Minimally Invasive Glaucoma Surgery: A Critical Appraisal of the Literature

Complications After Incisional/Excisional Minimally Invasive Glaucoma Surgery-An Update and Literature Review

PURPOSE

To discuss comprehensively the varied complications after stent-less incisional or excisional minimally invasive glaucoma surgery (MIGS).

METHOD

A review of reported complications after stent-less MIGS procedures including gonioscopy-assisted transluminal trabeculotomy (GATT), bent needle goniectomy (BANG), Kahook-dual blade goniotomy, and microincisional trabeculectomy (MIT) published between 2014-2024, were analyzed and summarized.

RESULTS

Apart from hyphema, peripheral anterior synechiae, and intraocular pressure spikes, other vision-threatening complications like cyclodialysis, Descemet's detachment, corneal edema, iridodilalysis, vitreous loss or vitreous hemorrhage can also occur intra- or postoperatively after any incisional or excisional MIGS procedures.

CONCLUSION

All possible complications are to be kept in mind during MIGS despite the procedures being minimally invasive. Adequate care should be taken during different stages of the surgery to avoid these complications.

Refractive Outcomes Following Combined Cataract and Microinvasive Glaucoma Surgery

PURPOSE

To compare refractive outcomes in eyes undergoing cataract extraction (CE) alone, CE with goniotomy (CE/goniotomy), and CE with Schlemm's canal stent (CE/SCS) insertion.

DESIGN

Retrospective cohort study.

PARTICIPANTS

Eyes from the Bascom Palmer Glaucoma Repository undergoing CE/goniotomy, CE/SCS insertion, or uncomplicated CE alone between July 2014 and February 2022 were identified.

METHODS

Refraction data were analyzed at postoperative month (POM) 1 and 6 with Kruskal-Wallis and Dunn's tests. Anisometropia was defined as a spherical equivalent (SE) difference of ≥2D.

MAIN OUTCOME MEASURES

The primary outcome was mean refraction at POM1 and POM6 across the 3 surgical groups. Secondary outcomes were comparisons of refraction and visual acuity (VA) among different goniotomy and Schlemm's canal stent (SCS) devices, as well as incidence of anisometropia.

RESULTS

A total of 8360 eyes (150 CE/goniotomy, 395 CE/SCS, and 7815 CE alone) from 6059 patients were analyzed. At POM1, mean SE in the CE/goniotomy, CE/SCS, and CE alone groups was -0.36 ± 0.91D, -0.31 ± 0.85D, and -0.39 ± 0.88D respectively (P = 0.019). Mean logarithm of the minimum angle of resolution VA was 0.10 ± 0.20, 0.08 ± 0.19, and 0.14 ± 0.26 respectively (P = 0.002, CE/SCS vs. CE alone). No statistically significant differences were noted at POM6. Anisometropia occurred at POM1 in 2 patients (13.3%) in the CE/goniotomy-CE group, 1 patient (3.2%) in the CE/SCS-CE group, and 184 patients (4.9%) in the CE-CE group (P = 0.217). At POM6, mean SEs were -0.38 ± 0.97D (CE/goniotomy), -0.35 ± 0.81D (CE/SCS), and -0.40 ± 0.91D (CE alone; P = 0.473). No significant differences in overall refractive outcomes were observed with different SCS or goniotomy devices. Among primary open-angle glaucoma/normal-tension glaucoma eyes, mean SE at POM1 was -0.36 ± 0.73D (CE/goniotomy), -0.24 ± 0.84D (CE/SCS), and -0.45 ± 0.81D (CE alone; P < 0.001).

CONCLUSIONS

Concurrent SCS insertion or goniotomy with CE was associated with some statistically significant differences in postoperative refraction and VA, although these small magnitude differences were unlikely to be clinically meaningful.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found after the references in the Footnotes and Disclosures at the end of this article.

A Randomized Controlled Trial Comparing STREAMLINE Canaloplasty to Trabecular Micro-Bypass Stent Implantation in Primary Open-Angle Glaucoma

Purpose

To report interim results of the VENICE study, a multi-center, randomized, controlled trial (RCT) comparing STREAMLINE Surgical System (STREAMLINE) canaloplasty with iStent inject W (iStent W) implantation in patients with mild-to-moderate primary open-angle glaucoma (POAG) undergoing phacoemulsification.

Patients and Methods

Safety and efficacy analyses involving the first 72 randomized eyes are included in this report. Following pre- (Screening) and post-medication washout (Eligibility) visits, one eye per subject was randomized 1:1 to STREAMLINE or iStent W after undergoing uncomplicated phacoemulsification. Subjects were evaluated postoperatively at Day 1, Week 1, Month 1, 3, and 6. Intraocular pressure (IOP) measurements, number of IOP-lowering medications, and adverse events (AEs) were assessed at each follow-up visit.

Results

Seventy-two eyes were randomized; 35 underwent STREAMLINE canaloplasty and 37 were implanted with the iStent W. Seventy eyes completed their 6-month follow-up. Both the mean morning post-washout Baseline IOP between STREAMLINE 24.86±3.05 mmHg and iStent W 25.16±3.41 mmHg and the mean IOP at 6 months between STREAMLINE eyes 16.52±3.63 mmHg and iStent W eyes 16.08±3.19 mmHg were not statistically significantly different (p=0.691 and 0.596, respectively). At 6 months, more eyes were on zero glaucoma medications in the STREAMLINE group (81.8%) compared to the iStent W group (78.4%). In medication-free eyes, the mean IOP was reduced from 24.80±2.79 mmHg to 16.00±3.40 mmHg and 24.60±3.18 mmHg to 15.80±2.21 mmHg in the STREAMLINE and iStent W groups, respectively (p=0.752). Both groups showed reduction in IOP-lowering medications at every visit, compared to pre-washout (Screening), with STREAMLINE resulting in numerically fewer medications 0.20±0.48 compared to iStent W 0.40±0.79 at 6 months (P=0.384). AEs were mild and self-limited.

Conclusion

To our knowledge, the VENICE trial is the first RCT involving canaloplasty. These interim findings demonstrated comparable IOP and medication reduction between STREAMLINE canaloplasty and iStent W implantation, when combined with phacoemulsification.

Global tendency and research trends of minimally invasive surgery for glaucoma from 1992 to 2023: A visual bibliometric analysis

Background

Minimally invasive glaucoma surgery has become a popular research topic over the past decade. However, no published studies have provided a systematic overview for this field. A bibliometric analysis is urgently required to characterise current international trends and provide an intuitive description of past and emerging trends.

Methods

This study analysed minimally invasive glaucoma surgery-related studies by searching the Web of Science for relevant articles published between 1992 and 2023. All the retrieved titles and abstracts were screened for eligibility, and only articles and reviews written in English were included in the analysis. CiteSpace (version 6.1.6), VOSviewer (version 1.6.19), and the bibliometric package in RStudio were used to construct and visualise the results.

Results

A total of 1533 publications were included in the analysis with 26072 citations. A total of 4482 authors from 1191 organizations in 57 countries and regions published papers in 139 journals. After 2010, the number of publications increased significantly, with the highest annual productivity occurring in 2022 (n = 229, 15 %). Most of these studies were published in ophthalmology journals. The journal "Ophthalmology" ranked first with 30 papers and 5275 citations. Among the 10 most productive countries, the United States had the largest share of publications (n = 423, 36 %) and Switzerland had the highest proportion of multiple-country publications (70 %). Neodymium was the first keyword discovered, appearing in 1992 and continuing for 21 years. Kahook dual-blade, progression, gonioscopy-assisted transluminal trabeculotomy, efficacy, minimally invasive glaucoma surgery, cataract extraction, and primary open-angle glaucoma were the most recent keywords since 2020.

Conclusions

This was the first bibliometric analysis of minimally invasive glaucoma surgery and provides an overview of the developments in this field. Our results identified outstanding studies, countries, institutions, journals, and authors in the field to point the way forward for scientific research and clinical applications of minimally invasive glaucoma surgery.

Double implantation of Xen 45 gel stent in primary open-angle glaucoma: a pilot study

PURPOSE

To describe the outcomes of double implantation of Xen 45 Gel Stent (Xen) using an ab externo approach with closed conjunctiva.

METHODS

Retrospective single-centre case series of primary open-angle glaucoma patients with at least six months of follow-up after implantation of a second Xen in the same eye via ab externo technique without conjunctival opening.

RESULTS

Eight pseudophakic eyes of 8 patients were included. Intraocular pressure (IOP) dropped from 30 ± 2.6 mmHg pre-operatively to 22.4 ± 2.3 mmHg one month after the first Xen implant (mean difference: -7.6 mmHg [95% confidence interval: -9.4, -5.9 mmHg], p = 0.0092). A second Xen was then implanted to achieve the target IOP. The procedure showed no significant intraoperative or postoperative complications. The IOP dropped to 16.1 ± 2.7 mmHg six months following this second implant (mean difference: -6.3 mmHg [95% confidence interval: -7.2, -5.3 mmHg], p = 0.0183); however, 3 patients needed medical therapy to further reduce the IOP towards the target value.

CONCLUSION

Sequential implantation of two Xen 45 Gel Stents using an ab externo approach with closed conjunctiva appears a promising procedure that showed a favorable safety and efficacy profile in this small case series. This pilot data might pave the way for further studies to evaluate the safety and efficacy of the procedure.

Advancing Glaucoma Care in Bangladesh With Minimally Invasive Glaucoma Surgery

Minimally invasive glaucoma surgery (MIGS) is a cutting-edge approach to treating glaucoma that provides a range of techniques and technology to reduce intraocular pressure (IOP). An 80-year-old man with visually significant cataracts and primary open-angle glaucoma (POAG) underwent combined cataract surgery and TrabEx+ (MicroSurgical Technology, Washington, United States) in his left eye, a unique type of MIGS, as we described in this study. Over the one-year follow-up, this patient showed improved visual function with well-controlled IOP without anti-glaucoma medications.

Lipid mediators in glaucoma: Unraveling their diverse roles and untapped therapeutic potential

Glaucoma is a complex neurodegenerative disease characterized by optic nerve damage and visual field loss, and remains a leading cause of irreversible blindness. Elevated intraocular pressure (IOP) is a critical risk factor that requires effective management. Emerging research underscores dual roles of bioactive lipid mediators in both IOP regulation, and the modulation of neurodegeneration and neuroinflammation in glaucoma. Bioactive lipids, encompassing eicosanoids, specialized pro-resolving mediators (SPMs), sphingolipids, and endocannabinoids, have emerged as crucial players in these processes, orchestrating inflammation and diverse effects on aqueous humor dynamics and tissue remodeling. Perturbations in these lipid mediators contribute to retinal ganglion cell loss, vascular dysfunction, oxidative stress, and neuroinflammation. Glaucoma management primarily targets IOP reduction via pharmacological agents and surgical interventions, with prostaglandin analogues at the forefront. Intriguingly, additional lipid mediators offer promise in attenuating inflammation and providing neuroprotection. Here we explore these pathways to shed light on their intricate roles, and to unveil novel therapeutic avenues for glaucoma management.

Two-Year Performance and Safety Results of the MINIject Supraciliary Implant in Patients With Primary Open-Angle Glaucoma: Meta-Analysis of the STAR-I, II, III Trials

PURPOSE

To evaluate the performance and safety of minimally invasive glaucoma surgery with a supraciliary drainage device (MINIject; iSTAR Medical, Wavre, Belgium) in primary open-angle glaucoma (POAG) as a stand-alone procedure.

DESIGN

Meta-analysis.

METHODS

At 11 sites in Colombia, France, Germany, India, Panama, and Spain, 82 patients were treated in 3 prospective, multicenter, interventional, nonrandomized trials (STAR-I, II, III). Data were pooled in a meta-analysis of up to 2 years of follow-up postimplantation. The main outcome measures were mean relative and absolute reduction in diurnal intraocular pressure (IOP) compared to baseline. Secondary outcomes included patients with IOP ≤18 mmHg, patients with IOP reduction ≥20%, number of IOP-lowering medications, adverse events, and endothelial cell density loss.

RESULTS

At the 2-year follow-up (n = 66), mean IOP was reduced from 23.8 ± 3.3 mmHg at baseline to 14.4 ± 4.5 mmHg (-39.3%; P < 0.0001). An IOP reduction of ≥20% was achieved in 89.4% of patients, with 84.8% having an IOP ≤18 mmHg. IOP-lowering medications were reduced from a mean of 2.4 ± 1.1 to 1.4 ± 1.4 (P < 0.0001), with 37.9% of patients being medication-free at 2 years. Mean endothelial cell density loss at 2 years was 6.2 ± 9.1% compared to baseline and no patient had a loss >30%.

CONCLUSIONS

This meta-analysis demonstrates the favorable safety and efficacy profile of a supraciliary device implanted in a stand-alone, ab-interno procedure in patients with mild-to-moderate POAG. The data demonstrate that MINIject is a safe and effective, bleb-free treatment option for patients requiring low target IOP up to 2 years.

XEN-45 in the management of early glaucoma surgery: A national Delphi consensus study

BACKGROUND AND OBJECTIVE

Recommendations on general glaucoma management and the use of early minimally invasive and microincisional surgeries are limited. This study aimed to establish consensus regarding glaucoma management, focusing on the XEN-45 gel stent implant.

METHODS

A Delphi consensus-driven process was used. The scientific committee led the study, identified the expert panel, and participated in elaborating the questionnaire. Fifty-one panelists were invited to complete, on a nine-point Likert scale, an 89-item questionnaire covering three topic blocks. Two Delphi rounds were performed. Consensus was achieved if ≥66.6% of panelists reached agreement or disagreement.

RESULTS

Panelists agreed on 84 items related to the patients' quality of life, the therapeutic algorithm and patient profile, and surgical and pre- and post-operative management. Panelists agreed on the suitability of XEN stent implants to treat glaucoma at different stages and for different patient profiles: young patients, elderly or with significant comorbidities, and with myopic glaucoma, patients who failed previous surgeries, and with previous poor post-operative experience. XEN surgery was considered a therapeutic step prior to classic filtering surgery and a possible first surgical option in elderly patients with comorbidities and uncontrolled intraocular pressure. XEN surgery allows the patient to return to routine daily activities faster than conventional filtering surgeries and to reduce and/or eliminate topical treatments.

CONCLUSIONS

This Delphi-driven consensus resulted in a series of general recommendations for glaucoma management, including those related to patient quality of life, therapeutic algorithm, and patient profile, and specific ones regarding the use of XEN stent gel surgery.

Quantification of Postoperative Inflammation in Laser and Surgical Procedures for Glaucoma with Laser Flare Photometry: A Review of the Literature

PURPOSE

To review the application of laser flare photometry (LFP) in the objective quantification of aqueous flare (anterior chamber inflammation) post laser and surgical procedures for glaucoma.

METHODS

A search was undertaken using the following: PubMed (all years), the Web of Science (all years), Ovid MEDLINE (R) (1980 to 30 March 2023), Ovid MEDLINE (R) Daily Update 30 March 2023, MEDLINE and MEDLINE non-indexed items, Embase (1980-2021, week 52), Ovid MEDLINE (R) and Epub Ahead of Print, in-Process & Other Non-Indexed Citations and Daily (1980 to 30 March 2023), CENTRAL (including Cochrane Eyes and Vision Trials Register), metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrial.gov) and the World Health Organization (WHO) International Clinical Trials Registry Platform (www.who.int/ictrp/search/en). Search terms included "aqueous flare," "anterior chamber inflammation," "tyndallometry," "laser flare photometry" combined with "laser," "iridotomy," "trabeculoplasty," "cataract surgery," "phacoemulsification," "glaucoma surgery," "minimally invasive glaucoma surgery," "trabeculectomy," "aqueous shunt," "glaucoma drainage" and "cyclophotocoagulation."

RESULTS

The majority of studies utilizing laser flare photometry in grading flare have been post laser trabeculoplasty. The degree of flare produced varies according to the type of glaucoma laser or surgery performed, with filtration procedures and glaucoma drainage devices having marked and prolonged detectable levels. Aqueous flare in cyclodestructive procedures positively correlated with intraocular pressure (IOP) reduction.

CONCLUSION

In comparison to clinician grading, laser flare photometry provides a more objective measure of post-surgical inflammation in eyes that have undergone laser and surgery for glaucoma. Further research is warranted into how this instrument can be utilized to identify eyes at high risk of failure and other adverse outcomes after glaucoma surgery.

The Evolution and Current Landscape of Minimally Invasive Glaucoma Surgeries: A Review

This review examines the evolution, current status, and future potential of minimally invasive glaucoma surgeries (MIGS), a significant advancement in the treatment of glaucoma, a leading cause of irreversible blindness. MIGS offer a less invasive alternative to traditional glaucoma surgeries, primarily aimed at reducing intraocular pressure, minimizing tissue trauma, and providing a safer profile. With the emergence of devices such as the Trabectome, iStent, and others, MIGS have expanded the surgical toolkit, allowing personalized, patient-centered care. Despite their advantages, MIGS face challenges such as efficacy in severe cases, long-term data, and accessibility. Ongoing research and technological innovations continue to refine their capabilities and applications, promising to further transform glaucoma management and patient outcomes. This paper provides an in-depth analysis of MIGS, reflecting on their impact and contemplating future directions in this dynamically evolving field.

Microfluidics in the eye: a review of glaucoma implants from an engineering perspective

Glaucoma is a progressive optic neuropathy in the eye, which is a leading cause of irreversible blindness worldwide and currently affects over 70 million individuals. Clinically, intraocular pressure (IOP) reduction is the only proven treatment to halt the progression of glaucoma. Microfluidic devices such as glaucoma drainage devices (GDDs) and minimally invasive glaucoma surgery (MIGS) devices are routinely used by ophthalmologists to manage elevated IOP, by creating an artificial pathway for the over-accumulated aqueous humor (AH) in a glaucomatous eye, when the natural pathways are severely blocked. Herein, a detailed modelling and analysis of both the natural microfluidic pathways of the AH in the eye and artificial microfluidic pathways formed additionally by the various glaucoma implants are conducted to provide an insight into the causes of the IOP abnormality and the improvement schemes of current implant designs. The mechanisms of representative glaucoma implants have been critically reviewed from the perspective of microfluidics, and we have categorized the current implants into four groups according to the targeted drainage sites of the AH, namely Schlemm's canal, suprachoroidal space, subconjunctival space, and ocular surface. In addition, we propose to divide the development and evolution of glaucoma implant designs into three technological waves, which include microtube (1st), microvalve (2nd) and microsystem (3rd). With the emerging trends of minimal invasiveness and artificial intelligence in the development of medical implants, we envision that a comprehensive glaucoma treatment microsystem is on the horizon, which is featured with active and wireless control of IOP, real-time continuous monitoring of IOP and aqueous rate, etc. The current review could potentially cast light on the unmatched needs, challenges, and future directions of the microfluidic structural and functional designs of glaucoma implants, which would enable an enhanced safety profile, reduced complications, increased efficacy of lowering IOP and reduced IOP fluctuations, closed-loop and on-demand control of IOP, etc.

Preventing Blindness with Early Cataract Surgery and Micro-Invasive Glaucoma Surgery in Patients Over 50: Guidance for Patients, Physicians and World Governments in Dealing with Glaucoma

Purpose

To offer clinical guidance and address safety and efficacy concerns regarding the growing use of micro-invasive glaucoma surgery (MIGS) as an initial treatment for glaucoma in adult patients.

Design

Narrative literature review.

Methods

A review was conducted to assess outcomes and complications of MIGS in the treatment of glaucoma, both alone and in combination with lens replacement. These outcomes were compared with those of standard glaucoma surgery and/or glaucoma management with medication.

Results

MIGS are effective at lowering intraocular pressure (IOP) over long periods of follow-up. These techniques share a similarly high safety profile between one another. MIGS were found to have lower complication rates and to be more effective in reducing the total amount of medication needed to maintain control of intraocular pressure than standard surgery approaches.

Conclusion

MIGS techniques are growing in popularity and have been demonstrated to be a safe and effective alternative to standard glaucoma surgery. Guidance in the implementation of these procedures has been outlined.

Is GATT the Answer?

How to cite this article: Bhartiya S, Aktas Z, Ichhpujani P. Is GATT the Answer? J Curr Glaucoma Pract 2023;17(4):167-168.

IOP-lowering and drug-sparing effects of trabectome surgery with or without cyclodialysis ab interno

PURPOSE

To compare the postoperative intraocular pressure (IOP) after ab interno trabeculectomy (AIT; trabectome surgery) alone or combined with cyclodialysis ab interno (AITC).

PATIENTS AND METHODS

Forty-three eyes with insufficiently controlled open-angle glaucoma were included in this consecutive case series. All eyes received AIT, combined with phacoemulsification and IOL-implantation in phakic instances, with or without additional cyclodialysis ab interno. Postoperative visual acuity, IOP, number of IOP-lowering medications and complications were registered over 12 months.

RESULTS

A total of 19 eyes (14 patients) received AIT and 24 (19 patients) received AITC. Both groups were comparable for baseline IOP (AIT: 19.7 ± 8.2 mmHg; AITC: 19.4 ± 6.8 mmHg; p = 0.96), there was a comparable IOP reduction after 6 months (AIT: - 3.8 ± 12.3, median (interquartile range (IQR)): - 3.8 (- 7.8-4.8) mmHg; AITC: - 4.9 ± 8.3, median (IQR): - 2.0 (- 10.8-2.0) mmHg; p = 0.95) and 12 months (AIT: - 4.3 ± 6.6, median (IQR): - 4.0 (- 8.0 to - 1.0) mmHg; AITC: - 3.7 ± 6.7, median (IQR): - 1.5 (- 5.5 to - 0.5) mmHg; p = 0.49). While final visual acuity was similar between the groups, they differed regarding topical IOP-lowering medications (baseline: AIT 2.9 ± 1.2 and AITC 2.9 ± 1.2; 1 year after surgery: AIT 2.6 ± 1.5 (p = 0.16) and AITC 1.3 ± 1.3; p < 0.001)). Depending on the definition, a complete or qualified success of 33.4-45.8% was achieved in AITC compared to 15.8-21.1% in AIT.

CONCLUSION

The additional suprachoroidal outflow when AIT is combined with cyclodialysis ab interno (AITC) seems to result in an additional drug sparing effect for at least 1 year without critical safety signals. Thus, AITC might be further investigated prospectively prior to advocating its use in routine minimally invasive glaucoma surgery.

Favorable effect of ripasudil use on surgical outcomes of microhook ab interno trabeculotomy

PURPOSE

We have previously demonstrated that prolonged use of glaucoma medications was associated with a poor surgical outcome of ab interno trabeculotomy (µTLO). Given that almost all types of glaucoma eye drop either enhance the drainage through the uveoscleral pathway or reduce aqueous humor production, we hypothesized that prolonged use of these medications might cause disuse atrophy of the conventional pathway. In contrast, ripasudil increases the conventional outflow and eventually shows a favorable outcome of µTLO. This study aimed to evaluate the effect of ripasudil use on µTLO outcomes.

METHOD

The medical charts of 218 patients who underwent µTLO were analyzed retrospectively. We compared the 1-year outcome between ripasudil users versus nonusers by using propensity score matching. We set the covariates as age, sex, glaucoma types, preoperative intraocular pressure (IOP), the mean deviation values of visual field tests, the presence or absence of concomitant cataract surgery, trabecular meshwork incision range, the presence or absence of any glaucoma medication except ripasudil and duration of glaucoma medical therapy. Success was defined as a postoperative IOP between 5 and 21 mmHg, a ≥ 20% IOP reduction from baseline, and no additional glaucoma surgery at postoperative 1 year.

RESULT

Fifty-seven patients each were allocated to the ripasudil users or nonusers. The 1-year success rates were 74% in ripasudil users and 51% in nonusers (p = 0.01). Kaplan‒Meier survival curves also showed that the ripasudil users had a higher survival distribution (p = 0.01).

CONCLUSION

The patients who took ripasudil showed a favorable 1-year outcome of µTLO.

Minimally Invasive Glaucoma Surgery: A Review of the Literature

Minimally invasive glaucoma surgery (MIGS) has emerged as a novel approach in the glaucoma treatment spectrum, offering a range of diverse procedures and devices aimed at reducing intraocular pressure (IOP). MIGS can be broadly classified into several categories: those that enhance trabecular outflow (Trabectome, iStent, Hydrus Microstent, Kahook Dual Blade, high frequency deep sclerotomy, and gonioscopy-assisted transluminal trabeculotomy), those that augment suprachoroidal outflow (CyPass Microstent and iStent Supra), those that target Schlemm's canal (TRAB360 and the OMNI Surgical System, Streamline, and Ab Interno Canaloplasty), and conjunctival bleb-forming procedures (EX-PRESS Glaucoma Filtration Device, Xen Gel Stent and PreserFlo MicroShunt). MIGS is considered to have a shorter surgical time and fewer severe complications when compared to traditional glaucoma surgeries such as trabeculectomy and glaucoma drainage device implantation (Ahmed, Baerveldt, and Molteno valves). This literature review comprehensively examines the distinct MIGS devices and procedures, their underlying mechanisms, and clinical outcomes, emphasizing the importance of evaluating the efficacy and complications of each approach individually. As the field of MIGS continues to evolve, it is crucial to prioritize high-quality, long-term studies to better understand the safety and effectiveness of these innovative interventions in glaucoma management.

Spotlight on Schlemm's Canal MicroStent Injection in Patients with Glaucoma

Minimally invasive glaucoma surgery (MIGS) has revolutionized glaucoma care with its favorable safety profile and ability to delay or minimize the need for traditional, bleb-based procedures. Microstent device implantation is a type of angle-based MIGS, which reduces intraocular pressure (IOP) through bypass of the juxtacanalicular trabecular meshwork (TM) and facilitation of aqueous outflow into the Schlemm's canal. Although there are limited microstent devices on the market, multiple studies have evaluated the safety and efficacy of iStent^® (Glaukos Corp.), iStent Inject^® (Glaukos Corp.), and Hydrus^® Microstent (Alcon) in the treatment of mild-to-moderate open-angle glaucoma, with and without concurrent phacoemulsification. This review attempts to provide a comprehensive evaluation of injectable angle-based microstent MIGS devices in the treatment of glaucoma.

Results from the Primary Tube Versus Trabeculectomy Study and translation to clinical practice

PURPOSE OF REVIEW

The Primary Tube Versus Trabeculectomy (PTVT) Study is a multicenter randomized clinical trial comparing the safety and efficacy of tube shunt surgery and trabeculectomy with mitomycin C (MMC) in eyes without previous incisional ocular surgery. This article reviews results from the PTVT Study and suggests how they may be translated to clinical practice.

RECENT FINDINGS

Tube shunt surgery had a higher failure rate than trabeculectomy with MMC in the PTVT Study, and the difference was statistically significant at 1 year but not at 3 years and 5 years. Both surgical procedures reduced intraocular pressure (IOP) to the low teens throughout 5 years of follow-up. Mean IOPs were lower after trabeculectomy with MMC compared with tube shunt implantation, and the differences were statistically significant during the first postoperative year and at 3 years. The greater IOP reduction after trabeculectomy with MMC was achieved with significantly fewer glaucoma medications relative to tube shunt placement. Surgical complications were common in the PTVT Study, but most were transient and self-limited. The incidence of early postoperative complications was significantly higher after trabeculectomy with MMC than tube shunt surgery. The rates of late postoperative complications, cataract progression, and vision loss were similar with both surgical procedures. Serious complications producing vision loss and/or requiring a reoperation to manage the complication developed more frequently after trabeculectomy with MMC compared with tube shunt surgery, and the difference was statistically significant at 1 year but not at 3 years and 5 years postoperatively.

SUMMARY

Tube shunt implantation and trabeculectomy with MMC are both viable surgical options for managing glaucoma in patients without previous incisional ocular surgery. Results from the PTVT Study support further expansion of tube shunt use beyond refractory glaucomas.

Preferential Loss of Contrast Decrement Responses in Human Glaucoma

Purpose

The purpose of this study was to determine whether glaucoma in human patients produces preferential damage to OFF visual pathways, as suggested by animal experimental models, patient electroretinogram (ERG), and retinal imaging data.

Methods

Steady-state visual evoked potentials (SSVEPs) were recorded monocularly from 50 patients with glaucoma and 28 age-similar controls in response to equal Weber contrast increments and decrements presented using 2.73 hertz (Hz) sawtooth temporal waveforms.

Results

The eyes of patients with glaucoma were separated into mild (better than -6 decibel [dB] mean deviation; n = 28) and moderate to severe (worse than -6 dB mean deviation, n = 22) groups based on their Humphrey 24-2 visual field measurements. Response amplitudes and phases from the two glaucoma-severity groups were compared to controls at the group level. SSVEP amplitudes were depressed in both glaucoma groups, more so in the moderate to severe glaucoma group. The differences between controls and the moderate-severe glaucoma groups were more statistically reliable for decrements than for increments. Mean responses to decremental sawtooth stimuli were larger than those to increments in controls and in the mild glaucoma but not in the moderate to severe glaucoma group at the first harmonic. OFF/decrement responses at the first harmonic were faster in controls, but not in patients.

Conclusions

The observed pattern of preferential loss of decremental responses in human glaucoma is consistent with prior reports of selective damage to OFF retinal ganglion cells in murine models and in data from human ERG and retinal imaging. These data motivate pursuit of SSVEP as a biomarker for glaucoma progression.

AZD6738 Inhibits fibrotic response of conjunctival fibroblasts by regulating checkpoint kinase 1/P53 and PI3K/AKT pathways

Trabeculectomy can effectively reduce intraocular pressure (IOP) in glaucoma patients, the long-term surgical failure is due to the excessive proliferation and fibrotic response of conjunctival fibroblasts which causes the subconjunctival scar and non-functional filtering bleb. In this study, we demonstrated that AZD6738 (Ceralasertib), a novel potent ataxia telangiectasia and Rad3-related (ATR) kinase inhibitor, can inhibit the fibrotic response of conjunctival fibroblasts for the first time. Our in vitro study demonstrated that AZD6738 inhibited the level and the phosphorylation of checkpoint kinase 1 (CHK1), reduced TGF-β1-induced cell proliferation and migration, and induced apoptosis of human conjunctival fibroblasts (HConFs) in the high-dose group (5 μM). Low-dose AZD6738 (0.1 μM) inhibited the phosphorylation of CHK1 and reduce fibrotic response but did not promote apoptosis of HConFs. Further molecular research indicated that AZD6738 regulates survival and apoptosis of HConFs by balancing the CHK1/P53 and PI3K/AKT pathways, and inhibiting TGF-β1-induced fibrotic response including myofibroblast activation and relative extracellular matrix (ECM) protein synthesis such as fibronectin (FN), collagen Ⅰ (COL1) and collagen Ⅳ (COL4) through a dual pharmacological mechanism. Hence, our results show that AZD6738 inhibits fibrotic responses in cultured HConFs in vitro and may become a potential therapeutic option for anti-subconjunctival scarring after trabeculectomy.

Minimally Invasive Glaucoma Surgery in Primary Angle-Closure Glaucoma

Primary angle-closure glaucoma (PACG) is responsible for half of the glaucoma-related blindness worldwide. Cataract surgery with or without trabeculectomy has been considered to be the first-line treatment in eyes with medically uncontrolled PACG. While minimally invasive glaucoma surgery has become an important surgical approach for primary open-angle glaucoma, its indications and benefits in PACG are less clear. This review summarizes the efficacy and safety profile of minimally invasive glaucoma surgery in PACG to unfold new insights into the surgical management of PACG.

A New and Easier Approach to Preserflo MicroShunt Implantation

PRESERFLO™ MicroShunt is a new minimally invasive glaucoma surgical (MIGS) device, implanted with an ab externo approach, which drains the aqueous humor to the subconjunctival space. It has been designed as a safer and less invasive approach for treating medically uncontrolled primary open-angle glaucoma (POAG) patients. The classic way of MicroShunt implantation involves different key steps, which includes creating a small scleral pocket with a 1mm blade; passing a 25-gauge (25G) needle through the scleral pocket into the anterior chamber (AC); and subsequently flushing the stent with a 23-gauge (23G) thin-wall cannula. However, sliding the needle into the scleral pocket can create false passages, thus making the device’s threading more difficult. The purpose of the current paper is to propose a simplified implantation approach. Our method proposes to make the scleral tunnel by using directly the 25G needle and, at the limbus, this 25G needle is used to slightly depress the sclera and enter into the AC. The MicroShunt is subsequently assembled on a 23G cannula mounted on a 1mL syringe. The syringe can then be used to flush the device. Outflow can thus be confirmed immediately by seeing drops of aqueous humor leaking from the external opening of the stent. This new approach may have different potential advantages, such as better control of the site of entry, avoids wrong passages, reduces or eliminates the risk of aqueous humor sideway flow, facilitates a parallel path to the iris plane, and it is faster.

Minimally Invasive Micro Sclerostomy (MIMS) Procedure: A Novel Glaucoma Filtration Procedure

PRCIS

Intermediate-term results suggest that ab interno Minimally Invasive Micro Sclerostomy (MIMS) stent-less subconjunctival filtration procedure is a promising treatment option for patients with open-angle glaucoma (OAG).

PURPOSE

MIMS is a novel ab interno, stent-less, subconjunctival filtration procedure. This study set to investigate the safety, performance, and efficacy of MIMS in OAG patients.

METHODS

Prospective, open-label, single arm clinical trial with intrasubject comparisons. Study participants were adults with OAG who were candidates for a filtration procedure. Patients were operated by a single surgeon (A.A.) in Chennai, India. Following mitomycin-C pretreatment, ab interno MIMS procedure was performed alone or combined with phacoemulsification surgery. Procedure-related complications and adverse events were assessed. Primary outcomes: patients (%) achieving an intraocular pressure (IOP) ≥5 mm Hg and ≤18 mm Hg, and an IOP reduction of >20% as compared with baseline, with or without hypotensive medications, with no need for recurrent surgery.

RESULTS

Twenty-one phacoemulsification-MIMS and 10 standalone MIMS procedures were performed. Mean age was 63.94±6.33 years. Mean duration of MIMS was 1:58±0:25 (min:s). Scleral tunnels were achieved in all cases. No device malfunctions, intraoperative complications, or serious adverse events were reported. Five (16.12%) patients presented with iris clogging 1 to 24 weeks following procedure. Two were treated with laser and 3 required trabeculectomy. Mean IOP change from baseline at 24 weeks was 47.4% (31.2 to 16.4 mm Hg, P<0.0001, n=23). The mean difference was -14.8 mm Hg (95% confidence interval: -17.6, -11.9) with no statistically significant differences between groups. Qualified success was achieved in 21 (84%), 17 (74%), and 13 (93%) after 12, 24, and 52 weeks, respectively. Complete success was achieved in 17 (68%), 13 (57%), and 8 (57%) after 12, 24, and 52 weeks, respectively.

CONCLUSIONS

The interim results suggest that MIMS procedure may be a simple and effective surgical option for early OAG patients requiring target IOP in high teens although iris clogging of incision site is the major concern with this procedure.

Long term outcomes from the HORIZON randomized trial for a Schlemm's canal microstent in combination cataract and glaucoma surgery

OBJECTIVE

5-year results of the HORIZON trial comparing cataract surgery combined with an intracanalicular microstent to cataract surgery alone.

DESIGN

Prospective, multicenter, controlled randomized clinical trial.

PARTICIPANTS

Patients with cataract and POAG treated with ≥ 1 glaucoma medication, washed out diurnal intraocular pressure (DIOP) 22-34 mmHg and no prior incisional glaucoma surgery.

METHODS

Eyes were randomized 2:1 to receive a Hydrus® Microstent (Ivantis, Inc.) or no stent after successful cataract surgery. Follow-up was conducted through 5 years postoperatively.

MAIN OUTCOME MEASURES

IOP, glaucoma medication usage, repeat glaucoma surgery, visual acuity, visual field, procedure related adverse events, and corneal endothelial cell counts.

RESULTS

369 eyes were randomized to microstent treatment (HMS) and 187 to cataract surgery only (CS). Study groups were well matched for preoperative IOP, medication usage, washed out DIOP, and glaucoma severity. Five year follow up was completed in 80% of patients. At 5 years, the HMS group had a higher proportion of eyes with IOP ≤18 mmHg without medications compared to CS (49.5% vs. 34.8%, p=0.003) as well as a greater likelihood of IOP reduction of ≥ 20% without medications compared to CS alone (54.2% vs. 32.8%, p<0.001). The number of glaucoma medications was 0.5 ± 0.9 in the HMS group and 0.9 ± 0.9 in the CS group (p<0.001), and 66% of eyes in the HMS group were medication free compared to 46% in the CS group (p<0.001). The cumulative risk of incisional glaucoma surgery was lower in the HMS group (2.4% vs. 6.2%, log-rank p=0.027). There was no clinical or statistically significant difference in the rate of endothelial cell loss from 3 months to 60 months between the HMS and CS groups (p=0.261). Visual acuity did not differ between groups, and there was no difference in long term postoperative adverse events.

CONCLUSIONS

The addition of a Schlemm's canal microstent in conjunction with cataract surgery was safe, resulted in lowered IOP and medication use, and reduced the need for postoperative incisional glaucoma filtration surgery compared to cataract surgery alone after 5 years. Long term presence of the implant did not adversely affect the corneal endothelium.

Conventional glaucoma implants and the new MIGS devices: a comprehensive review of current options and future directions

Glaucoma is a progressive optic neuropathy that is the second leading cause of preventable blindness worldwide, after cataract formation. A rise in the intraocular pressure (IOP) is considered to be a major risk factor for glaucoma and is associated with an abnormal increase of resistance to aqueous humour outflow from the anterior chamber. Glaucoma drainage devices have been developed to provide an alternative pathway through which aqueous humour can effectively exit the anterior chamber, thereby reducing IOP. These devices include the traditional aqueous shunts with tube-plate design, as well as more recent implants, such as the trabeculectomy-modifying EX-PRESS^® implant and the new minimally invasive glaucoma surgery (MIGS) devices. In this review, we will describe each implant in detail, focusing on their efficacy in reducing IOP and safety profile. Additionally, a critical and evidence-based comparison between these implants will be provided. Finally, we will propose potential developments that may help to improve the performance of current devices.

Endocyclophotocoagulation combined with phacoemulsification in surgically naive primary open-angle glaucoma: three-year results

OBJECTIVE

To assess the safety and efficacy of endocyclophotocoagulation with phacoemulsification (phaco-ECP) in surgically naive, primary open-angle glaucoma (POAG).

METHODS

A retrospective case series of patients undergoing phaco-ECP between 2007 and 2017 at a single centre in London, UK. The primary outcome was intraocular pressure (IOP). Secondary outcomes were visual acuity, visual field global indices, topical medications and surgical complications. Failure criteria were: (1) IOP > 21 mmHg or <20% reduction at two consecutive visits, (2) IOP <5 mmHg and (3) further IOP-lowering surgery.

RESULTS

Eighty-three eyes from 83 patients were eligible. Pre-operatively, mean IOP (±SD) was 18.4 ± 5.2 mmHg. The mean number of topical agents (±SD) was 2.7 ± 0.9. Mean IOP (±SD) significantly reduced to 14.3 ± 4.7 at 1 year, 14.1 ± 4.0 at 2 years and 13.6 ± 3.7 at 3 years (p < 0.0001). Topical medications were significantly reduced to 1.3 ± 1.2 at 1 year, 1.7 ± 1.2 at 2 years and 1.8 ± 1.3 at 3 years (p < 0.0001). Annual IOP 'survival' was 70%, 54% and 45% at year 1, 2 and 3, respectively. Complications included uveitis (6%), macular oedema (2%), IOP spikes (1%) and corneal decompensation (1%) with no episodes of hypotony or retinal detachment. One patient underwent filtration surgery within 3 years (1%).

CONCLUSION

Phaco-ECP facilitates significant IOP lowering and reduction of medication burden in surgically naive POAG requiring cataract extraction. The procedure is relatively safe and without the use of implants and their associated risks.

Factors associated with achieving intraocular pressure lower than 15 mmHg by Trabectome surgery in primary open-angle glaucoma

To assess good prognostic factors of Trabectome surgery in primary open-angle glaucoma (POAG), clinical records of patients with POAG who underwent Trabectome surgery with/without cataract surgery as the first additive therapy to eye drops between January 2015 and March 2018 were retrospectively reviewed. Overall, data of 79 eyes (79 patients; 50 men; mean age, 68.0 years) up to postoperative 24 months were analyzed. Their mean intraocular pressure (IOP) was 20.4 ± 6.0 mmHg at baseline. Forty-two eyes (53.2%) achieved an IOP < 15 mmHg and ≥ 20% reduction from baseline without additional treatments. Phakic eyes had a better survival probability than pseudophakic eyes after adjusting for age, sex, baseline IOP, best-corrected visual acuity, and eye drop score (hazard ratio 3.096; 95% confidence interval [95% CI] 1.367–7.013; P = 0.007). Phakic eyes treated with combined Trabectome and cataract surgeries (mean survival time, 22.250 months; 95% CI 17.606–26.894) had a better survival probability than pseudophakic eyes treated with Trabectome surgery only (mean survival time, 12.111 months; 95% CI 8.716–15.506; P = 0.009) after the adjustment. Among the eyes treated with Trabectome surgery only, phakic eyes required significantly less additional treatments than pseudophakic eyes (P = 0.04). Trabectome surgery may be indicated for phakic eyes with POAG in addition to eye-drop therapy.