Advanced glaucoma surgery techniques in clinical practice

Advanced glaucoma surgery techniques in clinical practice have undergone substantial transformation over the past decade, driven by a growing body of peer-reviewed evidence, improved device engineering, and refined patient selection criteria. Glaucoma remains a leading cause of irreversible blindness globally, and because optic nerve damage cannot be reversed, the sole modifiable treatment target remains intraocular pressure (IOP) reduction. Surgical strategies now range from microincisional trabecular approaches to complex drainage device implantations, each with distinct risk profiles, efficacy thresholds, and anatomical requirements.1

The Surgical Landscape: Conventional Filtration Surgery and Its Ongoing Role

Trabeculectomy, augmented with the antifibrotic agent mitomycin C (MMC), continues to be recognized as the gold standard operation for achieving low target IOPs in advanced glaucoma. Excessive postoperative wound healing and subconjunctival fibrosis remain the principal causes of trabeculectomy failure, and MMC has been in intraoperative clinical use since the 1980s as an alkylating antimetabolite to modulate scarring.2 Data from the EURACCUR study, which analyzed 300 consecutive glaucoma surgeries across European centers in 2025, found trabeculectomy accounted for 38.3% of procedures, with minimally invasive bleb-forming surgeries representing 28.3% and drainage devices 11.3%.3

The same EURACCUR dataset revealed that the median preoperative IOP at the time of surgical referral was 22 mmHg, mean deviation was -14.47 dB, and retinal nerve fibre layer thickness averaged 60 micrometres. Critically, referral was timely in only 34.7% of cases, later than optimal in 35.7%, and categorized as late in 29.7%, with late referrals associated with higher IOP, more advanced mean deviation, and thinner RNFL measurements.3 Prof. Keith Barton of Moorfields Eye Hospital has emphasized that performing multiple minimally invasive procedures on complex cases can generate more risk than benefit, and that efficacy must be balanced against safety considerations in advanced disease.4

Minimally Invasive Glaucoma Surgery: Trabecular and Canal-Based Techniques

Minimally invasive glaucoma surgery (MIGS) encompasses a broad classification of procedures targeting the trabecular meshwork and Schlemm's canal, offering a higher safety profile and faster postoperative recovery compared to traditional filtration surgery. The Tanito microhook (TMH) trabeculotomy combined with phacoemulsification has been studied in a retrospective cohort of 880 open-angle glaucoma eyes, including 761 primary open-angle and 119 exfoliation cases. Mean IOP decreased from 17.2 mmHg at baseline to 13.1 mmHg at both 12 and 24 months, and medication burden fell from 2.6 to 2.0 over the same period. Two-year cumulative success by AAO MIGS criteria reached 59.0%.5

Gonioscopy-assisted transluminal trabeculotomy (GATT) has demonstrated strong results in secondary glaucoma subtypes. In a multicenter retrospective study of 34 eyes with Fuchs uveitis syndrome-associated open-angle glaucoma, mean preoperative IOP was 34.9 mmHg on 3.5 medications. At final visit after a mean follow-up of 28 months, IOP fell to 15.7 mmHg, representing a 52.7% reduction, while medication burden dropped by 70.4% to 1.1 agents. The cumulative probability of qualified success at 24 months was 88.2%.6 A separate prospective series evaluated GATT combined with phacoemulsification for 32 eyes with progressive pigmentary glaucoma, defining qualified success as IOP at or below 18 mmHg with a 20% IOP reduction from baseline without further surgery at 24 months.7

Novel MIGS Protocols: 3T, Ab-Interno Canaloplasty, and Combination Implantation

Trabeculotome Tunneling Trabeculoplasty (3T) is a recently described MIGS protocol designed to restore physiological aqueous outflow while preserving trabecular meshwork architecture. The three-step technique involves trabecular fenestration using a trabeculotome, viscoelastic-mediated dilation of Schlemm's canal, and placement of a tension suture to maintain long-term canal patency. Published in the Journal of Visualized Experiments in 2026, representative single-center outcomes demonstrate significant IOP reduction and decreased antiglaucoma medication dependence with a low complication profile.8

Ab-interno canaloplasty using the iTrack microcatheter combined with concurrent Hydrus Microstent implantation during cataract surgery has been evaluated in severe glaucoma patients with a mean age of 74.6 years, predominantly primary open-angle disease (90%). Across 69 eyes followed for a mean of 27.9 months, mean IOP decreased from 17.8 to 15.5 mmHg, while mean medications fell by 47% from 2.10 to 1.12. Medication-free eyes increased from 7% at baseline to 43% at last follow-up.9 The iTrack Global Data Registry (iTGDR), a prospective multicentre study collecting real-world outcomes across approximately 20 sites in the US and Canada, is further quantifying canaloplasty results at scale.4

Drainage Devices and Tube Shunt Innovations for Advanced Disease

Glaucoma drainage devices (GDDs) remain a primary surgical option for advanced or refractory glaucoma, particularly in the context of corneal scarring, neovascular glaucoma, or prior failed trabeculectomies. A simplified technique for ciliary sulcus placement of GDDs was described from Moorfields Eye Hospital NHS Foundation Trust using a PAUL Glaucoma Implant or Baerveldt 350 mm2 device, with a 90-degree bent needle creating a controlled scleral tunnel. Mean follow-up was 47.7 months, mean IOP decreased from 28.7 to 14.4 mmHg, and median medications fell from three to 1.5.10 A novel retrobulbar/intraconal approach using a modified Ahmed ClearPath 250 mm2 device combined with cataract extraction was evaluated in Black and Afro-Latino patients with advanced glaucoma, reporting preliminary safety and device stability data at six months.11

The Japanese Flanged Cord (JFC) method, developed at Kyoto University Graduate School of Medicine, addresses postoperative hypotony following non-valved GDD implantation through a 5-0 PVDF or polypropylene monofilament suture fitted with a thermally created terminal flange functioning as an intraluminal plug. The external end is secured subconjunctivally for later removal, avoiding tube ligation while blocking aqueous flow during the early postoperative healing phase.12 Additionally, an upside-down pars plana Ahmed glaucoma valve technique evaluated in 10 eyes across a mean follow-up of 45.9 months showed mean IOP declining from 35.8 to 14.9 mmHg at 66 months, with average monthly corneal endothelial cell density loss at 0.28%.13

XEN Gel Stent: Indications, Surgical Approaches, and Outcomes

The XEN45 Gel Stent provides subconjunctival aqueous drainage and is positioned as a less invasive alternative to trabeculectomy for patients where topical therapy and laser trabeculoplasty have been insufficient. A 2026 systematic review and meta-analysis from researchers at King Saud bin Abdulaziz University analyzed 614 eyes across six retrospective studies comparing the ab-externo and ab-interno implantation approaches, with 318 eyes treated via ab-externo and the remainder via ab-interno, using PubMed, Cochrane Library, and Web of Science databases.14 A comprehensive narrative review published in Ophthalmology and Therapy in January 2026 further characterized predictors of clinical outcomes, adverse event profiles, and postoperative management strategies, drawing on literature and clinical experience to provide technique optimization recommendations.15

Patient-specific anatomical features, angle structure, and disease severity all influence XEN implant selection. The device targets patients where medical treatments have failed and is evaluated against trabeculectomy and tube shunts on the basis of predictability and vision-threatening complication rates. Postoperative needling and bleb management represent recognized components of XEN follow-up, and surgeon familiarity with revision techniques is considered essential to optimizing long-term results.15

Population-Specific Challenges and Robotic-Assisted Precision

African-derived populations face disproportionately elevated rates of primary open-angle glaucoma and carry increased risks of surgical failure linked to Tenon's capsule thickness, variable wound healing biology, and elevated scarring tendency. A perspectives report from six UK-based consultant glaucoma surgeons, including specialists from Moorfields, King's College Hospital, and Manchester Royal Eye Hospital, outlined strategies for optimizing trabeculectomy and Preserflo MicroShunt outcomes in this population. Preoperative recommendations include ocular surface optimization and reduction of preservative exposure from topical medications.16

Robotic-assisted surgical visualization represents an emerging area of technical development. A preclinical study evaluating the OQrimo endoscope-holding robot during Preserflo MicroShunt implantation in porcine eyes found that tube-endothelium distance was significantly greater in the robotic group under both normal visualization (1.96 vs 1.13 mm, p=0.009) and simulated corneal opacity conditions (1.85 vs 1.12 mm, p=0.015), indicating more favorable tube positioning. Continuous endoscopic visualization enabled successful MicroShunt implantation in all eyes without intraoperative mechanical trauma to the cornea, iris, or lens.17 These data position robotic assistance as a potential tool for expanding surgical feasibility in eyes with compromised anterior segment visualization, though clinical validation in human subjects remains an ongoing area of investigation.

Sources

1. Ophthalmology Advisor – Glaucoma Surgery: Conventional and Minimally Invasive (ophthalmologyadvisor.com)
2. TNOA Journal of Ophthalmic Science and Research – Intraoperative Mitomycin C in Trabeculectomy: Principles, Techniques, and Clinical Outcomes (doi.org/10.4103/tjosr.tjosr_140_25)
3. Graefe's Archive for Clinical and Experimental Ophthalmology – Referral for glaucoma surgery and types of surgery in different European regions in 2025, the EURACCUR study (link.springer.com/article/10.1007/s00417-026-07155-x)
4. Medical Independent – Challenges in managing complex glaucoma, Prof Keith Barton (medicalindependent.ie)
5. Nature Eye – Outcomes of phacoemulsification combined with ab interno trabeculotomy: stratified by incision extent, glaucoma severity, and baseline number of medications (nature.com/articles/s41433-026-04749-x)
6. Graefe's Archive for Clinical and Experimental Ophthalmology – Efficacy and safety of gonioscopy-assisted transluminal trabeculotomy in glaucoma secondary to Fuchs uveitis syndrome (link.springer.com/article/10.1007/s00417-026-07394-y)
7. Graefe's Archive for Clinical and Experimental Ophthalmology – Lens extraction combined with circumferential ab interno trabeculotomy to treat pigmentary glaucoma (link.springer.com/article/10.1007/s00417-026-07187-3)
8. Journal of Visualized Experiments – Trabeculotome Tunneling Trabeculoplasty (3T): A Step-by-step Surgical Protocol for Primary Open-angle Glaucoma (doi.org/10.3791/70148)
9. Dove Medical Press / Clinical Ophthalmology – Effectiveness and Safety of Combined Ab-Interno Canaloplasty and Microstent Implantation in Severe Glaucoma (dovepress.com)
10. Cureus – A Simplified Technique for Glaucoma Drainage Device Ciliary Sulcus Implantation (doi.org/10.7759/cureus.105123)
11. Frontiers in Ophthalmology – Novel retrobulbar/intraconal surgical approach with combined cataract extraction and modified AHMED ClearPath 250mm2 tube (frontiersin.org/articles/10.3389/fopht.2026.1738832)
12. Dove Medical Press / Clinical Ophthalmology – The JFC Method: A Proof-of-Concept Report on Flanged-Cord Temporary Occlusion for Non-Valved Glaucoma Drainage Devices (dovepress.com)
13. Cureus – Clinical and Imaging Outcomes of the Upside-Down Pars Plana Ahmed Glaucoma Valve Implantation (sah.borca.ai/papers/284675415)
14. Clinical Ophthalmology – Efficacy and Safety of Ab-externo vs Ab-interno Approach of XEN45 Gel Stent Implantation: A Systematic Review and Meta-Analysis (doi.org/10.2147/opth.s575562)
15. Ophthalmology and Therapy / Springer Nature – Update on XEN Gel Stent: A Narrative Review on Indications, Surgical Technique, and Postoperative Management (link.springer.com/article/10.1007/s40123-025-01295-9)
16. Clinical Ophthalmology / Dove Medical Press – Optimizing Filtration Surgery Procedures in African-Derived Populations: Trabeculectomy and Preserflo (doi.org/10.2147/opth.s570347)
17. Scientific Reports / Nature – Preclinical assessment of Preserflo MicroShunt implantation using an intraocular endoscope-holding robot (nature.com/articles/s41598-026-56997-2)