Using multiple trabecular micro-bypass stents in cataract patients to treat open-angle glaucoma

Managing coexistent cataract and glaucoma with iStent

The iStent is an intraocular implant that resides within Schlemm canal and allows for direct bypass of the trabecular meshwork by aqueous fluid. It is one of several procedures termed microinvasive glaucoma surgery. The prominence of microinvasive glaucoma surgery is growing because of its role in lowering intraocular pressure in mild to moderate glaucoma combined with its favorable safety profile. With transcleral glaucoma filtering surgery, there is an increased potential for significant complications including hypotony, suprachoroidal hemorrhage, and long-term risk of endophthalmitis. In comparison, the iStent minimizes this risk and has been shown to be similar to cataract surgery in terms of associated complications. As will be discussed, multiple publications have addressed both the safety and efficacy of the implant. This review additionally presents an overview of implantation technique as well as what to expect postoperatively. Looking forward, the second-generation models may ease implantation and the use of multiple stents may potentially play a role in more advanced disease.

Efficacy and safety of combined cataract surgery with 2 trabecular microbypass stents versus ab interno trabeculotomy

PURPOSE

To compare the outcomes of combined cataract surgery with trabecular microbypass stents and ab interno trabeculotomy in patients with open-angle glaucoma.

SETTING

University of Toronto, Toronto, Ontario, and University of Montreal, Montreal, Quebec, Canada, and Glaucoma Associates of Texas, Dallas, Texas, USA.

DESIGN

Retrospective case series.

METHODS

Patients with primary open-angle, pseudoexfoliative, or pigmentary dispersion glaucoma were included. Primary outcome measures were intraocular pressure (IOP), postoperative medications, success (IOP ≤18 mm Hg, no glaucoma medications or reoperations), and postoperative adverse events.

RESULTS

The average patient age was 76.5 years ± 12 [SD]. Forty-nine eyes had phacoemulsification and 2 had stent implantations; 52 eyes had phacoemulsification and trabeculotomy surgery with a 12-month postoperative follow-up. The analysis of variance indicated a significant reduction in mean IOP from baseline to 12 months for stent (19.6 ± 5.3 mm Hg to 14.3 ± 3.1 mm Hg; P < .001) and trabeculotomy (20.6 ± 6.8 mm Hg to 17.3 ± 6.5 mm Hg; P < .001) and lower mean IOP at 12 months in the stent group (P = .01). The median number of glaucoma medications decreased from baseline to 12 months in both groups and was lower in the stent group at 3, 6, and 12 months. Thirty-nine percent (19 eyes) in the stent group and 14% (7 eyes) in the trabeculotomy group achieved success at 12 months (P = .006). The incidence of hyphema was lower in the stent group (P = .008).

CONCLUSIONS

Both types of surgery achieved a significant reduction in IOP and medication use at 12 months, with the stent group achieving higher success and a reduced incidence of postoperative hyphema.

FINANCIAL DISCLOSURE

Dr. Ahmed is a consultant to and investigator for Glaukos Corp., Ivantis, Inc., Transcend Medical, Inc., and Aquesys, Inc., and has received speaker honoraria from Neomedix, Inc. Dr. Saheb has received travel funding from Glaukos Corp., Ivantis, Inc., and Transcend Medical, Inc., and a research grant from Ivantis, Inc. Dr. Harasymowycz has received a research grant from Ivantis, Inc. Dr. Fellman is a consultant to Endo Optiks, Inc., and has received honoraria from Optous and research funds from Ivantis, Inc., Glaukos Corp., and Transcend Medical, Inc. No other author has a financial or proprietary interest in any material or method mentioned.

Minimally invasive glaucoma surgery: current status and future prospects

Minimally invasive glaucoma surgery aims to provide a medication-sparing, conjunctival-sparing, ab interno approach to intraocular pressure reduction for patients with mild-to-moderate glaucoma that is safer than traditional incisional glaucoma surgery. The current approaches include: increasing trabecular outflow (Trabectome, iStent, Hydrus stent, gonioscopy-assisted transluminal trabeculotomy, excimer laser trabeculotomy); suprachoroidal shunts (Cypass micro-stent); reducing aqueous production (endocyclophotocoagulation); and subconjunctival filtration (XEN gel stent). The data on each surgical procedure for each of these approaches are reviewed in this article, patient selection pearls learned to date are discussed, and expectations for the future are examined.

[Modern methods of minimally invasive glaucoma surgery]

Over the years, glaucoma surgery has improved from iridectomy by A. Graefe and traumatizing procedures performed without magnification tools or microsurgical instrument to high-technology interventions that are not only microscopic, but also pathogenetically oriented. Various modifications of trabeculectomy, initially introduced by J. Cairns back in 1968, had been the gold standard for several decades and were notable for pronounced and stable hypotensive effects. However, there was also a strong association with such complications as choroidal detachment and hyphema, thus, boosting the development of so called nonfistulizing surgeries. Of the latter, the most widely used are non-penetrating procedures, including deep sclerectomy and viscocanalostomy. Although very safe, they appear unable to produce a truly long-lasting hypotensive effect. Moreover, just as fistulizing trabeculectomy, non-penetrating procedures damage the limbus and adjacent conjunctiva reducing the possibility of a second intervention. This fact together with other drawbacks mentioned above, on the one hand, and technical progress, on the other, were essential prerequisites for the appearance of a new type of surgery - minimally invasive glaucoma surgery (MIGS). Parameters that should be met for a procedure to be considered minimally invasive are debated. The main requirement has, however, been established: ab interno approach through a corneal incision. As surgical tools are enhanced and new techniques arise, options for glaucoma treatment widen greatly, ensuring our future move to higher level standards in the field. This review contains all recent data on minimally invasive techniques currently in use in glaucoma surgery or those under investigation. The authors have also analyzed effectiveness reports and present their conclusions regarding the current state of MIGS worldwide.

Prospective, randomized study of one, two, or three trabecular bypass stents in open-angle glaucoma subjects on topical hypotensive medication

PURPOSE

To assess the safety and efficacy of one, two, or three trabecular microbypass stents in eyes with primary open-angle glaucoma (OAG) not controlled on ocular hypotensive medication. A total of 119 subjects were followed for 18 months postoperatively.

MATERIALS AND METHODS

Subjects with medicated intraocular pressure (IOP) 18-30 mmHg and postmedication-washout baseline IOP 22-38 mmHg were randomized to implantation of one, two, or three stents. Ocular hypotensive medication was to be used if postoperative IOP exceeded 18 mmHg.

RESULTS

A total of 38 subjects were implanted with one stent, 41 subjects with two stents, and 40 subjects with three stents. Both month 12 IOP reduction ≥20% without ocular hypotensive medication vs baseline unmedicated IOP and month 12 unmedicated IOP ≤18 mmHg were achieved by 89.2%, 90.2%, and 92.1% of one-, two-, and three-stent eyes, respectively. Furthermore, 64.9%, 85.4%, and 92.1% of the three respective groups achieved unmedicated IOP ≤15 mmHg. Over the 18-month follow-up period, medication was required in seven one-stent subjects, four two-stent subjects, and three three-stent subjects. At 18 months, mean unmedicated IOP was 15.9±0.9 mmHg in one-stent subjects, 14.1±1.0 mmHg in two-stent subjects, and 12.2±1.1 mmHg in three-stent subjects. Month 18 IOP reduction was significantly greater (P<0.001) with implantation of each additional stent, with mean differences in reduction of 1.84 mmHg (95% confidence interval 0.96-2.73) for three-stent vs two-stent groups and 1.73 mmHg (95% confidence interval 0.83-2.64) for two-stent vs one-stent groups. Adverse events through 18 months were limited to cataract progression with best-corrected visual acuity loss and subsequent cataract surgery.

CONCLUSION

In this series, implantation of each additional stent resulted in significantly greater IOP reduction with reduced medication use. Titratability of stents as a sole procedure was shown to be effective and safe, with sustained effect through 18 months postoperatively in OAG not controlled with medication.

A prospective 3-year follow-up trial of implantation of two trabecular microbypass stents in open-angle glaucoma

Purpose

To evaluate 3-year safety and intraocular pressure (IOP) following two trabecular microbypass stents in phakic and pseudophakic subjects with open-angle glaucoma (OAG) not controlled on preoperative medication.

Patients and methods

In this prospective pilot study, phakic or pseudophakic subjects with OAG and IOP between 18 mmHg and 30 mmHg on one preoperative topical ocular hypotensive medication underwent medication washout. Thirty-nine qualified subjects with preoperative unmedicated IOP ≥22 mmHg and ≤38 mmHg received two stents. Postoperative examinations were scheduled at Day 1, Week 1, Months 1, 3, 6, and 12, and semiannually through Month 60. Ocular hypotensive medication was considered if postoperative IOP exceeded 21 mmHg. IOP, medication use, and safety were assessed at each visit. Subject follow-up through Month 36 was completed.

Results

Thirty-six eyes (92.3%; 95% confidence interval [CI] 79.1%, 98.4%) achieved the primary efficacy end point of Month 12 reduction in IOP ≥20% from baseline (unmedicated IOP) without ocular hypotensive medication. Four subjects required medication during the Month 36 follow-up period. Mean IOP at 36 months for subjects not taking medication was 15.2 mmHg. At 36 months, subjects sustained mean IOP decrease of 9.1±2.7 mmHg (95% CI 8.0 mmHg, 10.14 mmHg), or 37% IOP reduction, from unmedicated baseline IOP. Compared to preoperative medicated IOP, subjects had mean reduction at Month 36 of 5.5±2.7 mmHg (95% CI 4.5 mmHg, 6.6 mmHg), or 26% reduction. Both measures of IOP reduction were highly significant (P<0.001). Other than one case of early postoperative hyphema that resolved at 1 week, no postoperative adverse events were attributed to stent implantation.

Conclusion

In a pilot study, two trabecular microbypass stents to treat OAG subjects on one preoperative medication provided statistically significant, sustained, and safe reduction of IOP to ≤15 mmHg without medication through 36 months.

Emerging surgical therapy in the treatment of glaucoma

There is general consensus that surgery gives a better intraocular pressure (IOP) control than medical therapy, but surgery may be affected by complications and failures, and for this reason nowadays, it is reserved to advanced or clearly progressive glaucoma. In recent years, there have been a lot of efforts to enhance safety and efficacy of conventional surgery as to find new techniques more safer and more effective. Actually, this is a field in rapid evolution, and we have a great number of innovative procedures, often working on complete different basis. These procedures are classified according to their mechanism of action and the type of surgical approach, in order to clearly understand of what we are speaking about. From a general point of view, surgical procedures may be divided in procedures that increase outflow and procedures that reduce aqueous production: most of these procedures can be performed with an ab externo or an ab interno approach. The ab interno approach has great advantages and enormous potential of development; probably, its diffusion will be facilitated by the development of new devices for angle visualization. Nevertheless, it is important to remember that actually none of the new procedures has been validated in large controlled clinical trials and none of the new procedures is indicated when IOP target is very low.

Outcomes of combined phacoemulsification and deep sclerectomy: a 10-year UK single-centre study

PURPOSE

To report the outcomes of combined phacoemulsification and -deep sclerectomy (phaco-DS) from a single UK centre over a 10-year period.

METHODS

Retrospective analysis of phaco-DS data extracted from an ongoing glaucoma surgery database within Calderdale and Huddersfield NHS Trust. Two hundred and ninety-six eyes of 282 patients were included. Data included patient demographics, pre- and postoperative intraocular pressure (IOP), use of mitomycin C (MMC), spacer device implantation, and follow-up details including surgical success rates. IOP success criteria were: (A) IOP <19 mm Hg and/or 20% decrease from baseline and (B) IOP <16 mm Hg and/or 30% drop from baseline.

RESULTS

Mean follow-up was 63.5 ± 35.3 months. MMC was applied in 145 eyes (49%). Kaplan-Meier success rates in all eyes for criteria A were 89.1% and 80% with glaucoma medications (qualified success) and 81.2% and 68.3% without medications (unqualified success) at 2 and 5 years, respectively. Qualified success for criteria B was 72.4 and 61.4% and unqualified rates were 67.2 and 55.2% for the same time periods. Repeated-measures ANOVA showed significantly lower IOP in the phaco-DS with MMC group up to 3 years postoperatively (P = 0.002). Cox's proportional hazards for criteria B, however, showed no significant effect of MMC application in the long term (P = 0.2). Increasing age and laser goniopuncture were positively associated with success, whereas the absence of spacer devices was negatively associated. At last follow-up, 20% of eyes were on glaucoma medications. Complication rates were low with hypotony rates of 0.68%.

CONCLUSIONS

This study confirms the long-term safety and efficacy of phaco-DS as a primary glaucoma procedure.

iStent with Phacoemulsification versus Phacoemulsification Alone for Patients with Glaucoma and Cataract: A Meta-Analysis

Background

Minimally invasive glaucoma surgeries (MIGS) have attracted significant attention, as they have been reported to lower intra-ocular pressure (IOP) and have an excellent safety profile. The iStent is an example of a minimally invasive glaucoma device that has received particular attention due to its early and wide spread utilization. There is a growing body of evidence supporting its use at the time of phacoemulsification to help lower IOP. However, it is still not clear how much of the IOP lowering effect can be attributed to the iStent, the crystalline lens extraction or both when inserted concurrently at the time of phacoemulsification. This has been an important issue in understanding its potential role in the glaucoma management paradigm.

Purpose

To conduct a systematic review and meta-analysis comparing the IOP lowering effect of iStent insertion at the time of phacoemulsification versus phacoemulsification alone for patients with glaucoma and cataracts.

Methods

A systematic review was conducted utilizing various databases. Studies examining the IOP lowering effect of iStent insertion in combination with phacoemulsification, as well as studies examining the IOP lowering effect of phacoemulsification alone were included. Thirty-seven studies, reporting on 2495 patients, met the inclusion criteria. The percentage reduction in IOP (IOPR%) and mean reduction in topical glaucoma medications after surgery were determined. The standardized mean difference (SMD) was computed as a measure of the treatment effect for continuous outcomes taking into account heterogeneity. Fixed-effect and random-effect models were applied.

Results

A 4% IOP reduction (IOPR%) from baseline occurred following phacoemulsification as a solo procedure compared to 9% following an iStent implant with phacoemulsification, and 27% following 2 iStents implants with phacoemulsification. Compared with cataract extraction alone, iStent with phacoemulsification resulted in significant reduction in the post-operative IOP (IOPR%) (SMD = -0.46, 95% CI: [-0.87, -0.06]). A weighted mean reduction in the number of glaucoma medications per patient was 1.01 following phacoemulsification alone compared to 1.33 after one iStent implant with phacoemulsification, and 1.1 after 2 iStent implants with phacoemulsification. Compared to cataract extraction alone, iStent with cataract extraction showed a significant decrease in the number of glaucoma medications (SMD = -0.65, 95% CI: [-1.18, -0.12]). Funnel plots suggested the absence of publication bias.

Conclusion

Both iStent implantation with concurrent phacoemulsification and phacoemulsification alone result in a significant decrease in IOP and topical glaucoma medications. In terms of both reductions, iStent with phacoemulsification significantly outperforms phacoemulsification alone.

Use of Various Glaucoma Surgeries and Procedures in Medicare Beneficiaries from 1994 to 2012

PURPOSE

Determine how procedural treatments for glaucoma have changed between 1994-2012.

DESIGN

Retrospective, observational analysis.

PARTICIPANTS

Medicare Part B beneficiaries.

METHODS

We analyzed Medicare fee-for-service paid claims data between 1994-2012 to determine the number of surgical/laser procedures performed for glaucoma in the Medicare population each year.

MAIN OUTCOME MEASURES

Number of glaucoma-related procedures performed.

RESULTS

Trabeculectomies in eyes without previous scarring decreased 52% from 54 224 in 1994 to 25 758 in 2003, and a further 52% to 12 279 in 2012. Trabeculectomies in eyes with scarring ranged from 9054 to 13 604 between 1994-2003, but then decreased 48% from 11 018 to 5728 between 2003-2012. Mini-shunts done via an external approach (including ExPRESS [Alcon Inc, Fort Worth, TX]) increased 116% from 2718 in 2009 to 5870 in 2012. The number of aqueous shunts to the extraocular reservoir increased 231% from 2356 in 1994 to 7788 in 2003, and a further 54% to 12 021 in 2012. Total cyclophotocoagulation procedures increased 253% from 2582 in 1994 to 9106 in 2003, and a further 54% to 13 996 in 2012. Transscleral cyclophotocoagulations decreased 45% from 5978 to 3268 between 2005-2012; over the same period, the number of endoscopic cyclophotocoagulations (ECPs) increased 99% from 5383 to 10 728. From 2001 to 2005, the number of trabeculoplasties more than doubled from 75 647 in 2001 to 176 476 in 2005, but since 2005 the number of trabeculoplasties decreased 19% to 142 682 in 2012. The number of laser iridotomies was fairly consistent between 1994-2012, increasing 9% over this period and ranging from 63 773 to 85 426. Canaloplasties increased 1407% from 161 in 2007 to 2426 in 2012. Between 1994-2012, despite a 9% increase in beneficiaries, the total number of glaucoma procedures and the number of glaucoma procedures other than laser procedures decreased 16% and 31%, respectively.

CONCLUSIONS

Despite the increase in beneficiaries, the number of glaucoma procedures performed decreased. Glaucoma procedures demonstrating a significant increase in use include canaloplasty, mini-shunts (external approach), aqueous shunt to extraocular reservoir, and ECP. Trabeculectomy use continued its long-term downward trend. The continued movement away from trabeculectomy and toward alternative intraocular pressure-lowering procedures highlights the need for well-designed clinical trials comparing these procedures.

iStent inject in phakic open angle glaucoma

BACKGROUND

The effectiveness and complication profile of the iStent inject implantation among different open angle glaucoma subgroups were analyzed.

METHODS

In this retrospective cohort outcome study, 35 consecutive patients suffering from glaucoma (primary open angle glaucoma (POAG) N = 17, pseudoexfoliation glaucoma (PEX) N = 15, and pigmentary glaucoma (PG) N = 3) were treated with the iStent inject. The intraocular pressure (IOP) and the number of antiglaucoma medications before and after surgery were evaluated.

RESULTS

In POAG, the mean IOP at 6 months measured 14.19 ± 1.38 mmHg with an average decrease of 33 % from preoperative IOP (p < 0.001), and 15.33 ± 1.07 mmHg with an average decrease of 35 % in PEX (p < 0.001), respectively. The number of antiglaucoma medications significantly decreased from 2.19 ± 0.91 to 0.88 ± 0.62 in POAG (p < 0.001) and from 2.33 ± 1.23 to 1.04 ± 0.30 in PEX (p < 0.001) after 6 months. In PG, IOP before surgery was 28.31 ± 3.21 mmHg and the number of antiglaucoma medications was 3.66 ± 0.57. One day after surgery, IOP decreased significantly to 12.33 mmHg ± 4.93 (p < 0.001). Within four weeks after surgery, IOP was raised above 30 mmHg in every patient. To exclude a steroid response, topical steroids were stopped, but IOP did not decrease. To exclude blockage, Nd:YAG - laser treatment of the visible opening of the iStents was performed. Since the IOP stayed high and escalation of antiglaucoma medication was insufficient to control IOP, trabeculectomy was performed.

CONCLUSIONS

In conclusion, implantation of the iStent inject has the ability to lower the postoperative IOP significantly in POAG and PEX after a short follow-up of 6 months with a favorable risk profile. However, limitation of this surgical procedure in phakic PG may exist and need to be investigated in further studies.

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.

Trabecular micro-bypass shunt (iStent®): basic science, clinical, and future)

The trabecular bypass stent offers an alternative to filtration surgery. Patients who may be ideal candidates for considering this procedure are those with prior conjunctival surgery; for example, those who had a 360° peritomy from a scleral buckle might not do well with a trabeculectomy and there is no space for a tube. Highly myopic patients do not tolerate hypotony well, and the iSTB may be an option for some of these patients. I have used the iSTB in patients on anticoagulants who could not stop them, and they needed something beyond medications and laser to lower the IOP in subjects with open-angle glaucoma. Young patients, especially those with one eye, who need rapid visual recovery (for instance to return to work) may be good candidates to consider the iSTB as well. Because of the position used for clear corneal cataract surgery, the temporal approach is best for doing these. Therefore, if you are doing cataract surgery on someone who needs a lower IOP, you already are in the correct position to implant the devices. Patients may need some medications after the procedure to lower the IOP to the level desired. The results from Armenia are encouraging, given an IOP of 11.8 mmHg after 2 iSTB stents and taking daily travoprost. These results are difficult to reach even with a trabeculectomy. When selecting your fist patients, avoid those with the congested episcleral veins, look for patients with wide open angles, and if you can see aqueous veins at the slit-lamp it may indicate a viable outflow system. Probably avoid patients with IOPs over 35 mmHg. The micro-invasive trabecular bypass stents offer an alternative surgical intervention for select patients with open-angle glaucoma. Recent studies show that combining these micro-stents with medications can lead to as low of an intraocular pressure (IOP) as is achieved by many more invasive incisional surgeries. The technique is quite precise and learning the procedure is similar to clear corneal phacoemulsification followed by a goniotomy. Long-term data are starting to come in and the safety is favorable. The IOP success appears to be based on the patency of the outflow system for a given patient. Key factors in determining the success involve the placement of trabecular bypass devices into the canal of Schlemm and require a down-stream patency of the collector channel system and a low episcleral venous pressure. Because accessing the collector system may require placement by a patent channel, the placement of two stents, a longer stent with scaffolding or somehow imaging the outflow system may lead to the best control of the IOP.

Cataract surgery in the glaucoma patient

To summarize the role of cataract surgery in the glaucoma patient, in terms of the effect on intraocular pressure (IOP) as well as diagnostic and therapeutic considerations for those with both conditions. Recent evidence suggests that cataract extraction may produce a significant and sustained IOP reduction in individuals with open-angle glaucoma, ocular hypertension, and angle-closure glaucoma. Cataract removal may improve the practitioner's ability to interpret perimetric testing, and re-establishing perimetric and optic nerve imaging baselines is recommended after cataract surgery. The sequence of cataract surgery relative to glaucoma surgery impacts the likelihood of complications and surgical success. There are multiple benefits to perform cataract surgery prior to glaucoma surgery while cataract surgery after trabeculectomy increases the risk of subsequent filtration failure. As “minimally invasive glaucoma surgeries” continue to improve in terms of efficacy, there is an evolving role for combined cataract and glaucoma surgery in patients with early to moderate stages of glaucoma.

Ab interno stenting procedures

Trabecular bypass was first used as a surgical treatment for glaucoma more than 100 years ago and aims to circumvent the trabecular meshwork, thought to be the main site of aqueous humor outflow resistance. The emerging field of microinvasive glaucoma surgery has brought a new ab interno trabecular microbypass stent through the U.S. Food and Drug Administration-approval process, and data from long-term randomized prospective trials have shown the safety and intraocular pressure-lowering value of trabecular microbypass. This review discusses the historical evolution of trabecular microbypass and describes new and forthcoming surgical options along with available clinical safety and efficacy data.

FINANCIAL DISCLOSURE

Proprietary or commercial disclosures are listed after the references.

Prospective evaluation of microinvasive glaucoma surgery with trabecular microbypass stents and prostaglandin in open-angle glaucoma

PURPOSE

To evaluate the intraocular pressure (IOP) lowering effect of 2 trabecular microbypass stents and postoperative travoprost in patients with open-angle glaucoma (OAG) not controlled on 2 medications preoperatively.

SETTING

S.V. Malayan Ophthalmology Centre, Yerevan, Armenia.

DESIGN

Prospective open-label nonrandomized study.

METHODS

This prospective pilot study involved 39 qualified phakic patients with OAG, medicated IOP between 18 mm Hg and 30 mm Hg, and unmedicated baseline (after washout) IOP between 22 mm Hg and 38 mm Hg. Patients received 2 stents (iStent) through a clear corneal incision and were prescribed travoprost starting the night of postoperative day 1. Intraocular pressure, complications, and various safety measures were assessed at examinations through 18 months and planned for every 6 months thereafter until month 60. A washout of medications was performed 13 months postoperatively.

RESULTS

All patients achieved an IOP reduction of 20% or more from baseline to 12 months with reduction of 1 medication and with IOP 18 mm Hg or less. Follow-up through 18 months showed that medicated IOP decreased from 22.2 mm Hg ± 2.0 (SD) on 2 medications preoperatively to 14 mm Hg or less on 1 medication at the postoperative visits. The mean unmedicated IOP decreased from 25.3 ± 1.8 mm Hg preoperatively to 17.1 ± 2.2 mm Hg 13 months postoperatively. No intraoperative or serious device-related adverse events occurred.

CONCLUSIONS

Patients with OAG treated with 2 trabecular microbypass stents and 1 presumptive postoperative medication achieved a significant and sustained reduction in IOP and medication through 18 months.

FINANCIAL DISCLOSURE

Dr. Katz served as the medical monitor for this study. All authors are consultants to Glaukos Corp.

Implantation of 2 trabecular microbypass stents in a patient with primary open-angle glaucoma refractory to previous glaucoma-filtering surgeries

A 77-year-old woman with primary open-angle glaucoma was referred for surgical evaluation after failing to achieve target intraocular pressure (IOP) despite previous combined phacotrabeculectomy and Ahmed valve implantations. The IOP prior to surgery was 28 mm Hg on topical dorzolamide-timolol, latanoprost, and brimonidine. Trabecular bypass surgery with implantation of 2 iStents was performed. The IOP decreased by 11 mm Hg to 17 mm Hg after surgery and has remained stable for 2 years. This is the first published case reporting this magnitude of IOP reduction sustained for more than 2 years following insertion of 2 trabecular microbypass stents in a patient who had previous glaucoma-filtering surgeries. Further prospective studies are needed to establish expanded surgical indications for implantation of trabecular microbypass stents.

FINANCIAL DISCLOSURE

No author has a financial or proprietary interest in any material or method mentioned.

Achieving Target Pressures with Combined Surgery: Primary Patchless Ahmed Valve Combined with Phacoemulsification vs Primary Phacotrabeculectomy

PURPOSE

To evaluate the ability of phacoemulsification combined with either primary trabeculectomy (PT) or primary Ahmed glaucoma valve implantation (PAVI) to achieve target intraocular pressures (TIOP) in adults with primary open angle glaucoma.

MATERIALS AND METHODS

Chart review of 214 adult patients operated between January 2002 and June 2008 with a minimum follow-up of 6 months. Group 1 comprised 181 eyes of 166 patients undergoing PT while group 2 included 50 eyes of 49 patients in combination with primary AVI. Target lOPs were pre-determined for each patient and success was defined as an IOP at or lower than target with or without medications. An IOP above target, loss of light perception or need for additional procedures to lower IOP were considered a failure.

RESULTS

Mean preoperative IOP was 17.2 mm Hg in group 1 and 17.3 in group 2. Mean postoperative IOPs were 10.2 and 9.2 on day 1, 12.2 and 11.6 at year 1, and 10.7 in both groups at year 5. Survival rates in groups 1 and 2 were 96.7 vs 96% at 6 months, 89 vs 96% at 12 months, 83.5 vs 96% at 24 months and 79.4 vs 89.1% at 36, 48 and 72 months. Transient bleb leaks were more frequent in group 1 (26 eyes, 14.4 vs 0%, p = 0.001) and transient choroidal detachments were more frequent in group 2 (7 eyes, 3.9 vs 6 eyes, 12%, p = 0.038).

CONCLUSION

Midterm results for achieving target pressures using combined phacoemulsification with either PT or PAVI are comparable. The profile of complications is different for the two procedures. How to cite this article: Albis-Donado O, Sánchez-Noguera CC, Cárdenas-Gómez L, Castañeda-Diez R, Thomas R, Gil-Carrasco F. Achieving Target Pressures with Combined Surgery: Primary Patchless Ahmed Valve Combined with Phacoemulsification vs Primary Phacotrabeculectomy. J Curr Glaucoma Pract 2015;9(1):6-11.

[Possibilities for use of Scheimpflug technology in cataract surgery]

BACKGROUND

Since its first use in geography 100 years ago Scheimpflug photography has undergone much refinement making it a standard technique in anterior segment diagnostics and even surgical therapy. This review presents the perioperative applications of Scheimpflug photography in cataract and refractive lens surgery.

OBJECTIVES

Possible perioperative applications of Scheimpflug photography in cataract surgery and refractive lens surgery.

METHODS

Selective review of the literature and personal experiences.

RESULTS

In recent years there have been numerous new applications for Scheimpflug photography, with its main use in preoperative diagnostics and surgical planning. There are also useful applications for intraoperative visualization and postoperative counseling.

CONCLUSION

Multifunctional devices which enable a variety of further examinations besides Scheimpflug technology alone make the use of this technology possible and reasonable even in hospitals and practices without a focus on refractive surgery.

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.

Prospective unmasked randomized evaluation of the iStent inject (®) versus two ocular hypotensive agents in patients with primary open-angle glaucoma

PURPOSE

The purpose of this study was to compare outcomes of subjects with open-angle glaucoma (OAG) not controlled on one medication who underwent either implantation of two iStent inject (®) trabecular micro-bypass devices or received medical therapy consisting of a fixed combination of latanoprost/timolol.

PATIENTS AND METHODS

Of 192 subjects who qualified for the study and were enrolled, 94 were randomized to surgery with implantation of two iStent inject(®) devices in the treated eye and 98 to receive medical therapy.

RESULTS

At the month 12 visit, 94.7% of eyes (89/94) in the stent group reported an unmedicated intraocular pressure (IOP) reduction of ≥20% versus baseline unmedicated IOP, and 91.8% of eyes (88/98) in the medical therapy group reported an IOP reduction ≥20% versus baseline unmedicated IOP. A 17.5% between-group treatment difference in favor of the iStent inject group was statistically significant (P=0.02) at the ≥50% level of IOP reduction. An IOP ≤18 mmHg was reported in 92.6% of eyes (87/94) in the iStent inject group and 89.8% of eyes (88/98) in the medical therapy group. Mean (standard deviation) IOP decreases from screening of 8.1 (2.6) mmHg and 7.3 (2.2) mmHg were reported in the iStent inject and medical therapy groups, respectively. A high safety profile was also noted in this study in both the iStent inject and medical therapy groups, as measured by stable best corrected visual acuity, cup-to-disc ratio, and adverse events.

CONCLUSION

These data show that the use of iStent inject is at least as effective as two medications, with the clinical benefit of reducing medication burden and assuring continuous treatment with full compliance to implant therapy as well as having a highly favorable safety profile.

New options for combined cataract and glaucoma surgery

PURPOSE OF REVIEW

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.

RECENT FINDINGS

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.

SUMMARY

The newer glaucoma procedures appear less effective than trabeculectomy, but they are associated with a lower risk of surgical complications.

Improvement in outflow facility by two novel microinvasive glaucoma surgery implants

PURPOSE

To determine improvement in outflow facility (C) in human anterior segments implanted with a novel Schlemm's canal scaffold or two trabecular micro-bypasses.

METHODS

Human anterior segments were isolated from 12 pairs of eyes from donors with no history of ocular disease and then perfused at 50, 40, 30, 20, and 10 mm Hg pressures for 10 minutes each. Baseline C was calculated from perfusion pressures and flow rates. The scaffold was implanted into Schlemm's canal of one anterior segment, and two micro-bypasses were implanted three clock-hours apart in the contralateral anterior segment. Outflow facility and resistance were compared at various standardized perfusion pressures and between each device.

RESULTS

Compared to baseline, C increased by 0.16 ± 0.12 μL/min/mm Hg (74%) with the scaffold, and 0.08 ± 0.12 μL/min/mm Hg (34%) with two micro-bypasses. The scaffold increased C at perfusion pressures of 50, 40, 30, and 20 mm Hg (P < 0.005). Two micro-bypasses increased C at a perfusion pressure of 40 mm Hg (P < 0.05).

CONCLUSIONS

Both implants effectively increased C in human eyes ex vivo. The scaffold increased C by a greater percentage (73% vs. 34%) and at a greater range of perfusion pressures (20 to 50 mm Hg vs. 40 mm Hg) than the two micro-bypasses, suggesting that the 8-mm dilation of Schlemm's canal by the scaffold may have additional benefits in lowering the outflow resistance. The Hydrus Microstent scaffold may be an effective therapy for increasing outflow facility and thus reducing the IOP in patients with glaucoma.

Characterization of micro-invasive trabecular bypass stents by ex vivo perfusion and computational flow modeling

Micro-invasive glaucoma surgery with the Glaukos iStent® or iStent inject® (Glaukos Corporation, Laguna Hills, CA, USA) is intended to create a bypass through the trabecular meshwork to Schlemm’s canal to improve aqueous outflow through the natural physiologic pathway. While the iStent devices have been evaluated in ex vivo anterior segment models, they have not previously been evaluated in whole eye perfusion models nor characterized by computational fluid dynamics. Intraocular pressure (IOP) reduction with the iStent was evaluated in an ex vivo whole human eye perfusion model. Numerical modeling, including computational fluid dynamics, was used to evaluate the flow through the stents over physiologically relevant boundary conditions. In the ex vivo model, a single iStent reduced IOP by 6.0 mmHg from baseline, and addition of a second iStent further lowered IOP by 2.9 mmHg, for a total IOP reduction of 8.9 mmHg. Computational modeling showed that simulated flow through the iStent or iStent inject is smooth and laminar at physiological flow rates. Each stent was computed to have a negligible flow resistance consistent with an expected significant decrease in IOP. The present perfusion results agree with prior clinical and laboratory studies to show that both iStent and iStent inject therapies are potentially titratable, providing clinicians with the opportunity to achieve lower target IOPs by implanting additional stents.

Prospective, unmasked evaluation of the iStent® inject system for open-angle glaucoma: synergy trial

Introduction

Micro-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.

Methods

In 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.

Results

Sixty-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.

Conclusion

In 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 material

The online version of this article (doi:10.1007/s12325-014-0095-y) contains supplementary material, which is available to authorized users.

Techniques and outcomes of minimally invasive trabecular ablation and bypass surgery

Minimally invasive glaucoma surgeries (MIGS) can improve the conventional, pressure-dependent outflow by bypassing or ablating the trabecular meshwork (TM), or creating alternative drainage routes into the suprachoroidal or subconjunctival space. They have a highly favourable risk profile compared to penetrating surgeries, and lower intraocular pressure with variable efficacy that may depend on the extent of outflow segments accessed. Since they are highly standardised procedures that use clear corneal incisions, they can elegantly be combined with cataract and refractive procedures to improve vision in the same session. There is a growing need for surgeons to become proficient in MIGS to address the increasing prevalence of glaucoma and cataracts in a well-informed, aging population. Techniques of visualisation and instrumentation in an anatomically highly confined space with semitransparent tissues are fundamentally different from other anterior segment surgeries, and present even experienced surgeons with a substantial learning curve. Here, we provide practical tips, and review techniques and outcomes of TM bypass and ablation MIGS.

Update on Minimally Invasive Glaucoma Surgery (MIGS) and New Implants

Traditional glaucoma surgery has been challenged by the advent of innovative techniques and new implants in the past few years. There is an increasing demand for safer glaucoma surgery offering patients a timely surgical solution in reducing intraocular pressure (IOP) and improving their quality of life. The new procedures and devices aim to lower IOP with a higher safety profile than fistulating surgery (trabeculectomy/drainage tubes) and are collectively termed “minimally invasive glaucoma surgery (MIGS).” The main advantage of MIGS is that they are nonpenetrating and/or bleb-independent procedures, thus avoiding the major complications of fistulating surgery related to blebs and hypotony. In this review, the clinical results of the latest techniques and devices are presented by their approach, ab interno (trabeculotomy, excimer laser trabeculotomy, trabecular microbypass, suprachoroidal shunt, and intracanalicular scaffold) and ab externo (canaloplasty, Stegmann Canal Expander, suprachoroidal Gold microshunt). The drawback of MIGS is that some of these procedures produce a limited IOP reduction compared to trabeculectomy. Currently, MIGS is performed in glaucoma patients with early to moderate disease and preferably in combination with cataract surgery.