36-month effectiveness of ab-interno canaloplasty standalone versus combined with cataract surgery for the treatment of open-angle glaucoma

Canaloplasty via an ab-interno surgical technique in patients with primary angle closure glaucoma

PURPOSE

To investigate the clinical outcomes of canaloplasty performed with the iTrack microcatheter (Nova Eye Medical, Fremont, USA) as a standalone procedure and in combination with phacoemulsification in patients with primary angle-closure glaucoma (PACG).

METHODS

A single-center, retrospective case series of eyes undergoing canaloplasty via an ab-interno technique with a diagnosis of PACG based on gonioscopy findings (Shaffer grading). Patients were excluded if they had previously undergone a glaucoma procedure other than Laser Peripheral Iridotomy (LPI). Eyes were grouped by glaucoma severity based on mean deviation preoperative values. Outcome measures included intraocular pressure (IOP) and number of glaucoma medications.

RESULTS

Sixty eyes (9 canaloplasty-standalone, pseudophakic, and 51 canaloplasty + phaco) were eligible. The mean baseline IOP was 21.9 ± 7.3 mmHg and number of glaucoma medications was 1.95 ± 1.4. At the latest follow-up (mean 26 ± 9.2 months), they were reduced to 14.6 ± 3.7 mmHg (p < 0.001) and 0.96 ± 1.2 (p < 0.001). IOP reduction was statistically significant when canaloplasty was performed as a standalone procedure (baseline 22.78 ± 6.72 vs 17.00 ± 3.42 at the latest follow-up) or combined with phacoemulsification (21.75 ± 7.43 vs 14.21 ± 3.66) or if canaloplasty was performed in mild (20.8 ± 4.93 vs 15.5 ± 3.63), moderate (21.9 ± 8.58 vs 13.9 ± 3.90) or severe (23.5 ± 11.3 vs 12.4 ± 3.20) glaucoma eyes, with no difference between the groups postoperatively. Medication reduction was significant when canaloplasty was performed in combination with phacoemulsification and in mild glaucoma eyes. No serious intraoperative or postoperative complications were reported.

CONCLUSION

Canaloplasty via an ab-interno surgical technique, performed as standalone or combined with phacoemulsification, is a safe and clinically effective treatment in primary angle closure glaucoma patients up to 2 years.

Historical and Contemporary Debates in Schlemm's Canal-Based MIGS

Glaucoma is one of the primary causes of blindness worldwide. Canal opening surgery, a type of minimally invasive glaucoma surgery (MIGS) applied in cases of mild to moderate glaucoma, has gained increasing popularity in recent years due to its efficacy in reducing the intraocular pressure, its safety profile, the simplicity of its technique, and the reduced likelihood of compromised vision. Nevertheless, the existing body of histopathological studies remains insufficient for a comprehensive understanding of post-surgical wound healing. Consequently, debates persist among researchers regarding the mechanism through which Schlemm's canal opening surgery reduces the intraocular pressure, as well as the surgical techniques that may impact the outcomes and the factors influencing surgical success. As the history of MIGS is relatively short and lacks sufficient systemic reviews or meta-analyses evaluating the influence of individual factors, this review was conducted to illuminate the disparities in researchers' opinions at the current stage of research.

A Review of Canaloplasty in the Treatment and Management of Glaucoma

Aim

To review the published literature evaluating the safety and efficacy outcomes of canaloplasty performed in the treatment of glaucoma.

Background

Canaloplasty is a nonpenetrating glaucoma procedure involving combined 360° circumnavigation and viscodilation of Schlemm's canal. The procedure may be performed under an ab externo (with tensioning suture) or ab-interno (conjunctiva-sparing) approach. Given the wide variety of glaucoma procedure types and approaches, further investigation into the role of canaloplasty in ophthalmological practice is warranted. The objectives of this narrative review are to synthesize the existing literature in order to investigate indications, safety and efficacy outcomes, and the optimal place of canaloplasty in glaucoma treatment and management.

Review of results

A total of 60 articles were included in this review. Both ab externo and ab-interno canaloplasty (ABiC) were found to be significantly effective at reducing intraocular pressure (IOP) and glaucoma medication burdens in patients with mild-to-moderate open-angle glaucoma (OAG). These findings remained consistent regardless of phacoemulsification status. ABiC was found to exhibit a safety profile favorable compared to trabeculectomy and comparable to minimally invasive trabecular bypass implants.

Conclusion

Canaloplasty is a nonpenetrating surgical intervention that is highly effective in treating patients with mild-to-moderate OAG across a large variety of clinical scenarios.

Clinical significance

These findings support the clinical use of canaloplasty in ophthalmological practice, clarify its patient profile, and compare procedural outcomes to other minimally invasive glaucoma surgery (MIGS) devices on the market.

How to cite this article

Wagner IV, Towne C, Saade MC, et al. A Review of Canaloplasty in the Treatment and Management of Glaucoma. J Curr Glaucoma Pract 2024;18(2):79-85.

6-Year Efficacy and Safety of iTrack Ab-Interno Canaloplasty as a Stand-Alone Procedure and Combined With Cataract Surgery in Primary Open Angle and Pseudoexfoliative Glaucoma

PRCIS

Significant reductions in intraocular pressure (IOP) and the number of medications are sustained up to 6 years postoperatively for eyes that underwent ab-interno canaloplasty using the iTrack microcatheter, either as a stand-alone procedure or combined with cataract surgery.

PURPOSE

The purpose of this study was to evaluate the long-term effectiveness of iTrack (Nova Eye Medical Inc.) ab-interno canaloplasty for reducing IOP and the number of glaucoma medications in patients with primary open angle (POAG) and pseudoexfoliative glaucoma.

METHODS

A retrospective single-center consecutive case series. Patients were treated with either ab-interno canaloplasty performed as a stand-alone procedure or combined with cataract surgery and were followed for up to 6 years. iTrack was used to circumferentially catheterize and viscodilate the Schlemm canal over 360 degrees. Primary efficacy endpoints included IOP and number of glaucoma medications at 12, 24, 36, 48, 60, and 72 months after surgery.

RESULTS

Twenty-seven eyes of 22 patients, with a mean age of 76.9±6.3 years, were recruited. Mean IOP was reduced significantly from 19.9±5.2 mm Hg (n=27) at baseline (no washout) to 14.6±3.3 mm Hg at the 6-year follow-up (n=18; P <0.001). The number of medications was significantly reduced from 1.9±1 at baseline to 0.9±0.9 at 6 years (n=18; P =0.005). At all time points, there was no statistical difference between POAG (n=16) and pseudoexfoliative (n=11) eyes, nor between stand-alone procedures (n=4) and those combined with phacoemulsification (n=23). At 72 months, the mean reduction in IOP was 27% while 53% in the number of medications. No serious complications were recorded.

CONCLUSIONS

iTrack ab-interno canaloplasty performed as a stand-alone procedure or in combination with cataract surgery significantly reduced IOP and number of medications in patients with POAG up to 6 years after the procedure. To the authors' knowledge, this is the longest ab-interno canaloplasty follow-up available in the literature.

Consistency in Standalone Canaloplasty Outcomes Using the iTrack Microcatheter

Purpose

To study the consistency in outcomes of standalone canaloplasty performed via an ab-interno surgical technique in reducing intraocular pressure (IOP) and number of medications in uncontrolled open-angle glaucoma (OAG) eyes over a 12-month period.

Methods

This retrospective multicenter case series included patients who underwent standalone canaloplasty via an ab-interno surgical technique using the iTrack microcatheter (Nova Eye, Inc., Fremont, USA) and had preoperative uncontrolled OAG (IOP≥18mmHg) along with no previous glaucoma surgery. The iTrack microcatheter is used to circumnavigate 360° and viscodilate Schlemm's canal. Consistency of IOP and medications reduction on an eye-by-eye basis were evaluated to understand the outcomes in each single eye.

Results

Sixty-four eyes of 60 patients (age 71.5±13.4 years) were included. Six eyes (9%) that underwent additional glaucoma surgery were considered a failure and were subsequently excluded from analysis. At 12 months, IOP was reduced in 57 of the 58 (89%) remaining eyes; one eye had the same IOP with a reduced number of medications. Of the 57/58 eyes with a reduced IOP: 44 eyes (69%) required fewer medications; 12 eyes (19%) required the same number of medications. Of these 58 eyes, 78% of eyes had a ≥20% reduction in IOP compared to baseline; 69% eyes had a postoperative IOP ≤15 mmHg, and 86% eyes ≤18 mmHg at 12 months. Forty percent of the eyes were medication-free at 12 months compared to none at baseline.

Conclusion

Canaloplasty performed via an ab-interno surgical technique as a standalone procedure consistently reduced IOP and glaucoma medications in almost all eyes.

First-in-Human Safety Study of Femtosecond Laser Image-Guided Trabeculotomy for Glaucoma Treatment: 24-month Outcomes

Purpose

Pilot study to evaluate adverse events and intraocular pressure (IOP)-lowering of a novel, noninvasive glaucoma procedure, femtosecond laser, image-guided, high-precision trabeculotomy (FLIGHT).

Design

Prospective, nonrandomized, single-center, interventional, single-arm clinical trial.

Participants

Eighteen eyes from 12 patients with open-angle glaucoma.

Methods

Eighteen eyes from 12 patients underwent FLIGHT, creating a single channel measuring 500-μm wide by 200-μm high through the trabecular meshwork and into Schlemm's canal. Adverse events, IOP, and other parameters were evaluated out to 24 months.

Main Outcome Measures

Outcomes were the rates and types of adverse events and the rate of postprocedure best-corrected visual acuity loss (≥ 2 lines) compared with baseline. Efficacy outcomes were reduction in mean intraocular pressure (IOP) with respect to baseline and the percentage of eyes with a ≥ 20% reduction in IOP.

Results

Eighteen eyes from 12 patients were enrolled in the study; 11 patients (17 eyes) returned at 24 months. There were no serious adverse events related to the laser treatment. Well-defined channels were clearly visible at 24 months by gonioscopy and anterior segment OCT, with no evidence of closure. At 24 months, the mean IOP was reduced by 34.6% from 22.3 ± 5.5 to 14.5 ± 2.6 mmHg (P < 5e-5), with an average of 2.0 ± 1.2 hypotensive medications compared with 2.2 ± 1.1 at baseline (P = 0.22). Fourteen out of the 17 study eyes (82.3%) achieved a ≥ 20% reduction in IOP at 24 months when compared with baseline.

Conclusion

The FLIGHT system demonstrated a favorable safety profile in this initial pilot study, with no device-related serious adverse events. The channels appeared patent at 24 months, indicating medium-term durability.

Financial Disclosures

Proprietary or commercial disclosure may be found after the references.

Combined Phacoemulsification and STREAMLINE Surgical System Canal of Schlemm Transluminal Dilation in Eyes of Hispanic Patients with Mild to Moderate Glaucoma

Purpose

To characterize clinical outcomes of transluminal dilation of the canal of Schlemm using the STREAMLINE Surgical System combined with phacoemulsification in eyes of Hispanic patients diagnosed with mild to moderate primary open-angle glaucoma.

Methods

This was a prospective analysis of all cases performed and followed up to 12 months. All eyes underwent medication washout preoperatively. Reduction in intraocular pressure (IOP) from unmedicated baseline, as well as medications from pre-washout baseline, were analyzed at postoperative Day 1, Week 1, and Months 1, 3, 6, 9, and 12.

Results

All 37 patients were Hispanic, 83.8% were female, and mean (standard deviation) age was 66.0 (10.5) years. Mean medicated preoperative IOP was 16.9 (3.2) mmHg using a mean of 2.1 (0.9) medications, unmedicated baseline IOP (after washout) was 23.2 (2.3) mmHg, and mean IOP at every postoperative study visit was significantly lower (p<0.0002). Mean IOP from month 1 through the first postoperative year ranged from 14.7-16.2 mmHg, representing a reduction of 7.0-8.5 mmHg (30.7-36.5%). At month 12, 80% of all eyes (28/35) and 77.8% of medication-free eyes (14/18) had IOP reduction ≥20% from unmedicated baseline, and 51.4% of eyes (18/35) were medication-free. Mean medication use was significantly reduced (by 59.9-74.6%, p<0.0001) at every postoperative study visit. The only adverse event occurring in >1 eye was high IOP (n=4) which was responsive to topical medical therapy; no adverse events were attributed to the transluminal dilation procedure.

Conclusion

Transluminal dilation of the canal of Schlemm using the STREAMLINE Surgical System combined with phacoemulsification safely and effectively reduced both IOP and dependence on IOP-lowering medications in a Hispanic population diagnosed with POAG and should be considered at the time of phacoemulsification in Hispanic patients who have a need for IOP reduction, medication reduction, or both.

Canaloplasty and Trabeculotomy with the OMNI System in Patients with Open-Angle Glaucoma: Two-Year Results from the ROMEO Study

Purpose

To provide extended safety and effectiveness follow-up for eyes treated with circumferential canaloplasty and trabeculotomy (CP+TR) that were included in the 12-month ROMEO study.

Setting

Seven multi-subspecialty ophthalmology practices located in 6 states (Arkansas, California, Kansas, Louisiana, Missouri, and New York).

Design

Retrospective, multicenter, IRB approved.

Subjects

Eligible eyes had mild-moderate glaucoma and were treated with CP+TR with cataract surgery or as a standalone intervention.

Methods

Main outcome measures were mean IOP, mean number of ocular hypotensive medications, mean change in number of medications, proportion of patients with a ≥20% reduction in IOP or with IOP ≤18 mmHg, and proportion of patients medication free. Safety outcomes were adverse events and secondary surgical interventions (SSI).

Results

Eight surgeons at 7 centers contributed 72 patients stratified by pre-operative intraocular pressure (IOP); >18 mmHg (Grp1), ≤18 mmHg (Grp2). Mean follow-up of 2.1 years (min 1.4, max 3.5). 2-year IOP (SD) was 15.6 mmHg (-6.1 mmHg, -28% from baseline) on 1.4 medications (-0.9, -39%) for Grp1 with cataract surgery; 14.7 mmHg (-7.4 mmHg, -33% from baseline) on 1.6 medications (-0.7, -15%) for Grp1 standalone, 13.7 mmHg (-0.6 mmHg, -4.2%) on 1.2 medications (-0.8, -35%) for Grp2 with cataract surgery, 13.3 mmHg (-2.3 mmHg, -14.7%) on 1.2 medications (-1.0, -46%) for Grp2 standalone. The proportion of patients at 2 years with either a ≥20% IOP reduction or IOP between 6 and 18 mmHg and no increase in medication or SSI was 75% (54 of 72, 95% CI 69.9%, 80.1%). One-third of patients (24 of 72) were medication free whereas 9 of 72 were pre-surgical. No device-related adverse events during extended follow-up; 6 eyes (8.3%) required additional surgical or laser intervention for IOP control after 12 months.

Conclusion

CP+TR provides effective IOP control that is sustained for 2 years or more.

Long-Term Clinical and Safety Outcomes of Canaloplasty Performed across All Grades of Glaucoma Severity

Purpose

To investigate the clinical effectiveness of canaloplasty performed with an ab interno technique using the iTrack microcatheter (Nova Eye Medical) in patients with mild-moderate glaucoma as compared to severe glaucoma.

Methods

This is a retrospective single-center case series. Patients were preoperatively categorized as mild/moderate vs. severe glaucoma assessed using the mean deviation (MD) score and controlled group (baseline intraocular pressure (IOP) ≤18 mmHg) vs. uncontrolled group (>18 mmHg). All patients with glaucoma were eligible for recruitment except those who had undergone previous glaucoma surgery (with the exception of selective laser trabeculoplasty or SLT). Patients underwent canaloplasty via an ab interno surgical technique with or without phacoemulsification and were monitored for IOP, glaucoma medication usage, and surgical complications.

Results

In total, 72 eyes were followed for 3.4 ± 0.5 years. Mean pre-op IOP (mmHg) was 19.3 ± 7.7 in the standalone group (n = 9) and 18.5 ± 5.6 in the combined group (n = 63) (p=0.38). At the last follow-up, mean IOP reduced by 36% to 12.4 ± 4.4 (p=0.02) in the standalone group and by 26% to 13.7 ± 4.8 in the combined group (p < 0.001). Mean pre-op IOP (mmHg) was 18.6 ± 5.2 in the severe group (n = 24) and 18.6 ± 6.2 in the mild-moderate group (n = 48) (p=0.48). Mean IOP was 14.1 ± 6.3 (-24%; p < 0.001) and 13.3 ± 3.7 (-29%; p < 0.001), respectively, at the last follow-up. Mean glaucoma medication usage decreased from 2.5 ± 0.9 to 2.1 ± 0.9 (-15%; p=0.083) in the severe group and 2.3 ± 1.0 to 1.4 ± 1.3 (-40%; p < 0.001) in the mild/moderate group. There was one localized Descemet's membrane detachment in the moderate group.

Conclusion

iTrack canaloplasty achieved a statistically significant IOP reduction in mild-moderate and severe eyes and was found to be an effective option for reducing IOP and medications in patients with mild-moderate primary open-angle glaucoma (POAG). In severe eyes, it has reduced IOP while the medications remained stable.

Hydrus Microstent implantation with OMNI Surgical System Ab interno canaloplasty for the management of open-angle glaucoma in phakic patients refractory to medical therapy

Purpose

To report a series of 8 phakic eyes of 8 patients with open angle glaucoma with uncontrolled intraocular pressure on maximum tolerable medical therapy receiving Hydrus Microstent implants combined with concomitant OMNI Surgical System ab interno canaloplasty.

Observations

8 phakic eyes underwent Hydrus Microstent implantation with OMNI Surgical System ab interno canaloplasty. 2 patients underwent concurrent Kahook Dual Blade goniotomy and 1 patient underwent a concurrent micropulse transscleral cyclophotocoagulation. 6 out of 8 eyes achieved successful intraocular pressure reduction. Only 1 achieved success without the need for additional medical therapy. 1 required Neodymium-doped yttrium aluminum garnet laser to clear iris obstruction of the Hydrus inlet and 1 required selective laser trabeculoplasty for additional intraocular pressure lowering. 2 out of 8 eyes required subsequent incisional glaucoma surgery for unacceptable intraocular pressure levels despite maximum tolerable medical therapy.

Conclusions and Importance

The Hydrus Microstent combined with OMNI Surgical System ab interno canaloplasty can safely and successfully reduce intraocular pressure in phakic patients with open-angle glaucoma with uncontrolled intraocular pressure on maximum tolerable medical therapy with a low complication rate and rapid visual recovery.