Advanced Glaucoma Surgical Procedures: A Clinical Overview of Techniques, Outcomes, and Emerging Innovations

Advanced glaucoma surgical procedures represent the critical next step when topical ocular hypotensive treatment and selective laser trabeculoplasty fail to adequately control intraocular pressure (IOP). Because glaucoma-related optic nerve damage is irreversible, the clinical imperative is to intervene before progression accelerates. 1 The surgical landscape has expanded considerably, ranging from minimally invasive micro-stent implantation to complex drainage device placements and novel combination procedures tailored to disease severity, anatomy, and patient history. 2

The Clinical Rationale for Surgical Intervention

Glaucoma surgery is formally considered when medications do not halt disease progression, when a patient cannot tolerate daily eye drops, or when an acute presentation requires immediate pressure relief. 3 The American Academy of Ophthalmology (AAO) provides separate surgical guidance for primary open-angle glaucoma and primary angle-closure disease, recognizing that the anatomical subtype fundamentally governs which procedure is appropriate. 4 Approximately one in five patients presenting for cataract surgery has concurrent glaucoma, which creates a clinical rationale for simultaneous intervention through combined procedures that address both conditions in a single operative session. 5

Advanced glaucoma, defined by significant visual field loss and optic nerve cupping, generally requires more aggressive IOP targets and procedures capable of delivering more substantial pressure reduction than first-line MIGS alone can reliably achieve. Higher baseline medication burden has been consistently identified as a predictor of worse surgical success, underscoring the importance of earlier and more decisive intervention planning. 6

Minimally Invasive Glaucoma Surgery: Mechanisms and Evidence

Minimally invasive glaucoma surgery (MIGS) encompasses trabecular, canal-based, subconjunctival, and suprachoroidal approaches that use microscopic instruments and tiny incisions to lower IOP with a generally superior safety profile compared to traditional filtration surgery. 7 Gonioscopy-assisted transluminal trabeculotomy (GATT), a canal-based MIGS technique, has demonstrated efficacy across multiple disease subtypes. A 2026 prospective series of 32 eyes with progressive pigmentary glaucoma undergoing phacoemulsification combined with 360-degree GATT reported qualified success defined as IOP at or below 18 mmHg with a minimum 20% reduction from baseline at 24 months. 8

A retrospective cohort of 880 open-angle glaucoma eyes undergoing phacoemulsification combined with Tanito microhook trabeculotomy reported mean IOP decreasing from 17.2 mmHg at baseline to 13.1 mmHg at both 12 and 24 months, with medications declining from 2.6 to 2.0 over the same interval. 9 Two-year cumulative success by AAO MIGS criteria reached 59.0% (95% CI, 54.4 to 63.2). A novel technique, Trabeculotome Tunneling Trabeculoplasty (3T), combines trabecular fenestration, viscoelastic-mediated dilation of Schlemm's canal, and tension suture placement to maintain long-term canal patency while preserving trabecular meshwork structure. 10

Canal-Based and Subconjunctival Device Options

Ab-interno canaloplasty (ABiC) using the iTrack microcatheter dilates the entire circumference of Schlemm's canal to restore physiological outflow resistance. A retrospective study combining ABiC with Hydrus Microstent implantation in severe glaucoma patients (mean age 74.6 years, 90% primary open-angle) followed 69 eyes for a mean of 27.9 months. Mean IOP declined from 17.8 to 15.5 mmHg, medications fell by 47% from 2.10 to 1.12, and the proportion of medication-free eyes increased from 7% to 43%. 11

The XEN Gel Stent, a subconjunctival device offering greater predictability and fewer vision-threatening complications than trabeculectomy in appropriately selected patients, has been assessed in a comprehensive 2026 narrative review covering indications, surgical technique, postoperative management, and revision outcomes. 12 Atypical placements have also been reported: a 2026 Korean case report described successful XEN45 Gel Stent implantation into the ciliary sulcus in a patient with secondary traumatic glaucoma and an extremely narrow anterior chamber angle, where IOP decreased from 30 mmHg to a stable range of 6 to 10 mmHg over 12 months of follow-up. 13

Traditional Filtration Surgery and Glaucoma Drainage Devices

Trabeculectomy, the long-established gold-standard filtration procedure, creates a fistula in the sclera that allows aqueous humor to drain into a subconjunctival bleb. Computational fluid dynamics modeling published in 2025 demonstrated that modified non-penetrating deep sclerectomy including juxtacanalicular trabecular meshwork peel can achieve IOP reduction comparable to trabeculectomy, while standard non-penetrating deep sclerectomy alone produces a postoperative IOP of approximately 23.4 mmHg compared to 7 mmHg for trabeculectomy. 14 Glaucoma drainage devices (GDDs), such as the Baerveldt 350 mm², Ahmed valve, and PAUL Glaucoma Implant, are indicated for patients who have failed prior surgery or carry high-risk features for trabeculectomy failure.

A retrospective case series from Moorfields Eye Hospital reported ciliary sulcus placement of PAUL and Baerveldt implants in 10 eyes with mean follow-up of 47.7 months. Mean IOP decreased significantly from 28.7 mmHg preoperatively to 14.4 mmHg at final follow-up, and median medications fell from three to 1.5. 15 A novel flat drainage device, the Implante Plano Miranda (IPM), was assessed in a Phase II trial of 24 eyes with uncontrolled primary open-angle glaucoma despite maximal tolerated medical therapy, with results published in April 2026 by investigators at the John A. Moran Eye Center among other institutions. 16

Complex and Combination Procedures for Advanced Disease

Patients with primary angle-closure glaucoma (PACG) complicated by extensive peripheral anterior synechiae present a particular surgical challenge. A 2026 retrospective cohort pilot study evaluated phacogoniosynechialysis combined with viscocanalostomy and Ologen implant in 27 eyes with PACG and peripheral anterior synechiae of 270 degrees or greater. Complete success was achieved in 19 cases (70.4%), qualified success in 6 cases (22.2%), and failure in 2 cases (7.4%). Mean IOP decreased by 13.33 mmHg, and mean antiglaucoma medications decreased by 2.74. 17

For advanced glaucoma in populations with anatomical or demographic risk factors, novel device configurations are under investigation. A six-month retrospective study at Advanced Eyecare of New York assessed a modified Ahmed ClearPath 250 mm² glaucoma drainage device placed in the retrobulbar and intraconal space via inferior sclerotomy combined with cataract extraction in Black and Afro-Latino patients with advanced glaucoma. The study focused on surgical tolerability and device stability, with investigators acknowledging sample size limitations in a 12-patient cohort. 18 Combined ab-interno canaloplasty and GATT using the iTrack catheter has also been evaluated for secondary open-angle glaucoma caused by sustained IOP elevation following intravitreal anti-VEGF or steroid injections, with outcomes assessed using AAO surgical success criteria. 19

Emerging Technologies and Risk Considerations

Robotic assistance is beginning to enter the glaucoma surgical workflow. A 2026 preclinical study examined a robotic endoscope-holding system (OQrimo) for Preserflo MicroShunt implantation using porcine eyes with simulated corneal opacity. The robotic group achieved a tube-to-endothelium distance of 1.96 mm under normal conditions versus 1.13 mm in the conventional group, and 1.85 mm versus 1.12 mm under simulated opacity, indicating more favorable tube positioning. No intraoperative mechanical trauma to the cornea, iris, or lens occurred. 20 Sustained drug delivery implants and AI-guided surgical planning tools are also beginning to influence device selection and refractive outcome prediction. 21

Every surgical approach carries a distinct risk profile that clinicians and patients must weigh carefully. Trabeculectomy and tube shunts carry risks of hypotony, bleb-related infection, and late failure from fibrosis. MIGS procedures carry lower individual complication rates but may be insufficient for advanced disease requiring very low IOP targets. Angle-closure surgeries carry specific risks including malignant glaucoma, which occurred in three of 27 patients in the PACG viscocanalostomy series. 17 The Japanese Flanged Cord (JFC) method, developed at Kyoto University, addresses postoperative hypotony following non-valved GDD implantation using a polyvinylidene fluoride suture with a thermally created terminal flange as an intraluminal plug, illustrating how technical refinements continue to address known complication pathways. 22

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13. Journal of the Korean Ophthalmological Society - XEN Gel Stent Implantation into the Ciliary Sulcus in Secondary Traumatic Glaucoma (jkos.org)
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