Trabecular Micro-bypass Stent Research Articles

Clinical evaluation of a trabecular microbypass stent with phacoemulsification in patients with open-angle glaucoma and cataract.

PurposeTo evaluate the safety and efficacy of the iStent trabecular microbypass stent in combination with cataract surgery in patients with open-angle glaucoma (OAG).MethodsRetrospective, consecutive case series from October 2012 to December 2015 with no exclusion criteria. The series comprised of 350 eyes with OAG and cataract. Data were collected both preoperatively and postoperatively at day 1 week 1, months 1, 3, 6, 12, 18, and 24. Data included intraocular pressure (IOP), number of glaucoma medications, visual acuity, the incidence of postoperative IOP pressure spikes of greater than ≥15 mmHg at any time point, and need for additional surgery.ResultsThe mean preoperative IOP was 19.13±6.34 mmHg. At 2 years postoperation, mean IOP was 15.17±3.53 mmHg (P<0.0001). The mean number of glaucoma medications was 1.19±1.00 preoperatively and 0.61±0.96 (P<0.0001) at 2 years postoperation. At 1 day postoperatively, 31 eyes (12.4%) experienced an IOP increase of 15 mmHg above their baseline IOP that responded to topical therapy. Two patients required additional tube shunt surgery.ConclusionThe insertion of the iStent trabecular microbypass stent in combination with cataract surgery effectively lowers IOP in OAG patients. The magnitude of IOP reduction was more significant in patients with higher preoperative pressure. Medication use was also significantly reduced postoperatively. The safety profile appears favorable with a low rate of IOP spikes and only two eyes (<1%) requiring additional surgery.

Outcomes after combined phacoemulsification and trabecular microbypass stent implantation in controlled open-angle glaucoma

To study the effect of combined phacoemulsification cataract surgery and iStent (trabecular microbypass stent) implantation on intraocular pressure (IOP) and medication use in open-angle glaucoma (OAG) patients with a low mean preoperative IOP. University of Colorado Health Eye Center, Aurora, Colorado, USA. Retrospective case series. Treatment outcomes analyzed included IOP, medication use, and corrected distance visual acuity (CDVA). Treatment success was defined as a 20% or more IOP reduction or discontinuation of at least 1medication. Sixty-four eyes of 45 patients were included in the analysis. At 1year, the mean IOP was significantly reduced from 14.7±3.2 mm Hg (SD) to 13.2±2.8mm Hg (P<.01) and the mean medication use decreased from 1.81±1.13 to 1.41±1.48 (P=.0001). The estimated IOP reduction at 1, 3, 6, and 12months was 3.5% (P=.23), 7.9% (P=.04), 9.7% (P=.01), and 12.2% (P=.002), respectively. Treatment success at 1year was achieved in 76.1% of patients, and 41% of patients were medication free at 1year. The CDVA was significantly improved from 0.4±0.38 logMAR at baseline to 0.17±0.35 at 1year (P<.0001). Combined cataract surgery and trabecular microbypass stent implantation was statistically effective in reducing IOP and/or medication burden in OAG patients with a low preoperative IOP. During the informed surgical consent process, the physician and patient should consider the clinical benefit of modest IOP lowering and/or a decrease in medication use. Drs. Seibold, SooHoo, Pantcheva, and Kahook have received grant support from Glaukos Corp. No other author has a financial or proprietary interest in any material or method mentioned.

IStent® Trabecular Microbypass Stent: An Update

Due to the high rates of complications and failure experienced with current glaucoma procedures, there is a continuous search for a safer and more effective glaucoma surgery. A new class of procedures termed minimally invasive glaucoma surgeries (MIGS) aim to fill this void by offering an alternative method of IOP reduction associated with markedly reduced complication rates and shorter recovery times. The iStent, a trabecular microbypass stent, is a MIGS device that has quickly gained popularity. The device allows aqueous humor to directly drain from the anterior chamber into Schlemm's canal by bypassing an obstructed trabecular meshwork. This review examines publications about the iStent, focusing on the device's efficacy, safety, and cost when a single iStent or multiple iStents are implanted in combination with cataract surgery or as a solo procedure. Current data suggest that the iStent is a safe and effective tool in the management of mild-to-moderate glaucoma, notable for its limited complications and absence of serious adverse events following implantation. As valuable experience is gained performing ab interno MIGS, increasing familiarity with angle anatomy and iStent placement, and as newer stent designs are developed, there is promise of continual improvement in the surgical management of glaucoma.

Trabecular micro-bypass stent implantation during small-incision cataract surgery for open-angle glaucoma or ocular hypertension: Long-term results

To evaluate long-term safety and efficacy of iStent trabecular micro-bypass stent implantation during cataract surgery in patients with primary open-angle, pseudo-exfoliation glaucoma, ocular hypertension, or secondary or post-traumatic glaucoma. AaM Augenklinik am Marienplatz, Munich, Germany. Prospective, open-label, non-randomized study. Preoperative and postoperative evaluations included intra-ocular pressure (IOP), topical ocular hypotensive medication use, cup/disc ratio, corrected-distance visual acuity (CDVA), complications, and adverse events. A single trabecular micro-bypass stent was implanted through the same temporal, limbal incision used for cataract surgery via phacoemulsification in a consecutive series of 62 eyes of 43 patients. To date, a total of 41 eyes have been followed for 3 years postoperatively, whereas long-term postoperative follow-up on the remaining patients is ongoing. Mean preoperative IOP was 24.1 ± 6.9 mm Hg on a mean of 1.8 medications (±0.9). Analyses of eyes with no secondary surgical intervention showed mean IOP reduction to 14.8 ± 4.2 mm Hg at 12 months (n = 61), 14.5 ± 2.2 mm Hg at 24 months (n = 42), and 14.9 ± 2.3 mm Hg at 36 months (n = 39). Medications were eliminated in 74% of eyes at 36 months. Five eyes, 4 with previous glaucoma surgeries and 1 with pseudo-exfoliation syndrome, required additional glaucoma surgery after stent implantation. No intra-operative or postoperative complications typically seen with conventional glaucoma surgeries occurred after stent implantation. At 36 months, CDVA was 20/40 or better in 38 eyes (93%). Trabecular micro-bypass stent implantation during cataract surgery was safe and effective in patients with ocular hypertension or glaucoma as measured by a sustained reduction in IOP and medication use and an excellent safety profile through 3 years after surgery. Dr. Neuhann has no financial or proprietary interest in any material or method mentioned. Glaukos Corp. provided editorial assistance in the preparation of the manuscript.

A review of the iStent(®) trabecular micro-bypass stent: safety and efficacy.

There is a significant demand for procedures that can effectively treat glaucoma with low risk and good visual outcomes. To fill this void, procedures termed “minimally invasive glaucoma surgery”, are gaining in popularity. This review will focus on the safety and efficacy of one such minimally invasive glaucoma surgery procedure, the trabecular micro-bypass stent. This stent is intended to lower intraocular pressure by directly cannulating Schlemm’s canal and thereby enhancing aqueous outflow. Recent randomized controlled trials and case series have demonstrated the micro-bypass stent to be a relatively safe procedure, with limited complications and no serious adverse sequelae. The most common complication across all studies was stent obstruction or malposition, which generally did not result in any adverse outcome in vision or pressure control. In addition, increased rates of hypotony, choroidal hemorrhage, or infection were not seen with the micro-bypass stent in comparison to cataract surgery alone.

IStent trabecular micro-bypass stent for open-angle glaucoma.

Trabecular micro-bypass stents, commonly known as iStents, are micro-invasive glaucoma surgery (MIGS) devices used to treat open-angle glaucoma. Like other MIGS procedures that enhance trabecular outflow, the iStent lowers intraocular pressure (IOP) by creating a direct channel between the anterior chamber and Schlemm’s canal. iStents are typically implanted at the time of phacoemulsification for patients with open-angle glaucoma and visually significant cataracts. This review summarizes the published data regarding the efficacy, safety, and cost considerations of trabecular micro-bypass stents. Most studies found statistically significant reductions in mean IOP and ocular medication use after combined phacoemulsification with single or double iStent implantation. The devices were found to be very safe, with a safety profile similar to that of cataract surgery. Complications were infrequent, with the most common complications being temporary stent obstruction or malposition, which resolved with observation or secondary procedures. Future studies are needed to evaluate long-term outcomes, patient satisfaction, cost effectiveness, and expanded indications.

New options for combined cataract and glaucoma surgery

To review the current literature regarding the effectiveness and risks of new surgeries that can be combined with phacoemulsification in the management of cataract and glaucoma. Surgical options for concurrently managing cataract and glaucoma have expanded in recent years. Endoscopic cyclophotocoagulation, trabecular micro-bypass stent, ab interno trabeculectomy, and canaloplasty may be performed in conjunction with cataract extraction to provide additional intraocular pressure (IOP) reduction. Studies evaluating these new glaucoma procedures combined with phacoemulsification generally include retrospective case series without a comparison group. Because cataract surgery alone is associated with IOP reduction, the relative contribution of the glaucoma procedure in lowering IOP cannot be determined in these studies. Randomized clinical trials are needed to better evaluate the efficacy and safety of newer glaucoma procedures in combination with cataract surgery. The newer glaucoma procedures appear less effective than trabeculectomy, but they are associated with a lower risk of surgical complications.

Prospective, Unmasked Evaluation of the iStent® Inject System for Open-Angle Glaucoma: Synergy Trial

IntroductionMicro-invasive glaucoma surgical implantation of trabecular micro-bypass stents, previously shown to be safe and effective for open-angle glaucoma (OAG) subjects during cataract surgery, was considered for evaluation as a sole procedure. The aim of this study was to evaluate the safety and intraocular pressure (IOP)-lowering efficacy after ab interno implantation of two Glaukos Trabecular Micro-Bypass iStent inject second generation devices in subjects with OAG. This study was performed at sites in France, Germany, Italy, Republic of Armenia, and Spain.MethodsIn this pan-European, multi-center prospective, post-market, unmasked study, 99 patients with OAG on at least two topical ocular hypotensive medications who required additional IOP lowering to control glaucoma disease underwent implantation of two GTS400 stents in a stand-alone procedure. Patients were qualified if they presented with preoperative mean IOP between 22 and 38 mmHg after medication washout. Postoperatively, subjects were assessed at Day 1, Months 1, 3, 6, 7, 9, and 12. IOP, medication use and safety were assessed at each visit.ResultsSixty-six percent of subjects achieved IOP ≤18 mmHg at 12 months without medication, and 81% of subjects achieved Month 12 IOP ≤ 18 mmHg with either a single medication or no medication. Mean baseline washout IOP values decreased by 10.2 mmHg or 39.7% from 26.3 (SD 3.5) mmHg to 15.7 (SD 3.7) mmHg at Month 12. Mean IOP at 12 months was 14.7 (SD 3.1) mmHg in subjects not using ocular hypotensive medications. Reduction from preoperative medication burden was achieved in 86.9% of patients, including 15.2% with reduction of one medication and 71.7% with reduction of two or more medications. Postoperative complications occurred at a low rate and resolved without persistent effects.ConclusionIn this series, implantation of two trabecular micro-bypass second generation stents in subjects with OAG resulted in IOP and medication reduction and favorable safety outcomes.Electronic supplementary materialThe online version of this article (doi:10.1007/s12325-014-0095-y) contains supplementary material, which is available to authorized users.

Cataract surgery with trabecular micro-bypass stent implantation in patients with mild-to-moderate open-angle glaucoma and cataract: Two-year follow-up

To assess the long-term safety and efficacy of a single trabecular micro-bypass stent with concomitant cataract surgery versus cataract surgery alone for mild to moderate open-angle glaucoma. Twenty-nine investigational sites, United States. Prospective randomized controlled multicenter clinical trial. Eyes with mild to moderate glaucoma with an unmedicated intraocular pressure (IOP) of 22 mm Hg or higher and 36 mm Hg or lower were randomly assigned to have cataract surgery with iStent trabecular micro-bypass stent implantation (stent group) or cataract surgery alone (control group). Patients were followed for 24 months postoperatively. The incidence of adverse events was low in both groups through 24 months of follow-up. At 24 months, the proportion of patients with an IOP of 21 mm Hg or lower without ocular hypotensive medications was significantly higher in the stent group than in the control group (P=.036). Overall, the mean IOP was stable between 12 months and 24 months (17.0 mm Hg ± 2.8 [SD] and 17.1 ± 2.9 mm Hg, respectively) in the stent group but increased (17.0 ± 3.1 mm Hg to 17.8 ± 3.3 mm Hg, respectively) in the control group. Ocular hypotensive medication was statistically significantly lower in the stent group at 12 months; it was also lower at 24 months, although the difference was no longer statistically significant. Patients with combined single trabecular micro-bypass stent and cataract surgery had significantly better IOP control on no medication through 24 months than patients having cataract surgery alone. Both groups had a similar favorable long-term safety profile. Dr. Craven was an investigator in the clinical trial of the iStent. Dr. Katz is a consultant to Glaukos and was the medical monitor for the clinical trial of the iStent. Dr. Katz is a stockholder in Glaukos. Mr. Wells and Ms. Giamporcaro are employees of Glaukos.

Micro-invasive glaucoma surgery

There is an increasing interest and availability of micro-invasive glaucoma surgery (MIGS) procedures. It is important that this increase is supported by sound, peer-reviewed evidence. This article will define MIGS, review relevant publications in the period of annual review and discuss future directions. The results of the pivotal trial comparing a trabecular micro-bypass stent (iStent, Glaukos Corporation, Laguna Hills, CA, USA) combined with phacoemulsification to phacoemulsification alone showed a significantly higher percentage of patients with unmedicated intraocular pressure (IOP) ≤ 21 mmHg, and a comparable safety profile. Initial results are published regarding a second-generation micro-bypass stent (iStent inject, Glaukos Corporation, Laguna Hills, CA, USA), a canalicular scaffold (Hydrus, Ivantis Inc., Irvine, CA, USA) and an ab interno suprachoroidal microstent (CyPass, Transcend Medical, Menlo Park, CA, USA), showing a decrease in mean postoperative IOP. Phaco-Trabectome (Ab interno trabeculectomy Trabectome, NeoMedix Inc., Tustin, CA, USA) was compared to phacotrabeculectomy and showed less IOP reduction, less postoperative complications, and a similar success rate. Similar success rates were found with the comparison of excimer laser trabeculostomy (ELT, AIDA, Glautec AG, Nurnberg, Germany) and selective laser trabeculoplasty. A number of publications review the importance of the location of implantable devices, intraoperative gonioscopy, cost-effectiveness and quality-of-life studies, and randomized clinical trials. MIGS procedures offer reduction in IOP, decrease in dependence on glaucoma medications and an excellent safety profile. Their role within our glaucoma treatment algorithm continues to be clarified and differs from the role of more invasive glaucoma surgeries such as trabeculectomy or glaucoma drainage devices.

Randomized Evaluation of the Trabecular Micro-Bypass Stent with Phacoemulsification in Patients with Glaucoma and Cataract

To assess the safety and efficacy of the iStent trabecular micro-bypass stent (Glaukos Corporation, Laguna Hills, CA) in combination with cataract surgery in subjects with mild to moderate open-angle glaucoma. Prospective, randomized, open-label, controlled, multicenter clinical trial. A total of 240 eyes with mild to moderate open-angle glaucoma with intraocular pressure (IOP) ≤24 mmHg controlled on 1 to 3 medications were randomized to undergo cataract surgery with iStent implantation (treatment group) or cataract surgery only (control). Fifty additional subjects were enrolled to undergo cataract surgery with iStent implantation under protocol expansion. Data in this report are based on the first 240 eyes enrolled. Implantation of the iStent trabecular micro-bypass stent in conjunction with cataract surgery or cataract surgery only. The primary efficacy measure was unmedicated IOP ≤21 mmHg at 1 year. A secondary measure was unmedicated IOP reduction ≥20% at 1 year. Safety measures included best-corrected visual acuity (BCVA), slit-lamp observations, complications, and adverse events. The study met the primary outcome, with 72% of treatment eyes versus 50% of control eyes achieving the criterion (P<0.001). At 1 year, IOP in both treatment groups was statistically significantly lower from baseline values. Sixty-six percent of treatment eyes versus 48% of control eyes achieved ≥20% IOP reduction without medication (P = 0.003). The overall incidence of adverse events was similar between groups with no unanticipated adverse device effects. Pressure reduction on fewer medications was clinically and statistically significantly better 1 year after stent plus cataract surgery versus cataract surgery alone, with an overall safety profile similar to that of cataract surgery alone.

IStent®: trabecular micro-bypass stent for open-angle glaucoma

Glaucoma afflicts tens of millions worldwide and is a leading cause of irreversible blindness. The primary objective in managing glaucoma is the reduction of elevated intraocular pressure. Bypassing outflow resistance at the level of the trabecular meshwork can re-establish physiologic aqueous humor outflow from the anterior chamber, thus reducing intraocular pressure. The iStent® trabecular micro-bypass stent is implanted directly into Schlemm’s canal through a clear corneal incision as a standalone procedure or in conjunction with cataract surgery to facilitate aqueous outflow through Schlemm’s canal. iStent is a minimally invasive alternative to current treatments for patients with open-angle glaucoma and has also been shown to offer distinct clinical advantages in the early stages of the disease.

Coexistent Primary Open-Angle Glaucoma and Cataract: Interim Analysis of a Trabecular Micro-Bypass Stent and Concurrent Cataract Surgery

To evaluate the safety and efficacy of the iStent Trabecular Micro-bypass Stent in patients undergoing concurrent cataract and glaucoma surgery. Prospective, 24-month, uncontrolled, multicenter, multicountry evaluation of 58 patients with uncontrolled primary open-angle glaucoma (including pseudoexfoliation and pigmentary) and cataract. Patients underwent clear cornea phacoemulsification followed by ab interno gonioscopically guided implantation of the iStent. Of the 48 per protocol population, 42 patients completed 12 months of the 24-month study, and their data are included in this interim analysis. At baseline, mean (+/-SD) intraocular pressure (IOP) was 21.7+/-3.98 mmHg. At 12 months, mean IOP was reduced to 17.4+/-2.99 mmHg, a mean IOP reduction of 4.4+/-4.54 mmHg (p<0.001, 18.3%). At baseline, patients were taking a mean 1.6+/-0.8 medications. By 12 months, the mean number of medications was reduced to 0.4+/-0.62 (p<0.001). Half the patients achieved an IOP < or =18 mmHg and were able to discontinue hypotensive medication by the 12-month visit. The most commonly reported device-related adverse events were the appearance of stent lumen obstruction (7 eyes) and stent malposition (6 eyes). None of the adverse events were deemed serious. In patients undergoing concurrent cataract and glaucoma surgery, the iStent was safe and efficacious for the reduction of IOP and medication therapy.

Glaukos iStent® trabecular micro-bypass

The iStent trabecular micro-bypass system (Glaukos Corp. Laguna Hills, CA) was developed to address the limitations of current medical and surgical therapies for glaucoma treatment. The iStent® is inserted ab interno through a small temporal clear corneal incision, bypassing the trabecular meshwork and placed in Schlemm's canal at the lower nasal quadrant. Implantation of this stent into Schlemm's canal allows aqueous humor to drain directly from the anterior chamber into Schlemm's canal bypassing the obstructed trabecular meshwork. For this review, a Medline search was performed using the terms “trabecular micro-bypass stent” and “trabecular bypass stent.” The online abstract database for the American Academy of Ophthalmology was also reviewed. s which duplicated published articles were excluded. All relevant papers (n is equal to three) and abstracts (n is equal to one) were included in this review. Multiple, prospective multi-country, clinical trials have demonstrated the safety and efficacy of iStent in reducing IOP, when compared to traditional treatment modalities, while reducing/ eliminating the need for ocular antihypertensive drugs when implanted in OAG patients during combined cataract surgery or in patients with glaucoma refractory to traditional treatment modalities.

Coexistent primary open-angle glaucoma and cataract: Preliminary analysis of treatment by cataract surgery and the iStent trabecular micro-bypass stent

Reducing intraocular pressure (IOP) is the only proven treatment modality for reducing the risk of glaucomatous progression. In this study, we evaluated the safety and efficacy of a new tool in IOP reduction, implanted with cataract surgery: the Glaukos iStent trabecular micro-bypass stent. This was a prospective, 24-month, uncontrolled, non-randomised, multicentre study. Subjects with uncontrolled primary open-angle glaucoma (including pseudoexfoliation and pigmentary) and a cataract underwent clear cornea phacoemulsification cataract extraction with ab-interno gonioscopically guided implantation of the study stent. Subjects who had completed at least 6 months of follow-up were included in this interim analysis (n=47). At baseline, mean (+/-standard deviation) IOP was 21.5+/-3.7 mmHg, and subjects were taking a mean of 1.5+/-0.7 ocular hypotensive medications. Six months after implantation of the study stent the mean IOP was 15.8+/- 3.0 mmHg, a mean IOP reduction of 5.7+/-3.8 mmHg (25.4%, P<0.001). The mean number of patient medications after 6 months was 0.5+/-0.8 medications, a mean decrease of 1.0+/-0.8 medications (66.7%, P<0.001). Most subjects (70%) were able to discontinue all glaucoma medications. There were no complications traditionally associated with filtering surgery, and no serious adverse events were reported. In this interim analysis of subjects with glaucoma and cataracts, this novel stent implantation in subjects undergoing cataract surgery represents a new surgical approach to provide clinically significant decreases in IOP and drug burden.

Initial clinical experience with the trabecular micro-bypass stent in patients with glaucoma

This study was undertaken to evaluate the efficiency of a trabecular micro-bypass stent designed to allow direct aqueous drainage from the anterior chamber into Schlemm's canal in patients with glaucoma. In this prospective case series of 6 patients with open-angle glaucoma, the microstent was inserted ab interno under local anesthesia in an ophthalmic operating room. Patients were seen postoperatively at 1 to 2 d, 1 wk, and 1, 2, 6, and 12 mo. All stents were successfully placed within Schlemm's canal. Mean intraocular pressure (IOP) at preoperative baseline was 20.2+/-6.3 mm Hg (range, 14-31 mm Hg). Mean IOP decreased during the immediate postoperative period to approximately 12 to 13 mm Hg and was stabilized at 14 to 15 mm Hg with reduction of medication throughout 1 y of follow-up. No major complications occurred. According to observations reported in this feasibility study, the microstent was effective in reducing IOP and in decreasing the number of glaucoma medications required to control IOP. Implantation procedures were safe, and stents remained in place throughout the follow-up period. None of the complications traditionally associated with filtering surgery were reported. Further research on this stent in a larger group of patients is needed to assess its role in glaucoma therapy.