AAO 2023: Combined dual trabecular and suprachoroidal outflow pathways in MIGS procedure

(Image Credit: AdobeStock/rohane)

Reviewed by Gautam Kamthan, MD

Dual-outflow minimally invasive glaucoma surgery (MIGS) intervention of the canal and the suprachoroidal space is surgically and clinically feasible and has a potentially additive/synergistic effect, reported Gautam Kamthan, MD, and colleagues at the American Academy of Ophthalmology annual meeting in San Francisco. He is an Assistant Professor of Ophthalmology at the New York Eye and Ear Infirmary of Mount Sinai, New York.

The 2 major outflow pathways for targeted glaucoma intervention, ie, the trabecular and choroidal outflow pathways, account for more than 60% and 40% to 50%, respectively, of the aqueous outflow; however, the current surgical MIGS paradigm is primarily limited to trabecular/canal surgery and single outflow intervention, Kamthan explained.

The investigators theorized that dual aqueous outflow may be a logical next step that can maximize intraocular pressure (IOP) lowering in glaucoma surgery.

Dual-outflow MIGS procedure

They conducted the first-in-human dual outflow MIGS procedure with combined suprachoroidal biostenting and circumferential trabecular MIGS intervention to determine the surgical feasibility, technique, and outcomes of dual-pathway approach, he explained.

Seven patients were included who underwent the dual intervention: ab interno supraciliary biostenting with donor allograft scleral tissue and canal-based guided circumferential trabeculorrhexis using a super-elastic, shape-memory nitinol device (T-Rex, Iantrek, Inc.) to increase the total aqueous outflow; the device facilitates continuous, non-cutting, guided trabeculorrhexis up to 180 degrees.

Phacoemulsification was performed in all cases.

The minimally modified homologous scleral allograft used to facilitate supraciliary cleft reinforcement and scaffolding was described as a conforming implant material, ie, a soft, scleral-wall compliant bio-tissue to structurally reinforce the cyclodialysis cleft. There was no hardware such as plastic, metal, or a rigid foreign body, involved.

Dual outflow results

The investigators reported that the 7 subjects had a successful supraciliary, canal, and phacoemulsification intervention. One patient underwent pre-treatment with the miLoop (Zeiss) microintervential lens fragmentation device.

Among the 7 patients, the average baseline IOP was 19.1 mmHg that decreased to 12.2 mmHg at 6 months. The average number of medications decreased from 1 at baseline to 0.80 at 6 months.

No adverse events occurred intraoperatively or postoperatively.

Kamthan summarized the results:

• Successful dual-outflow pathway implantable plus non-implantable ab-interno MIGS intervention was achieved in all subjects.
• No serious and clinically significant intraoperative complications occurred.
• The initial MIGS intervention did not interfere with the successful completion of the subsequent MIGS procedure or follow-on phacoemulsification
• For optimal visualization, canal intervention should precede supraciliary intervention
• There was a sustained reduction in IOP from the preoperative baseline value with a concurrent reduction in IOP-lowering medications.
• No persistent and visually significant postoperative hyphema, hypotony, or iritis developed

The authors concluded, “Dual-outflow MIGS intervention of the canal and the suprachoroidal space is surgically and clinically feasible and had a potentially additive/synergistic effect. The safety profile of the dual-outflow intervention appears consistent with the MIGS-like safety profile of the underlying interventions.”