Canaloplasty and trabeculotomy with the OMNI® surgical system in OAG with prior trabecular microbypass stenting

Visual Function After Schlemm's Canal-Based MIGS

Filtration surgery is highly effective in lowering intraocular pressure; however, it is associated with a higher risk of severe complications. Visual dysfunction may persist in relatively uneventful cases because of induced astigmatism or worsening optical aberrations. Therefore, for early- to moderate-stage glaucoma, an increasing number of surgeons are prioritizing surgical safety and preserving postoperative visual function by opting for minimally invasive glaucoma surgery (MIGS). Among the various MIGS techniques, canal-opening surgery-targeting aqueous outflow through the Schlemm's canal (Schlemm's canal-based MIGS, CB-MIGS)-has gained increasing popularity. Unlike filtration surgery, CB-MIGS does not require creating an aqueous outflow pathway between the intraocular and extraocular spaces. Consequently, it is considered a minimally invasive procedure with a reduced risk of severe complications and is increasingly being chosen for suitable cases. Although this surgical technique has limitations in lowering intraocular pressure, it avoids the manipulation of the conjunctiva or sclera and is primarily performed through a small corneal incision. Therefore, a minimal impact on induced astigmatism or postoperative refractive changes is expected. However, few reviews comprehensively summarize postoperative changes in visual function. Therefore, this study reviews the literature on visual function after CB-MIGS, focusing on changes in best-corrected visual acuity (BCVA), refraction, astigmatism, and the effectiveness of visual field preservation to assess the extent of these postoperative changes. Hyphema is the primary cause of early postoperative vision loss and is often transient in cases in which other complications would have led to visual impairment. Severe complications that threaten vision are rare. Additionally, compared with filtration surgery, postoperative visual recovery tends to be faster, and the degree of induced astigmatism is comparable to that of standalone cataract surgery. When combined with cataract surgery, the refractive error is at the same level as that of cataract surgery alone. However, in some cases, mild hyperopic shifts may occur because of axial length shortening, depending on the extent of intraocular pressure reduction. This possibility has been highlighted in several studies. Regarding the effectiveness of slowing the progression of visual field defects, most studies have focused on short- to medium-term postoperative outcomes. Many of these studies have reported the sufficient suppression of progression rates. However, studies with large sample sizes and long-term prospective designs are limited. To establish more robust evidence, future research should focus on conducting larger-scale, long-term investigations.

Historical and Contemporary Debates in Schlemm's Canal-Based MIGS

Glaucoma is one of the primary causes of blindness worldwide. Canal opening surgery, a type of minimally invasive glaucoma surgery (MIGS) applied in cases of mild to moderate glaucoma, has gained increasing popularity in recent years due to its efficacy in reducing the intraocular pressure, its safety profile, the simplicity of its technique, and the reduced likelihood of compromised vision. Nevertheless, the existing body of histopathological studies remains insufficient for a comprehensive understanding of post-surgical wound healing. Consequently, debates persist among researchers regarding the mechanism through which Schlemm's canal opening surgery reduces the intraocular pressure, as well as the surgical techniques that may impact the outcomes and the factors influencing surgical success. As the history of MIGS is relatively short and lacks sufficient systemic reviews or meta-analyses evaluating the influence of individual factors, this review was conducted to illuminate the disparities in researchers' opinions at the current stage of research.

Canaloplasty and Trabeculotomy Using the OMNI Surgical System in Three Patients with Angle Closure: A Case Series

Aim and background

The OMNI surgical system allows for 360° canaloplasty and trabeculotomy for patients with glaucoma, either as a standalone procedure or in combination with cataract surgery. There is currently limited evidence on its use in forms of angle-closure glaucoma, though other microinvasive glaucoma surgeries have been used. We present three patients with angle closure who underwent the procedure.

Methods

Retrospective review of three patients who underwent canaloplasty and trabeculotomy with the OMNI surgical system with forms of angle closure. Data on demographics, intraocular pressure (IOP), glaucoma medication use, best corrected visual acuity (BCVA), visual fields (VFs), and complications were collected for a 6-month period.

Results

Three eyes of three patients underwent the procedure: one with primary angle closure glaucoma (PACG), one acute angle closure, and one primary angle closure (PAC). All had surgery combined with phacoemulsification and intraocular lens (IOL) implantation. The mean age was 56 years. Preoperative IOP was 25.33 ± 2.49 mm Hg, improving to 11.67 ± 2.87 mm Hg at 6 months. Mean glaucoma medication use was reduced by 3.00, from 3.67 ± 1.21 to 0.67 ± 0.94. Preoperative mean BCVA was 0.10 ± 0.08 and 0.20 ± 0.08 LogMAR at 6 months. Mean deviation (MD) on VFs was -9.67 preoperatively and -6.72 at 6 months. Two patients had mild, self-limiting hyphema postoperatively which resolved without further intervention; no other complications were reported.

Conclusion

We have found the OMNI surgical system to be a safe, effective tool in the management of angle-closure glaucomas in a small cohort of patients.

Clinical significance

The OMNI surgical system has the potential to add a less invasive surgical solution in the management of angle closure glaucoma, prior to the use of filtering surgery such as trabeculectomy or glaucoma drainage device. Larger trials assessing the use of microinvasive glaucoma surgery (MIGS) in these patients will be eagerly received.

How to cite this article

Richardson-May J, Ibrahim SA, Law K, et al. Canaloplasty and Trabeculotomy Using the OMNI Surgical System in Three Patients with Angle Closure: A Case Series. J Curr Glaucoma Pract 2024;18(3):117-120.

Ab Interno Canaloplasty and Trabeculotomy Outcomes for Mild, Moderate, and Advanced Open-Angle Glaucoma: A ROMEO Analysis

Purpose

To determine if there was an association between severity of glaucoma and intraocular pressure (IOP) and medication (med) outcomes for patients in the ROMEO (Retrospective, Observational, Multicenter Evaluation of OMNI) study.

Setting

Eleven ophthalmology practices in 8 US states.

Design

Post-hoc analysis of all eyes enrolled and treated with ab interno canaloplasty and trabeculotomy in the retrospective, multicenter ROMEO study.

Methods

Eyes were grouped according to visual field mean deviation (MD): mild (MD better than -6 dB), moderate (MD between -6 and -12 dB), advanced (-12 dB or worse). IOP and med outcomes at 12 months were compared across groups. Least squares regression was used to assess the relationship of MD with month 12 IOP. Outcomes for 1st and last MD deciles were compared as a sensitivity analysis.

Results

One hundred and twenty-seven eyes were available for analysis including 79 mild, 42 moderate, 6 advanced. Most eyes had a reduction in IOP at Month 12 (70%) with most at 18 mmHg or less. Percentage IOP reduction was similar across the groups (mild 16.9%, moderate 18.6%, advanced 18.0%) with mean month 12 IOP between 14 and 16 mmHg. Medications were also reduced in all three groups; -0.8 (mild, P < 0.001), -0.55 (moderate, P < 0.05), and -1.0 (advanced, P = 0.139, ns). Regression analysis revealed no relationship between month 12 IOP and MD. Med reductions were observed for all groups with a reduction of 1 or more medications seen in (%, 95% CI) 69%, 59-79 (mild), 50%, 35-65 (moderate), and 60%, 21-99 (advanced). Secondary interventions tended to have greater incidence with worse MD likely reflecting lower desired IOP targets.

Conclusion

Analysis of data from the ROMEO study suggests that similar meaningful IOP and med reductions can be expected across the range of disease severity studied.

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.

Alternatives to Topical Glaucoma Medication for Glaucoma Management

Topical glaucoma medications have favorable safety and efficacy, but their use is limited by factors such as side effects, nonadherence, costs, ocular surface disease, intraocular pressure fluctuations, diminished quality of life, and the inherent difficulty of penetrating the corneal surface. Although traditionally these limitations have been accepted as an inevitable part of glaucoma treatment, a rapidly-evolving arena of minimally invasive surgical and laser interventions has initiated the beginnings of a reevaluation of the glaucoma treatment paradigm. This reevaluation encompasses an overall shift away from the reactive, topical-medication-first default and a shift toward earlier intervention with laser or surgical therapies such as selective laser trabeculoplasty, sustained-release drug delivery, and micro-invasive glaucoma surgery. Aside from favorable safety, these interventions may have clinically important attributes such as consistent IOP control, cost-effectiveness, independence from patient adherence, prevention of disease progression, and improved quality of life.

36-Month Outcomes from the Prospective GEMINI Study: Canaloplasty and Trabeculotomy Combined with Cataract Surgery for Patients with Primary Open-Angle Glaucoma

Purpose

To provide long-term intraocular pressure (IOP) and ocular hypotensive medication usage outcomes through 36 months for patients treated with canaloplasty and trabeculotomy (OMNI Surgical System) combined with cataract surgery as participants in the GEMINI study.

Setting

Eleven ophthalmology practices in 10 US states.

Design

Non-interventional 36-month extension of the 12-month, prospective, multicenter, GEMINI study.

Methods

GEMINI patients had visually significant cataract, mild-to-moderate glaucoma (ICD-10 guidelines), medicated IOP <33 mmHg, and unmedicated mean diurnal IOP (DIOP) (after washout) 21-36 mmHg. Patients from GEMINI were eligible for inclusion. Outcome measures were reduction in mean unmedicated DIOP, reduction in mean IOP-lowering medications, percent of eyes with ≥20% reduction in unmedicated DIOP, and percent of eyes with unmedicated DIOP ≥6 and ≤18 mmHg.

Results

A total of 66 patients provided consent and were enrolled. Mean (SD) unmedicated DIOP was 23.1 (2.7) mmHg at baseline, 16.7 (4.1), 16.3 (3.3) at 24 and 36 months; mean reductions of 6.2 (4.1) and 6.9 (3.4) mmHg. Twelve-month IOP at the end of GEMINI was 15.6 mmHg. The proportion of eyes with ≥20% reduction in IOP was 77% and 78% (months 24 and 36) compared to 87% at month 12 from GEMINI. About 68% of patients had an IOP between 6 and 18 mmHg at 24 months and 71% at 36 months. Mean IOP-lowering medications was 1.7 at baseline, which was reduced to 0.4 (24 months, -1.3) and 0.3 (36 months, -1.4). About 74% of patients (46 of 62) were medication free at 36 months.

Conclusion

GEMINI demonstrated 12-month effectiveness of canaloplasty and trabeculotomy with OMNI combined with cataract surgery for IOP and medication reduction in mild-to-moderate glaucoma. However, longer-term data is key to the decision making in the selection of a surgical treatment. This GEMINI extension demonstrates that the 12-month outcomes from GEMINI were sustained through 36 months.

Minimally Invasive Glaucoma Surgery: Latest Developments and Future Challenges

The development of minimally invasive glaucoma surgeries (MIGSs) was intended to provide safe and modestly efficacious modalities for early intervention of mild-to-moderate glaucoma, with minimal trauma and rapid recovery. They were mainly ab interno procedures that reduce intraocular pressure by facilitating the aqueous outflow by bypassing the trabecular meshwork resistance, reinforcing the uveoscleral flow via the supraciliary space, and reducing aqueous production by the ciliary body. While the cumulating evidence helps shape the role of the available MIGS, the exponential new development and advancement in this field has expanded the territory of MIGS. Apart from developing subconjunctival MIGS filtration devices (Xen gel stent and PRESERFLO MicroShunt), there is a tendency to revisit the "traditional" MIGS for alternative use and to modify the procedures with consideration of the fundamental aqueous outflow physiology. Combined MIGS has also been suggested, based on the theory that their different mechanisms may provide additive or synergistic effects. The advancement of laser procedures is also promising and could supplement unmet needs along the glaucoma treatment algorithm. This review examines the broad array of MIGS, updates the recent findings, discusses their potential alternative applications, and explores future challenges.