Stegmann Canal Expander Research Articles

Flap-sparing canaloplasty: a modified approach to Schlemm's canal.

To present a modified surgical technique for canaloplasty with the Stegmann Canal Expander obviating the need for lamellar scleral dissection. After limbal peritomy of the conjunctiva, the sclera is not dissected in the classic lamellar fashion with superficial and deep scleral flaps but is successively 'scratched' down by radial incision until Schlemm's canal (SC) is opened (trench cut). Following canal opening and viscodilation with a microcannula and sodium hyaluronidate, one Stegmann Canal Expander is implanted on either side of the canal ostia and the scleral incision is closed watertight. Twenty-seven eyes with primary open-angle glaucoma (POAG) were consecutively operated on using this modified technique. In all eyes, SC was successively opened, but exposure of the choroid and rupture of trabeculo-Descemet's membrane with iris prolapse or filtering blebs were not found. Adverse events included trimming of the expander in one eye for incomplete implantation during surgery, and transient microhyphaema in five eyes post-surgery. Mean intraocular pressure (IOP) was 31.9mmHg ± 6.0 (SD) before surgery and 14.0mmHg ± 2.5 (SD) 6months and 15.2mmHg ± 1.95 (SD) 12months after surgery. The flap-sparing, trench-cut incision technique may reduce the risk of complications in canaloplasty with the Stegmann Canal Expander while effectively lowering IOP in POAG patients.

Comparing the mid‐term efficacy and safety of the Stegmann Canal Expander Canaloplasty with the prolene suture Canaloplasty in cases of open angle glaucoma

Comparing the mid‐term efficacy and safety of the Stegmann Canal Expander Canaloplasty with the prolene suture Canaloplasty in cases of open angle glaucoma

Stegmann Canal Expander for canaloplasty: A novel technique.

The concept of canaloplasty is to increase aqueous egress through all structures that control the aqueous outflow, such as the trabecular meshwork, Schlemm's canal, and collector channels, by viscomodulation and by placing of a suture stent into the canal. Clinical studies show canaloplasty to be safe and efficient in lowering the intraocular pressure; however, proper knotting of the tensioning suture is technically challenging and even impossible if circumferential cannulation cannot be achieved; furthermore, protrusion of the suture stent is a potential lifelong risk. The specific design of the Stegmann Canal Expander allows a permanent expansion of the canal and distension of the trabecular meshwork. Two expanders are implanted on either side of the surgically created ostium of Schlemm's canal to treat half of the circumferential outflow system. This article describes the technique step by step, provides the clinician with surgical pearls, and highlights the management of adverse events. Technically, implantation of the Stegmann Canal Expander is simple and does not require a long learning curve, compared to placing and knotting a tensioning suture. Most issues are related to the two-flap dissection technique (deep sclerectomy technique) and not to implantation of the Stegmann Canal Expander. Intraocular pressure reduction without medications to the low teens can be achieved. The Stegmann Canal Expander is a novel micro-device that has the potential to make canaloplasty a simplified, more controlled, and reproducible surgical procedure.

Canaloplasty with Stegmann Canal Expander for primary open‐angle glaucoma: two‐year clinical results

To examine longer-term postsurgical safety and efficacy of a new expander for Schlemm's canal. In a non-comparative, prospective study, 42 White patients with medically uncontrolled primary open-angle glaucoma (POAG) underwent primary canaloplasty with >2-year follow-up. The bleb-independent procedure comprised catheter-assisted canaloplasty and implantation of two Stegmann Canal Expanders to maintain trabecular distension and canal patency over 180°. Intraocular pressure (IOP), glaucoma medication use and complications were assessed. Mean IOP was 26.8±5.6mmHg presurgery, 12.8±1.5mmHg at 6months, 13.2±1.2mmHg at 12months and 13.3±2.5mmHg at 24months (p<0.001). Rate of complete success, defined as IOP ≤21, ≤18 and ≤16mmHg and a≥30% IOP reduction, was 85% (95% CI: 0.76-0.95), 85% (0.76-0.95) and 82% (0.70-0.96) at 12months and 83% (0.73-0.94), 80% (0.70-0.92) and 80% (0.70-0.92) at 24months. Preoperative factors were not significant predictors of ≤16mmHg IOP reduction: IOP (hazard ratio [HR]: 0.68; 95% CI: 0.44-1.04; p=0.08), mean visual defect (1.06; 0.90-1.20; p=0.47), number of medications (0.59; 0.17-2.14; p=0.42) and age (0.96; 0.87-1.13; p=0.41). Number of medications dropped from 2.8±0.4 presurgery to 0.2±0.5 postsurgery (p<0.001). Mean preoperative best-corrected visual acuity was 0.19±SD 0.21 (range: 0-1.6), and logMAR was similar to 0.23±0.16 (range: 0-1.6; p=0.42) after a mean follow-up of 27.4months. Complications included peripheral Descemet's membrane detachment (7.2%) and trimming of the expander (4.7%) during surgery, and transient microhyphaema (23.8%) and IOP elevation (7.2%) postsurgery. Canaloplasty with the Stegmann Canal Expander was a safe and effective procedure to reduce IOP in White patients with moderate to advanced POAG.

Viscocanalostomy and Canaloplasty: ab Externo Schlemm's Canal Surgery.

Ab externo Schlemm's canal (SC) surgery (e.g., viscocanalostomy and canaloplasty) is a valuable alternative to glaucoma filtration surgery. It targets the abnormally high resistance to outflow in the trabecular meshwork (TM) and reestablishes the physiologic outflow system. In viscocanalostomy, viscoelastic substance is injected to dilate SC, which in turn leads to microdisruptions of the inner wall. In canaloplasty, the additional intracanalicular stent (suture or Stegmann Canal Expander®) keeps the canal patent and enhances the circumferential flow. A prerequisite for these procedures to work is the integrity of the distal outflow system, which can be evaluated by 2 clinical tests before surgery: provocative gonioscopy with blood reflux, and fluorescein channelography. Ab externo SC surgery is suitable for open-angle glaucoma, but also for angle closure glaucoma in combination with cataract extraction. Intraocular pressure reduction to the mid-teens for viscocanalostomy and to the lower-teens for canaloplasty can be expected. The majority of complications seen in filtering surgery are largely eliminated by the nonpenetrating and bleb-independent approach. Postoperative care is minimal as no bleb management such as needling is required, and hypotony-related complications are largely avoided by the intrinsic resistance of the physiologic outflow system. With its efficacy and high safety profile, ab externo SC surgery will continue to play an increasing role and will change the current concept of glaucoma surgery towards earlier intervention. Surgeons will be well advised to implement these antimetabolite-free procedures into their armamentarium to meet the expectations of the demanding glaucoma patient.

Canaloplasty with Stegmann's Canal Expander® for open‐angle glaucoma

PurposeTo evaluate the surgical outcome of canaloplasty using Stegmann's canal expander in open‐angle glaucoma (OAG).MethodsProspective, non‐comparative, interventional study. We recruited patients with uncontrolled OAG. All cases were operated by the same surgeon using a standardized canaloplasty procedure with 360‐degrees dilatation of Schlemm's canal (SC) using a flexible ophthalmic microcannula followed by the insertion of the expander into both surgically created SC ostia. Primary outcomes: mean change in intraocular pressure (IOP) and number of glaucoma medications following surgery. Secondary outcomes: complication rates; percentage of eyes with successful insertion of the expander in SC.Results44 eyes of 42 consecutive patients included. 38 (86%) were Caucasians; 32 (73%) female; primary‐, pseudoexfoliative‐, pigmentary‐ OAG had 25 (57%), 17 (39%), 2 (4%) respectively; 30 (68%) were pseudophakic; mean age (±SD) was 77 ± 8 years. All patients reached month‐6 follow‐up visit (range: 6–24). Mean IOP decreased from 22.4 ± 7.8 mmHg before surgery to 8.4 ± 4.2, 12.05 ± 3.59, 11.07 ± 4.08, 11.3 ± 3.51, 11.2 ± 2.6, 11.1 ± 2.7, 11.6 ± 2.3 at day‐1, week‐1, month‐1, ‐3, ‐6, ‐12, ‐24 respectively (p &lt; 0.01). Mean number of glaucoma medications reduced from 3.36 ± 0.74 before surgery to 0.15 ± 0.47 at the last recorded visit (p &lt; 0.01, Wilcoxon). No complication was recorded in 20 eyes (45%); a spontaneously‐resolving hyphema in 14 (32%); a choroidal detachment in 4 eyes (9%); a Descemet's membrane detachment and anterior uveitis each in 3 eyes (7%). Uneventful insertion was achieved in 29 eyes (66%). The stent was trimmed in 2 eyes (4.5%) due to some resistance during insertion and it was inserted only in one side in 8 eyes (18%).ConclusionsCanaloplasty with Stegmann's expander appears to reduce IOP in OAG with minor and self‐limited complications.

A New Expander for Schlemm Canal Surgery in Primary Open-angle Glaucoma-Interim Clinical Results.

To evaluate a new canal expander in circumferential viscocanalostomy (canaloplasty) for whites with primary open-angle glaucoma (POAG). Prospective, single-center, noncomparative study. Twenty-two eyes of 22 consecutive patients with medically uncontrolled POAG underwent primary viscocanalostomy and implantation of the Stegmann Canal Expander into Schlemm canal with a follow-up time of at least 1 year. Schlemm canal was unroofed ab externo, and dilated with viscoelastic material and microcatheter. The Stegmann Canal Expander is a flexible, fenestrated hollow implant of 9 mm in length. One expander was implanted into either side of the surgically created of ostium to keep the Schlemm canal permanently open. The superficial scleral flap was closed watertight. Laser goniopuncture of the trabeculo-Descemet membrane window was performed if postoperative intraocular pressure (IOP) exceeded 16 mm Hg. Complete successes were defined as a confirmed IOP≤21, ≤18, and ≤16 mm Hg without medications, respectively, combined with a 30% IOP reduction. Number of antiglaucomatous medications, best-corrected visual acuity, and intraoperative and postoperative complications were recorded. The mean IOP dropped from 27.1±5.3 mm Hg preoperatively to 13.6±1.6 mm Hg at 6 months, 13.0±1.5 mm Hg at 9 months, and 13.1±2.2 mm Hg at 12 months (P<0.001). The complete success rates for an IOP≤21, ≤18, and ≤16 mm Hg combined with a 30% IOP reduction were 91% [95% confidence interval (CI), 0.80-1.0], 91% (95% CI, 0.80-1.0), and 91.0% (95% CI, 0.80-1.0) at 6 months, and 86% (95% CI, 0.73-1.0), 82% (95% CI, 0.67-1.0), and 82.0% (95% CI, 0.67-1.0) at 12 months. The success rate of an IOP≤16 mm Hg without medications did not depend on age [hazard ratios (HR) 1.02; 95% CI, 0.85-1.12; P=0.74], preoperative IOP (HR 0.97; 95% CI, 0.83-1.23; P=0.89), and mean visual defect (HR 1.05; 95% CI, 0.72-1.27; P=0.76). Laser goniopuncture was performed on 2 eyes (9%) 4.1 months postoperatively; the mean IOP was 19.5 mm Hg before and 13.6 mm Hg after goniopuncture. The number of medications dropped from 2.9±0.6 before surgery to 0.05±0.2 after surgery (P<0.001). The postoperative best-corrected visual acuity at last visit (0.12±0.09; range, 0 to 0.39) was comparable to preoperative values (mean±SD, 0.16±0.10; range, 0 to 0.39) (P=0.35). Minor intraoperative or postoperative complications included microhyphema (8 eyes) and transient elevated IOP (steroid responder; 2 eyes). Implantation of the Stegmann Canal Expander in canaloplasty lowered IOP significantly in POAG without complications related to the device in this 1-year observation period.

Canaloplasty with the Stegmann Canal expander – two years results

PurposeTo assess the safety and efficacy of circumferential viscocanalostomy (canaloplasty) using a new canal expander in Caucasians with primary open‐angle glaucoma (POAG).MethodsThirty‐five eyes of 35 consecutive patients with medically uncontrolled POAG underwent primary canaloplasty and implantation of the Stegmann Canal Expander into Schlemm's canal. Schlemm's canal was unroofed ab externo, and dilated with viscoelastic material and microcatheter. The Stegmann Canal Expander was implanted into the canal lumen, and the superficial scleral flap was closed watertight. Laser goniopuncture of the trabeculo‐Descemet's membrane window was performed if postoperative intraocular pressure (IOP) exceeded 16 mmHg.ResultsThe mean IOP dropped from 26.6 ± 4.2 mm Hg preoperatively to 12.1 ± 2.6 mm Hg at 1 month, 13.1 ± 1.9 mmHg at 6 months, 13.0 ± 1.9 mm Hg at 12 months, and 13.4 ± 2.4 mm Hg at 24 months (p &lt; 0.001). Laser goniopuncture was performed on 5 eyes (14.7%) 6.4 months after surgery; the mean IOP was 19.1 mm Hg before and 14.1 mm Hg after goniopuncture. The number of medications dropped from 2.9 ± 0.3 before surgery to 0.08 ± 0.3 after surgery (p &lt; 0.001). The postoperative BCVA at last visit (0.12 ± 0.09; range, 0–0.39) was comparable to preoperative values (0.16 ± SD 0.10; range, 0–0.39) (p = 0.35). Complications were minor and included microhyphema (14 eyes) and transient elevated IOP (steroid responder; 4 eyes), partial peripheral Descemet's membrane detachment (2 eyes).ConclusionsCanaloplasty with implantation of the Stegmann Canal Expander reduced IOP significantly in POAG with a low risk for complications.

Coming full circle: Canal surgery with/without implants

SummaryCanaloplasty, one of the latest ab externo, non‐penetrating procedures in glaucoma, reduces intraocular pressure by targeting the pathologically high resistance to aqueous outflow and restoring the natural outflow system. After (circumferential) viscodilation of Schlemm's canal, a polypropylene suture is looped through the canal and tightened to distend the trabecular meshwork; alternatively a new device, the Stegmann Canal Expander is implanted. The main advantage of canaloplasty over fistulating trabeculectomy is the independence of a filtering bleb. Furthermore, there is no need for antimetabolites and needling procedures. Canaloplasty as a stand‐alone procedure or combined cataract extraction is proven to be safe and efficient. Technically, the surgeon must understand and respect the microanatomy of the outflow system and the mechanics of the procedure itself. This presentation guides the surgeon through standard canaloplasty and the implantation of the Stegmann Canal Expander, highlights tips and pitfalls, and presents new clinical data.

Channelography and mechanism of action in canaloplasty

Canaloplasty lowers the intraocular pressure (IOP) by restoring the natural outflow system. The success of canaloplasty depends on the function of this system. To evaluate the natural outflow system regarding canaloplasty by two clinical tests, provocative gonioscopy and channelography and to describe the mechanism of action of canaloplasty. Provocative gonioscopy evaluates the pattern of blood reflux which is induced by ocular hypotension as the result of a reversed pressure gradient between the episcleral venous pressure and IOP following paracentesis. In channelography the transtrabecular diffusion and the filling properties of the episcleral venous system are assessed by a microcatheter and a fluorescein tracer. Blood reflux varied greatly in glaucomatous eyes and showed an inverse correlation with the preoperative IOP. The higher the IOP, the poorer the blood reflux. The filling qualities of the episcleral venous system and diffusion through the trabecular meshwork were different. Poor trabecular passage and good episcleral fluorescein outflow indicates patent distal outflow pathways, poor trabecular passage and poor episcleral fluorescein outflow indicates obstructed trabecular meshwork and closed collector channels and good trabecular passage together with poor episcleral fluorescein outflow suggests that the site of impairment is mainly in the distal outflow system. The quality of blood reflux and the characteristics of the episcleral filling and the transtrabecular diffusion by fluorescein represent the clinical state of the outflow pathway and help in the prediction of the surgical outcome in canaloplasty. The mechanism for canaloplasty is not yet completely clarified; currently under discussion are circumferential viscodilation, permanent distension of the inner wall of Schlemm's canal using a suture and a Stegmann canal expander.

Update on Minimally Invasive Glaucoma Surgery (MIGS) and New Implants

Traditional glaucoma surgery has been challenged by the advent of innovative techniques and new implants in the past few years. There is an increasing demand for safer glaucoma surgery offering patients a timely surgical solution in reducing intraocular pressure (IOP) and improving their quality of life. The new procedures and devices aim to lower IOP with a higher safety profile than fistulating surgery (trabeculectomy/drainage tubes) and are collectively termed “minimally invasive glaucoma surgery (MIGS).” The main advantage of MIGS is that they are nonpenetrating and/or bleb-independent procedures, thus avoiding the major complications of fistulating surgery related to blebs and hypotony. In this review, the clinical results of the latest techniques and devices are presented by their approach, ab interno (trabeculotomy, excimer laser trabeculotomy, trabecular microbypass, suprachoroidal shunt, and intracanalicular scaffold) and ab externo (canaloplasty, Stegmann Canal Expander, suprachoroidal Gold microshunt). The drawback of MIGS is that some of these procedures produce a limited IOP reduction compared to trabeculectomy. Currently, MIGS is performed in glaucoma patients with early to moderate disease and preferably in combination with cataract surgery.