Uveoscleral outflow reloaded: bio-interventional cyclodialysis
The contents of this article are informational only and are not intended to be a substitute for professional medical advice, diagnosis, or treatment recommendations. This editorial presents the views and experiences of the authors and does not reflect the opinions or recommendations of the publisher of Ophthalmology 360.
By Ike Ahmed, MD; Robert Weinreb, MD; John McInnes, MD, JD
Quiet Transformation: The Emergence of BIGS
The crowded interventional glaucoma landscape garners much attention in glaucoma, and significant advancements can sometimes be overlooked. Last year, however, was quietly notable for the evolution of uveoscleral outflow surgery, marked by the introduction of new interventional technologies.
Iantrek focuses on developing methods to surgically enhance uveoscleral outflow. In parallel, the company has introduced a new category of treatment: bio-interventional glaucoma surgery (BIGS). Recent peer-reviewed data have provided evidence supporting this approach, suggesting its potential to expand surgical options for the management of glaucoma.1,2
Cyclodialysis Reinvented: Bio-Interventional Surgery With Allogeneic Bio-Tissue
Cyclodialysis, first introduced in 1907, is undergoing renewed interest as a method for accessing the uveoscleral pathway. Historically, it was one of the earliest ab-interno outflow procedures, creating a conduit for aqueous flow. While initially adopted as a glaucoma treatment, its use declined due to limitations in instrumentation and issues with restenosis of the filtration conduit. Advances in surgical techniques and instrumentation now offer an opportunity to address these challenges.
Iantrek’s CycloPen™ is a tool designed for controlled, standardized ab-interno cyclodialysis. This procedure is performed as one part of a multi-step intervention in which the creation of a cyclodialysis is followed by visco-cycloplasty to delineate the filtration reservoir. A second procedure is then performed: scleral reinforcement using AlloFlo™ bio-tissue. This is a homologous allogeneic bio-tissue that provides endoscleral reinforcement.
This approach aims to enhance the durability and functionality of the filtration conduit while minimizing complications associated with previous techniques. The properties of AlloFlo™ biologic scaffold material address some of the limitations of rigid implants. The porous, hydroconductive, acellular biomatrix is sterile, non-resorbable, and has a long shelf life. Its use reduces the likelihood of inflammatory or fibrotic responses and avoids the risks associated with rigid hardware, such as impact on adjacent tissues.3
Clinical Outcomes and Real-World Evidence
Emerging clinical data demonstrate the potential of bio-interventional cyclodialysis. In a peer-reviewed study of 117 eyes, patients experienced a 27.1% reduction in mean medicated intraocular pressure (IOP) at 12 months.1 Among eyes with a baseline medicated IOP >21 mmHg (n=45), the reduction was 39.7%, with a significant decrease in the mean number of medications to 0.8 ± 0.9 (P<.01).1
The procedure’s safety profile was consistent with other angle-based surgeries, with no major adverse events reported. This study included a diverse patient population, reflecting real-world conditions, and did not require washout periods. Nearly half of the patients had mild glaucoma, suggesting potential applications for this technique in combination with cataract surgery. The findings also indicate a possible role in standalone procedures for moderate-to-advanced glaucoma cases. These outcomes align with the mechanism of action of prostaglandin analogues, which enhance uveoscleral outflow and are widely used as first-line pharmacotherapy.
Reimbursement
Bio-reinforced cyclodialysis is a multi-interventional surgical approach consisting of discrete procedures: (1) cyclodialysis creation with visco-cycloplasty and (2) endoscleral allograft reinforcement. These are enhanced interventions using modernized instrumentation and technical approaches for conventional procedures. Therefore, a well-trodden reimbursement paradigm is in place.
For cyclodialysis and scleral reinforcement, there are well-established category I CPT codes. The cyclodialysis CPT code 66740 covers the cyclodialysis procedure which is the primary mechanism for enhanced outflow. The scleral reinforcement code 67255 covers the procedure for endoscleral reinforcement and includes the allograft. This is no different than the decades-long precedent of scleral reinforcement for glaucoma drainage implants (GDIs; eg, the Ahmed and Baerveldt shunts), which is the prevailing clinical use of scleral reinforcement in ocular surgery.
In the specific case of external shunts, we no longer bill 67255 separately after the AMA created a separate CPT code for GDIs that bundles the allograft scleral reinforcement procedure and the allograft tissue.
Conclusion
The renewed focus on uveoscleral outflow and the application of bio-interventional techniques highlight a significant evolution in glaucoma surgery. Advances in instrumentation, combined with bio-compatible materials like AlloFlo™, offer a new avenue for addressing long-standing challenges in glaucoma management. While further studies are needed to validate long-term outcomes, the early evidence positions this approach as a promising addition to the surgical landscape, offering potential benefits for a wide range of patients.
Ike Ahmed, MD, is the John R. and Hazel M. Robertson Presidential Endowed Chair and Professor in the Department of Ophthalmology and Visual Sciences at the University of Utah, USA. He is also Research Director of the Kensington Eye Institute at the University of Toronto in Canada and Chief Innovation Officer of the Prism Eye Institute in Oakville, Ontario, Canada. Disclosures: Consultant – Iantrek.
Robert N. Weinreb, MD, is the Distinguished Professor and Chair of Ophthalmology; Director of the Shiley Eye Institute; Distinguished Professor of Bioengineering; Director of the Hamilton Glaucoma Center; and Morris Gleich MD Chair of Glaucoma at the University of California, San Diego. Disclosures: Board of Directors – Iantrek.
John McInnes, MD, JD, is an ophthalmologist and practices law at Arnold & Porter. He rejoined the firm after several years as the Director of the Division of Outpatient Care in the Center for Medicare at the Centers for Medicare & Medicaid Services (CMS) and as a Medical Officer at the Center for Medicare and Medicaid Innovation at CMS. Disclosures: Consultant – Iantrek.
References
- Ianchulev T, Weinreb RN, Calvo EA, et al. Bio-interventional cyclodialysis and allograft scleral reinforcement for uveoscleral outflow enhancement in open-angle glaucoma patients: one-year clinical outcomes. Clin Ophthalmol. 2024;18:3605-3614. doi:10.2147/OPTH.S496631
- Chaya CJ, Herndon LW, Lince J, et al. Surgical outcomes, ocular safety and tolerability of bio-interventional cyclodialysis with allograft scleral reinforcement: clinical experience of more than 240 cases. J Clin Med. 2024;13(16):4593. doi:10.3390/JCM13164593
- Carnicer-Lombarte, A, Barone DG, Dimov IB, et al. Mechanical matching of implant to host minimizes foreign body reaction. bioRxiv. 2019. https://doi.org/10.1101/829648