Canaloplasty with Suprachoroidal Drainage in Patients with Pseudoexfoliation Glaucoma - Four Years Results

Long-term outcomes of canaloplasty and phaco-canaloplasty in the treatment of open angle glaucoma: a single-surgeon experience

PURPOSE

To evaluate and compare the long-term outcomes of canaloplasty and phaco-canaloplasty in the treatment of open angle glaucoma and assess the prognostic factors associated with surgical outcome.

METHODS

A 48-month retrospective analysis was performed on n = 133 open angle glaucoma eyes treated with canaloplasty and n = 57 open angle glaucoma eyes treated with phaco-canaloplasty by a single surgeon. Surgical success was defined according to six criteria, achieving a target intraocular pressure (IOP) ≤ 21, 18 or 15 mmHg on glaucoma medications (qualified success) or without any further treatment (complete success), including laser therapy or surgery. Kaplan-Meier survival analysis and Cox regression analysis were performed to evaluate surgical success and preoperative factors associated with surgical outcome. Surgical complications in the early postoperative period were compared between canaloplasty and phaco-canaloplasty.

RESULTS

Canaloplasty and phaco-canaloplasty significantly reduced postoperative IOP and number of glaucoma medications (p = 0.001 for both). Phaco-canaloplasty showed higher rates of cumulative surgical success over canaloplasty, but only for target IOP ≤ 21 and ≤ 18 (p = 0.018 and p = 0.011, respectively). A preoperative number of > 4 glaucoma medications predicted surgical failure. Phaco-canaloplasty was associated with a higher rate of IOP peaks in the first month compared with canaloplasty (40.4% vs 12.7%, p = 0.000).

CONCLUSION

Canaloplasty and phaco-canaloplasty demonstrated long-term efficacy in the treatment of open angle glaucoma, with phaco-canaloplasty showing higher rates of surgical success compared to canaloplasty, but not for target IOPs lower than 16 mmHg. Patients on more than 4 preoperative glaucoma medications may not be good candidates for canaloplasty and may benefit from other surgical options.

Advances in Canaloplasty-Modified Techniques Yield Strong Pressure Reduction with Low Risk Profile

For decades, trabeculectomy (TE) was considered the gold standard for surgical treatment of open-angle glaucoma owing to its powerful intraocular pressure (IOP)-lowering potency. However, owing to the invasive nature and high-risk profile of TE, this standard is changing, and minimally invasive procedures are becoming more preferable. In particular, canaloplasty (CP) has been established as a much gentler alternative in everyday life and is under development as a full-fledged replacement. This technique involves probing Schlemm's canal with a microcatheter and inserting a pouch suture that places the trabecular meshwork under permanent tension. It aims to restore the natural outflow pathways of the aqueous humor and is independent of external wound healing. This physiological approach results in a significantly lower complication rate and allows considerably simplified perioperative management. There is now extensive evidence that canaloplasty achieves sufficient pressure reduction as well as a significant reduction in postoperative glaucoma medications. Unlike MIGS procedures, the indication is not only mild to moderate glaucoma; today, even advanced glaucoma benefits from the very low hypotony rate, which largely avoids a wipeout phenomenon. However, approximately half of patients are not completely medication-free after canaloplasty. As a consequence, a number of canaloplasty modifications have been developed with the goal of further enhancing the IOP-lowering effect while avoiding the risk of serious complications. By combining canaloplasty with the newly developed suprachoroidal drainage procedure, the individual improvements in trabecular facility and uveoscleral outflow facility appear to have an additive effect. Thus, for the first time, an IOP-lowering effect comparable to a successful trabeculectomy can be achieved. Other implant modifications also enhance the potential of canaloplasty or offer additional benefits such as the possibility of telemetric IOP self-measurement by the patient. This article reviews the modifications of canaloplasty, which has the potential to become a new gold standard in glaucoma surgery via stepwise refinement.

[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.

Modified suture-assisted canaloplasty in Asians with primary open-angle glaucoma: a prospective study with 12-month follow-up

BACKGROUND

To evaluate the efficacy and safety of modified suture-assisted canaloplasty in Asians with primary open-angle glaucoma (POAG).

METHODS

A prospective, consecutive cases study, evaluating a modified canaloplasty by twisted 6/0 suture was performed on Asian POAG patients. Three modifications of this canaloplasty included opening the Schlemm's canal by viscocanalostomy, circumferential probing by a twisted 6/0 suture and loose suture of the superficial scleral flap. The twisted 6/0 suture was selected as a prober based on characteristical analysis of size and contact measurement as well as chemical composition conducted among 5/0, twisted 6/0 polypropylene sutures and the microcatheter. Success criteria were defined as intraocular pressure (IOP) ≤ 21 mmHg, 18 mmHg, 15 mmHg, and ≥ 20% reduction without (complete success) or with medications (qualified success). Efficacy was assessed by the success rate of circumferential catheterization, IOP values, the success rate of the surgery, the number of IOP-lowering medications, best-corrected vision acuity (BCVA), cup-to-disc ratio (C/D), and mean deviation (MD). Safety was evaluated by adverse events.

RESULTS

Forty eyes from 40 consecutive patients were included with a mean follow-up of 14.8 ± 3.0 months. Circumferential catheterization was successfully conducted in 36 eyes (90%). Mean IOP decreased from 26.2 ± 6.9 mmHg to 14.5 ± 2.7 mmHg at 12 months postoperatively. While medication numbers were reduced from 3.2 ± 0.6 to 0.5 ± 0.8 at month 12 (both p < 0.001). Qualified success rate was 97.2% [95% confidence interval (CI) 0.92-1.03], 86.1% (95% CI 0.74-0.98) and 66.7% (95% CI 0.51-0.83) at 12 months with three criteria. BCVA, C/D and MD did not show progression at 1-year follow-up (p > 0.05). Age, baseline IOP, and spherical equivalent negatively influenced the success rate significantly (all p < 0.05). Adverse events included hyphema (30.6%), IOP spike > 25 mmHg (8.3%), and peripheral synechia to the trabecular-Descemet's membrane (2.7%).

CONCLUSION

Twisted 6/0 suture can be an ideal material for cannulation. Modified suture-assisted canaloplasty is an effective, safe alternative with a cost-efficient feature for patients with POAG, especially in developing countries.

TRIAL REGISTRATION

This trial was registered in the Chinese Clinical Trial Registry ( ChiCTR1900028618 , 29/12/2019).

Canaloplasty in Pseudoexfoliation Glaucoma. Can It Still Be Considered a Good Choice?

Purpose: The aim of this study was to assess the long-term outcomes of canaloplasty surgery in pseudoexfoliation glaucoma (PEXG) patients. Material and Methods: A total of 116 PEXG patients with an intraocular pressure (IOP) > 21 mm/Hg and maximum tolerated local medical therapy who underwent canaloplasty from February 2008 to January 2022 were considered. Every six months, all subjects underwent a complete ophthalmic examination. The period of follow-up ranged from 2 to 167 months. Inclusion criteria included only patients for whom the entire procedure could be completed with a follow-up of at least 2 years. Results: Amongst the 116 PEXG patients, the entire procedure could not be performed in 10 eyes (8.6%), and thus they were not considered in the analysis. Twenty-three patients did not reach the two-year follow-up and another 16 patients during this time period were lost. A total of 67 patients with a mean follow-up of 49 ± 32.3 months were considered in the analysis. The pre-operative mean IOP was 31.2 ± 8.7 mm/Hg (range 20−60). The mean IOP at the two-year follow-up was 17.2 ± 6.7 mmHg, with a mean reduction from baseline of 44.9%. After two years, the qualified success rates according to three different criteria (IOP ≤ 21, ≤18 and ≤16 mmHg) were 80.6%, 73.1% and 61.0%, respectively. The total number of medications used pre- and at the follow-up at 2 years was 3.5 ± 0.8 and 1.2 ± 1.4, respectively. Early complications included: hyphema, in about 30% of cases; Descemet membrane detachment (4.9%); and IOP spikes > 10 mmHg (9.7%). A late failure with an acute IOP rise of up to 50 mmHg was observed in 41 cases (61.2%) after 3 to 72 months. Conclusions: Long-term post-operative outcomes of canaloplasty in PEXG patients appear to be quite good on average; however, an acute rise in IOP can be observed in more than 60% of the cases after a long period of satisfactory IOP control. For this reason, canaloplasty may not be suitable in eyes with PEXG, especially in patients with severe functional damage.

[Secondary open-angle glaucoma: pseudoexfoliative glaucoma, pigmentary glaucoma and neovascular glaucoma]

Secondary open-angle glaucomas are a heterogeneous group of diseases in which a variety of pathophysiological mechanisms result in an elevation of intraocular pressure. This article is the first part of a review of the more common forms of secondary open-angle glaucomas. The pathogenesis, characteristic clinical findings and treatment of pseudoexfoliative glaucoma, pigmentary glaucoma and neovascular glaucoma are discussed. An emphasis is placed on the differences in treatment compared to primary open-angle glaucoma and prophylactic treatment approaches are explained where possible.