Canaloplasty ab interno (AbiC) - 2-Year-Results of a Novel Minimally Invasive Glaucoma Surgery (MIGS) Technique

Angle-based minimally invasive glaucoma surgery in normal tension glaucoma: A systematic review and meta-analysis

BACKGROUND

This systematic review and meta-analysis quantitatively examines the efficacy of angle-based minimally invasive glaucoma surgery (MIGS) in normal tension glaucoma (NTG).

METHODS

A literature search was performed on Medline, Embase, PubMed, CINAHL and Cochrane Library from inception until 20 December 2022. Pilot, cohort, observational studies and randomised controlled trials including at least 5 subjects undergoing angle-based MIGS (trabecular-bypass devices, excisional trabeculotomy, goniotomy and ab-interno canaloplasty) for NTG, with or without cataract surgery, were included. Meta-analysis of continuous outcome using the meta routine in R version 2022.12.0+353 was performed to determine mean intraocular pressure (IOP) and anti-glaucoma medication (AGM) reduction post-operatively.

RESULTS

Of the 846 studies initially identified, 15 studies with a pooled total of 367 eyes which underwent combined phacoemulsification and angle-based MIGS were included for final meta-analysis. Outcomes of the iStent were reported in 5 studies, iStent inject in 7 studies, Hydrus Microstent in 1 study, Kahook Dual Blade in 3 studies, and Trabectome in 2 studies. There was significant reduction in both IOP and AGM post-operatively at 6 months (2.44 mmHg, 95%CI: 1.83-3.06; 1.21 AGM, 95%CI: 0.99-1.44), 12 months (2.28 mmHg, 95%CI: 1.71-2.84; 1.18 AGM, 95%CI: 0.90-1.47), 24 months (2.10 mmHg, 95%CI: 1.51-2.68; 1.26 AGM, 95%CI: 0.85-1.68) and 36 months (2.43 mmHg, 95%CI: 1.71-3.15, 0.87 AGM, 95%CI: 0.21-1.53) (all p < 0.05). Subgroup analysis on combined phacoemulsification-iStent inject surgery demonstrated a reduction in both IOP (2.31 mmHg, 95%CI: 1.07-3.56, p < 0.001) and AGM (1.07 AGM, 95%CI: 0.86-1.29, p < 0.001) at 12 months post-operatively.

CONCLUSIONS

Angle-based MIGS combined with phacoemulsification effectively reduces IOP and AGM in NTG eyes for up to 36 months after surgery.

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.

Four-Year Efficacy and Safety of iTrack Ab-interno Canaloplasty as a Standalone Procedure and Combined with Cataract Surgery in Open-Angle Glaucoma

PURPOSE

To evaluate the long-term effectiveness of ab-interno canaloplasty (ABiC), performed with the iTrack microcatheter (Nova Eye Medical, Fremont, CA, USA), in reducing intraocular pressure (IOP) as well as the number of required glaucoma medications in patients with open-angle glaucoma (OAG).

METHODS

In this retrospective single-center consecutive case series, 27 eyes of 21 patients (mean age 77.3 ± 5.8 years) were treated with ABiC performed as a standalone procedure or combined with cataract surgery. Patients with uncontrolled IOP OAG or controlled IOP (≤ 18 mmHg) OAG with intolerance to medications or lack of compliance were included. Patients were followed for up to 4 years following the procedure. The iTrack microcatheter was used to perform a 360-degree circumferential intubation and viscodilation of Schlemm's canal. Primary efficacy endpoints included IOP and the number of glaucoma medications at 12, 24, 36, and 48 months after surgery.

RESULTS

In all eyes, mean IOP and number of glaucoma medications were significantly reduced from 19.8 ± 5.2 mmHg and 1.9 ± 1.00 at baseline to 14.6 ± 3 mmHg and 0.9 ± 0.8, respectively, at the 48-month follow-up (p < 0.001). IOP was stable from 12 months to 48 months (p > 0.005). After 48 months, 39% of the eyes required zero medications compared to 3.7% at baseline, and 72.2% of eyes required only one medication or less. Of all eyes, 77.8% recorded an IOP ≤ 17 mmHg. No serious complications were recorded.

CONCLUSION

iTrack ABiC performed as a standalone procedure or in combination with cataract surgery significantly reduced IOP and number of medications in patients with OAG up to 4 years after the procedure.

Viscodilation of Schlemm's Canal Combined with Goniectomy Using a 30 G Needle (Visco-Bent Ab Interno Needle Goniectomy)

Background and aim

Bent ab interno needle goniectomy (BANG) is a low-cost minimally invasive glaucoma surgery (MIGS) technique that has gained wide popularity in developing nations. However, the risk of injury to surrounding angle structures and especially the outer wall of Schlemm's canal (SC) is the main drawback of this technique. We describe a simple and easy-to-perform modification, "Visco-BANG," to improve the safety and efficacy of the BANG procedure.

Technique

A 30 gauge (G) needle attached to a syringe filled with cohesive viscoelastic is used. The needle is bent at the proximal junction of the bevel with bevel towards the operating surgeon. The needle is then inserted into the SC and viscoelastic injected to dilate the canal, creating a buffer between the inner and outer walls of SC, which is followed by cutting of a trabecular meshwork (TM) strip.

Conclusion

The current modification can prevent damage to adjoining angle structures, including the outer wall of SC, which is critical for aqueous outflow. It can potentially increase efficacy of the BANG procedure by incorporating viscodilation of the SC along with removal of the TM.

Clinical significance

Injury to surrounding structures causes a fibrotic response, which is the main cause of failure for the BANG procedure. Prevention of injury to adjoining structures and dilatation of the SC can potentially increase the long-term success rates of this procedure.

How to cite this article

Dada T, Beri N, Sethi A, et al. Viscodilation of Schlemm's Canal Combined with Goniectomy Using a 30 G Needle (Visco-Bent Ab Interno Needle Goniectomy). J Curr Glaucoma Pract 2023;17(4):210-213.

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.

Emerging glaucoma treatments: are we seeing an improvement in adherence?

Introduction

Non-adherence to glaucoma medication and poor follow-up is a global health concern.

Areas covered

Glaucoma remains one of the largest causes of irreversible blindness worldwide. Traditional treatment guidelines suggest topical eye drop medication as first line therapy followed by addition of supplementary medications before proceeding to more invasive glaucoma surgeries. Unfortunately, poor glaucoma self-management remains high, leading to disease progression and blindness. Recent advancements in the field of pharmacotherapies, surgeries, and behavioral approaches have taken aim at increasing support for glaucoma self-management. We review the current and emerging approaches towards glaucoma management, with the exception of bleb-based surgical approaches, to investigate if they have had an impact on adherence. Literature searches were conducted via MEDLINE (PubMed), Embase (Elsevier), Cochrane Library (Wiley), and Preprints from January 1st, 2018, to January 26th, 2023.

Expert opinion

The ability to offer patients a multitude of choices enables patients to tailor their glaucoma treatment to their values and lifestyle. Offering personalized patient education and coaching to support chronic glaucoma self-management would better enable patient engagement in whichever treatment path is chosen. Currently, literature regarding the impact of these new advancements on treatment engagement is lacking; this field is ripe for additional intervention and assessment.

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.

Minimally Invasive Glaucoma Surgery: Safety of Individual Devices

Primary open-angle glaucoma progression in those already on maximal medical therapy has traditionally been treated with trabeculectomy, a surgical procedure that carries a high degree of morbidity. In the last few decades, significant advances have been made in the field of minimally invasive glaucoma surgery (MIGS) devices, which aim to defer or prevent trabeculectomy via less arduous surgical techniques in certain types of glaucoma. Although reviews have been published examining the efficacy of various MIGS techniques, no article synthesises the comparative safety of all available devices. We performed a literature review examining the safety of MIGS devices. Fifteen devices were included, variously attempting to increase aqueous outflow through the trabecular meshwork or the suprachoroidal space, shunting into the subconjunctival space, or reducing aqueous production through ciliary body ablation. Notably, the earliest product attempting to increase outflow to the suprachoroidal space, Alcon's CyPass Micro-Stent, was withdrawn from the market due to concerns regarding increased corneal endothelial cell loss at five years post-implantation. All other devices were described as well-tolerated, with the most common adverse effects including hyphaema, intraocular pressure spikes, and device migration or obstruction. MIGS devices are purported to be uniformly safe, and many studies report no statistically significant increased complications beyond those associated with cataract surgery alone. It is important to note, however, the generally poor quality of current studies, with a dearth of randomised, or even prospective, data, and a large proportion of studies funded by device producers.

Canaloplasty and Trabeculotomy Combined with Phacoemulsification for Glaucoma: 12-Month Results of the GEMINI Study

Purpose

To report 12-month efficacy outcomes of 360° canaloplasty and 180° trabeculotomy using the OMNI surgical system in combination with phacoemulsification in patients with mild-moderate open-angle glaucoma (OAG) and visually significant cataract.

Setting

Fifteen multi-subspecialty ophthalmology practices and surgery centers located in 14 US states.

Design

Prospective, multicenter, IRB approved study of patients treated with canaloplasty (360°) and trabeculotomy (180°). Eligible patients had cataract and mild-moderate OAG with intraocular pressure (IOP) ≤33 mmHg on 1 to 4 hypotensive medications. Unmedicated post-washout mean diurnal IOP (DIOP) ≥21 and ≤36 mmHg.

Methods

Medication washout preoperatively and prior to month 12 DIOP. Effectiveness outcomes were IOP and IOP lowering medication use. Safety outcomes included adverse events and secondary surgical interventions (SSIs). Evaluations at 1, 3, 6, and 12 months.

Results

A total of 149 subjects underwent surgery and 120 were included in the final effectiveness analysis. Mean (standard deviation) unmedicated diurnal IOP was reduced from 23.8 (3.1) mmHg at baseline to 15.6 (4.0) at month 12 (−35%) and medications (before washout) were reduced from 1.8 (0.9) at baseline to 0.4 (0.9) at month 12 (−80%). At month 12, 84.2% of eyes achieved IOP reductions >20% from baseline, 80% of eyes were medication-free, and 76% of eyes achieved IOP between 6–18 mmHg inclusive. Adverse events were uncommon. Most were mild and self-limited including transient hyphema (9 of 149; 6%) and transient IOP elevations (3 of 149; 2.0%). No eyes required SSIs or experienced loss of VA that was attributable to the device or procedure.

Conclusion

Canaloplasty and trabeculotomy performed with the OMNI surgical system at the time of phacoemulsification significantly reduces unmedicated mean diurnal IOP and medication use 12 months postoperatively, with an excellent safety profile. This procedure should be considered for eyes with mild-moderate OAG to reduce IOP, medication burden, or both.

Interim Analysis of STREAMLINE® Surgical System Clinical Outcomes in Eyes with Glaucoma

Purpose

To characterize the clinical outcomes of a novel ab interno minimally invasive procedure with the STREAMLINE^® Surgical System for creation of incisional goniotomies and canal of Schlemm viscodilation in eyes with mild to severe primary open-angle glaucoma (POAG).

Methods

In a prospective, single-arm, first-in-human case series, 20 eyes of 20 subjects with mild to severe POAG underwent creation of incisional goniotomies and canal of Schlemm viscodilation following phacoemulsification cataract extraction after washout of all intraocular pressure (IOP)-lowering medications. The angle surgery portion was performed with a single-use handpiece tipped with a microcannula that creates precise goniotomies through the trabecular meshwork into the canal of Schlemm and delivers a small volume of ophthalmic viscosurgical device directly into the canal via precise catheterization. Outcomes in this interim analysis included mean reduction in IOP and medications through 6 months of follow-up, as well as the proportion of eyes achieving IOP reduction ≥20% from baseline.

Results

At month 6, mean IOP reduction of ≥20% from baseline was achieved in 89.5% of eyes (17/19). Mean (standard deviation) medicated IOP at screening was 16.3 (3.6) mmHg and unmedicated baseline IOP (after washout) was 23.5 (2.5) mmHg. Mean IOP was significantly reduced from baseline through 6 months of follow-up to 14.7 (2.4) mmHg (p<0.001), representing an IOP reduction of 8.8 mmHg (36.9%). Overall, 57.9% (11/19) of eyes decreased dependence on IOP-lowering medications by at least one medication, and 42.1% (8/19) were medication free. Mean medication use was reduced from 2.0 (0.8) at screening to 1.1 (1.1) at 6 months (p<0.001). Three eyes had transient IOP spikes treated with topical medications.

Conclusion

The creation of incisional goniotomies and canal of Schlemm viscodilation safely and effectively reduced IOP and the need for IOP-lowering medications by both clinically and statistically significant magnitudes in eyes with mild to severe POAG undergoing concomitant phacoemulsification cataract extraction through the first 6 months of follow-up.

360° Ab-Interno Schlemm's Canal Viscodilation with OMNI Viscosurgical Systems for Open-Angle Glaucoma-Midterm Results

Purpose: To evaluate the effectiveness of ab-interno microcatheterization and 360° viscodilation of Schlemm’s canal (SC) performed with OMNI viscosurgical system in open angle glaucoma (OAG) together or not with phacoemulsification. Setting: Two surgical sites. Design: Retrospective, observational. Methods: Eighty eyes from 73 patients with mild to moderate OAG underwent ab- interno SC viscodilation performed with OMNI system. Fifty eyes (Group 1) underwent only SC viscodilation, while 30 eyes (Group 2) underwent glaucoma surgery + cataract extraction. Primary success endpoint at 12 months was an intraocular pressure (IOP) reduction higher than 25% from baseline with an absolute value of 18 mmHg or lower, either on the same number or fewer ocular hypotensive medications, without further interventions. Secondary effectiveness endpoints included mean IOP, number of medications and comparison of outcomes between groups. Safety endpoints consisted of best-corrected visual acuity (BCVA), adverse events (AEs), and subsequent surgical procedures. Results: Primary success was achieved in 40.0% and 67.9% in Groups 1 and 2, respectively. Mean IOP at 12-month follow-up showed a significant reduction in both groups (from 23.0 to 15.6 mmHg, p < 0.001, and from 21.5 to 14.1, p < 0.001, in Groups 1 and 2, respectively). Mean medication number decreased in both groups (from 3.0 to 2.0, p < 0.001 and from 3.4 to 1.9, p < 0.001, in Groups 1 and 2, respectively). AEs included hyphema (2 eyes), mild hypotony (4 eyes), IOP spikes one month after surgery (1 eye). Twelve eyes (15.0%) required subsequent surgical procedures. No BCVA reduction was observed. Conclusions: Viscodilation of SC using OMNI viscosurgical systems is safe and relatively effective in reducing IOP in adult patients with OAG.

Minimally Invasive Glaucoma Surgery-to Remove or Preserve the Trabecular Meshwork: That is the Question?

How to cite this article: Dada T, Mahalingam K, Bhartiya S. Minimally Invasive Glaucoma Surgery—to Remove or Preserve the Trabecular Meshwork: That is the Question? J Curr Glaucoma Pract 2021;15(2):47–51.

Long-term medication reduction in controlled glaucoma with iTrack ab-interno canaloplasty as a standalone procedure and combined with cataract surgery

Purpose:

To evaluate the long-term effectiveness of iTrack (Nova Eye Medical, Fremont, USA) ab-interno canaloplasty performed as a standalone procedure, or combined with cataract surgery, in reducing antiglaucoma medication dependence and maintaining intraocular pressure within target range in patients with controlled primary open-angle glaucoma.

Methods:

This is a retrospective, single-center, case series study of patients who underwent iTrack ab-interno canaloplasty as a standalone procedure (n = 34) or in combination with cataract surgery (n = 11). Eyes with controlled mild or moderate glaucoma (intraocular pressure ⩽17 mmHg) were included; those with prior glaucoma surgeries were excluded. The primary outcome was the mean reduction in glaucoma medication and the secondary outcome was the maintenance of controlled intraocular pressure postoperatively.

Results:

A total of 35 patients (45 eyes) with a mean age of 73 ± 9.7 years were included in the study. For all eyes, a significant decrease (61%) in the mean number of medications was seen at 36 months (1.89 ± 0.93 versus 0.60 ± 0.82; p < 0.001), with 56% (14/25) of eyes medication free. No significant difference was observed in the reduction of medication use whether iTrack was performed with or without cataract surgery at 12 and 36 months. Mean baseline intraocular pressure of 14.42 ± 2.2 mmHg for all eyes was maintained at the 12-, 24-, and 36-month follow-up visits (14.6 ± 3.65, 15.06 ± 2.26, and 14.19 ± 2.91, respectively), with no significant difference between the two groups (p = 0.08).

Conclusion:

The iTrack ab-interno canaloplasty significantly reduced medication dependency and maintained intraocular pressure within target range in patients with controlled mild or moderate primary open-angle glaucoma, while showing a good safety profile, both as a standalone procedure or in combination with cataract surgery.

24-Month Efficacy of Viscodilation of Schlemm's Canal and the Distal Outflow System with iTrack Ab-Interno Canaloplasty for the Treatment of Primary Open-Angle Glaucoma

PURPOSE

This study aimed to evaluate the 24-month efficacy of viscodilation of Schlemm's canal and the distal outflow system with iTrack ab-interno canaloplasty in reducing intraocular pressure (IOP) and antiglaucoma medication use in patients with primary open-angle glaucoma (POAG).

PATIENTS AND METHODS

This retrospective, comparative, and consecutive case series assessed the 24-month outcomes of iTrack as a standalone procedure (iTrack-alone) or in conjunction with cataract surgery (iTrack+phaco), in cases of mild, moderate or severe POAG. Data were collected at baseline and the 12- and 24-month follow-up visits.

RESULTS

The study included 53 patients (60 eyes) with a mean age of 73.6±9 years. For all eyes, a significant reduction in mean IOP was seen at 12 and 24 months, reducing from 20±4.9 mmHg at baseline to 13.6±1.9 mmHg and 13.5±2.6 mmHg, respectively (P<0.001). The reduction in medications was also significant, reducing to 1.12±1.09 and 1.7±1.29 medications at 12 months and 24 months, respectively, from a baseline of 2.77±0.91 (P<0.001). Similar results were achieved whether iTrack was performed as a standalone procedure, or in conjunction with cataract surgery. While the iTrack-alone group started with a higher IOP at baseline, both groups experienced similar and stable IOP reduction of more than 30% from baseline. The reduction in medication use was also significant in both groups, decreasing from 3±0.7 for iTrack-alone and 2.5±1.1 for iTrack+phaco at baseline to 2.1±1.3 and 1.3±1.2 at 24 months, respectively (P<0.001). The 24-month efficacy outcomes were similar in cases of mild-moderate versus severe glaucoma. No serious adverse events were recorded.

CONCLUSION

Twenty-four-month follow-up data demonstrate that iTrack ab-interno canaloplasty can effectively reduce IOP and medication dependence, with a good safety profile. These results also demonstrate that iTrack can be effectively performed as a standalone procedure or in combination with cataract surgery, and in all grades of glaucoma severity.