iStent inject as a reasonable alternative procedure following failed trabeculectomy?

[Micro-invasive glaucoma surgery]

Glaucoma is a severe, rapidly progressing disease that in the absence of proper treatment leads to blindness in 20% of patients. According to the World Glaucoma Association, this disease is the most socially significant in modern ophthalmology and requires searching for new and effective methods of treatment. This article presents the results of research and reviews on this issue, considers both conservative therapy and surgical methods of treatment, analyzes in detail modern methods of micro-invasive eye surgery actively used in clinical practice. The article also describes indications for a various types of interventions, as well as the effect achieved by them and the possible complications, and presents the conclusions about the possibility of using these procedures in wide clinical practice.

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

INTRODUCTION

To evaluate the intraocular pressure (IOP)-lowering effect of second-generation trabecular microbypass stents (iStent® inject) with cataract extraction (combination group) and compare refractive changes in the combination group and the control (phacoemulsification only) group.

METHODS

This retrospective case-control study included 36 eyes with cataract and medically controlled open-angle glaucoma with IOP < 21 mmHg and 100 nonglaucomatous eyes with cataract. Data were collected preoperatively and for 6 months postoperatively. Data included IOP, number of glaucoma medications, corrected distance visual acuity, and mean absolute error (MAE) from target refraction, and astigmatic vector analysis. Surgical success for the combination group was defined according to three criteria: (A) IOP < 15 mmHg without medication, (B) IOP < 18 mmHg without medication, and (C) IOP < 18 mmHg with or without medication.

RESULTS

In the combination group, mean IOP was reduced from 15.1 ± 2.9 mmHg to 12.5 ± 2.0 mmHg, and the mean number of medications decreased from 1.9 ± 1.0 to 0.4 ± 0.8 at postoperative 6 months (both P < 0.001). Surgical success rates were 77.8%, 83.3%, and 97.2% at 6 months by criteria A, B, and C, respectively. Mean IOP was reduced from 14.3 ± 2.7 mmHg to 13.1 ± 2.1 mmHg at 1 month in the control group (P < 0.001). The MAE was 0.33 ± 0.26 D, and 83.3% of eyes had spherical equivalent difference within 0.50 D in the combination group (0.38 ± 0.33 D and 76.0% in the control group; P = 0.309 and P = 0.363, respectively). Preoperative and postoperative centroid values were 0.51 D @ 1° and 0.66 D @ 178°, respectively (0.23 D @ 176° and 0.66 D @ 1° in the control group). There were no statistical differences between the two groups with respect to preoperative and postoperative mean absolute values (P = 0.154 and P = 0.322, respectively).

CONCLUSIONS

On the basis of our results using Korean real-world interim experience, iStent® inject with cataract extraction has favorable IOP-lowering effects and minimally impacts refractive outcomes.

iStent versus iStent inject implantation combined with phacoemulsification in open angle glaucoma

Purpose

To compare the outcomes of iStent vs. iStent inject implantation combined with phacoemulsification.

Methods

This single center retrospective comparative case series included subjects with open angle glaucoma who underwent iStent or iStent inject implantation combined with phacoemulsification with ≥1 year follow-up. The main outcome measures were in-group and between-group changes in intraocular pressure (IOP) and medication number, proportion of eyes that achieved IOP ≤15 mmHg, and surgical success defined as 20% IOP reduction from baseline at 6/12 months. Univariate/multivariate regression analyses were done to identify predictors of surgical failure.

Results

One hundred ninety-seven eyes of 148 patients were included (122 iStent, 75 iStent inject). Both groups achieved significant IOP and medication reduction at months 6/12 (P < 0.05). At month 6, IOP was significantly lower in iStent inject vs. iStent eyes (P = 0.003), but the difference was insignificant by month 12 (P = 0.172). Medication number was comparable in both groups at months 6/12 (P > 0.05). More iStent inject eyes achieved IOP ≤15 mmHg at month 6 (P = 0.003) and 12 (P = 0.047). Surgical success was comparable in both groups at months 6/12 (P > 0.05). Kaplan-Meier survival analysis showed similar cumulative rate of surgical failure at year-1 in both groups (P = 0.644). The multivariate model identified older age (P = 0.017) and lower baseline IOP (P = 0.002) as the strongest predictors of surgical failure.

Conclusion

Compared to iStent, iStent inject achieved lower IOP at month 6 and higher proportion of eyes achieved IOP ≤15 mmHg at month 6/12. However, surgical success was similar in both groups. Predictors of surgical failure were older age and lower baseline IOP rather than the stent type.

iStent inject: comprehensive review

Microinvasive glaucoma surgeries (MIGSs) are new surgical procedures for treatment of glaucoma. They aim to safely and effectively reduce intraocular pressure (IOP) with minimal trauma to the eye and less complications. The first-generation iStent is the first approved ab interno MIGS implant for management of open-angle glaucoma. It works by allowing aqueous humor to drain directly from the anterior chamber into Schlemm canal bypassing the trabecular meshwork, the major site of outflow resistance. The second-generation iStent inject is the smallest available trabecular device that occupies less than 0.5 mm. It is designed to facilitate the surgical technique and allow simultaneous implantation of 2 stents, aiming for more IOP reduction. This review examines publications about the iStent inject, focusing on the device's efficacy, safety, and comparison with the first generation iStent. Both devices were found to be a safe and effective tool in management of open-angle glaucoma.

XEN® Gel Stent compared to PRESERFLO™ MicroShunt implantation for primary open-angle glaucoma: two-year results

Purpose

To evaluate the long‐term efficacy and safety of two minimally invasive glaucoma surgery implants with a subconjunctival drainage approach: the XEN45 Gel Stent^® (Xen) implant and the PRESERFLO™ MicroShunt (MicroShunt).

Methods

Retrospective comparative case series of primary open‐angle glaucoma (POAG) patients with at least 6 months of follow‐up after a MicroShunt or Xen implantation augmented with mitomycin C.

Results

Forty‐one eyes of 31 patients underwent Xen implantation, and 41 eyes of 33 patients, MicroShunt implantation. Baseline characteristics were similar, except for more combined surgeries with phacoemulsification in the Xen group (37% vs. 2%). Mean baseline IOP ± standard deviation dropped from 19.2 ± 4.4 to 13.8 ± 3.8 mmHg (n = 26) in the Xen group and from 20.1 ± 5.0 to 12.1 ± 3.5 (n = 14) in the MicroShunt group at 24 months of follow‐up (p = 0.19, t‐test). The number of IOP‐lowering medications dropped from 2.5 ± 1.4 to 0.9 ± 1.2 in the Xen group and from 2.3 ± 1.5 to 0.7 ± 1.1 in the MicroShunt group. The probability of qualified success was 73% and 79% at 24 months of follow‐up for the Xen and MicroShunt groups, respectively. Postoperative complications were usually mild and self‐limiting. The number of bleb needling and secondary glaucoma surgery procedures was similar in both groups; however, in the Xen group more additional MicroPulse^® transscleral cyclophotocoagulation procedures were performed.

Conclusion

Xen Gel Stent and PreserFlo MicroShunt implantations achieved comparable results in POAG eyes in terms of IOP‐lowering and surgical success, with a similar high safety profile.

Kahook Dual Blade Goniotomy vs iStent inject: Long-Term Results in Patients with Open-Angle Glaucoma

Purpose

Efficacy and safety evaluation of Kahook Dual Blade (KDB) goniotomy vs iStent inject implantation.

Materials and Methods

Retrospective study in patients that underwent goniotomy with KDB or iStent inject implantation, stand-alone or combined with cataract surgery. Main outcome parameters were intraocular pressure (IOP), number of glaucoma medications, proportion of eyes achieving >20% IOP reduction and number of eyes with postoperative IOP <19 mmHg at last follow-up.

Results

A total of 29 patients (30 eyes) were included in the iStent inject group and 30 patients (32 eyes) in the KDB group. Mean follow-ups were 20.9±6.5 (KDB-alone) to 29.5±7.6 (phaco-iStent inject) months. Pre- and post-operative IOPs were 22.2±5.8 mmHg and 15.9±4.3 mmHg (P=0.004) in the KDB-alone, 24.2±6.8 mmHg and 16.2±6.7 mmHg (P=0.001) in the phaco-KDB, 20.6±5.4 mmHg and 20.9±6.8 mmHg (P=0.598) in the iStent inject-alone as well as 20.9±5.5 mmHg and 15.6±3.4 mmHg (P=0.003) in the phaco-iStent inject subgroups. No major complications occurred.

Conclusion

All KDB and iStent subgroups except the stand-alone iStent inject subgroup showed a clinically significant IOP-lowering effect as a stand-alone procedure or combined with cataract surgery. Goniotomy with KDB in this setting seems to offer an advantageous IOP reduction compared to iStent inject.

Comparing the trabecular outflow by the response to topical pilocarpine in patients with and without glaucoma filtering surgery

PURPOSE

To compare the trabecular outflow by the response to topical pilocarpine administration in patients with and without prior glaucoma filtering surgery.

STUDY DESIGN

Prospective, cross-sectional, randomized, double-blinded study.

METHODS

Open-angle glaucoma (OAG) patients without any prior glaucoma surgery, and those with prior trabeculectomy or tube shunt surgery aged 18-90 years were included. Both groups were randomized into pilocarpine or artificial tears (ATs). Intraocular pressure (IOP) was measured before and 90 min after the instillation of eye drops.

RESULTS

A total of 189 eyes of 189 patients were included: 92 eyes in the pilocarpine and 97 eyes in the ATs group. There was a mean ± standard deviation of - 0.81 ± 3.08 mmHg decrease in IOP with pilocarpine in those without prior surgery, significantly higher than the ATs group (0.55 ± 2.31 mmHg; p = 0.02). No significant change in IOP with pilocarpine was noted in the surgical group compared to the ATs group (p = 0.90). In the surgery group, greater IOP reduction was observed with pilocarpine in those who had undergone surgery within the last three years than those who had surgery three or more years prior (- 1.56 ± 2.64 versus 1.41 ± 2.77 mmHg; p = 0.001).

CONCLUSION

Less IOP reduction was observed with pilocarpine in patients who had filtering surgery more than three years previously compared to those with more recent surgery.