performed via an ab interno or ab externo approach, he said.
“The patients have a rapid visual recovery and can usually return to a relatively normal level of activity within 1 to 2 weeks. Many would argue that the gel stent is safer and less invasive than a traditional trabeculectomy or a tube shunt, and based on various studies, the success rates are usually somewhat similar,” he said.
Two strong approaches
Both ab interno and ab externo approaches with the Xen work well, Buznego said, but the ab externo approach allows the surgeon to use their dominant hand regardless of whether the procedure is on the right or left eye. The ab interno approach requires a surgeon to use their nondominant hand for half of cases.
The Xen is a bleb-forming procedure, which may dissuade physicians from the surgery. Based on several international studies, the needling rate postoperatively is usually between 20% and 40%, Grover said.
“My partner, Ron Fellman, MD, and I developed a microshunt spatula (GF microshunt spatula, Epsilon USA) that has allowed postoperative wound management and manipulation to be safer and more predictable,” Grover said.
The PreserFlo is in the same unique category of subconjunctival MIGS procedures as the Xen. Both create a more predictable outflow pathway, have an increased safety profile and show improved anterior chamber stability, he said.
While not yet approved by the FDA, many expect the PreserFlo to soon be approved, Buznego said.
The device requires the opening of the conjunctiva, followed by a scleral tunnel incision with entry into the anterior chamber using a specialized keratome, he said.
“The stent is then placed in that tunnel with the tip into the anterior chamber and the distal tip in the subconjunctival space. The technique also utilizes mitomycin C and a straightforward conjunctival closure. To this point, the device has not yet been available to clinicians in the U.S. outside of the clinical trial,” he said.
Options for all surgeons
Buznego and Grover both agreed the Xen and the PreserFlo will continue to be adapted by glaucoma surgeons into their practices, noting that comprehensive ophthalmologists who are comfortable with bleb management and conjunctiva dissection may also find the MIGS devices acceptable.
The surgeries can be “more readily adapted” by comprehensive ophthalmologists who treat patients with moderate to advanced glaucoma but are not comfortable with trabeculectomies or tubes, Grover said.
“Before one can jump into these surgeries, proper training is required with an emphasis on intraoperative and postoperative management and decision making,” he said.
Surgeons who use trabecular micro-bypass stents may find the necessary postoperative care for these MIGS procedures to be too extensive, Buznego said. – by Robert Linnehan
- Forand RL. Santen plans entry in US glaucoma market. www.healio.com/ophthalmology/ophthalmic-business/news/online/%7B2df7d81d-306a-45ae-bc8b-f60f38d29675%7D/santen-plans-entry-in-us-glaucoma-market. Published Jan. 14, 2020. Accessed Feb. 11, 2020.
- Needling revision beneficial after Xen implantation. www.healio.com/ophthalmology/glaucoma/news/online/%7B6b045256-0183-425a-a038-c3a37d44a8aa%7D/needling-revision-beneficial-after-xen-implantation. Published Jan. 3, 2020. Accessed Feb. 11, 2020.
- For more information:
- Carlos Buznego, MD, can be reached at Center for Excellence in Eye Care, 8940 N. Kendall Drive, 400 East, Miami, FL 33176; email: firstname.lastname@example.org.
- Davinder S. Grover, MD, MPH, can be reached at Glaucoma Associates of Texas, 10740 N. Central Expressway, Suite 300, Dallas, TX 75231; email: email@example.com.
Disclosures: Buznego reports he is a consultant and speaker for Alcon, Allergan, Glaukos, Bausch + Lomb, Kala, Sun, Lensar; consultant and shareholder for Eyevance; shareholder for RxSight and CXLO; and investigator for Glaukos. Grover reports he receives research support from Alcon and Allergan; is a consultant and speaker with Allergan, New World Medical and Reichert; is a speaker for Aerie Pharmaceuticals, Bausch + Lomb and Glaukos; is on the medical advisory board for MicroOptx; and was an investigator for the InnFocus FDA trial, now called PreserFlo.