Clinical Outcomes After Second-Generation Trabecular Microbypass Stents (iStent inject®) with Phacoemulsification in Korean Patients

Five-Year Outcomes of iStent inject Implantation With or Without Phacoemulsification in Eyes with Open-Angle Glaucoma

INTRODUCTION

Minimally invasive glaucoma surgery (MIGS) has become more widespread in open-angle glaucoma (OAG) management. Broad evidence has shown a greater decrease in mean intraocular pressure (IOP) when cataract surgery is combined with MIGS, compared with cataract surgery alone. In this study, we evaluated the effectiveness and safety of second-generation trabecular micro-bypass implantation (iStent inject®) either in combination with cataract surgery (Combined subgroup) or as a standalone procedure (Standalone subgroup) in eyes with OAG. Our hypothesis was that implementing interventional glaucoma management would provide meaningful reductions in IOP and topical medication burden.

METHODS

This long-term retrospective consecutive case series included patients with mild to moderate OAG who received the iStent inject® Trabecular Micro-bypass stent with or without phacoemulsification between 2018 and 2024. Eligible patients were ≥ 18 years of age with mild or moderate OAG, cataract requiring surgery (for the Combined subgroup), and the need for IOP and/or medication reduction. Study outcomes included mean and proportional analyses of IOP and medications over time. Analyses were completed for the overall population and for the Combined/Standalone and Mild/Moderate subgroups.

RESULTS

The study included 271 eyes with mean age 69 years and a mean of 40 months of follow-up (range 10-79 months). In the overall population, mean IOP decreased from 16.4 mmHg at baseline to 13.7 mmHg at last follow-up (p = 0.001), while the mean number of medications decreased from 2.24 at baseline to 0.62 at last follow-up (p = 0.001). IOP reductions were also significant in the Combined/Standalone subgroups and in the Mild/Moderate subgroups (p = 0.001 for all), and all subgroups experienced increased proportions of eyes on no topical medications at last follow-up versus preoperative (p = 0.001 for all).

CONCLUSION

This 5-year real-world study showed significant and sustained reductions in IOP and topical medication burden following iStent inject trabecular micro-bypass with or without cataract surgery in eyes with mild and moderate open-angle glaucoma.

Surgically induced astigmatism and refractive outcomes after minimally invasive glaucoma surgery combined with cataract surgery

Minimally invasive glaucoma surgery (MIGS) is believed to induce less surgically induced astigmatism (SIA) due to smaller incisions, yet few studies have evaluated SIA in MIGS patients. This retrospective cohort study compared SIA and refractive outcomes among three MIGS techniques: first-generation trabecular micro-bypass stent (iStent [IS], n = 36), second-generation iStent inject W (IW, n = 39), and microhook ab interno trabeculotomy (μLOT, n = 36). SIA, refractive prediction error (RPE), intraocular pressure (IOP), and glaucoma subtype were analyzed. SIA remained minimal, with no significant differences between groups (p = 0.95, linear mixed model). RPE significantly differed between IW and μLOT (p = 0.025) but remained mild in both. The μLOT group exhibited a slight myopic shift and greater IOP reduction. However, absolute prediction error did not significantly differ among groups (p = 0.062). Subgroup analysis confirmed the refractive neutrality of MIGS across primary open-angle glaucoma, pseudoexfoliative glaucoma, and chronic angle-closure glaucoma. These findings support the refractive stability of MIGS when combined with cataract surgery, suggesting IS, IW, and μLOT as equally viable options from a refractive standpoint.

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.

Standalone interventional glaucoma: evolution from the combination-cataract paradigm

One of the most impactful recent developments in the glaucoma community has been the concept of interventional glaucoma. In brief, this paradigm shift involves proactive rather than reactive intervention to address glaucoma earlier in the disease process, including in both standalone and combination-cataract settings. By intervening earlier with minimally invasive surgical, laser, or drug-delivery treatments instead of prolonged topical medications, interventional glaucoma aims to take the burden of medication compliance off the patient. It also allows for standalone surgical interventions rather than letting cataract surgery dictate the glaucoma treatment plan. This interventional mindset has been made possible by the increasing diversity and availability of effective minimally invasive treatment options. With these options as a springboard, it is time to reevaluate and advance the traditional glaucoma treatment paradigm.

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.

Outcomes of iStent inject combined with cataract surgery in Asian eyes: Australian data from the Fight Glaucoma Blindness international registry

PURPOSE

To analyse real-world outcomes in Asian eyes of iStent inject, a second-generation trabecular micro-bypass stent, combined with phacoemulsification.

METHODS

This is a multi-centre, observational study of glaucomatous Asian eyes that have undergone iStent inject implantation combined with cataract surgery. Patient data were extracted from the Fight Glaucoma Blindness! Registry. Outcome measures included those of IOP reduction, glaucoma medication reduction, and adverse events including the need for secondary surgery.

RESULTS

123 eyes of 86 patients with a mean age of 68.4 ± 9.3 years underwent iStent inject implantation with phacoemulsification. At baseline, the mean ± SD preoperative intraocular pressure (IOP) was 16.0 ± 4.4 mmHg, and the mean preoperative number of topical glaucoma medications was 1.9 ± 1.4. At 12 months 30.8% of eyes demonstrated a reduction in IOP greater than 20%, the mean IOP reduction was 12.5% with an additional reduction of 0.7 glaucoma medications. 40% of eyes were using no medications at 12 months compared to 16.3% preoperatively. 8.2% of eyes required a subsequent procedure within the 12-month follow-up window.

CONCLUSION

iStent inject implantation combined with phacoemulsification in Asian eyes showed a reduction of IOP and glaucoma medication use in a real-world clinical setting. The safety profile of the device is good with minimal adverse outcomes, however, a subset of patients required secondary procedures within the 12 month follow up.

Five-Year Outcomes of Single Trabecular Microbypass Stent (iStent®) Implantation with Phacoemulsification in Korean Patients

INTRODUCTION

This study reports the long-term intraocular pressure (IOP)-lowering efficacy and safety of a single trabecular microbypass stent (iStent®; Glaukos Corp., San Clemente, CA, USA) for medically controlled open-angle glaucoma in Korean patients.

METHODS

This retrospective observational study included 42 eyes of 35 patients with primary open-angle glaucoma (POAG). All subjects underwent single first-generation iStent® implantation with phacoemulsification by a single surgeon with 5 years follow-up. The primary outcomes were changes in IOP and the number of antiglaucoma medications compared to the preoperative values. The secondary outcome was the proportion of eyes with IOP ≤ 18 mmHg without medication, ≤ 15 mmHg without medication, and ≤ 18 mmHg with or without medication. Adverse events and need for secondary glaucoma surgery were also recorded.

RESULTS

The mean IOP decreased from 15.8 ± 2.8 to 13.8 ± 1.7 mmHg and the mean number of medications was reduced from 2.24 ± 1.18 to 0.83 ± 1.12, respectively, at year 5. At 3 and 5 years, 80.6% and 78.6% of eyes, respectively, were receiving fewer medications than preoperative numbers. In contrast, only 50% of eyes on four preoperative medications showed medication reductions at 5 years. At years 3 and 5, 61.3% and 53.5% of eyes achieved IOP ≤ 18 mmHg without medication, whereas 90.3% and 89.3% of eyes achieved ≤ 18 mmHg regardless of medication use, respectively. Four eyes required additional glaucoma surgery (two Ahmed glaucoma valve implantations, one trabeculectomy, and one XEN 45 Gel Stent implantation), and all were receiving four preoperative antiglaucoma medications. Transient IOP elevation (14.3%) was the most common complication, followed by five hyphema, one stent obstruction, one stent malposition, and one severe anterior chamber reaction.

CONCLUSION

This study demonstrated a good safety profile and sustained IOP reduction after the implantation of a single trabecular microbypass stent (iStent®) with phacoemulsification in Korean patients. The majority of subjects with POAG showed a relatively good response; however, eyes receiving a higher number of medications preoperatively (especially four medications) had difficulty achieving a low target IOP.

Prospective 12-month outcomes of combined iStent inject implantation and phacoemulsification in Asian eyes with normal tension glaucoma

BACKGROUND

Glaucoma is the leading cause of irreversible blindness. Normal tension glaucoma (NTG) is a subset of open-angle glaucoma, demonstrating glaucomatous optic nerve damage in the absence of raised intraocular pressure (IOP). NTG is more prevalent in Asian populations. While generally slow-progressing, NTG may be associated with significant central visual field loss. In recent years, minimally invasive glaucoma surgery has been added to the armamentarium of glaucoma surgery. This prospective study aims to evaluate 12-month surgical outcomes of combined iStent inject (Glaukos Corporation, Laguna Hills, CA) implantation and phacoemulsification in Asian eyes with NTG.

METHODS

This is a prospective, single-centre case series of 30 eyes followed up until 12 months after surgery. Outcome measures included IOP, number of glaucoma medications, best-corrected visual acuity (BCVA) and intra and postoperative complications.

RESULTS

Mean age of subjects was 73.1 ± 6.3 years. Majority were ethnic Chinese (n = 27, 90%). Baseline medicated mean IOP was 13.8 ± 2.4 mmHg and mean number of glaucoma medications was 1.3 ± 0.7. Mean Humphrey visual field mean deviation was - 13.7 ± 7.6. The mean IOP reduction at all timepoints from postoperative month (POM) 3 onwards was statistically significant (all P < 0.05), with mean reduction of 1.2 mmHg (95% CI: 0.1-2.2, P = 0.037) by POM12. There was statistically significant reduction in mean number of medications from postoperative day (POD) 1 onwards (all P < 0.05), with mean decrease of 1.0 medication (95% CI: 0.9-1.1, P < 0.001) by POM12. By POM12, 25 (83.3%) eyes were medication-free. Three (10%) eyes had stent occlusion by iris requiring laser iridoplasty. One eye had gross hyphema which resolved on conservative management before POM1. Mean BCVA improved from the baseline 0.3 ± 0.3 logMAR to 0.1 ± 0.1 logMAR postoperatively (P < 0.001). There were no major adverse or sight-threatening events. No eyes required further glaucoma surgery during the 12-month follow-up period.

CONCLUSION

Asian eyes with NTG which underwent combined iStent inject implantation and phacoemulsification demonstrated a significant and sustained reduction in IOP and glaucoma medications, up to 12 months postoperatively.