Canaloplasty: Current Value in the Management of Glaucoma

Color Doppler Imaging Assessment of Ocular Blood Flow Following Ab Externo Canaloplasty in Primary Open-Angle Glaucoma

Background/Objectives: Glaucomatous neuropathy, a progressive deterioration of retinal ganglion cells, is the leading cause of irreversible blindness worldwide. While elevated intraocular pressure (IOP) is a well-established modifiable risk factor, increasing attention is being directed towards IOP-independent factors, such as vascular alterations. Color Doppler imaging (CDI) is a prominent technique for investigating blood flow parameters in extraocular vessels. This prospective, nonrandomized clinical trial aimed to assess the impact of ab externo canaloplasty on ocular blood flow parameters in patients with primary open-angle glaucoma (POAG) at a three-month follow-up. Methods: Twenty-five eyes of twenty-five patients with early or moderate POAG underwent canaloplasty with simultaneous cataract removal. CDI was used to measure peak systolic velocity (PSV), end-diastolic velocity (EDV), and resistive index (RI) in the ophthalmic artery (OA), central retinal artery (CRA), and short posterior ciliary arteries (SPCAs) before and after surgery. Results: The results showed a significant reduction in IOP and improvement in mean deviation at three months post-surgery. Best corrected visual acuity and retinal nerve fiber layer thickness significantly increased at each postoperative control visit. However, no significant changes were observed in PSV, EDV, and RI in the studied vessels. Conclusions: In conclusion, while canaloplasty effectively reduced IOP and medication burden, it did not significantly improve blood flow parameters in vessels supplying the optic nerve at three months post-surgery. Careful patient selection considering glaucoma severity and vascular risk factors is crucial when choosing between canaloplasty and more invasive procedures like trabeculectomy. Further larger studies are needed to comprehensively analyze this issue.

Effects of Schlemm's Canal Suture Implantation Surgery and Pilocarpine Eye Drops on Trabecular Meshwork Pulsatile Motion

The trabecular meshwork is an important structure in the outflow pathway of aqueous humor, and its movement ability directly affects the resistance of aqueous humor outflow, thereby affecting the steady state of intraocular pressure (IOP). (1) Objective: The purpose of this study was to preliminarily estimate the effects of pilocarpine eye drops and trabeculotomy tunneling trabeculoplasty (3T) on trabecular meshwork (TM) pulsatile motion via phase-sensitive optical coherence tomography (Phs-OCT). (2) Method: In a prospective single-arm study, we mainly recruited patients with primary open-angle glaucoma who did not have a history of glaucoma surgery, and mainly excluded angle closure glaucoma and other diseases that may cause visual field damage. The maximum velocity (MV) and cumulative displacement (CDisp) of the TM were quantified via Phs-OCT. All subjects underwent Phs-OCT examinations before and after the use of pilocarpine eye drops. Then, all subjects received 3T surgery and examinations of IOP at baseline, 1 day, 1 week, 1 month, 3 months, and 6 months post-surgery. Phaco-OCT examinations were performed at 3 and 6 months post-surgery, and the measurements were compared and analyzed. (3) Results: The MV of TM before and after the use of pilocarpine eye drops was 21.32 ± 2.63 μm/s and 17.00 ± 2.43 μm/s. The CDisp of TM before and after the use of pilocarpine eye drops was 0.204 ± 0.034 μm and 0.184 ± 0.035 μm. After the use of pilocarpine eye drops, both the MV and CDisp significantly decreased compared to those before use (p < 0.001 and 0.013, respectively). The IOP decreased from baseline at 22.16 ± 5.23 mmHg to 15.85 ± 3.71 mmHg after 3 months post-surgery and from 16.33 ± 2.51 mmHg at 6 months post-surgery, showing statistically significant differences (p < 0.001). The use of glaucoma medication decreased from baseline at 3.63 ± 0.65 to 1.17 ± 1.75 at 3 months and 1.00 ± 1.51 at 6 months post-surgery; the differences were statistically significant (p < 0.001). Additionally, there was no statistically significant difference in the MV between 3 and 6 months after surgery compared to baseline (p = 0.404 and 0.139, respectively). Further, there was no statistically significant difference in the CDisp between 3 and 6 months after surgery compared to baseline (p = 0.560 and 0.576, respectively) (4) Conclusions: After the preliminary study, we found that pilocarpine eye drops can attenuate TM pulsatile motion, and that 3T surgery may reduce IOP without affecting the pulsatile motion status of the TM.

Efficacy and Safety of ab Externo Phaco-Canaloplasty versus First-Generation iStent Bypass Implantation Combined with Phacoemulsification in Patients with Primary Open Angle Glaucoma-Early Results

This study evaluated the early outcomes of the hypotensive efficacy and safety profile of ab externo phaco-canaloplasty versus first-generation iStent bypass implantation combined with phacoemulsification in patients with primary open-angle glaucoma (POAG). In total, 82 patients with POAG comprising 92 eyes were divided into phaco-canaloplasty (Group PC, (n = 47) or iStent combined with phacoemulsification (Group PiS, n = 45) groups. Primary outcome measures were intraocular pressure (IOP) reduction and number of glaucoma medications. Secondary outcome measures were best-corrected visual acuity (BCVA), endothelial cell density (EECD), changes in anterior chamber depth (ACD), and complication rate. The follow-up period was approximately 6 months. Preoperative IOPs were 17.30 (15.00; 19.85) mmHg and 17.50 (15.10; 20.90) mmHg in the PC and PiS groups, respectively (p = 0.876). At the end of the follow-up, IOP decreased to 15.00 (13.00; 16.00) mmHg and 15.00 (14.00; 17.00) mmHg in the PC and PiS groups, respectively (p = 0.438). Medication usage decreased from 2.08 to 0.12 and 1.40 to 0.04 in PC and PiS eyes, respectively. Most patients in both groups were medication-free at 6 months follow-up. After 6 months of observation, EECD in PC and PiS groups decreased from 2309.50 (2032.00; 2533.00) to 1966.50 (1262.00; 2353.50) and 2160.00 (1958.50; 2372.50), to1231.00 (1089.00; 2050.00), respectively (p = 0.037). Pre-surgery BCVA was 0.80 (0.50; 1.00) and 0.60 (0.40; 1.00) in PC and PiS eyes, respectively (p = 0.456). Follow-up BCVA was 0.95 (0.60; 1.00) for PC and 1.00 (1.00; 1.00) for PiS. Hyphema and corneal oedema were noted on the first day post-surgery in both groups. Subsequent complications included a transient increase in IOP in the PC group. Phaco-canaloplasty and iStent bypass implantation combined with phacoemulsification significantly lowered IOP and decreased medication burden. All eyes in both groups maintained or exhibited improved BCVA relative to baseline. Both surgeries had low postoperative complication rates and exhibited comparable safety profiles over 6-month follow-up in patients with POAG.

Size Matters: Ab Interno Canaloplasty Revision with Suture Trabeculotomy

Aim

To report the efficacy of the revision of failed ab interno canaloplasty with micro-invasive suture trabeculotomy (MIST) over a follow-up period of 24 months.

Materials and methods

A retrospective analysis was performed on 23 eyes with open-angle glaucoma (OAG), on whom an ab interno canaloplasty revision with MIST was performed for glaucoma progression. The primary outcome was the proportion of eyes with a significant intraocular pressure (IOP) reduction at 12 months post trabeculotomy, defined as an IOP ≤ 18 mm Hg or ≥20% reduction in IOP without any secondary intervention (SI), and with the same or fewer number of glaucoma medications (NGM). All parameters, including best corrected visual acuity (BCVA), IOP, NGM, and SI, were evaluated at 1, 6, 12, 18, and 24 months.

Results

At 12 months, eight out of 23 eyes (36.4%) achieved complete success, maintained in six eyes (27.3%) at 24 months. A significantly lower mean IOP was recorded at all visits [14.3 ± 4.0 mm Hg at 24 months vs 23.1 ± 6.8 mm Hg at baseline (BL)] with a percent IOP change of up to 27.3% at 24 months postoperatively. NGM and BCVA did not significantly decrease from BL. A total of 11 eyes (47.8%) needed an SI throughout the follow-up period.

Conclusion

Ab interno trabeculotomy in patients with failed canaloplasty was not shown to be effective in providing a satisfactory control of IOP in OAG patients, possibly due to the small suture gauge used in the initial canaloplasty.

Clinical significance

Further research is needed to optimize the surgical outcome.

How to cite this article

Seif R, Jalbout NDE, Sadaka A, et al. Size Matters: Ab Interno Canaloplasty Revision with Suture Trabeculotomy. J Curr Glaucoma Pract 2022;16(3):152-157.

Clinical application of the CO2 laser in Ab externo Schlemm's canal surgery

Purpose

This study aimed to investigate the clinical application of laser as a knife in Ab externo Schlemm's canal (SC) surgery and compare the efficacy and safety of the CO₂ laser with the conventional procedure using a surgical knife.

Methods

Patients who underwent either canaloplasty or trabeculotomy with CO₂ laser system which was used to locate and ablate the outer wall of SC at the time interval between May 2020 and May 2021 were identified, their medical files were reviewed, and their results were compared with conventional surgery group who underwent canaloplasty or trabeculotomy with conventional surgical knife at the same time period. The following datas were conducted and compared: age, sex, intraocular pressure (IOP), number of drugs, best-corrected visual acuity (BCVA), mean deviation and pattern standard deviation of visual field examination, SC opening related complications.

Results

A total of 49 patients (49 eyes) were included in this study, including 23 in the Laser surgery group and 26 in the conventional surgery group. Time for SC opening was 49.33 ± 25.23 s and 116.50 ± 31.79 s for laser surgery group and conventional surgery group, respectively. This difference between the two groups was statistically significant (P < 0.01). Hemorrhage occurred in five eyes during ablation for the laser surgery group and in 24 eyes for the conventional surgery group. In addition, anterior chamber penetration occurred in two cases for the laser surgery group and in six cases for the conventional surgery group. The success rate of identifying and opening outer wall of SC was 91.30% (21 eyes) for the laser surgery group and 76.92% (20 eyes) for the conventional surgery group. The difference between preoperative and postoperative intraocular pressure for each group was statistically significant (P < 0.01), and there were no statistically significant differences across the two groups in terms of postoperative IOP (P = 0.238) and BCVA (P = 0.389).

Conclusion

Compared with the conventional procedure using a surgical knife, CO₂ laser-assisted ablation of the outer wall of SC was less time-consuming and less technically challenging. CO₂ laser-assisted ablation also resulted in fewer complications. Furthermore, it had a shorter learning curve and a higher success rate of identifying and opening SC.

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.

Combined Ab interno viscocanaloplasty (ABiC) in open-angle glaucoma: 12-month outcomes

PURPOSE

The aim of this study was to analyse the safety profile and efficacy of ab interno viscocanaloplasty (ABiC) through to 12 months post-operatively.

METHODS

In this retrospective study, the medical records of all patients who underwent ABiC between September 2015 and December 2019 were analysed. Complete success was defined as a 12-month reduction in intraocular pressure (IOP) ≥ 20% from baseline with no concomitant medications. Qualified success criteria were identical, with no more medications than at baseline.

RESULTS

In all, 54 eyes of 41 patients were analysed. Mean IOP decreased from 23.6 ± 7.4 mmHg preoperatively to 14.2 ± 2.9 mmHg (-39.8%; p < 0.001) after 12 months. Concomitantly, the number of anti-glaucoma treatment dropped from 2.9 ± 1.0 to 0.6 ± 1.1 (-79.3%; p < 0.001). Amongst patients with a baseline MD < -12.0 dBs, mean IOP decreased from 22.8 ± 9.8 mmHg to 13.8 ± 4.4 mmHg (p = 0.049), with a concomitant reduction of medications from 2.8 ± 1.3 to 1.2 ± 1.3 (p < 0.001). Complete success at 12 months was achieved in 46% of eyes, and qualified success was achieved in 65% of eyes. Amongst eyes with a baseline MD < -12.0 dBs, 50% achieved complete success, and 83.3% achieved qualified success. A total of 19 eyes (35.2%) were considered surgical failure, all due to uncontrolled IOP. Of them, 7 eyes (13.0%) required further filtering surgery. Twelve post-operative adverse events were observed, with early post-operative IOP spikes being the most common (22.2%).

CONCLUSIONS

ABIC achieved a statistically significant reduction in IOP and anti-glaucoma medications through 12 months, while maintaining a favourable safety profile in mild-to-severe open-angle glaucoma.

The Efficacy of Ab Externo Canaloplasty by Using a Nonabsorbable Suture and No Viscoelastics; IOP Results, Intraoperative and Early Complication Rates within 6-Month Follow-Up Period

BACKGROUND

To report the efficacy of ab externo canaloplasty by exclusively using only a nonabsorbable suture as a standalone operation or combined with phacoemulsification in terms of mean intraocular pressure (IOP), medication reduction, and intra- and postoperative complication rates as well as additional glaucoma surgery.

PATIENTS AND METHODS

Forty-eight patients with primary open-angle glaucoma (POAG) and 50 eyes were divided into two groups according to the operation performed (Group A canaloplasty, n = 34 and Group B canaloplasty combined with phaco, n = 16), respectively. The success criteria were evaluated between three IOP ranges: a) IOP ≤ 16 mmHg, b) ≤ 18 mmHg, and c) ≤ 21 mmHg. Complete success was considered the percentage of eyes reaching these goals with no medication and qualified success with or without medication. Groups A and B were compared with the Kaplan-Meier test. Mean IOP and medication reduction as well as additional glaucoma surgery were also evaluated. The follow-up time was 6 months. Statistical importance was given at p < 0.05.

RESULTS

Fail rate and intraoperative conversion of canaloplasty to other surgery (trabeculotomy due to extensive cheese-wiring) accounted for 12% (6 eyes), while a mandatory usage of the iTrack 250A microcatheter to successfully overcome intracanalicular bridging of the Schlemm's canal accounted for 20% (10 eyes). The most common early postoperative complications in both groups were hyphema, cheese wiring, and transient IOP rising. The mean IOP in Group A reduced from 23.67 ± 6.06 mmHg to 13.35 ± 4.23 mmHg and in Group B, it reduced from 23.55 ± 6.19 mmHg to 12.75 ± 1.5 mmHg at 6 months (p < 0.001). Group A's absolute success rates accounted for a) 44%, b) 47.1%, and c) 52.9% in comparison to Group B [a) 50%, b) 50%, and c) 56.3%] at 6 months (p < 0.05). Qualified success with or without medication showed no statistical differences between the groups. The mean medication reduction was significantly lower (p < 0.001) in both groups (Group A from baseline 3.2 ± 1.23 to 0.95 ± 1.35 and Group B from 3.12 ± 0.88 to 1.12 ± 0.75 at 6 months, respectively). Five eyes (10%) required additional glaucoma surgery.

CONCLUSIONS

Ab externo canaloplasty by exclusively using only a nonabsorbable suture as a standalone operation or combined with phacoemulsification seems to lower the mean IOP and medication sufficiently. However, they pose a greater surgical challenge and intraoperative complication rate. Additional glaucoma surgery or medication following both procedures may be necessary to achieve an optimal target IOP.

Feasibility of microscope-integrated swept-source optical coherence tomography in canaloplasty

Background

Several researchers have used commercial microscope-integrated optical coherence tomography (OCT) systems in glaucoma surgery, including ab interno trabeculectomy and canaloplasty. However, the 840 nm wavelength light source of the OCT systems is not ideal for imaging the anterior chamber angle structures because of its limited penetration. We evaluated the potential value of a microscope-integrated swept-source OCT system with a 1,310 nm center-wavelength light in canaloplasty for glaucoma.

Methods

Sixteen porcine eyes were used to simulate canaloplasty. The critical surgical steps were monitored using a prototype microscope-integrated OCT system with a 1,310 nm light source and a high axial scan rate of 100 kHz. The images from swept-source OCT and three-dimensional images from the microscope were projected simultaneously onto a liquid crystal display three-dimensional monitor (LMD-4251TD, Sony, Japan). The changes in the collector vessel (aqueous drainage structure in the porcine eye, similar to Schlemm’s canal in humans) were measured using Image J software. Histological sections stained with hematoxylin and eosin were used to assess surgical efficacy.

Results

High-resolution real-time images of the anterior segment were acquired during canaloplasty using the microscope-integrated OCT system. With the real-time OCT images, the position of the collector vessel was identified and the scleral flap could be created at the ideal location. The expansion of the collector vessel after viscoelastic injection was also visualized in real time. Compared with baseline, there was a significant increase in the cross-sectional area (from 14,502.98±9,242.55 to 59,499.04±20,506.41 µm², P<0.001) of the collector vessel.

Conclusions

Using the microscope-integrated OCT system, real-time images of the anterior segment were successfully acquired during the operation. The microscope-integrated OCT system might be useful in future anti-glaucoma surgery.

Level-Set Method for Image Analysis of Schlemm's Canal and Trabecular Meshwork

Purpose

To evaluate different segmentation methods in analyzing Schlemm's canal (SC) and the trabecular meshwork (TM) in ultrasound biomicroscopy (UBM) images.

Methods

Twenty-six healthy volunteers were recruited. The intraocular pressure (IOP) was measured while study subjects blew a trumpet. Images were obtained at different IOPs by 50-MHz UBM. ImageJ software and three segmentation methods—K-means, fuzzy C-means, and level set—were applied to segment the UBM images. The quantitative analysis of the TM-SC region was based on the segmentation results. The relative error and the interclass correlation coefficient (ICC) were used to quantify the accuracy and the repeatability of measurements. Pearson correlation analysis was conducted to evaluate the associations between the IOP and the TM and SC geometric measurements.

Results

A total of 104 UBM images were obtained. Among them, 84 were adequately clear to be segmented. The level-set method results had a higher similarity to ImageJ results than the other two methods. The ICC values of the level-set method were 0.97, 0.95, 0.9, and 0.57, respectively. Pearson correlation coefficients for the IOP to the SC area, SC perimeter, SC length, and TM width were −0.91, −0.72, −0.66, and −0.61 (P < 0.0001), respectively.

Conclusions

The level-set method showed better accuracy than the other two methods. Compared with manual methods, it can achieve similar precision, better repeatability, and greater efficiency. Therefore, the level-set method can be used for reliable UBM image segmentation.

Translational Relevance

The level-set method can be used to analyze TM and SC region in UBM images semiautomatically.

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.

Real world use of loteprednol etabonate ophthalmic gel 0.5% in cases representative of comorbid pathologies responding to minimally invasive glaucoma surgery

Purpose

With the increasing use of minimally invasive surgical techniques for intraocular pressure (IOP) lowering in glaucoma patients, there is a need to examine best practices regarding the postoperative management of these patients. Corticosteroids, though effective in controlling postoperative ocular pain and inflammation, present distinct challenges in glaucoma surgery patients, as their use can be associated with IOP elevation. Loteprednol etabonate (LE) is an ocular corticosteroid designed to have an improved safety profile relative to other corticosteroids.

Methods

We report here a representative selection of cases in which patients were successfully treated with LE ophthalmic gel 0.5% (LE gel) following a variety of minimally invasive glaucoma surgery (MIGS) procedures. Cases included patients undergoing various procedures including a Trabectome combined with cataract surgery; micro-stent surgery (iStent) combined with cataract surgery; supraciliary CyPass Micro-Stent placement combined with cataract surgery; Kahook Dual Blade goniotomy; and ab interno canaloplasty using the iTrack catheter.

Observations

In all cases, use of LE gel during the postoperative period appeared effective and safe in reducing inflammation and controlling pain. No adverse events or IOP elevations were noted, even in those patients continuing use of LE gel past the postoperative period for longer than six months with documented follow-up. In two cases, patients with elevated IOP using either prednisolone or difluprednate postoperatively were switched to LE gel, with a subsequent reduction in IOP.

Conclusions

This selection of cases involving patients undergoing MIGS suggests that LE gel may be an effective and safe option for treating postoperative inflammation and pain following such procedures with minimal to no effect on IOP or other negative sequalae.

Ab externo canaloplasty results and efficacy: a retrospective cohort study with a 12-month follow-up

Background

The aim of this study is to review the outcomes of canaloplasty versus canaloplasty combined with phacoemulsification in a retrospective cohort study and to evaluate the efficacy of these methods in terms of intraocular pressure (IOP) lowering effect, postoperative complications and additional glaucoma surgery or reintroduction of medical therapy over a 12-month follow-up.

Methods

In a retrospective cohort study, 602 eyes with primary open angle glaucoma (POAG) were treated with canaloplasty or canaloplasty combined with phacoemulsification. The results were evaluated separately in two main groups; group A canaloplasty (262 eyes) and group B canaloplasty combined with phaco (322 eyes). Each group was then subdivided into three additional groups according to the severity of glaucoma. The criteria for successful treatment were evaluated between three IOP ranges; IOP ≤ 16 mmHg, 18 mmHg and 21 mmHg. Complete success was considered the percentage of eyes reaching target IOP with no medication and partial success with medication. Groups A and B subgroups were compared using the Kaplan Meier test. Mean IOP, reduction of antiglaucoma agents and additional IOP lowering methods were also evaluated. The follow-up time was 12 months. Statistical significance was set at p < 0.05.

Results

An incomplete intraoperative cannulation of Schlemm’s canal resulting in conversion to other glaucoma surgery occurred in 18 eyes (2.99%). In both of the main groups, postoperative hyphema, descemet membrane detachment and transient IOP rise were the most common postoperative complications. The mean IOP in group A and subgroups at 12 months was 13.26 ± 4.5 mmHg, 15.19 ± 3.97 mmHg and 18.09 ± 3.75 mmHg. Respectively in group B mean IOP was 14.51 ± 4.69 mmHg, 14.40 ± 4.11 mmHg and 14.25 ± 2.76 mmHg. Complete success was achieved in group A in 69.19, 74.51 and 74.31% of eyes. In group B complete success was achieved in 81.60, 77.33 and 83.33% of eyes respectively. Kaplan Meier between groups A and B was statistically significant for IOP ≤ 16 mmHg and IOP ≤ 21 mmHg (p = 0.0041 and p = 0.0312), but not for IOP ≤ 18 mmHg (p = 0.6935). Partial success for IOP ≤ 16 mmHg was 95.23 and 92.26%, for IOP ≤ 18 mmHg was 91.66 and 90.47% and for IOP ≤ 21 mmHg, 90.00 and 93.10%, in groups A and B respectively. Twenty-three eyes received additional surgery (3.93%), 10 trabeculectomies and 2 cyclophotocoagulation in group A, and 9 trabeculectomies and 2 cyclophotocoagulation in group B.

Conclusion

Canaloplasty and canaloplasty combined with phacoemulsification significantly lower the IOP and have a lower postoperative complication rate. Additional glaucoma surgery or medication following both procedures is necessary if target IOP is unsatisfactory. In this study, canaloplasty combined with phacoemulsification demonstrated superior success rate compared to canaloplasty alone.

Comparison of performance between two microcatheter systems in ab externo canaloplasty: A retrospective comparison study

Purpose:

To compare the performance of two different microcatheter systems, iTrack™ 250A and Glaucolight, in ab externo canaloplasty in three major categories: intraocular pressure reduction, drug therapy reintroduction, and evaluation of viscodilation over distension of the inner wall of Schlemm’s canal.

Methods:

A total of 56 and 46 eyes from different glaucoma types underwent ab externo canaloplasty using two different microcatheter systems. Group formation was made according to microcatheter system used. Kaplan–Meier test was performed for drug therapy reintroduction in relation to the two microcatheters. Tests of between-subject effects in two-way analysis of variance evaluated the efficacy of the two microcatheters and their features in relation to intraocular pressure reduction.

Results:

Kaplan–Meier test was not statistically significant (p = 0.20) regardless of microcatheter system. Tests of between-subject effects in relation to intraocular pressure reduction was not statistically different between the two microcatheters (p = 0.26) or between microcatheter and follow-up (p = 0.90). Intraocular pressure reduction in different glaucoma type was statistically significant during the follow-up period and glaucoma types showed different results between them in relation to follow-up (p < 0.001 and p = 0.002, respectively), but the pairwise comparison was not statistically important (p = 0.42). Intraocular pressure reduction was better in pseudophakic eyes in comparison with phakic eyes (p = 0.03), but the selection of microcatheter seemed not to affect this result (p = 0.11 and p = 0.32, respectively).

Conclusion:

Both microcatheter systems performed equal in terms of intraocular pressure reduction. Drug therapy reintroduction was not affected by the selection of the two microcatheters. Different types of glaucoma responded different to canaloplasty. Pseudophakic eyes responded better to treatment than phakic eyes, but the microcatheter selection seemed not affect this result.

Canaloplasty in the Treatment of Open-Angle Glaucoma: A Review of Patient Selection and Outcomes

Canaloplasty is a relatively new non-penetrating surgery for the reduction of intraocular pressure in patients affected by glaucoma. The technique uses a microcatheter to perform a 360 º cannulation of Schlemm’s canal and leaves in place a tension suture providing an inward distension. It aims to restore the physiological outflow pathways of the aqueous humour and is independent of external wound healing. Several studies have shown that canaloplasty is effective in reducing intraocular pressure and has a low rate of complications, especially compared with trabeculectomy, the gold standard for glaucoma surgery. Currently, canaloplasty is indicated in patients with open-angle glaucoma, having a mild to moderate disease, and the combination with cataract phacoemulsification may provide further intraocular pressure reduction. This article reviews canaloplasty indications, results and complications and analyses its outcomes compared with traditional penetrating and non-penetrating techniques.

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

Purpose

To compare the efficacy of minimally invasive ab-interno canaloplasty (ABiC) vs ab-externo canaloplasty (CP) in reducing intraocular pressure (IOP) and glaucoma medication dependence.

Patients and methods

This nonrandomized, retrospective, single-center, paired eye study assessed the 12-month outcomes of 12 patients with primary open-angle glaucoma who underwent ABiC in one eye and CP in the other eye, either as stand-alone procedures or combined with cataract extraction. Primary endpoints included mean IOP and number of glaucoma medications at 12 months postoperative. Secondary endpoints included surgical complications and secondary interventions.

Results

Four males and eight females with a mean age of 73.8±12.6 years were included. In the CP group, the mean preoperative IOP was 18.1±3.9 mmHg on 2.4±0.5 medications, which reduced to 13.5±2.2 mmHg (P<0.05) on 0.9±0.9 medications (P<0.001). In the ABiC group, the mean preoperative IOP was 18.5±3.4 mmHg on 2.4±0.5 medications and postoperative IOP was 13.8±2.2 mmHg (P<0.05) on 0.8±0.8 medications (P<0.05). There was no significant difference in IOP and medication use between treatment groups at 12 months postoperative. No serious adverse events were recorded in either group, though two patients in the CP group developed pressure spikes 10 mmHg beyond preoperative IOP.

Conclusion

This paired eye study found ABiC to have comparable IOP lowering and glaucoma medication reduction to CP in open-angle glaucoma. This suggests ABiC may be a suitable method for improving aqueous outflow via the trabecular pathway. Further large-scale investigation is needed.

A retrospective analysis of the use of loteprednol etabonate ophthalmic suspension 0.5% following canaloplasty

Background

While loteprednol etabonate (LE) suspension 0.5% is approved for the treatment of postoperative ocular inflammation, there have been no reported studies of its use in glaucoma patients undergoing canaloplasty.

Methods

This was a retrospective medical chart review conducted at a single US center. Data were collected on patients with glaucoma who underwent canaloplasty with or without cataract surgery, and were prescribed LE suspension 0.5% postoperatively. Outcomes evaluated included postsurgical inflammation (anterior chamber [AC] cells and flare), intraocular pressure (IOP), number of IOP-lowering medications, and postsurgical complications.

Results

Data were collected on 204 patients (262 eyes) with a mean (SD) age of 71.6 (11.3) years. The most frequent LE dosing regimens at day 1, week 1, and month 1 postsurgery were QID (92.3%; 241/261), TID (52.6%; 133/253), and QD (65.5%; 78/119), respectively. Inflammation (AC flare and cells), mostly mild, was noted in 33.2% (86/259) of eyes on postoperative day 1 and 8.6% (21/244) of eyes at month 1. Mean IOP and mean number of IOP-lowering medications were significantly reduced from baseline (P<0.001) at all time points postoperatively. Complete (no IOP-lowering medication) or qualified (use of ≤2 IOP-lowering medications) surgical success was achieved in 78.8% and 90.6% of eyes, respectively, at month 6 and 63.4% and 92.7% of eyes at month 36. The most frequently observed postoperative complication was hyphema in 48.7% (126/259) eyes at day 1, which decreased to 0.4% (1/244) of eyes by month 1. IOP ≥30 mmHg was noted in 13 (5.3%) eyes at postoperative week 1 and rarely thereafter, and no patient discontinued therapy because of an IOP increase.

Conclusion

These real-world data suggest that canaloplasty with or without cataract surgery managed postoperatively with LE suspension 0.5% is effective and safe in the glaucoma patient.

Experimental circumferential canaloplasty with a new Schlemm canal microcatheter

AIM

To present a new, simple, inexpensive Schlemm canal microcatheter for circumferential canaloplasty in a rabbit model.

METHODS

A rabbit glaucoma animal model was established by intravitreal injection of triamcinolone acetonide. Circumferential canaloplasty with a new Schlemm canal microcatheter (patent license number: 201220029850.0) was performed. The Schlemm canal microcatheter was composed of microcatheter wall and lumen. The wall was made of high refractive index plastic optical fiber that could be attached to an illuminant so that the whole lighted microcatheter was visible during circumferential canaloplasty. The lumen could be attached to an injector for injection of viscoelastic during catheterization. Rabbits were divided randomly into the control, model and treatment groups. Intraocular pressure (IOP) was measured with a Tono-pen tonometer pre-operation and 3, 7, 14, 21 and 28d post-operation. Ultrasound biomicroscopy was performed to visualize the Schlemm canal microcatheter in the Schlemm canal and the sclera pool.

RESULTS

The Schlemm canal microcatheter could be used to perform circumferential canaloplasty in the rabbit glaucoma animal model. IOP was lower in the treatment group than that in the model group 3, 7, 14 and 28d after operation. There were no significant differences in IOP between the control group and treatment group. The differences among the three groups were statistically significant (3d: F=41.985, P<0.001; 7d: F=65.696, P<0.001; 14d: F=114.599, P<0.001; 28d: F=55.006, P<0.001).

CONCLUSION

Circumferential canaloplasty is safe and effective in control of experimental glaucoma model in rabbits.

Ab Interno Trabeculectomy With the Trabectome as a Valuable Therapeutic Option for Failed Filtering Blebs

PURPOSE

Uncontrolled intraocular pressure (IOP) after glaucoma filtration surgery is a challenging problem in the management of glaucoma patients. The Trabectome is a device for selective electroablation of the trabecular meshwork through a clear cornea incision without affecting the conjunctiva. Minimally invasive glaucoma surgery using the Trabectome is safe and effective as primary glaucoma surgery. Here we investigate the results of ab interno trabeculectomy with the Trabectome for IOP control in patients with a failed filtering bleb.

METHODS

A total of 60 eyes of 60 consecutive patients with primary open-angle glaucoma (POAG) or pseudoexfoliative glaucoma (PXG) were enrolled in this single center observational study. Trabectome surgery was performed alone or in combination with phacoemulsification by 2 experienced surgeons. IOP readings and number of IOP lowering medication as primary outcome parameters were taken by an independent examiner. Intraoperative and postoperative medication were recorded systematically.

RESULTS

Mean IOP before surgery was 24.5±3.5 mm Hg and decreased to 15.7±3.4 (-36%) after mean follow-up of 415 days. The number of necessary IOP lowering medication dropped from 2.1±1.3 to 1.8±1.2 (14% reduction from baseline). A total of 25% (n=15) of cases reported here needed additional surgery after 517 days (range: 6 to 1563 d). No major complications were observed. After mean follow-up, we found a qualified success rate for PXG of 87% and 50% for POAG as revealed by the Kaplan-Meier analysis according to the definitions for success in advanced glaucoma cases according to the World Glaucoma Association (40% reduction from baseline IOP and maximum IOP of 15 mm Hg).

DISCUSSION

Trabectome surgery for uncontrolled IOP after trabeculectomy is safe and effective especially in PXG patients. Given the demanding subgroup of patients studied here, it is not surprising that success rates are lower compared with previous studies investigating the Trabectome for primary glaucoma surgery. The number of necessary IOP lowering medication drops at first, but seems to reach preoperative values after 20 months of follow-up. Trabectome surgery should be considered as a valuable escape procedure for patients with failed filtering blebs and uncontrolled IOP.

An Analysis of 3-Year Outcomes Following Canaloplasty for the Treatment of Open-Angle Glaucoma

Purpose

To report 3-year results investigating the safety and efficacy of canaloplasty for open-angle glaucoma.

Setting

University of Oklahoma, Dean McGee Eye Institute, Oklahoma, United States of America.

Design

Nonrandomized single-center retrospective chart review.

Methods

Adult open-angle glaucoma eyes underwent canaloplasty or combined cataract-canaloplasty surgery. A tensioning suture was placed into Schlemm's canal in all eyes. Primary endpoints included the mean IOP and mean number of glaucoma medications at each follow-up visit. Secondary endpoints included visual acuity and surgical/postsurgical complications.

Results

The study cohort included 277 eyes (mean age, 72.8 years). Overall, the mean baseline IOP of 19.7 mmHg was reduced to 14.3 mmHg,14.0 mmHg, and 15.2 mmHg at 1, 2, and 3 years, respectively (p < 0.001). The average medicine use was reduced from 2.1 preoperatively to 0.4 at 12 months, and 0.5 and 0.6 at two and three years, respectively (p < 0.001). The frequency of surgical and postsurgical complications was low with no serious adverse events recorded.

Conclusion

Canaloplasty was safe and effective in achieving long-term IOP reductions and reduced dependence on antiglaucoma medications.

Clinical investigation of new glaucoma procedures

PURPOSE OF REVIEW

This article reviews recent studies evaluating the efficacy and complication profiles of novel glaucoma procedures promoting aqueous outflow.

RECENT FINDINGS

Literature from the 2015 to 2016 review period includes abundant data regarding new and emerging glaucoma procedures. Notable findings from recent randomized clinical trials include titratability of intraocular pressure with multiple trabecular microbypass stents (iStent; Glaukos, Laguna Hills, California, USA) and greater reduction in intraocular pressure and medication usage following intracanalicular scaffolding (Hydrus Microstent; Ivantis Inc., Irvine, California, USA) combined with phacoemulsification vs. phacoemulsification alone. A supraciliary microstent (CyPass Micro-Stent; Transcend Medical, Inc., Menlo Park, California, USA) received approval from the Food and Drug Administration after a pivotal trial demonstrated its efficacy and safety. Early studies of investigational subconjunctival filtering devices (XEN Gel Stent; AqueSys, Inc., Aliso Viejo, California, USA and InnFocus MicroShunt; InnFocus Inc., Miami, Florida, USA) offer promising evidence, but late complications are as yet unknown.

SUMMARY

Newer glaucoma procedures targeting different aqueous outflow pathways have improved the safety profile of glaucoma surgery while preserving modest efficacy. Most can be combined with phacoemulsification, allowing for simultaneous treatment of comorbid cataract and glaucoma. Well-designed randomized clinical trials with extended follow-up remain necessary to evaluate the long-term efficacy and late complications of these novel procedures.