Nonpenetrating filtering procedures: viscocanalostomy and collagen wick

Outcomes of 360° suture trabeculotomy after unsuccessful canaloplasty

BACKGROUND

Canaloplasty is a well-established non-penetrating glaucoma surgery. Unsuccessful outcomes can be enhanced by micro-invasive 360° suture trabeculotomy (360°trabeculotomy), analyzed in this study.

METHODS

This retrospective study included twenty eyes of 19 patients, mean age 59.7±17.2 years, with primary open-angle glaucoma (POWG n = 14), pseudoexfoliation glaucoma (PEX n = 3), juvenile glaucoma (n = 2) and aphakic glaucoma (n = 1), who underwent micro-invasive 360° trabeculotomy after unsuccessful (intraocular pressure (IOP) >21 mmHg under maximum glaucoma eye drop therapy (Meds)) canaloplasty. IOPs, Meds, complications and failure rates (IOP >21 mmHg at two consecutive follow-ups) were evaluated. Complete success (no Meds) and qualified success (with Meds) rates for IOP levels ≤21 mmHg and ≤ 18 mmHg at the last follow-up were evaluated.

RESULTS

IOPs and Meds were significantly reduced from before to 1 week (10.3±3.1 days) after 360° trabeculotomy (IOP, 28.3±6.0 mmHg to 15.8±4.5 mmHg; p < 0.001; Meds, 3.1 ± 1.2 to 1.0 ± 1.2; p < 0.001). IOPs (p = 0.37) and Meds (p = 0.33) did not decrease further from 1 week until the last follow-up (18.3 ± 8.2 months (IOP, 14.4±3.8 mmHg; Meds, 1.5±1.3)). Complete and qualified success was 25% (5/20) and 70% (14/20) for IOP ≤21 mmHg, as well as 25% (5/20) and 60% (12/20) for IOP ≤18 mmHg. Four eyes had postoperative hyphema, which resolved after a mean period of 4.0 ± 2.2 days. Five failures occurred after a mean of 40.6 ± 51.9 days after 360° trabeculotomy. All failures underwent trabeculectomy. Eyes that needed early (≤3 months post canaloplasty) 360° trabeculotomy showed higher IOPs before (p < 0.001) and lower (p = 0.03) IOPs 2 months post 360° trabeculotomy than eyes with late (>3 months) 360° trabeculotomy surgery.

CONCLUSIONS

360° trabeculotomy is a safe, micro-invasive, simple and successful method to enhance failed canaloplasty.

Combined glaucoma and cataract surgery: Comparison of viscocanalostomy, endocyclophotocoagulation, and ab interno trabeculectomy

PURPOSE

To compare outcomes of phacoemulsification combined with viscocanalostomy, endocyclophotocoagulation (ECP), or ab interno trabulectomy for intraocular pressure (IOP) control and safety in eyes with open-angle glaucoma and visually significant cataract.

SETTING

Farabi Eye Hospital, Tehran, Iran.

DESIGN

Retrospective case series.

METHODS

Medical records of patients who had combined surgery and were followed for at least 1 year were reviewed. Complete success, postoperative IOP, number of medications at each visit, and complications were evaluated and compared before and after adjustments for confounders.

RESULTS

Forty-six eyes had combined phacoviscocanalostomy, 35 had phaco-ECP, and 28 eyes phaco-ab interno trabulectomy. The groups were matched for baseline IOP (P = .24). At the final follow-up (mean 17.2 months ± 5.5 [SD]), the phacoviscocanalostomy group had the lowest mean IOP (13.5 ± 4.7 mm Hg, 29% decrease) (P = .01). There was no significant difference in the final IOP between phaco-ECP and phaco-ab interno trabulectomy (16.4 ± 3.9 mm Hg, 20% decrease versus 15.8 ± 4.2 mm Hg, 15% decrease) (P = .88). The reduction in the number of medications was greater with phacoviscocanalostomy (77%) than with phaco-ECP (40%) and phaco-ab interno trabulectomy (44%) (P = .01). Phacoemulsification-ab interno trabulectomy had the fewest complications. Intraocular pressure spikes were more frequent in the phaco-ECP group (20%) than in the other groups (4%) (P = .05).

CONCLUSIONS

All procedures significantly lowered IOP. Phacoemulsification-ab interno trabulectomy resulted in fewest complications and phacoviscocanalostomy led to the largest IOP drop and largest reduction of medications.

Trabeculectomy combined with deep sclerectomy and scleral flap suture tension adjustment under an anterior chamber maintainer: a new modification of trabeculectomy

The objective of this study was to investigate the efficacy and safety of trabeculectomy combined with deep sclerectomy in patients with primary open angled glaucoma (POAG) and to compare the results with those from conventional trabeculectomy. In the study 12 eyes of 10 patients operated with trabeculectomy combined with deep sclerectomy (Group I) and 16 eyes of 16 patients operated with conventional trabeculectomy surgery (Group II) were included. In the described form of combined deep sclerectomy with the trabeculectomy technique the superficial scleral flap was sutured with 10/0 monofilament, the number and tension of sutures were adjusted according to the outflow dynamics, under the scleral flap, of balanced salt solution (BSS) provided by an anterior chamber maintainer. In groups I and II all the patients were male POAG cases with mean ages of 60.0 +/- 19.4 and 67.0 +/- 7.1 years, respectively. The mean follow-up periods were 8.3 +/- 3.5 months for group I and 16.6 +/- 7.0 months for group II. Preoperative mean IOP were 29.7 +/- 8.3 and 29.1 +/- 12.8 mmHg mmHg, and average topical antiglaucomatous medications were 2.9 +/- 0.7 and 2.7 +/- 1.1 for groups I and II, respectively. Postoperatively mean IOP measurements were reduced in groups I and II to 10.5 +/- 2.9 vs. 9.6 +/- 4.8 mmHg at 1 week, 13.7 +/- 5.6 vs. 16.0 +/- 9.8 at 1st month, 12.3 +/- 6.4 vs. 17.3 +/- 8.0 at 3rd month, 11.0 +/- 4.1 vs. 15.3 +/- 5.8 at 6th month, 10.8 +/- 1.6 vs. 16.1 +/- 4.4 at 12th month, and 11.0 +/- 1.0 vs. 16.7 +/- 5.0 at 18th month. Statistical analysis revealed that mean postoperative IOP measurements for group I were significantly lower than for group II for all measurements except the first week (P < 0.05). At 12th month, the complete (IOP <22 mmHg without medication) and qualified (IOP <22 mmHg with medication) success rates were 83.3 and 100% for group I and 63.6 and 90.9% for group II. Postoperatively at 12th month, the mean number of antiglaucoma medications had fallen to 0.0 +/- 0.0 in group I and 0.81 +/- 1.1 in group II. Trabeculectomy surgery combined with deep sclerectomy and suture adjustment under an anterior chamber maintainer provided sufficient IOP decrease and diffuse bleb morphology. This technique could be used as a safe method for management of glaucoma.

Nonpenetrating glaucoma surgery

Nonpenetrating glaucoma surgeries have been developed in recent years in order to improve the safety of conventional filtering procedures. The goal of nonpenetrating filtering procedures is to reduce intraocular pressure by enhancing the natural aqueous outflow channels, while reducing outflow resistance located in the inner wall of the Schlemm's canal and the juxtacanalicular trabecular meshwork. In the last few years viscocanalostomy and deep sclerectomy with external trabeculectomy have become the most popular nonpenetrating filtering procedures. Both involve removal of a deep scleral flap, the external wall of Schlemm's canal and corneal stroma behind the anterior trabeculum and Descemet's membrane, thus creating an intrascleral space. The aqueous humour leaves the anterior chamber through the intact trabeculo-Descemet's membrane into the scleral space, from where it will egress into different pathways. The technique is associated with a long learning curve. Published clinical trials comparing nonpenetrating glaucoma surgery to full-thickness trabeculectomy have a consensus on the superior safety profile of nonpenetrating glaucoma surgery but are not in agreement when it comes to efficacy, where conflicting results have been found. This article reviews the nonpenetrating surgical techniques, mechanisms of action, indications, contraindications, complications, and results.

Effects of viscoelastic injection into Schlemm's canal in primate and human eyes: potential relevance to viscocanalostomy

OBJECTIVE

To study possible initial mechanisms of alterations in aqueous outflow that may result from the injection of viscoelastic into Schlemm's canal (SC) during viscocanalostomy.

DESIGN

Experimental animal (Macaca nemestrina) and human autopsy study.

METHODS

Eyes were dissected into a limbal ring and hemisected or quartered. Uncannulated segments served as controls. In treated segments, SC was cannulated and viscoelastic injected. Segments were fixed and sectioned into continuous 500 to 1000 microm pieces, examined at the dissecting microscope, and photomicrographs were taken. Representative tissue was further prepared for scanning electron microscopy or sectioned at 1 microm.

MAIN OUTCOME MEASURES

Tissue sections were examined to determine the extent of dilation and disruption of SC and related structures. SC dimensions were measured in segments from controls, cannulated regions, and regions of viscoelastic injection beyond the cannula insertion. In the hemisected segments, the circumferential extent of SC dilation was determined, and structures within the canal were described and counted.

RESULTS

SC was dilated with increased anteroposterior length and height in cannulated and viscoelastic-injected segments in both primate and human eyes relative to untreated controls. The walls of SC were disrupted in both regions of cannulation and of viscoelastic injection, and the collector channels were widely dilated by viscoelastic. With decreasing effectiveness, the injected viscoelastic circumferentially dilated SC as far as 14 mm and 16 mm in primate and human hemisections, respectively. Structures that bridged between the walls of SC were often disrupted.

CONCLUSIONS

Cannulation of SC and injection of viscoelastic beyond the cannula resulted in marked dilation of SC and associated collector channels. Lateral walls, inner wall endothelium, and bridging structures of SC were frequently disrupted by cannulation and sometimes by injected viscoelastic. These findings suggest that viscocanalostomy may acutely cause a direct communication between SC and the juxtacanalicular space, and so may initially enhance conventional aqueous outflow. Controlled clinical trials will be necessary to determine the long-term outcomes of this procedure.