Circumferential viscodilation of Schlemm's canal for open-angle glaucoma: ab-interno vs ab-externo canaloplasty with tensioning suture

Efficacy and safety of combined Kahook Dual Blade goniotomy with phacoemulsification in Chinese patients with primary open angle glaucoma

AIM

To report the one-year surgical outcome Kahook Dual Blade goniotomy combined with phacoemulsification (KDB-Phaco) in Chinese patients with primary open angle glaucoma (POAG).

METHODS

This is a retrospective study included 43 eyes of 28 Chinese POAG patients with cataract who accepted KDB-Phaco and followed-up for 12mo. Intraocular pressure (IOP), glaucoma medications and surgical complications were recorded. Success 1 and success 2 was defined as 5-21 mm Hg and 5-18 mm Hg, and success plus was determined if additional criteria of IOP reduction ≥20% from baseline was reached. A corrected IOP by adding 3 mm Hg for each medication was used to do correlation test. Cox's proportional hazards regression model was used to test the hazard ratio for factors associated with surgical success.

RESULTS

After a 12-month follow up, the IOP decreased from 28.1±6.3 to 13.8±3.0 mm Hg (47.92% reduction, P<0.001), and the medications used decreased from 2.0 (1.0) to 0.0 (0.0) (95% reduction, P<0.001). The mean IOP of all postoperative visits were lower than preoperative IOP (all P<0.001), so as the number of glaucoma medications (all P<0.001). Complete success 1 and qualified success 1 were 87.80% and 100.00% respectively. The complete success 1 plus and qualified success 1 plus were 85.37% and 97.56%, respectively. Totally 82.93% and 90.24% of patients got complete success 2 and qualified success 2 while 80.49% and 87.80% of patients satisfied complete success 2 plus and qualified success 2 plus. Age (r=-0.511, P=0.001) and visual acuity (VA; r=-0.321, P=0.041) were negatively correlated with postoperative corrected IOP at 12mo, while anterior chamber depth (r=0.432, P=0.005), mean deviation (r=0.617, P<0.001) and visual field index (r=0.524, P<0.001) were positively correlated with it. Preoperative VA (OR=33.092, P=0.004) and MD (OR=1.481, P=0.018) were hazard factors associated with failure based on qualified success as 18 mm Hg. The main complications of KDB were hyphema (9.30%), IOP spike (11.63%) and peripheral anterior synechia (6.98%).

CONCLUSION

KDB goniotomy is a safe and effective in the treatment for Chinese POAG patients. Preoperative VA and mean deviation may predict the surgical success.

Pathological Mechanism and Clinical Therapy Progress of Schlemm's Canal

Schlemm's canal (SC) is a small circular canal in the deep part of the sclera at the junction of the sclera and cornea. As an integral component of the aqueous humor outflow, its structure and function are essential in regulating intraocular pressure (IOP). If SC develops lesions, the drainage of aqueous humor would be obstructed, leading to increased intraocular pressure and injury to the optic nerve. With the rapid development of minimally invasive glaucoma surgery, an increasing number of surgeons became familiar with SC, and the area generated substantial academic attention. The pathological mechanism and the therapy for SC that had been studied in recent years are summarized in this article, hoping to provide ideas for the treatment of glaucoma in the future.

Evaluating the 1-year success and safety of ab interno canaloplasty in combination with cataract surgery in glaucoma patients

PURPOSE

To evaluate the treatment success and safety of ab interno canaloplasty (AbiC) combined with cataract surgery in glaucoma patients.

METHODS

The prospective case study included 43 eyes that received an AbiC combined with cataract surgery (age 73.3 ± 8.2 years). The 360° microcatheterization and viscodilatation of the Schlemm's canal was conducted using VISCO 360 (Sight Sciences, CA, USA). The observation period was 12 months with visits at 2 and 6 as well as 12 months, 7 eyes were lost to follow up.

RESULTS

The preoperative IOP was 19.8 ± 4.9 mmHg and was reduced to 14.5 ± 2.8 mmHg 12 months after AbiC (p < 0.0001). The relative IOP reduction was 23.6 ± 23.1% after 12 months. Topical glaucoma medication was also reduced from 2.4 ± 1.1 drugs to 1.1 ± 1.4 (p < 0.001) after 12 months. The complete surgical success rate (defined as IOP < 18 mmHg without topical therapy) was 31.6% whereas the qualified surgical success was 89.5% (IOP < 18 mmHg, with local therapy) There were no relevant intra- or postoperative complications.

CONCLUSION

AbiC in combination with cataract surgery is a safe and effective procedure to achieve a significant reduction of IOP and local glaucoma medication 12 months after surgery.

Ab interno canaloplasty versus gonioscopy-assisted transluminal trabeculotomy in open-angle glaucoma: a randomised controlled trial

OBJECTIVE

To compare the efficacy and safety of ab interno canaloplasty (ABiC) with gonioscopy-assisted transluminal trabeculotomy (GATT) in patients with open-angle glaucoma (OAG).

METHOD

This randomised clinical trial recruited eyes with OAG and no previous incisional ocular surgery, among which 38 were randomised to ABiC and 39 to GATT. Follow-ups were performed at 1, 3, 6 and 12 months postoperatively. The primary outcome measures were intraocular pressure (IOP) and use of glaucoma medication at 12 months postoperatively. The secondary outcome measure was complete surgical success (not requiring glaucoma surgery, IOP ≤21 mm Hg and non-use of glaucoma medications).

RESULTS

Both groups had similar demographic and ocular characteristics. A total of 71 of the 77 subjects (92.2%) completed 12-month follow-up. At 12 months, mean IOP was 19.0±5.2 mm Hg in the ABiC group and 16.0±3.1 mm Hg in the GATT group (p=0.003). Overall, 57.2% of ABiC patients and 77.8% of GATT patients were medication free (p=0.06). The number of glaucoma medications was 0.9±1.3 in the ABiC group and 0.6±1.2 in the GATT group (p=0.27). The 12-month cumulative rate of complete surgical success was 56% in the ABiC group and 75% in the GATT group (p=0.09). Three eyes in the ABiC group and one eye in the GATT group required additional glaucoma surgery. Hyphema (87% vs 47%) and supraciliary effusion (92% vs 71%) were noted more often in the GATT group than in the ABiC group.

CONCLUSIONS

The preliminary result showed that GATT had an advantage over ABiC in IOP reduction for OAG patients, accompanied by favourable safety at 12-month postoperatively.

TRIAL REGISTRATION NUMBER

ChiCTR1800016933.

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.

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.

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.

Managing primary open-angle glaucoma in the setting of suboptimal surgical outcomes in the fellow eye

A 62-year-old woman with mild myopia presented to her local optometrist for a routine examination and was found to have intraocular pressure (IOP) of 30 mm Hg in both eyes and cupped nerves. She had a family history of glaucoma in her father. She was started on latanoprost in both eyes and was referred for a glaucoma evaluation. On initial evaluation, her IOP was 25 mm Hg in the right eye and 26 mm Hg in the left eye. Central corneal thickness measured 592 µm in the right eye and 581 µm in the left eye. Her angles were open to gonioscopy without any peripheral anterior synechia. She had 1+ nuclear sclerosis with a corrected distance visual acuity (CDVA) of 20/25 in the right eye and 20/30- in the left eye and uncorrected near visual acuity of J1+ in each eye. Her nerves were 0.85 mm in the right eye and 0.75 mm in the left eye. Optical coherence tomography (OCT) showed retinal nerve fiber layer thinning and a dense superior arcuate scotoma into fixation in her right eye, and superior and inferior arcuate scotomas in her left eye (Figures 1 and 2JOURNAL/jcrs/04.03/02158034-202307000-00019/figure1/v/2023-06-26T195222Z/r/image-tiffJOURNAL/jcrs/04.03/02158034-202307000-00019/figure2/v/2023-06-26T195222Z/r/image-tiff, Supplemental Figures 1 and 2, available at http://links.lww.com/JRS/A882 and http://links.lww.com/JRS/A883). She was successively trialed on fixed combination brimonidine-timolol, dorzolamide, and netarsudil, in addition to her latanoprost, but her IOP remained in the mid- to upper 20s in both eyes. The addition of acetazolamide lowered the pressure to 19 mm Hg in both eyes, but she tolerated it poorly. Methazolamide was also attempted with similar side effects. We elected to perform left eye cataract surgery combined with 360-degree viscocanaloplasty and insertion of a Hydrus microstent (Alcon Laboratories, Inc.). Surgery was uncomplicated with IOP of 16 mm Hg on postoperative day 1 with no glaucoma medications. However, by postoperative week 3, IOP returned to 27 mm Hg, and despite restarting latanoprost-netarsudil and finishing her steroid taper, IOP remained at 27 mm Hg by postoperative week 6. Brimonidine-timolol was added back to her left eye regimen and at postoperative week 8, IOP had elevated to 45 mm Hg. Maximizing her therapy with the addition of topical dorzolamide and oral methazolamide brought her IOP back down to 30 mm Hg. At that point, the decision was made to proceed with trabeculectomy of the left eye. The trabeculectomy was uneventful. However, postoperative attempts to augment filtration were rendered less successful by extremely thick Tenon layer. At her most recent follow-up the pressure in the left eye was mid-teens with brimonidine-timolol and dorzolamide. Her right eye IOP is in the upper 20s on maximum topical therapy. Knowing her postoperative course in the left eye, how would you manage the right eye? In addition to currently available options, would you consider a supraciliary shunt such as the MINIject (iSTAR) if such a device were U.S. Food and Drug Administration (FDA)-approved?

[Minimally invasive glaucoma surgery-Comparison of angle based procedures]

Surgical procedures are playing an increasing role in the care of patients with glaucoma. Within the last decade, new surgical procedures have been established, which are summarized under the term minimally invasive glaucoma surgery (MIGS). A wide variety of different procedures are aimed at the structures in the angle of the anterior chamber, such as the trabecular meshwork and Schlemm's canal, to improve the physiological outflow or to improve the alternative uveoscleral outflow. The implementation of the treatment goal differs in the individual procedures, as does the maximum pressure reduction that can be achieved. Compared to trabeculectomy with the use of cytostatic agents, the achievable pressure reduction is usually significantly lower. In contrast, the significantly lower intraoperative and postoperative complication rates are emphasized as an advantage of these procedures. With increasing clinical experience and the growth of sufficient data on these new surgical procedures, a well-founded classification in the treatment algorithm of glaucoma surgery becomes easier; nevertheless, due to the small differences with respect to efficacy and safety profile, the final decision for an individual procedure often remains dependent on the surgeon's personal preferences.

The case for standalone micro-invasive glaucoma surgery: rethinking the role of surgery in the glaucoma treatment paradigm

PURPOSE OF REVIEW

To highlight progress in glaucoma therapy challenging the traditional medication-first approach and present evidence supporting early standalone surgery in the era of micro-invasive glaucoma surgery (MIGS).

RECENT FINDINGS

Medical therapy is limited by well documented poor adherence that compromises the quality of intraocular pressure reduction. Results from modern clinical trials demonstrate advantages of selective laser trabeculoplasty and MIGS procedures in terms of both IOP control and progression risk.

SUMMARY

The MIGS options for pseudophakic or precataractous patients are limited by regulatory rules that require the performance of some procedures only at the time of cataract surgery. These include the iStent/iStent Inject and the Hydrus implants. Nonbleb-forming procedures currently available for standalone use in eyes with mild-moderate primary open-angle glaucoma include gonioscopy-assisted transluminal trabeculotomy (which lowers IOP by 28-61% and medication use by 38-73% in various studies), trabecular ablation with the Trabectome (23-39% and 21-43%, respectively), excisional goniotomy with the Kahook Dual Blade (15-36% and 15-40%, respectively), ab interno canaloplasty (35% and 57%, respectively), and combined canaloplasty and trabeculotomy using the OMNI system (39-40% and 64-73%, respectively). For patients who would benefit from early standalone surgery, these procedures offer meaningful reductions in both IOP and medication burden.

Intraocular Pressure Fluctuation in Primary Open-Angle Glaucoma with Canaloplasty and Microcatheter Assisted Trabeculotomy

Background: Schlemm’s canal (SC) targeted procedures constitute a promising therapy for open angle glaucoma (POAG), safer and less invasive. However, little attention was paid to the intraocular pressure (IOP) variation in patients receiving these procedures, which is the risk factor for POAG progression. This study is to evaluate the IOP variation in eyes with POAG after modified canaloplasty (MC) and microcatheter assisted trabeculotomy (MAT). (2) Methods: POAG with good IOP in office hours after MC or MAT and age-matched normal subjects were recruited in this prospective coherent study. IOP in sitting and supine positions and 24-h IOP was measured. Aqueous vein and blood reflux into the SC were examined. (3) Results: Among 20 normal subjects, 25 eyes with MC eyes and 30 eyes with MAT were recruited in this study. Aqueous veins are frequently located in the inferior nasal quadrants in all groups. No pulsatile signs were observed in an aqueous vein in the MAT group but they were observed in 68% of the MC group. Blood reflux in the SC could be seen in all the operated eyes. The IOP in the sitting position was not significant different among groups (p = 0.419). Compared to normal, the IOP increased dramatically after lying down for 5 min in the MC and MAT groups (PMC vs. normal = 0.003, PMAT vs. normal = 0.004), which is similar for IOP change after lying down for 60 min (PMC vs. normal < 0.001, PMAT vs. normal < 0.001). In terms of diurnal IOP, subjects were stable in the MAT group (p < 0.01), variable in the normal group (p = 0.002), and most fluctuant in MC group (p < 0.001). (4) Conclusions: MC and MAT reduce the IOP but present aberrant short-term IOP regulation, which should be paid attention to in clinical settings.

Long-term effect of canaloplasty on intraocular pressure and use of intraocular pressure-lowering medications in patients with open-angle glaucoma

PURPOSE

To assess the long-term safety and effectiveness of canaloplasty in reducing intraocular pressure (IOP) and use of IOP-lowering medications in eyes with open-angle glaucoma (OAG).

SETTING

Surgical center (Augencentrum Köln, Köln, Germany).

DESIGN

Retrospective study.

METHODS

206 eyes from 130 patients were included. Canaloplasty was performed using the VISCO360 or OMNI surgical system as a stand-alone procedure in 22 eyes and concomitantly with cataract extraction (CE) in 185 eyes with chronic OAG insufficiently controlled or intolerant to IOP-lowering medications. The number of hypotensive medications and IOP were recorded at baseline, day 1, week 1, month 1, month 3, and every 3 months thereafter, with the last follow-up visit at 36 ± 6 months postoperatively. Patients were stratified by baseline IOP (Group 1, IOP >18 mm Hg; Group 2, IOP ≤18 mm Hg). Treatment success in Group 1 was defined as a reduction in IOP and the use of IOP-lowering medications; Group 2 success was defined as maintenance of a lower IOP and a reduction in medication use.

RESULTS

The preoperative mean IOP of both groups was 21.1 ± 8.8 mm Hg, with a mean of 2.0 ± 0.9 hypotensive medications. The primary success end point was met by 73% of patients, with a mean IOP reduction in Group 1 (131 eyes; 21.8 to 15.6 mm Hg, P < .0001) and a maintenance of IOP control in Group 2 (76 eyes; 15.4 to 13.9 mm Hg, P = .24). Medications decreased from 2.2 ± 0.9 to 0.9 ± 1.1 in Group 1 ( P = .024) and from 1.8 ± 0.8 to 0.7 ± 1.0 in Group 2 ( P = .003).

CONCLUSIONS

Canaloplasty alone or in conjunction with CE with the VISCO360 or OMNI surgical system is a safe, tissue-sparing, and effective minimally invasive glaucoma surgery, using a clear corneal incision in phakic or pseudophakic eyes. Canaloplasty performed with both evaluated devices achieved statistically significant, consistent, and clinically meaningful reductions in IOP and use of IOP-lowering medications in adult patients with OAG. In the consistent cohort (n = 42), the IOP-lowering effect lasted up to 42 months, with ongoing data collection expected to describe long-term effectiveness of this intervention.

Updates on the Diagnosis and Management of Glaucoma

Glaucoma is the leading cause of blindness throughout the world (after cataracts); therefore, general physicians should be familiar with the diagnosis and management of affected patients. Glaucomas are usually categorized by the anatomy of the anterior chamber angle (open vs narrow/closed), rapidity of onset (acute vs chronic), and major etiology (primary vs secondary). Most glaucomas are primary (ie, without a contributing comorbidity); however, several coexisting ophthalmic conditions may serve as the underlying etiologies of secondary glaucomas. Chronic glaucoma occurs most commonly; thus, regular eye examinations should be performed in at-risk patients to prevent the insidious loss of vision that can develop before diagnosis. Glaucoma damages the optic nerve and retinal nerve fiber layer, leading to peripheral and central visual field defects. Elevated intraocular pressure (IOP), a crucial determinant of disease progression, remains the only modifiable risk factor; thus, all current treatments (medications, lasers, and operations) aim to reduce the IOP. Pharmacotherapy is the usual first-line therapy, but noncompliance, undesirable adverse effects, and cost limit effectiveness. Laser and surgical treatments may lower IOP significantly over long periods and may be more cost effective than pharmacotherapy, but they are plagued by greater procedural risks and frequent treatment failures. Traditional incisional procedures have recently been replaced by several novel, minimally invasive glaucoma surgeries with improved safety profiles and only minimal decreases in efficacy. Minimally invasive glaucoma surgeries have dramatically transformed the surgical management of glaucoma; nevertheless, large, randomized trials are required to assess their long-term efficacy.

[Modifications of canaloplasty : Strong pressure-lowering effect with a low risk profile]

Trabeculectomy still achieves the strongest intraocular pressure (IOP) reduction of all glaucoma surgical techniques, but with the drawback of a significant risk profile. Against this background, canaloplasty has established itself as a much gentler alternative which achieves sufficient IOP reduction and enables a significant reduction in postoperative glaucoma medication. However, approximately half of patients are not completely medication free. In response, a number of modifications have been developed with the goal of further enhancing the IOP-lowering effect of canaloplasty, but without the risk of serious complications. By combining canaloplasty with the newly developed suprachoroidal drainage, a uveoscleral drainage is created in addition to the trabecular outflow improvement, which seems to have an additive effect. Thus, for the first time, an IOP-lowering effect comparable to successful trabeculectomy can be achieved. Numerous other modifications with implants also enhance the potential of canaloplasty or offer other additional benefits such as the possibility of telemetric IOP self-measurement by the patient. The additional creation of a subconjunctival drainage with or without use of cytostatic drugs also seems promising. Ab interno procedures, on the other hand, have limited pressure-lowering potential but may provide some additional benefit in mild glaucoma and in the setting of cataract surgery.

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.

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

PURPOSE

To report the 36-month effectiveness of ab-interno canaloplasty performed with the iTrack microcatheter (Nova Eye Medical, Fremont, USA) as a standalone procedure or combined with cataract surgery.

DESIGN

A single-center, retrospective case series PARTICIPANTS: Eyes diagnosed with primary open-angle glaucoma (POAG).

METHODS

Eyes with POAG were treated with either ab-interno canaloplasty as a standalone procedure (iTrack-alone) or in conjunction with phacoemulsification (iTrack+phaco).

MAIN OUTCOME MEASURES

The main outcome was mean reduction in intraocular pressure (IOP) and number of glaucoma medications at 12, 24, and 36 months postoperatively. Secondary endpoints consisted of visual acuity and the rate of complications.

RESULTS

44 eyes of 44 patients with open-angle glaucoma were included: 23 eyes in the iTrack-alone group and 21 eyes in the iTrack+phaco group. When both groups were analyzed together, both IOP and the number of medications were significantly reduced at 12 months (p<0.0001) and remained stable at 24 and 36 months. IOP decreased from 20.5±5.1 mmHg preoperatively to 13.3±2.1, 13.1±2.4 and 13.3±2.1 mmHg at 12-24-36 months respectively; the number of medications was reduced from 2.8±0.9 preoperatively to 1.1±1.1, 1.0±1.1 and 1.3±1.3 at 12-24 and 36 months postoperatively. Comparable results were observed in the iTrack-alone and iTrack+phaco groups, from a baseline 20.9±6.1 and 20.0±3.9 to 13.2±2.1 and 13.5±2.2 at 36-month respectively. At 36 months, 95.5% of eyes had IOP ≤17 mmHg and 68.2% of eyes were on ≤1 medication. No serious intra-operative or postoperative complications were reported.

CONCLUSION

Ab-interno canaloplasty performed with the iTrack microcatheter was found to be effective in reducing IOP and medication dependence. Comparable results were observed when employed as a standalone procedure or when combined with cataract surgery.

Canaloplasty in the spotlight: surgical alternatives and future perspectives

The modern glaucoma surgeon is faced with many surgical alternatives for the management of glaucoma. In recent years, numerous techniques that make Schlemm's canal (SC) more accessible for surgery by being less invasive and surgically less challenging were introduced. Since its first introduction, canaloplasty has become a well-established method of glaucoma surgery. The aim of this paper was to present an overview of canaloplasty and its modifications, and to highlight their strong points and potential drawbacks based on available data on the effectiveness of each technique. Furthermore, it offered an overview of the development of canaloplasty over time and the clinical aspects that should be considered in patient selection. Abbreviations: ABiC = Canaloplasty ab interno, AH = aqueous humour, CSD = Canaloplasty with suprachoroidal drainage, IOP = intraocular pressure, MIGS = minimally invasive glaucoma surgery, OAG = open angle glaucoma, PEXG = pseudoexfoliation glaucoma, SC = Schlemm's canal, TDM = trabeculo-Descemet's membrane.

Clinical Results of Ab Interno Canaloplasty in Patients with Open-Angle Glaucoma

Purpose

To report treatment outcomes of ab interno canaloplasty using the Visco360 and Omni system devices as a standalone procedure or combined with cataract surgery in patients with open-angle glaucoma (OAG).

Design

Retrospective, single-center, consecutive case series.

Study Patients

Eighty-nine eyes of 64 patients aged 43 to 91 with open-angle glaucoma treated with ab interno canaloplasty between January 2018 and September 2019. Eyes with previous incisional glaucoma surgery and eyes with less than 90 degrees of viscodilation were excluded.

Intervention

Patients underwent ab interno canaloplasty as a stand-alone procedure or in conjunction with cataract surgery. Ab interno canaloplasty was performed with either the Visco360 or Omni System devices (Sight Sciences, Menlo Park, CA). Treatment consisted of viscodilation without trabeculotomy.

Main Outcome Measures

Primary outcome measures were mean IOP and mean number of glaucoma medications. Additional analysis included the impact of degrees of treatment on treatment outcomes.

Results

Preoperative mean IOP was 24.5 ± 8.3; the number of preoperative glaucoma medications was 2.5 ± 1.3. At 18 months postoperative, the mean IOP was reduced 36% to 15.8 ± 2.5 (P<0.001) and glaucoma medications were reduced 32% to 1.7 ± 1.5 (P<0.05). Higher preoperative IOP was significantly correlated with increased IOP lowering. Reduction of mean IOP and medications were not significantly different between standalone ab interno canaloplasty vs cataract surgery/ab interno canaloplasty. Reduction of mean IOP and medications were not significantly different between patients with 180 degrees of treatment vs 360 degrees of treatment.

Conclusion

Ab interno canaloplasty reduces IOP and glaucoma medication use in patients with OAG whether as a standalone surgery or in combination with cataract surgery.

Deconstructing aqueous humor outflow - The last 50 years

Herein partially summarizes one scientist-clinician's wanderings through the jungles of primate aqueous humor outflow over the past ~45 years. Totally removing the iris has no effect on outflow facility or its response to pilocarpine, whereas disinserting the ciliary muscle (CM) from the scleral spur/trabecular meshwork (TM) completely abolishes pilocarpine's effect. Epinephrine increases facility in CM disinserted eyes. Cytochalasins and latrunculins increase outflow facility, subthreshold doses of cytochalasins and epinephrine given together increase facility, and phalloidin, which has no effect on facility, partially blocks the effect of both cytochalasins and epinephrine. H-7, ML7, Y27632 and nitric oxide - donating compounds all increase facility, consistent with a mechanosensitive TM/SC. Adenosine A1 agonists increase and angiotensin II decrease facility. OCT and optical imaging techniques now permit visualization and digital recording of the distal outflow pathways in real time. Prostaglandin (PG) F2α analogues increase the synthesis and release of matrix metalloproteinases by the CM cells, causing remodeling and thinning of the interbundle extracellular matrix (ECM), thereby increasing uveoscleral outflow and reducing IOP. Combination molecules (one molecule, two or more effects) and fixed combination products (two molecules in one bottle) simplify drug regimens for patients. Gene and stem cell therapies to enhance aqueous outflow have been successful in laboratory models and may fill an unmet need in terms of patient compliance, taking the patient out of the delivery system. Functional transfer of genes inhibiting the rho cascade or decoupling actin from myosin increase facility, while genes preferentially expressed in the glaucomatous TM decrease facility. In live NHP, reporter genes are expressed for 2+ years in the TM after a single intracameral injection, with no adverse reaction. However, except for one recent report, injection of facility-effective genes in monkey organ cultured anterior segments (MOCAS) have no effect in live NHP. While intracameral injection of an FIV. BOVPGFS-myc.GFP PGF synthase vector construct reproducibly induces an ~2 mmHg reduction in IOP, the effect is much less than that of topical PGF2⍺ analogue eyedrops, and dissipates after 5 months. The turnoff mechanism has yet to be defeated, although proteasome inhibition enhances reporter gene expression in MOCAS. Intracanalicular injection might minimize off-target effects that activate turn-off mechanisms. An AD-P21 vector injected sub-tenon is effective in 'right-timing' wound healing after trabeculectomy in live laser-induced glaucomatous monkeys. In human (H)OCAS, depletion of TM cells by saponification eliminates the aqueous flow response to pressure elevation, which can be restored by either cultured TM cells or by IPSC-derived TM cells. There were many other steps along the way, but much was accomplished, biologically and therapeutically over the past half century of research and development focused on one very small but complex ocular apparatus. I am deeply grateful for this award, named for a giant in our field that none of us can live up to.

Visual outcomes of combined cataract surgery and minimally invasive glaucoma surgery

Minimally invasive glaucoma surgery (MIGS) has become a reliable standard of care for the treatment of glaucoma when combined with cataract surgery. This review describes the MIGS procedures currently combined with and without cataract surgery with a focus on visual outcomes based on the literature and the experience of the ASCRS Glaucoma Clinical Committee.

Circumferential Viscodilation Ab Interno Combined with Phacoemulsification for Treatment of Open-Angle Glaucoma: 12-Month Outcomes

Purpose

To evaluate reduction in intraocular pressure (IOP) and medications for open-angle glaucoma (OAG) patients 12 months post-ab-interno circumferential viscodilation (VISCO360, Sight Sciences, Menlo Park, CA) in conjunction with cataract surgery.

Setting

Surgical center (New York, United States).

Design

Retrospective study of all OAG patients treated with 360-degree ab-interno viscodilation with cataract surgery by a single surgeon (NR) having 12 months of follow-up. Eyes were stratified by baseline IOP. Group 1: ≥18 mmHg (n=111). Group 2: <18 mmHg (n=69).

Methods

IOP was measured using Goldmann applanation tonometry. Medications, the number of medication-free eyes in each group at 12 months, and adverse events (AE) are reported. Analysis includes descriptive statistics and t-tests evaluating change from baseline.

Results

Groups 1 and 2 had mean baseline IOP of 22 and 14.3 mmHg. Medication use was 0.9 and 1.1 for Groups 1 and 2. At 12 months IOP for Group 1 was reduced 22% to 17.2 mmHg (p<0.0001) on 1.0 medications (p=0.7). IOP for Group 2 was similar to baseline (15.4 mmHg) but with a reduction in medications to 0.6 (p<0.05). The proportion medication free at 12 months was 32% and 47% for Groups 1 and 2 versus 34% and 26% at baseline, respectively. There were few AE (hyphema 1.7%, IOP elevation >10 mmHg >30 days post-op 1.1%, mild inflammation <1%) and no secondary surgical interventions excepting a single paracentesis, one-day postoperative.

Discussion

Treatment goals for the two groups differed. Pressure reduction (Group 1) or medication reduction (Group 2). Viscodilation achieved significant IOP reduction in Group 1 and medication reduction in Group 2 with many patients (both groups) medication free at 12 months. AE were infrequent and transient.

Conclusion

Circumferential ab-interno viscodilation can be combined with cataract surgery and provide an IOP lowering and medication reduction benefit sustained for at least 12 months, for many patients with OAG.

Minimally Invasive Glaucoma Surgery: What Do We Know? Where Should We Go?

With the arrival of a plethora of new and revolving minimally invasive glaucoma surgery techniques, glaucoma specialists currently are fortunate to have various surgical options that aim to recovery of the function of the aqueous outflow system in different ways. Meanwhile, the aqueous outflow system has become the hot point of researching. In ARVO 2019, a special interest group session was held on new perspectives on minimally invasive glaucoma surgery. Ten surgeons, clinical professors, and experimental scientists were invited to report their latest studies and discussed on five hot topics in this special interest group. This review summarizes the special interest group session and posts the issues of greatest concern, providing insight to the aqueous outflow system and areas that require further study.

Circumferential canal surgery: a brief history

PURPOSE OF REVIEW

Most microinvasive glaucoma surgery (MIGS) procedures bypass outflow resistance residing proximally in the trabecular meshwork and inner wall of Schlemm's canal. A novel procedure combining trabeculotomy with viscodilation adds to this by also addressing distal resistance of the canal and collector channel ostia. This review examines the development and evidence for both trabeculotomy and canaloplasty separately and the combination in a single procedure.

RECENT FINDINGS

Recent aqueous angiography studies have confirmed the segmental nature of outflow through Schlemm's canal highlighting the need to address distal outflow pathway resistance. Combined trabeculotomy and viscodilation ab interno is a novel approach with a new purpose-designed device (OMNI Surgical System) becoming available to surgeons in early 2018. Recent results as both a standalone and combined with cataract procedure demonstrate significant intraocular pressure reductions with an average 41% reduction from baseline in the pseudophakic group.

SUMMARY

Targeting both distal as well as proximal points of outflow resistance in the conventional pathway may prove to be a highly efficacious MIGS modality. Additional large prospective studies are currently ongoing to confirm these preliminary results.

Ab interno canaloplasty combined with trabecular bypass stenting in eyes with primary open-angle glaucoma

Purpose

Evaluate outcomes of trabecular meshwork (TM) bypass (iStent^® GTS100) with cataract extraction (CE) and TM-bypass + ab interno canaloplasty (CP) (VISCO360^®) with CE in patients with primary open-angle glaucoma (POAG).

Setting

Private surgical center for a comprehensive ophthalmology practice

Design

Retrospective analysis of 186 eyes from 130 consecutive patients with 6 months follow-up.

Methods

Eligible eyes had POAG, indicated for CE, and had received CE + TM-bypass or CE + TM-bypass + CP. Exclusions: glaucomas not POAG, SLT within 6 months, or previous ALT. IOP, visual acuity, and medication use assessed at baseline, months 1, 3, and 6. Endpoints were mean reduction in IOP from baseline at 6 months, proportion with IOP reduction at 6 months of ≥20% and IOP <18 mmHg on same or fewer medications, mean medication reduction, and proportion medication independent.

Results

Eighty-six eyes comprised the CE + TM-bypass + CP group; 100 eyes in the CE + TM-bypass group. At 6 months: mean IOP reduction was 2.9±3.6 mmHg for CE + TM-bypass + CP and 1.7±3.1 mmHg for CE + TM-bypass group (P<0.05); the proportion with IOP reduction of ≥20% and an IOP <18 mmHg on the same or fewer medications was 46% for CE + TM-bypass + CP and 35% for CE + TM-bypass; for both CE + TM-bypass + CP and CE + TM-bypass, mean number of medications was decreased (0.9 and 0.7, P<0.0001) with 56% and 48% off all medication. The most common AE were inflammation (6%) for CE + TM-bypass + CP group and VA loss (8%) for CE + TM-bypass.

Conclusion

At six months, a greater proportion of CE + TM-bypass + CP patients achieved IOP reduction of ≥20% and an IOP <18 mmHg on the same or fewer medications than for TM-bypass + CE.

360° ab-interno Schlemm's canal viscodilation in primary open-angle glaucoma

Purpose: To evaluate the safety and effectiveness of ab-interno microcatheterization and 360° viscodilation of Schlemm’s canal (SC) using the VISCO360^® Viscosurgical System in treatment of primary open angle glaucoma (POAG).

Setting: Surgical center (Augencentrum Köln, Köln, Germany).

Design: Retrospective analysis of 106 eyes from 71 consecutive patients.

Methods: Ab-interno canal viscodilation (VISCO360^®) with or without cataract extraction was performed in two groups of patients with mild-moderate POAG: Group 1 had a baseline intraocular pressure (IOP) ≥18 mmHg (n=72 eyes) and Group 2 had a baseline IOP <18 mmHg (n=34 eyes). IOP without washout was measured and number of IOP-lowering medications were documented at all visits. Effectiveness was determined by reduction in IOP and reduction in the number of IOP-lowering medications at 12±3 months from baseline. Safety was determined by the rate of adverse events (AEs) and secondary surgical interventions (SSI).

Results: In Group 1, all eyes available at 12±3 months (n=72), had a 41.0% reduction in mean IOP (from 24.6±7.1 mmHg to 14.6±2.8 mmHg), 87% (n=62) of which showed an IOP reduction of ≥20% with no increase in IOP-lowering medications. In Group 2, all eyes (n=34) maintained their baseline IOP at all postoperative visits. In both groups, a significant decrease (>89%) in mean number of IOP-lowering medications was seen at 12 months with 86% of eyes completely off medication with no increase in IOP. The most common AE seen was hyphema (13%) and no eye required SSI during the study period.

Conclusion: Ab-interno SC viscodilation (VISCO360) is safe and effective in lowering IOP and reducing hypotensive medications in patients with OAG.

Hemorrhagic Descemet Membrane Detachment during Ab Interno Canaloplasty

Purpose

To describe a Descemet membrane detachment in peripheral cornea after canaloplasty with ab interno approach in glaucoma.

Case Report

A 60-year-old male with uncontrolled primary open-angle glaucoma (POAG) underwent ab interno canaloplasty in the left eye. The previous corrected visual acuity was 20/400 and intraocular pressure 26 mmHg with maximum medical therapy. There was evidence of minor intrastromal bleeding and limited Descemet membrane detachment during the introduction of intracanalicular viscoelastic. Speculate that the Descemet detachment occurred owing to the excessive pressure while injecting the viscoelastic. A conservative management was decided due to the size of the detachment outside the visual axis. On the first postsurgical day, the slit lamp biomicroscopy confirmed that the paralimbal extension of the pre-Descemet hemorrhage was 3mm and the radial extension was 2mm. Moreover the initial thickness of the pre-Descemet hemorrhage measurement with anterior segment OCT was 0.6mm. The follow-up was done weekly. At 3 months postoperatively, cornea recovered its transparency and morphology and intraocular pressure was 18mmHg with maximum medical therapy.

Conclusion

Descemet membrane detachment by viscoelastic with partial intrastromal hematoma is a rare complication of the ab interno canaloplasty, which can be managed conservatively if it has not compromised the visual axis and has a limited extension.