Coverage Policy Manual
Policy #: 2010017
Category: Medicine
Initiated: April 2010
Last Review: July 2018
  Aqueous Shunts and Devices for Glaucoma

Description:
Glaucoma surgery is intended to reduce intraocular pressure (IOP) when the target IOP cannot be reached with medications. Due to complications with established surgical approaches such as trabeculectomy, a variety of devices, including aqueous shunts, are being evaluated as alternative surgical treatments for patients with glaucoma.
 
Background
Surgical procedures for glaucoma aim to reduce intraocular pressure (IOP) resulting from impaired aqueous humor drainage in the trabecular meshwork and/or Schlemm’s canal. In the primary (conventional) outflow pathway from the eye, aqueous humor passes through the trabecular meshwork, enters a space lined with endothelial cells (Schlemm’s canal), drains into collector channels, and then into the aqueous veins. Increases in resistance in the trabecular meshwork and/or the inner wall of Schlemm’s canal can disrupt the balance of aqueous humor inflow and outflow, resulting in an increase in IOP and glaucoma risk.
 
Surgical intervention may be indicated in patients with glaucoma when the target IOP cannot be reached pharmacologically. Trabeculectomy (guarded filtration surgery) is the most established surgical procedure for glaucoma, allowing aqueous humor to directly enter the subconjunctival space. This procedure creates a subconjunctival reservoir, which can effectively reduce IOP, but commonly results in filtering “blebs” on the eye, and is associated with numerous complications (e.g., leaks or bleb-related endophthalmitis) and long-term failure. Other surgical procedures (not addressed in this policy) include trabecular laser ablation, deep sclerectomy, which removes the outer wall of Schlemm’s canal and excises deep sclera and peripheral cornea, and viscocanalostomy, which unroofs and dilates Schlemm’s canal without penetrating the trabecular meshwork or anterior chamber.
 
More recently the Trabectome™, an electrocautery device with irrigation and aspiration, has been used to selectively ablate the trabecular meshwork and inner wall of Schlemm’s canal without external access or creation of a subconjunctival bleb. IOP with this ab interno procedure is typically higher than the pressure achieved with standard filtering trabeculectomy. Canaloplasty involves dilation and tension of Schlemm’s canal with a suture loop between the inner wall of the canal and the trabecular meshwork. This ab externo procedure uses the iTrack™ illuminated microcatheter (iScience Interventional) to access and dilate the entire length of Schlemm’s canal and to pass the suture loop through the canal.
 
Aqueous shunts may also be placed between the anterior chamber (or vitreous chamber) and Schlemm’s canal to facilitate drainage of aqueous humor. Established shunts include the Ahmed (New World Medical), Baerveldt (Advanced Medical Optics), Krupin (Eagle Vision) and Molteno (Molteno Ophthalmic). These devices differ depending on explant surface areas, shape, plate thickness, the presence or absence of a valve, and details of surgical installation. Generally, the risk of hypotony (low pressure) is reduced with aqueous shunts in comparison with trabeculectomy, but IOP outcomes are higher than after standard guarded filtration surgery. Complications of anterior chamber shunts include corneal endothelial failure and erosion of the overlying conjunctiva. The risk of postoperative infection is less than after trabeculectomy, and failure rates are similar, with about 10% of devices failing each year. The primary indication for aqueous shunts is when prior medical or surgical therapy has failed, although some ophthalmologists have advocated their use as a primary surgical intervention, particularly for selected conditions such as congenital glaucoma, trauma, chemical burn, or pemphigoid.
 
The first generation Ahmed (New World Medical), Baerveldt (Advanced Medical Optics), Krupin (Eagle Vision), and Molteno (Molteno Ophthalmic) aqueous shunts received marketing clearance from the FDA between 1989 and 1993; modified Ahmed and Molteno devices were most recently cleared in 2006. Their indication for use is “in patients with intractable glaucoma to reduce intraocular pressure where medical and conventional surgical treatments have failed.” The AquaFlow™ Collagen Glaucoma Drainage Device received premarket approval from the FDA in 2001 for the maintenance of sub-scleral space following non-penetrating deep sclerectomy. The Ex-PRESS™ Mini Glaucoma Shunt received 510(k) marketing clearance in 2003. The Ex-PRESS shunt is placed under a partial thickness scleral flap and transports aqueous fluid from the anterior chamber of the eye into a conjunctival filtering bleb.
 
In 2012, the FDA approved the Glaukos Corporation’s iStent® Trabecular Micro-Bypass Stent, PMA P080030, as indicated for use in conjunction with cataract surgery for the reduction of IOP in adult patients with mild to moderate open-angle glaucoma currently treated with ocular hypotensive medication.
The labeling describes the following precautions:
 
    1. The safety and effectiveness of the iStent Trabecular Micro-Bypass Stent has not been established as an alternative to the primary treatment of glaucoma with medications. The effectiveness of this device has been demonstrated only in patients with mild to moderate open-angle glaucoma who are currently treated with ocular hypotensive medication and who are undergoing concurrent cataract surgery for visually significant cataract.
    2. The safety and effectiveness of the iStent® Trabecular Micro-Bypass Stent has not been established in patients with the following circumstances or conditions, which were not studied in the pivotal trial:
 
      • In children
      • In eyes with significant prior trauma
      • In eyes with abnormal anterior segment
      • In eyes with chronic inflammation
      • In glaucoma associated with vascular disorders
      • In pseudophakic patients with glaucoma
      • In uveitic glaucoma
      • In patients with prior glaucoma surgery of any type including argon laser trabeculoplasty
      • In patients with medicated intraocular pressure greater than 24 mm Hg
      • In patients with unmedicated IOP less than 22 mm Hg nor greater than 36 mm Hg after  "washout" of medications
      • For implantation of more than a single stent
      • After complications during cataract surgery, including but not limited to, severe corneal burn, vitreous removal/vitrectomy required, corneal injuries, or complications requiring the placement of an anterior chamber IOL [intraocular lens]
      • When implantation has been without concomitant cataract surgery with IOL implantation for visually significant cataract
 
The CyPass® Micro-Stent was approved by the FDA on July 29, 2016 for use in conjunction with cataract surgery for the reduction of intraocular pressure in adult patients with mild to moderate primary open-angle glaucoma.
  
The Solx gold shunt is currently in U.S. Food and Drug Administration (FDA)-regulated trials.  The Solx gold shunt has received regulatory approval in Europe but is not FDA-approved/cleared for use in the U.S. at this time.
 
 
Coding
 
Effective July 2017, CPT released a specific CPT code for the CyPass Stent:
 
0474T  Insertion of anterior segment aqueous drainage device, with creation of intraocular reservoir, internal approach, into the supraciliary space.
 
Effective in 2015, CPT released the following codes:
 
0376T  Insertion of anterior segment aqueous drainage device, without extraocular reservoir, internal approach, into the trabecular meshwork; each additional device insertion (List separately in addition to code for primary procedure)
 
The insertion of a drug-eluting implant would be reported using:
0356T  Insertion of drug-eluting implant (including punctal dilation and implant removal when performed) into lacrimal canaliculus, each
 
The CPT codes for these procedures were changed in 2011. The current codes are as follows:
 
0191T – Insertion of anterior segment aqueous drainage device, without extraocular reservoir; internal approach
0192T – Insertion of anterior segment aqueous drainage device, without extraocular reservoir; external approach
0253T - Insertion of anterior segment aqueous drainage device, without extraocular reservoir; internal approach, into the suprachoroidal space
 
Insertion of aqueous shunts might have previously been coded using one of the following codes:
 
66180: Aqueous shunt to extraocular reservoir
66170: Fistulization of sclera for glaucoma; trabeculectomy ab externo in absence of previous surgery
66172: Fistulization of sclera for glaucoma; trabeculectomy ab externo with scarring from previous ocular surgery or trauma (includes injection of antifibrotic agents)
66999: Unlisted procedure, anterior segment of eye.
 

Policy/
Coverage:
Effective August 2018
 
Meets Primary Coverage Criteria Or Is Covered For Contracts Without Primary Coverage Criteria
 
Insertion of aqueous shunts approved by the U.S. Food and Drug Administration (FDA) as a method to reduce intraocular pressure in patients with glaucoma where medical therapy has failed to adequately control intraocular pressure meets primary coverage criteria that there be scientific evidence of effectiveness in improving health outcomes.
 
Implantation of up to three FDA-approved micro-stents (e.g., iStent®) in conjunction with cataract surgery in patients who are intolerant of medications meets member benefit certificate primary coverage criteria that there be scientific evidence of effectiveness in improving health outcomes.
 
Implantation of a single FDA-approved CyPass micro-stent (one stent per eye) in conjunction with cataract surgery in patients who are intolerant of medications meets member benefit certificate primary coverage criteria that there be scientific evidence of effectiveness in improving health outcomes.
 
Implantation of a single FDA-approved Xen Gel Stent (one stent per eye) in conjunction with cataract surgery or without cataract surgery in patients who have failed surgical treatment OR have reached maximum response to OR are intolerant of medications for treatment of refractory glaucoma meets member benefit certificate primary coverage criteria that there be scientific evidence of effectiveness in improving health outcomes.
 
Does Not Meet Primary Coverage Criteria Or Is Investigational For Contracts Without Primary Coverage Criteria
 
Use of an aqueous shunt for all other conditions, including patients with glaucoma when intraocular pressure is adequately controlled by medications does not meet member benefit certificate primary coverage criteria that there be scientific evidence of effectiveness in improving health outcomes.
 
For members with contracts without primary coverage criteria, the use of an aqueous shunt for all other conditions, including patients with glaucoma when intraocular pressure is adequately controlled by medications, is considered investigational. Investigational services are exclusions in most member benefit certificates of coverage.
 
The use of a micro-stent for all other conditions does not meet member benefit certificate primary coverage criteria that there be scientific evidence of effectiveness in improving health outcomes.
 
For members with contracts without primary coverage criteria, the use of a micro-stent for all other conditions is considered investigational. Investigational services are exclusions in most member benefit certificates of coverage.
 
Implantation of a single FDA-approved Xen Gel Stent for all other conditions does not meet member benefit certificate primary coverage criteria that there be scientific evidence of effectiveness in improving health outcomes.
 
For members with contracts without primary coverage criteria, the implantation of a single FDA-approved Xen Gel Stent for all other conditions is considered investigational. Investigational services are exclusions in most member benefit certificates of coverage.
 
The use of a drug-eluting implant for the treatment of glaucoma does not meet member benefit certificate primary coverage criteria that there be scientific evidence of effectiveness.
 
For members with contracts without primary coverage criteria, the use of a drug-eluting implant for the treatment of glaucoma, is considered investigational. Investigational services are exclusions in most member benefit certificates of coverage.
 
Effective Prior to August 2018
 
Meets Primary Coverage Criteria Or Is Covered For Contracts Without Primary Coverage Criteria
 
Insertion of aqueous shunts approved by the U.S. Food and Drug Administration (FDA) as a method to reduce intraocular pressure in patients with glaucoma where medical therapy has failed to adequately control intraocular pressure meets primary coverage criteria that there be scientific evidence of effectiveness in improving health outcomes.
 
Implantation of up to three FDA-approved micro-stents (e.g., iStent®) in conjunction with cataract surgery in patients who are intolerant of medications meets member benefit certificate primary coverage criteria that there be scientific evidence of effectiveness in improving health outcomes.
 
Implantation of a single FDA-approved CyPass micro-stent (one stent per eye) in conjunction with cataract surgery in patients who are intolerant of medications meets member benefit certificate primary coverage criteria that there be scientific evidence of effectiveness in improving health outcomes.
 
Does Not Meet Primary Coverage Criteria Or Is Investigational For Contracts Without Primary Coverage Criteria
 
Use of an aqueous shunt for all other conditions, including patients with glaucoma when intraocular pressure is adequately controlled by medications does not meet member benefit certificate primary coverage criteria that there be scientific evidence of effectiveness in improving health outcomes.
 
For members with contracts without primary coverage criteria, the use of an aqueous shunt for all other conditions, including patients with glaucoma when intraocular pressure is adequately controlled by medications, is considered investigational. Investigational services are exclusions in most member benefit certificates of coverage.
 
The use of a micro-stent for all other conditions does not meet member benefit certificate primary coverage criteria that there be scientific evidence of effectiveness in improving health outcomes.
 
For members with contracts without primary coverage criteria, the use of a micro-stent for all other conditions is considered investigational. Investigational services are exclusions in most member benefit certificates of coverage.
 
The use of a drug-eluting implant for the treatment of glaucoma does not meet member benefit certificate primary coverage criteria that there be scientific evidence of effectiveness.
 
For members with contracts without primary coverage criteria, the use of a drug-eluting implant for the treatment of glaucoma, is considered investigational. Investigational services are exclusions in most member benefit certificates of coverage.
 
Effective March 2015 – October 2016
 
Meets Primary Coverage Criteria Or Is Covered For Contracts Without Primary Coverage Criteria
 
Insertion of aqueous shunts approved by the U.S. Food and Drug Administration (FDA) as a method to reduce intraocular pressure in patients with glaucoma where medical therapy has failed to adequately control intraocular pressure meets primary coverage criteria that there be scientific evidence of effectiveness in improving health outcomes.
 
Implantation of up to three FDA-approved micro-stents (e.g., iStent®) in conjunction with cataract surgery in patients who are intolerant of medications meets member benefit certificate primary coverage criteria that there be scientific evidence of effectiveness in improving health outcomes.
 
Does Not Meet Primary Coverage Criteria Or Is Investigational For Contracts Without Primary Coverage Criteria
 
Use of an aqueous shunt for all other conditions, including patients with glaucoma when intraocular pressure is adequately controlled by medications does not meet member benefit certificate primary coverage criteria that there be scientific evidence of effectiveness in improving health outcomes.
 
For members with contracts without primary coverage criteria, the use of an aqueous shunt for all other conditions, including patients with glaucoma when intraocular pressure is adequately controlled by medications, is considered investigational. Investigational services are exclusions in most member benefit certificates of coverage.
 
The use of a micro-stent for all other conditions does not meet member benefit certificate primary coverage criteria that there be scientific evidence of effectiveness in improving health outcomes.
 
For members with contracts without primary coverage criteria, the use of a micro-stent for all other conditions is considered investigational. Investigational services are exclusions in most member benefit certificates of coverage.
 
The use of a drug-eluting implant for the treatment of glaucoma does not meet member benefit certificate primary coverage criteria that there be scientific evidence of effectiveness. For members with contracts without primary coverage criteria, the use of a drug-eluting implant for the treatment of glaucoma, is considered investigational. Investigational services are exclusions in most member benefit certificates of coverage.
 
Effective September 2013 – February 2015
  
Meets Primary Coverage Criteria Or Is Covered For Contracts Without Primary Coverage Criteria
 
Insertion of aqueous shunts approved by the U.S. Food and Drug Administration (FDA)  as a method to reduce intraocular pressure in patients with glaucoma where medical therapy has failed to adequately control intraocular pressure meets primary coverage criteria that there be scientific evidence of effectiveness in improving health outcomes.
 
Implantation of up to three FDA-approved micro-stents (e.g., iStent®) in conjunction with cataract surgery in patients who are intolerant of medications meets member benefit certificate primary coverage criteria that there be scientific evidence of effectiveness in improving health outcomes.
 
Does Not Meet Primary Coverage Criteria Or Is Investigational For Contracts Without Primary Coverage Criteria
 
Use of an aqueous shunt for all other conditions, including patients with glaucoma when intraocular pressure is adequately controlled by medications does not meet member benefit certificate primary coverage criteria that there be scientific evidence of effectiveness in improving health outcomes.
 
For members with contracts without primary coverage criteria, the use of an aqueous shunt for all other conditions, including patients with glaucoma when intraocular pressure is adequately controlled by medications, is considered investigational.  Investigational services are exclusions in most member benefit certificates of coverage.
 
The use of a micro-stent for all other conditions does not meet member benefit certificate primary coverage criteria that there be scientific evidence of effectiveness in improving health outcomes.
 
For members with contracts without primary coverage criteria, the use of a micro-stent for all other conditions is considered investigational.  Investigational services are exclusions in most member benefit certificates of coverage.
 
Effective September 2011 – August 2013
Insertion of aqueous shunts approved by the U.S. Food and Drug Administration (FDA)  as a method to reduce intraocular pressure in patients with glaucoma where medical therapy has failed to adequately control intraocular pressure meets primary coverage criteria that there be scientific evidence of effectiveness in improving health outcomes.
 
Use of an aqueous shunt for all other conditions, including patients with glaucoma when intraocular pressure is adequately controlled by medications does not meet member benefit certificate primary coverage criteria that there be scientific evidence of effectiveness in improving health outcomes.
 
Use of an aqueous shunt for all other conditions, including patients with glaucoma when intraocular pressure is adequately controlled by medications, is considered investigational.  Investigational services are exclusions in most member benefit certificates of coverage.
 
Canaloplasty meets primary coverage criteria that there be scientific evidence of effectiveness in improving health outcomes as a method to reduce intraocular pressure in patients with chronic primary open-angle glaucoma under the following conditions:
 
    • Medical therapy has failed to adequately control intraocular pressure, AND
    • The patient is not a candidate for any other intraocular pressure lowering procedure (e.g. trabeculectomy or glaucoma drainage implant) due to a high risk for complications.
 
Canaloplasty as a method to reduce intraocular pressure in all other conditions, including but not limited to, angle-closure glaucoma does not meet member benefit certificate primary coverage criteria that there be scientific evidence of effectiveness in improving health outcomes.
 
For members with contracts without primary coverage criteria, canaloplasty as a method to reduce intraocular pressure in all other conditions, including but not limited to, angle-closure glaucoma is considered investigational. Investigational services are exclusions in most member benefit certificates of coverage.
 
Effective prior to September 2011
 
Insertion of aqueous shunts approved by the U.S. Food and Drug Administration (FDA)  as a method to reduce intraocular pressure in patients with glaucoma where medical therapy has failed to adequately control intraocular pressure meets primary coverage criteria that there be scientific evidence of effectiveness in improving health outcomes.
 
Use of an aqueous shunt for all other conditions, including patients with glaucoma when intraocular pressure is adequately controlled by medications does not meet member benefit certificate primary coverage criteria that there be scientific evidence of effectiveness in improving health outcomes.
 
Use of an aqueous shunt for all other conditions, including patients with glaucoma when intraocular pressure is adequately controlled by medications, is considered investigational.  Investigational services are exclusions in most member benefit certificates of coverage.
 
Canaloplasty does not meet primary coverage criteria that there be scientific evidence of effectiveness in improving health outcomes.
 
Canaloplasty is considered investigational as a method to reduce intraocular pressure in patients with glaucoma. Investigational services are exclusions in most member benefit certificates of coverage.
 

Rationale:
FDA-Approved/Cleared Aqueous Shunts
A 2006 Cochrane review evaluated 15 randomized or pseudo-randomized controlled trials (RCTs), with a total of 1,153 participants, on the Ahmed, Baerveldt, Molteno, and Schocket shunts (Minckler, 2006).  Trabeculectomy was found to result in a lower mean IOP (by 3.8 mmHg) than the Ahmed shunt at 1 year. A limitation of this report is that complications were not compared, as the authors considered them to be too variably reported to allow comparative tabulation. There was no evidence of superiority of one shunt over another.
 
A literature review on commercially available aqueous shunts, including the Ahmed, Baerveldt, Krupin, and Molteno devices, for an American Academy of Ophthalmology (AAO) technology assessment was published in 2008 (Minckler, 2008).   This review indicated that the IOP will generally settle at higher levels (approximately 18 mmHg) with aqueous shunts than after standard trabeculectomy (14-16 mmHg) or after trabeculectomy with anti-fibrotic agents 5-fluoracil or mitomycin C (8-10 mmHg). In 1 study, mean IOPs with the Baerveldt shunt and adjunct medications were found to be equivalent to trabeculectomy with mitomycin C (13 mmHg). Five-year success rates for the two procedures were found to be similar (50%). The assessment concluded that aqueous shunts were comparable with trabeculectomy for IOP control and duration of benefit. The risk of postoperative infection was less with aqueous shunts than after trabeculectomy. Complications of aqueous shunts were noted to include: immediate hypotony after surgery; excessive capsule fibrosis and clinical failure; erosion of the tube or plate edge; strabismus; and, very rarely, infection. The most problematic long-term consequence of anterior chamber tube placement was described as accelerated damage to the corneal endothelium over time.
 
Implantation of the Ex-PRESS mini shunt under a scleral flap was compared with standard trabeculectomy in a randomized study of 78 patients (80 eyes) with a diagnosis of open-angle glaucoma that could not be controlled with maximal-tolerated medical therapy (de Jong, 2009).  The 2 groups were similar after randomization, with the exception of difference in the mean age (62 years for the Ex-PRESS group and 69 years for the trabeculectomy group). At an average 12 months’ follow-up, mean IOP had improved from 23 to 12 mm Hg in the Ex-PRESS group and from 22 to 14 mm Hg in the trabeculectomy group. Both groups of patients used fewer antiglaucoma medications postoperatively than before the procedure (from 2.8 at baseline to 0.3 in the Ex-PRESS group and from 3.0 at baseline to 0.6 in the trabeculectomy group). Twelve-month Kaplan-Meier success rates (defined as an IOP of >4 mm Hg or <18 mm Hg without use of antiglaucoma medications) were 82% for the Ex-PRESS shunt and 48% for trabeculectomy. There was a similar level of postoperative complications in the two groups.
 
One year results from the iStent U.S. investigational device exemption (IDE) open-label 29 site multicenter randomized clinical trial were reported to the FDA in 2010 and published in 2011 (Samuelson, 2011). The objective of the trial was to measure the incremental effect on IOP from iStent implantation over that of cataract surgery alone and to determine the potential benefit of combining 2 therapeutic treatments into 1 surgical event. A total of 240 patients (mean age of 73 years) with cataracts and mild to moderate open-angle glaucoma (IOP < 24 mm Hg controlled on 1 to 3 medications) were randomized to undergo cataract surgery with iStent implantation or cataract surgery only. The mean number of medications at baseline was 1.5. The medicated IOP at baseline was 18.7 mm Hg in the stent group and 18.04 in the control group. After washout, the mean IOP was 25 mm Hg and mean visual acuity (logMAR) was 0.36. Follow-up visits were performed at 1, 3, 6, and 12 months. Results were assessed by intent-to-treat analysis with the last observation carried forward and per protocol analysis. Of the 117 subjects randomized to iStent implantation, 111 underwent cataract surgery with stent implantation, and 106 (91%) completed the 12-month postoperative visit. Of the 123 subjects randomized to cataract surgery only, 117 underwent cataract surgery and 3 exited the study because of complications of cataract surgery. Of the remaining 114 subjects, 112 (91%) completed the 12-month visit. The proportion of eyes meeting both the primary (unmedicated IOP <21 mm Hg) and secondary outcomes (IOP reduction >20% without hypotensive medications) was higher in the treatment group than in the control group at every visit. At 1-year follow-up, 72% of treatment eyes and 50% of control eyes achieved the primary efficacy endpoint. The proportion of patients achieving the secondary efficacy endpoint was 66% in the treatment group versus 48% in the control group. Ocular hypotensive medications were initiated later in the postoperative period and used in a lower proportion of patients in the treatment group at every postoperative interval (e.g., 15% vs. 35% at 12 months). The mean reduction in IOP was similar in the 2 groups, with a higher level of medication used in the control group (mean of 0.4 medications) in comparison with the treatment group (0.2 medications). The overall incidence of adverse events was similar between the groups.
 
Aqueous Shunts Not Approved by the FDA
The published literature on non-FDA approved/cleared aqueous drainage devices consists of small case series on the iStent and EyePass (Spiegel, 2007) (Dietlein, 2008).   A search of aqueous shunts and glaucoma in www.clinicaltrials.gov during 2008 and 2009 found a number of clinical trials in progress. The iStent was being studied under an FDA category B investigational device exemption. Neither  the iStent or EyePass had undergone FDA approval/clearance.
 
Transluminal Dilation (Canaloplasty)
 
Lewis et al reported interim data analysis from a company-sponsored multicenter safety/efficacy study on canaloplasty using the iTrack microcatheter (Lewis, 2007).  Catheterization of the canal was achieved in 83 of 94 patients enrolled (88%); tension sutures were successfully placed in 74 patients (79%) with a mean IOP of 24 mm Hg. At 3-month follow-up, 57 patients (77% of 74 implanted) had an IOP of 16 mm Hg, and at 12 months 48 patients (65%) had a mean IOP of 15 mm Hg. Ten ocular adverse events (11%) were reported, including hyphema (3%), elevated IOP (3%), Descemet’s membrane detachment, hypotony, choroidal effusion, and exposed closure suture (1% each). Eleven patients (12%) had a subconjunctival bleb, 6 of which resolved by 3 months. The study design included 5-year follow-up. These results were limited by the lack of randomization and high loss to follow-up.
 
Interim 1-year results from a company-sponsored multicenter study were reported for 40 patients who had combined canaloplasty and cataract surgery (Shingleton, 2008).   Inclusion criteria included: a glaucoma diagnosis of primary open-angle glaucoma (POAG), pigmentary glaucoma, exfoliation glaucoma, or POAG with narrow but not occludable angles after laser iridectomy; a treated IOP of 16 mm Hg or higher at baseline; and a historical untreated IOP of 21 mm Hg or higher. Of the 54 eyes enrolled, successful circumferential catheterization was achieved in 44 eyes (81%) and sutures were successfully placed in 40 eyes (74%). The 14 eyes (26%) that did not have sutures placed were due to the microcatheter entering a collector channel or meeting other resistance during catheterization; successful suture placement was reported to increase with surgeon experience. Two eyes were considered failures, with 1 conversion to trabeculectomy. Clinical results were reported for 25 patients (46% of 54) who were both due for and reported for 12-month follow-up. Of these, 3 eyes (12%) had low subconjunctival blebs at 12 months. No case of suture erosion through the trabecular meshwork or sclera was noted during follow-up. IOP was reduced from a mean of 24 mm Hg to 13 mm Hg at 6 months (reported for 42 eyes; 40 were reported to be successfully treated) and remained under 14 mm Hg in the 25 patients who were evaluated at 12 months. The number of antiglaucoma medications decreased from a mean of 1.5 medications to a mean of 0.1 at 1 month and 0.2 at 12 months. This trial is ongoing, and longer follow-up on a larger number of patients is needed.
 
The American Academy of Ophthalmology (AAO) published a 2008 technology assessment on commercially available aqueous shunts, including the Ahmed, Baerveldt, Krupin, and Molteno devices (Minckler, 2008).  The assessment indicated that in general, the IOP will settle at higher levels (approximately 18 mm Hg) with shunts than after standard trabeculectomy (14–16 mm Hg). Five year success rates of 50% have been found for the two procedures, indicating that aqueous shunts are comparable with trabeculectomy for IOP control and duration of benefit. (based on level I evidence; well-designed randomized controlled trials). The assessment indicated that although aqueous shunts have been generally reserved for intractable glaucoma when prior medical or surgical therapy has failed, indications for shunts have broadened (based on level III evidence; case series, case reports, and poor-quality case-control or cohort studies). The AAO concluded that based on level I evidence, aqueous shunts offer a valuable alternative to standard filtering surgery or to cyclodestructive therapy for many patients with refractory glaucoma.
 
Summary
 
Randomized controlled trials have shown that the use of shunts results in success rates at least as good as standard filtering surgery, with similar complication rates.
 
Other studies have reported use of shunts in patients with both cataracts and less advanced glaucoma, where the IOP is at least partially controlled with medication. Results from these studies indicate that IOP may be lowered below baseline with decreased need for medication in some patients, but complications may lead to trabeculectomy within 6 months in a number of eyes. Since it cannot be determined whether trabeculectomy would have been required had these patients remained on medical therapy, randomized controlled trials with longer follow-up are needed to compare clinical outcomes from patients who have undergone cataract surgery combined with device placement or with continued medical management. In addition, the Trabectome study group reports that 3% of patients required subsequent glaucoma surgery following combined Trabectome/cataract surgery in a large series (Francis, 2008) (Minckler, 2008).  Therefore, comparative trials with the Trabectome would help to evaluate whether device placement provides a health benefit over an ab interno surgical procedure that does not require permanent device implantation.
 
2011 Update
Lewis et al. reported 2-year and 3-year results from the multicenter study in 2009 and 2011, respectively (Lewis, 2009) (Lewis, 2011). Enrolled in the follow-up study were 157 patients with a diagnosis of primary open-angle glaucoma, pigmentary glaucoma, exfoliative glaucoma, and a baseline IOP of 16 mm Hg or higher before surgery, with a historical IOP of 21 mm Hg or higher. Exclusion criteria were neovascular disease, uveitis, peripheral anterior synechiae, angle recession, and developmental or secondary glaucoma (except for pigmentary and exfoliative glaucoma). At baseline, the mean IOP was 23.8 and patients were on an average 1.8 medications; 21% of eyes were on 3 or more antiglaucoma medications, and 12 eyes (7.6%) were on no medications. Twenty-five eyes (15.9%) were pseudophakic. Canaloplasty (with or without cataract surgery) was successful in 133 eyes (85%). Eyes that did not have placement of a tensioning suture were viscodilated to the extent possible by catheterizing the canal from both ostia. At 3 years postoperatively, 134 study eyes (85% follow-up) had a mean IOP of 15.2 mm Hg and mean glaucoma medication use of 0.8 medications; 4 eyes (3%) were on 3 or more antiglaucoma medications, and 66 eyes (49.3%) were on no medications. Another 7 patients (4.4%) had additional glaucoma surgery. Six eyes lost 2 or more lines of corrected visual acuity related to glaucoma progression. With qualified success defined as achieving IOP of 18 mm Hg or lower (with 0 to 2 medications), success was achieved in 69 of the 89 eyes (77.5%) that had successful suture implantation alone and 24 of the 27 eyes (89%) with successful suture placement combined with phacoemulsification. Early surgical/postoperative complications included microhyphema (12%), hyphema (10%), elevated intraocular pressure (6%), Descemet membrane detachment (3%), suture extrusion (1%), and hypotony (1%). Late postoperative complications included cataract (12.7%), transient IOP elevation (6.4%), and partial suture extrusion through the trabecular meshwork (0.6%).
 
Koerber et al. reported on 15 of the patients who participated in the multicenter trial described above who had bilateral POAG and received canaloplasty in one eye and viscocanalostomy in the contralateral eye (Koerber, 2011). Qualifying preoperative IOPs were 18 mm Hg or greater with historical IOPs of at least 21 mm Hg. For the canaloplasty eye, the baseline IOP averaged 26.5 mm Hg on 2.1 medications. All patients had successful suture placement. Follow-up at 18 months showed IOP of 14.5 on 0.3 medications. For the viscocanalostomy eye, the baseline eye averaged 24.3 mm Hg on 1.9 medications; follow-up at 18 months showed an average IOP of 16.1 on 0.4 medications. The reduction in IOP from baseline was significantly greater with canaloplasty (12.0 mm Hg) than with viscocanalostomy (8.2 mm Hg). There was no loss in visual acuity and no adverse events from either procedure. The authors noted that this study effectively compares the additional effects of the 2 major additional maneuvers associated with canaloplasty: first, 360 degrees viscodilation of Schlemm’s canal, as opposed to partial dilation achieved with viscocanalostomy, and second, prolonged opening and tensioning of Schlemm’s canal with suture placement.
 
Grieshaber et al. reported a prospective series of 60 consecutive black South African patients with POAG who underwent canaloplasty (Grieshaber, 2010). The mean preoperative IOP was 45 mm Hg. At 12 month follow-up, the IOP was 15 mm Hg (n=54), and at 36 months, the IOP was 13.3 mm Hg (n=49). Eleven patients (18%) were lost to follow-up at 3 years. With qualified success defined as achieving IOP of 21 mm Hg or lower (with or without medications), success was achieved in 40 of 49 patients (82%). When defined as an IOP of 16 mm Hg or less without medications, 47% of eyes met criteria for complete success. There were no severe complications in this series.
 
Mosaed and colleagues published a comparative effectiveness review of newer (Trabectome and canaloplasty) and older (trabeculectomy and Baerveldt shunt) surgeries for glaucoma in 2009 (Mosaed, 2009). Twelve-month outcomes (intracocular pressure adjunctive medications and complications) were compared after glaucoma-only and combined glaucoma-phacoemulsification surgeries. The review found that Trabectome and canaloplasty provided modest IOP reduction (to about 16 mm Hg) with minimal intraoperative or postoperative complications. Results of Baerveldt glaucoma implant IOP reduction were comparable to trabeculectomy (about 12 mm Hg), but typically this shunt required more postoperative IOP-lowering medication (average of 1.3 vs. 0.5 medications, respectively) to achieve a success rate comparable to trabeculectomy. Patients treated with Trabectome required more medications (average of 1.5) to control IOP than patients treated with canaloplasty (average of 0.6). The authors concluded that Trabectome and canaloplasty are reasonable surgical therapy choices for patients in which IOPs in the mid-teens seem adequate; although trabeculectomy remains the most effective IOP-lowering procedure, it also has the highest serious complication rates.
 
A search of the online site: Clinicaltrials.gov in August 2011 found 2 randomized trials comparing canaloplasty to trabeculectomy. Both studies (NCT01228799 and NCT00854256) are expected to enroll 60 subjects with completion in 2012.
 
In summary, recently, positive 2- to 3-year outcomes have been reported for canaloplasty, along with a systematic review that found that Trabectome and canaloplasty provided modest IOP reduction (to about 16 mm Hg) with minimal intraoperative or postoperative complications. When combined with expert opinion, evidence is sufficient to consider canaloplasty in the subset of patients for whom medical therapy has failed to adequately control intraocular pressure and in whom other surgical procedures (e.g. trabeculectomy or a glaucoma drainage implant) are contraindicated.
 
2012 Update
A literature search was conducted using the MEDLINE database through July 2012.  The key identified literature is summarized below.
 
A comparative effectiveness review (CER) on glaucoma treatments was prepared by the Johns Hopkins Evidence-based Practice Center for the Agency for Healthcare Research and Quality (AHRQ) in 2012 (Boland, 2012). The CER found that the data available on the role of aqueous drainage devices in open-angle glaucoma (primary studies, systematic review) were inadequate to draw conclusions on the comparative effectiveness of these treatments in comparison with laser and other surgical treatments.
 
A 2011 technology assessment from the AAO (literature search up to October 2009) reviewed the evidence on novel, or emerging, glaucoma procedures (Francis, 2011).  Included in the technology assessment were devices and procedures that either had FDA clearance or were in phase III clinical trials in the U.S. at the time. These included the Ex-PRESS™ mini glaucoma shunt, the SOLX Gold Shunt, and the iStent, along with various surgical procedures. The technology assessment concluded that these techniques and devices are still in the initial state (<5 years) of clinical experience and lacking widespread use. The clinical studies generally provided only level III evidence in support of the procedures. Based on the literature available at the time, it was not possible to conclude if the novel procedures were superior, equal to, or inferior to surgery such as trabeculectomy or to one another.
 
The U.K.’s National Institute for Health and Clinical Excellence provided guidance on trabecular stent bypass microsurgery for open angle glaucoma in 2011 (NICE, 2011). The guidance states that current evidence on trabecular stent bypass microsurgery for open angle glaucoma raises no major safety concerns. There is evidence of efficacy in the short term, but this is based on small numbers of patients. Therefore, this procedure should only be used with special arrangements for clinical governance, consent, and audit or research.
 
On June 25, 2012, the iStent (Glaukos) received FDA 510(K) marketing clearance for use in conjunction with cataract surgery for the reduction of intraocular pressure (IOP) in adult patients with mild to moderate open-angle glaucoma who are currently treated with ocular hypotensive medication. Information regarding the iStent was moved to the section of the rationale for FDA-Approved/Cleared Aqueous Shunts.
 
2013 Update
This policy is being updated with a literature search using the MEDLINE database through August 2013. Information addressing canaloplasty is moved to policy #2011064.
 
FDA-Approved/Cleared Aqueous Shunts
 
Baerveldt Glaucoma Shunt
In 2012, Gedde et al. reported 5-year follow-up from the Tube Versus Trabeculectomy (TVT) study (Gedde, 2012). The study included 212 eyes of 212 patients (18-85 years) who had previous trabeculectomy and/or cataract extraction with intraocular lens implantation and uncontrolled glaucoma with IOP of 18 mm Hg or greater and 40 mm Hg or lower on maximum tolerated medical therapy. Excluding patients who had died, the study had 82% follow-up at 5 years, with a similar proportion of patients in the tube and trabeculectomy groups. At 5 years, neither IOP (14.3 mm Hg in the tube group and 13.6 mm Hg in the trabeculectomy group) nor number of glaucoma medications (1.4 in the tube group and 1.2 in the trabeculectomy group) were significantly different with intent-to-treat analysis. The cumulative probability of failure over the 5 years was lower in the tube group than the trabeculectomy group (29.8% vs. 46.9%), and the rate of reoperation was lower (9% vs. 29%). The rate of loss of 2 or more lines of visual acuity was similar in the 2 groups (46% in the tube group and 43% in the trabeculectomy group).
 
 
iStent
At 2-year follow-up, there were 199 of the original 239 patients (83%) remaining in the study. The primary endpoint, IOP of 21 mm Hg or less without use of medication, was reached by 61% of patients in the treatment group compared to 50% of controls (p=0.036) (Craven, 2012). The secondary outcomes of IOP reduction of 20% or more without medication (53% vs. 44%) and mean number of medications used (0.3 vs. 0.5) were no longer significantly different between the groups at 2 years. As noted by the FDA, this study was conducted in a restricted population of patients who had an unmedicated IOP of 22 mm Hg or higher and 36 mm Hg or lower. The results of this study indicate that treatment of this specific population with a microstent is likely to improve outcomes at 1 year compared to cataract surgery alone. However, given the 2-year results of this study, it is not possible to conclude with certainty that health outcomes are improved at longer periods of follow-up.
 
In 2010, Fea reported a randomized double-blind clinical trial of cataract surgery with or without iStent implantation (2:1 ratio) in 36 patients (Fea, 2010). Inclusion criteria were a previous diagnosis of primary open-angle glaucoma with an IOP above 18 mm Hg at 3 separate visits, and on 1 or more hypotensive medications. The stent was implanted using the same small temporal clear corneal incision (approximately 3.0 mm) that had been used for phacoemulsification and intra-ocular lens placement and was guided into Schlemm’s canal by an applicator and ab interno gonioscopy. Follow-up visits with investigators who were masked to the treatment condition were conducted at 24 hours, 1 week, and 1, 2, 3, 6, 9, 12, and 15 months. Prescription of hypotensive medications was performed according to pre-set guidelines. Primary outcomes were IOP and reduction in medication use over 15 months and IOP after a 1-month washout of ocular hypotensive agents (16 months postoperatively). At baseline, IOP was an average of 17.9 mm Hg with 2.0 medications in the stent group and 17.3 mm Hg with 1.9 medications in the control group. The mean IOP at 15 months was 14.8 mm Hg, with 0.4 medications in the stent group and 15.7 mm Hg with 1.3 medications in the control group. Eight patients in the stent group (67% of 12) and 5 in the control group (24% of 21) did not require ocular hypotensive medication. The authors commented that patient compliance is an ongoing concern for most ophthalmologists; therefore, a main goal is to keep the patient as free as possible from medications postoperatively. After washout of medications, mean IOP was 16.6 in the stent group and 19.2 in the control group. Two stents were malpositioned, but one of these appeared to be functioning, and there were no reported adverse events related to stent implantation. This small study suggests that without hypotensive medication, the iStent lowers IOP by about 2.5 mm Hg beyond that generated by cataract surgery alone (approximately 25% decrease in the risk of glaucomatous progression).
 
Use of multiple iStents in combination with cataract surgery was reported in an open-label prospective series of 53 eyes (47 patients) in 2012 (Belovay, 2012). Of the 53 eyes, 28 had implantation of 2 stents and 25 had implantation of 3 stents, based on the need for greater IOP control, as determined by the operating surgeon. Best-corrected visual acuity (BCVA) improved or remained stable in 89% of eyes. IOP decreased from a mean of 18.0 m Hg to 14.3 mm Hg, and the number of hypotensive medications decreased from a mean of 2.7 to 0.7 at 1 year postoperatively. Target IOP was reached in 77% of eyes, while 59% of patients discontinued use of all medications in the study eye. At 1 year, the mean number of hypotensive medications decreased to 1.0 in the 2-stent group and 0.4 in the 3-stent group. Medication use had been stopped in 46% of eyes in the 2-stent group compared to 72% in the 3-stent group. Stent blockage occurred in the early postoperative period in 15% of eyes and was successfully treated with laser.
 
The policy statement is changed to included a coverage statement addressing the use of the iStent.
 
Aqueous Shunts and Stents Not Approved by the FDA
Case series has been identified on the EyePass and CyPass micro-stent (Dietlein, 2008; Hoeh, 2013). The CyPass has not received FDA approval/clearance at this time. The EyePass is no longer being developed.
 
Practice Guidelines and Position Statements
A 2012 position statement by the American Glaucoma Society (AGS) states that new technology whose intraocular pressure-lowering effect allows for a reduction in medications, or a reduction in the need for more advanced surgical care, or improves patient adherence to care, would provide advantages to glaucoma patients (AGS, 2012). If effective and safe, the AGS believe that these benefits and the fact that these technologies will not have bleb-related complications would represent an “improvement in net health outcomes.” In addition, the AGS states that some categories of new surgical devices and techniques are utilized at the time of concomitant cataract surgery. Since cataract surgery alone has been shown to lower intraocular pressure, a control group of patients with similar entry criteria undergoing cataract surgery alone may be appropriate for these technologies.
 
2014 Update
 
A literature search conducted through August 2014 did not reveal any new information that would prompt a change in the coverage statement. The key identified literature is summarized below.
 
Ex-PRESS Mini Shunt
A 2014 publication described a U.S. multicenter randomized trial of trabeculectomy compared with EX-PRESS® implantation in 120 patients (120 eyes) (Netland, 2014).The groups were comparable at baseline, with a preoperative IOP of 25.1 mm Hg on a mean of 3.1 medications for the EX-PRESS® group, compared with 26.4 mm Hg on a mean of 3.1 medications in the trabeculectomy group. Throughout 2 years of follow-up after surgery, the average IOP and number of medications were similar in the 2 groups. At 2 years, mean IOP was 14.7 mm Hg on 0.9 medications in the EX-PRESS® group and 14.6 mm Hg on 0.7 medications in the trabeculectomy group. Surgical success was 90% and 87% at 1 year and 83% and 79% at 3 years in the EX-PRESS® and trabeculectomy groups, respectively. Visual acuity returned to near baseline levels at 1 month after EX-PRESS® implantation and 3 months after trabeculectomy (p=0.041), with a median time to return to baseline vision of 0.7 months and 2.2 months, respectively. Postoperative complications were higher after trabeculectomy (41%) than after EX-PRESS® implantation (18.6%).
 
Five-year follow-up was reported in 2011 (de Jong, 2011). At 5 years, the success rates were not significantly different between the 2 groups. In the EX-PRESS® group, IOP remained stable from year 1 (12.0 mm Hg) to year 5 (11.5 mm Hg), while in the trabeculectomy group, IOP decreased from year 3 (13.5 mm Hg) to year 5 (11.3 mm Hg). There were more complications after trabeculectomy than after EX-PRESS® implantation.
 
iStent inject®
An industry-sponsored multicenter unblinded randomized trial compared implantation of 2 iStent inject® devices versus 2 ocular hypotensive agents (Fea, 2014). The 192 patients enrolled in this unmasked trial had an IOP that was not controlled by 1 hypotensive medication. At 12-month follow-up, the 2 groups were comparable for IOP reduction of at least 20%, IOP of 18 mm Hg or less, and mean decrease in IOP. A greater proportion of patients in the iStent inject® group achieved an IOP reduction of at least 50% (53.2% vs 35.7%). One patient in the iStent inject® group experienced elevated IOP (48 mm Hg) and 4 required ocular hypotensive medication. Longer-term studies are in progress.
 
 
Viscocanalostomy
A 2010 meta-analysis by Chai and Loon compared the safety and efficacy of viscocanalostomy with the gold standard of trabeculectomy (Chai, 2010).Ten randomized controlled trials with a total of 458 eyes (397 patients) with medically uncontrolled glaucoma were included in the analysis. The number of eyes in each study ranged from 20 to 60, with follow-up ranging from 6 months to 4 years. The majority of eyes
(81%) had primary open angle glaucoma, while 16.4% had secondary open angle glaucoma, and 1.7% had primary angle closure glaucoma. Meta-analysis found that trabeculectomy had a significantly better pressure-lowering outcome. The difference in intraocular pressure between the treatments was 2.25 mm Hg at 6 months, 3.64 mm Hg at 12 months, and 3.42 mm Hg at 24 months. Viscocanalostomy had a significantly higher relative risk (RR) of perforation of Descemet’s membrane (RR: 7.72). In contrast, viscocanalostomy had significantly fewer postoperative events compared with trabeculectomy (hypotony RR: 0.29, hyphema RR: 0.50, shallow anterior chamber RR: 0.19, and cataract formation RR: 0.31). Although viscocanalostomy had a better risk profile, most of the adverse events associated with trabeculectomy were considered to be mild and reversible. Similar results were obtained in a 2014 Cochrane review and meta-analysis by Edaly et al that included 2 small randomized trials (50 eyes( (Eldaly, 2014).
 
 
The primary literature on canaloplasty consists mainly of case series that compare post-treatment IOP with pretreatment IOP. One retrospective comparative study evaluated outcomes from 33 eyes (33 patients) that underwent canaloplasty and 46 eyes (46 patients) that underwent trabeculectomy during a 2 year period and had a minimum of 12 months’ of follow-up (Ayyala, 2011). This study group was drawn from a larger group of 243 patients who underwent surgery during the same 2 year period (87 canaloplasty procedures and 156 trabeculectomy procedures). The specific procedure was determined by the ability to obtain insurance coverage for canaloplasty, and the groups were comparable in demographics, previous surgery, and visual acuity at baseline. At 12 months after surgery, the mean reduction in IOP from preoperative values was 32% for canaloplasty and 43% for trabeculectomy (p=.072). IOP was slightly lower in the trabeculectomy group (11.6 vs 13.8 mm Hg; p=.03) and fewer patients needed postoperative glaucoma medications. There was no significant difference in surgical reoperation rates between the 2 procedures (15% canaloplasty and 11% trabeculectomy). This study is limited by the potential for bias in the selection of patients for the study. Only a minority of all surgical patients had 12-month follow-up data and was included in the study and section into treatment groups was dependent on insurance status.
 
Three year follow-up from an independent series of 214 patients treated with canaloplasty in Europe was reported by Brusini in 2014 (Brusini. 2014). Mean IOP was reduced from 29.4 mm Hg at baseline to 17.0 mm Hg, after excluding 17 patients (7.9%) who later underwent trabeculectomy,. IOP was 21 mm Hg or lower in 86.2% of patients, 18 mm Hg or lower in 58.6%, and 16 mm Hg or lower in 37.9% of patients. There was a decrease in mean medication use, from 3.3 at baseline to 1.3 at follow-up. Complications, which included hyphema, descement membrane detachment, IOP spikes, and hypotony, were fewer than is typically seen with trabeculectomy. Several disadvantages of the procedure were noted, including the inability to complete the procedure in 16.4% of eyes.
 
Ongoing Clinical Trials
A search of the online site ClinicalTrials.gov in July 2014 found 2 randomized trials comparing canaloplasty to trabeculectomy. NCT01228799 enrolled 64 patients and was completed December 2012. No results have been posted to date.
 
NCT00854256 has an expected enrollment of 60 patients with completion in May 2014. NCT01726543 will compare canaloplasty with non-penetrating deep sclerectomy. This study has an estimated enrollment of 80 patients with completion in December 2014.
 
2016 Update
A literature search conducted through February 2016 did not reveal any new randomized controlled trials or any new information that would prompt a change in the coverage statement. The key identified literature are summarized below.
 
Ex-PRESS Mini Shunt
Two additional small RCTs were published in 2015 by Gonzalez-Rodriguez (Gonzalez-Rodriguez, 2015) et al (n=63) and Wagschal et al (Wagschal, 2015) (n=64). Both of these studies corroborated the results of the earlier RCTs, reporting that there were no differences between the trabeculectomy and Ex-PRESS shunt groups on the outcomes of mean IOP, success rates, number of medications used, or complication rates.
 
A Cochrane review was published in 2015 that evaluated the efficacy of adjunctive procedures added to trabeculectomy (Wang, 2015). The Ex-PRESS Mini Shunt was one procedure included and there were three RCTs included that compared trabeculectomy alone with trabeculectomy plus Ex-PRESS mini shunt. The three trials were rated as having high or unclear risk of bias by the Cochrane risk of bias tool. None of the three individual RCTs reported a significant improvement for the Ex-PRESS group. On combined analysis the IOP was slightly lower in the combination group compared with trabeculectomy alone (weighted mean difference -1.58, 95% CI -2.74 to -0.42). Combined analysis also showed that subsequent cataract surgery was less frequent in the combination group compared with trabeculectomy alone (Relative Risk 0.34, 95% CI 0.14-0.74). There was also a lower rate of some complications in the combination group, such as hyphema and needling, but no difference in the rate of other complications such as bleb leakage and anterior chamber flattening.
 
iStent
Four year follow-up from an earlier discussed study (Fea, 2010) was published in 2015 (Fea, 2015). A total of 24 of 36 patients were available at four years of follow-up. At this longer time point, the differences between treatment group remained non-significant, with a mean IOP of 15.9mmHg in the stent group and 17mmHg in the control group (p=NS).
One RCT comparing the efficacy of one iStent versus multiple iStents was published in 2015 (Katz, 2015). This study, from a single institution in Armenia, randomized 119 patients with OAG and an IOP between 22-38mmHg (off medications) to either one shunt (n=38), two shunts (n=41), or three shunts (n=40). Randomization was performed using a pseudorandom number generator. The main outcome measure was IOP at 12 months. The primary end point was the percent of patients with ≥20% reduction in IOP off medications. This endpoint was reached by 89.2% (95% CI 74.6-97.0%) of patients in the one stent group, 90.2% (95% CI 76.9-97.3%) of patients in the two stent group, and 92.1% (95% CI 78.6-98.3) of patients in the three stent group. The secondary endpoint was the percent of patients who achieved an IOP of ≤15 off medications. This endpoint was reached by 64.9% (95% CI 47.5-79.8%) of patients in the one stent group, 85.4% (95% CI 70.8-94.4%) of patients in the two stent group, and 92.1% (95% CI 78.6-98.3) of patients in the three stent group. There were no between group statistical comparisons reported.
 
A prospective case series enrolled 39 patients with OAG and IOP between 18 and 30mmHg (Donnenfeld, 2015). Each patient was treated with two microstents and medications as needed, and follow-up was for three years. At study completion, the mean reduction in IOP was 9.1mmHg (95% CI 8.0-10.1). There was one postoperative complication, which was a hyphema that resolved without further intervention.
 
2018 Update
Annual policy review completed with a literature search using the MEDLINE database through May 2018. Coverage statement revised. The key identified literature is summarized below.
 
Randomized Controlled Trials
Kotecha et al assessed vision-related quality of life outcomes in the TVT study (Kotecha, 2017). Quality of life was measured using the National Eye Institute Visual Functioning Questionnaire-25, administered at baseline and annual follow-ups over 5 years. A comparison of composite quality of life scores and change in scores over time among the 2 groups revealed no significant differences at any of the follow-up measurements.
 
Observational Studies
Dib Bustros et al published a retrospective chart review that offered 1-year results from 56 African American patients who underwent Ex-PRESS (n=28) implantation or trabeculectomy (n=28)(Dib Bustros, 2017). Outcomes included IOP and glaucoma medication used presurgery, postsurgery, and at 12-months of follow-up. In both groups, IOP and glaucoma-related medication use dropped significantly. Postoperative and follow-up interventions included 5-fluorouracil injections and laser suture lysis. Patients who underwent trabeculectomy needed a significantly greater number of laser suture lysis and 5-fluorouracil interventions in the 3 months after surgery (trabeculectomy: 3.89; EX-PRESS: 2.36, p=0.007). The results showed that Ex-PRESS was noninferior to trabeculectomy in reducing IOP and reducing the need for glaucoma-related medications.
 
Comparative Effectiveness Analyses
Christakis et al analyzed 5-year pooled data from the ABC and AVB trials comparing the relative efficacy of the 2 implants (Christakis, 2017). Patients were randomized to an Ahmet implant (n=267) or a Baerveldt implant (n=247). IOP, glaucoma medication use, and visual acuity were compared. At year 5, mean IOP was 15.8 mm Hg in the Ahmed group and 13.2 mm Hg in the Baerveldt group (p=.007). The cumulative failure rate in the Ahmed group was 49%; in the Baerveldt group, it was 37%. Mean glaucoma medication use was significantly lower in patients receiving the Baerveldt implant than in patients receiving the Ahmed implant (p=0.007). Visual acuity was similar between both groups. While efficacy measures were significantly better in the Baerveldt group, these patients experienced more hypotony (4.5%) than patients in the Ahmet group (0.4%; p=.002).
 
Comparative Studies
Schlenker et al published a multicenter, retrospective interventional cohort study that compared the risk, safety, and efficacy for stand-alone ab interno microstent implantation with mitomycin C (MMC) and trabeculectomy plus MMC (Schlenker, 2017). Implantations of the ab interno XEN 45 gelatin microstent is a new less invasive surgery than trabeculectomy. This study included 293 patients (354 eyes) across 4 ophthalmology centers in Canada, Germany, Austria, and Belgium. One hundred fifty-nine patients (185 eyes) underwent the microstent implantation, and 139 patients (169 eyes) underwent trabeculectomy. Outcomes included: IOP differences, medication reductions, interventions, complications, and the need for additional surgery. The primary outcome was the hazard ratio of failure. Failure was defined as 2 consecutive IOP readings of less than 6 mm Hg, including vision loss. Success was measured by the withdrawal of glaucoma-related medications at 1 month postsurgery. The adjusted hazard ratio of failure of the microstent relative to trabeculectomy was 1.2 for complete success (95% CI, 0.7 to 2.0). Both surgeries had a 75% survival of approximately 10 months for complete success. During the last reported follow-up (varying times), antiglaucoma medications were being used by 25% of patients who received the microstent implantation and 33% of trabeculectomy patients. Patients in both groups reported similar numbers of postoperative interventions, such as laser suture lysis and needling. The need for reoperation was higher among those who had undergone microstent implantation—but this difference was not statistically significant. The authors concluded that the ab interno gelatin microstent with MMC was noninferior to trabeculectomy plus MMC.
 
Noncomparative Studies
Mansouri et al reported on results from a study of 149 eyes (113 patients); 109 eyes received the XEN implant pluscataract surgery and 40 eyes received the implant alone (Mansouri, 2017).\l " There was a range of glaucoma severity represented in the study sample, with most patients in the mild-to-moderate stages. Of the 149 eyes, data for 87 (58%) eyes was available at 12 months. The high loss to follow-up was mainly due to high travel times for patients referred to the study treatment center from various provinces and countries, and to lack of interest among physicians to treat referred patients. At 12 months, mean IOP and mean medication use both decreased.  The proportion achieving 20% or more reduction in IOP was higher among patients receiving XEN alone than those undergoing cataract surgery and XEN implantation. Adverse events included bleb revision (n=5), choroidal detachment (n=2), and second glaucoma surgery (n=9).
 
Grover et al published results from the single-arm, open-label clinical study evaluating the effectiveness and safety of the XEN Glaucoma Treatment System in 65 patients with refractory glaucoma (Grover, 2017). Effectiveness data were collected for 12 months and safety data for 18 months. The mean diurnal IOP was 25 mm Hg at baseline on a mean of 3.5 IOP-lowering medications. Forty-six (75%) patients of 61 with available data had a 12-month mean diurnal IOP reduction of 20% or more without increasing IOP-lowering medications. The mean IOP reduction at 12 months was -9.1 mm Hg (95% CI, -10.7 to -7.5 mm Hg) on a mean of 1.7 medications. Efficacy was consistent across age groups, baseline IOP, baseline medication use, sex, and ethnicity. The most common adverse events were glaucoma surgery, hypotony, IOP increase of 10 mm Hg or more, and needling procedures. FDA cited results from this study to conclude that the XEN System was as safe and effective as predicate devices.
 
Hengerer et al retrospectively analyzed 146 patients (242 eyes) receiving the XEN implant for treatment refractory to antiglaucoma medication or glaucoma surgery (Hengerer, 2017). In the subset of eyes with 12-month data (n=148), IOP reduction of 20% or more was achieved by 73.0% of patients. Mean antiglaucoma medications decreased. The decreases in IOP and medication use were statistically significant, in patients receiving the XEN implant alone and in patients receiving the XEN implant while undergoing cataract surgery.
 
Five smaller case series have also assessed the use of the XEN. These case series reported significant reductions in IOP and medication use (Perez-Torregrosa, 2016; De Gregorio, 2017; Galal, 2017; Ozal, 2017; Tan, 2018). Low rates of the following complications were reported: hypotony (which resolved), need for bleb intervention, iris tissue obstruction, implant extrusion, and choroidal detachment.
 
Observational Studies
Kurji et al reported on 2 surgical methods, phaco-trabectome and phaco-iStent, to control IOP in patients with open-angle glaucoma undergoing cataract surgery (Kurji, 2017). Fifty-five patients (70 eyes) were analyzed in this retrospective comparative case series, 36 receiving PT and 34 receiving phaco-iStent. Outcomes included IOP reduction, glaucoma medication reduction, patients’ safety profile, and best-corrected visual acuity. At baseline, the mean IOP of patients in the phaco-trabectome group (30 patients [36 eyes], 20.92 mm Hg]) was higher than those in the phaco-iStent group (25 patients [34 eyes], 17.47 mm Hg; p=0.026]). At 12-month follow-up, both groups experienced significant reductions in IOP; however, there was no statistically significant difference between groups (phaco-trabectome, -5.09 mm Hg 24% relative reduction vs phaco-iStent, -3.84 mm Hg, 22% relative reduction; p=0.331). Glaucoma medication usage did not decrease significantly from baseline to 12 months in either group; moreover, there was no significant difference in reduction between the groups. Phaco-iStent patients had fewer individual complications.
 
Ferguson et al reported on a series of 59 patients with severe primary open-angle glaucoma who were implanted with 1 trabecular micro-bypass stent (iStent) during cataract surgery (Ferguson, 2018). Patients were followed for 2 years. IOP at baseline was 19.3 mm Hg at baseline, decreasing significantly to 14.4 mm Hg at 12 months and 14.9 mm Hg at 24 months (p<0.01). Mean number of glaucoma medications also decreased, from 2.3 at baseline to 1.6 at 24 months.
 
Multiple Stents
An RCT comparing the efficacy of 1 iStent with multiple iStent devices was published by Katz et al (Katz, 2015). This trial, from a single institution in Armenia, randomized 119 patients with mild-to-moderate open-angle glaucoma and an IOP between 22 and 38 mm Hg (off medications) to 1 stent (n=38), 2 stents (n=41), or 3 stents (n=40). Randomization was performed using a pseudorandom number generator. The main outcome was IOP at 12 months. The primary end point was the percentage of patients with a reduction of 20% or more in IOP off medications. This end point was reached by 89.2% (95% CI, 74.6% to 97.0%) of the 1-stent group, by 90.2% (95% CI, 76.9% to 97.3%) of the 2-stent group, and by 92.1% (95% CI, 78.6% to 98.3%) of the 3-stent group. The secondary end point (percentage of patients achieving an IOP £15 mm Hg off medication) was reached by 64.9% (95% CI, 47.5% to 79.8%) of the 1-stent group, by 85.4% (95% CI, 70.8% to 94.4%) of the 2-stent group, and by 92.1% (95% CI, 78.6% to 98.3) of the 3-stent group. Forty-two-month follow-up results for 109 patients were published by Katz et al (Katz, 2018). Mean medicated IOPs for the 1-stent, 2-stent, and 3-stent groups were 15.0 ± 2.8 mm Hg, 15.7 ± 1.0 mm Hg, and 14.8 ± 1.3 mm Hg, respectively. No between-group statistical comparisons were reported.
 
Vlasov et al conducted a retrospective chart review of patients with open-angle glaucoma receiving either 1 iStent (n=39) or 2 iStents (n=30) during cataract surgery (Vlasov, 2017). Both groups experienced statistically significant reductions in IOP, and there was no significant difference between them in IOP reduction. Only the group receiving 2 iStents experienced a statistically significant reduction in medication use.
 
Practice Guidelines and Position Statements
 
European Glaucoma Society
The European Glaucoma Society’s Terminology and Guidelines for Glaucoma (2014) provided evidence-based guidelines on the treatment of primary open-angle glaucoma (European Glaucoma Society, 2014). The guidelines were updated in 2017 (European Glaucoma Society, 2017). The guidelines stated that there are no well-controlled comparative trials to support the superiority in safety or efficacy of MIGS, including both ab interno and ab externo procedures, over trabeculectomy.    

CPT/HCPCS:
0191TInsertion of anterior segment aqueous drainage device, without extraocular reservoir, internal approach, into the trabecular meshwork; initial insertion
0253TInsertion of anterior segment aqueous drainage device, without extraocular reservoir, internal approach, into the suprachoroidal space
0356TInsertion of drug-eluting implant (including punctal dilation and implant removal when performed) into lacrimal canaliculus, each
0376TInsertion of anterior segment aqueous drainage device, without extraocular reservoir, internal approach, into the trabecular meshwork; each additional device insertion (List separately in addition to code for primary procedure)
0444TInitial placement of a drug-eluting ocular insert under one or more eyelids, including fitting, training, and insertion, unilateral or bilateral
0445TSubsequent placement of a drug-eluting ocular insert under one or more eyelids, including re-training, and removal of existing insert, unilateral or bilateral
0449TInsertion of aqueous drainage device, without extraocular reservoir, internal approach, into the subconjunctival space; initial device
0450TInsertion of aqueous drainage device, without extraocular reservoir, internal approach, into the subconjunctival space; each additional device (List separately in addition to code for primary procedure)
0474TInsertion of anterior segment aqueous drainage device, with creation of intraocular reservoir, internal approach, into the supraciliary space
66179Aqueous shunt to extraocular equatorial plate reservoir, external approach; without graft
66180Aqueous shunt to extraocular equatorial plate reservoir, external approach; with graft
66183Insertion of anterior segment aqueous drainage device, without extraocular reservoir, external approach
66184Revision of aqueous shunt to extraocular equatorial plate reservoir; without graft

References: Gedde SJ, Schiffman JC, Feuer WJ et al.(2012) Treatment outcomes in the Tube Versus Trabeculectomy (TVT) study after five years of follow-up. Am J Ophthalmol 2012; 153(5):789-803 e2.

American Glaucoma Society. Position statement on new glaucoma surgical procedures. 2012. Available online at: http://www.americanglaucomasociety.net/professionals/policy_statements/new_glaucoma_surgical_procedures. Last accessed May, 2013.

Ayyala RS, Chaudhry AL, Okogbaa CB, et al.(2011) Comparison of surgical outcomes between canaloplasty and trabeculectomy at 12 months' follow-up. Ophthalmology. Dec 2011;118(12):2427-2433. PMID 21856008

Belovay GW, Naqi A, Chan BJ et al.(2012) Using multiple trabecular micro-bypass stents in cataract patients to treat open-angle glaucoma. J Cataract Refract Surg 2012; 38(11):1911-7.

Boland MV, Ervin AM, Friedman D et al.(2012) Treatment for Glaucoma: Comparative Effectiveness. Comparative Effectiveness Review No. 60. (Prepared by the Johns Hopkins University Evidence-based Practice Center under Contract No. HHSA 290-2007-10061-I.) AHRQ Publication No. 12-EHC038-EF. Rockville, MD: Agency for Healthcare Research and Quality; April 2012.

Brusini P.(2014) Canaloplasty in open-angle glaucoma surgery: a four-year follow-up. ScientificWorldJournal. 2014;2014:469609. PMID 24574892

Chai C, Loon SC.(2010) Meta-analysis of viscocanalostomy versus trabeculectomy in uncontrolled glaucoma. J Glaucoma. Oct-Nov 2010;19(8):519-527. PMID 20179632

Christakis PG, Zhang D, Budenz DL, et al.(2017) Five-year pooled data analysis of the Ahmed Baerveldt comparison study and the Ahmed versus Baerveldt Study. Am J Ophthalmol. Apr 2017;176:118-126. PMID 28104418

Craven ER, Katz LJ, Wells JM et al.(2012) Cataract surgery with trabecular micro-bypass stent implantation in patients with mild-to-moderate open-angle glaucoma and cataract: Two-year follow-up. J Cataract Refract Surg 2012; 38(8):1339-45.

De Gregorio A, Pedrotti E, Russo L, et al.(2017) Minimally invasive combined glaucoma and cataract surgery: clinical results of the smallest ab interno gel stent. Int Ophthalmol. May 29 2017. PMID 28555256

de Jong L, Lafuma A, Aguade AS, et al.(2011) Five-year extension of a clinical trial comparing the EX-PRESS glaucoma filtration device and trabeculectomy in primary open-angle glaucoma. Clin Ophthalmol. 2011;5:527-533. PMID 21607021

de Jong LA.(2009) The Ex-PRESS glaucoma shunt versus trabeculectomy in open-angle glaucoma: a prospective randomized study. Adv Ther 2009; 26(3):336-45.

Dib Bustros Y, Fechtner R, A SK.(2017) Outcomes of Ex-PRESS and trabeculectomy in a glaucoma population of African origin: one year results J Curr Glaucoma Pract. May-Aug 2017;11(2):42-47. PMID 28924337

Dietlein TS, Jordan JF, Schild A et al.(2008) Combined cataract-glaucoma surgery using the intracanalicular Eyepass glaucoma implant: first clinical results of a prospective pilot study. J Cataract Refract Surg 2008; 34(2):247-52.

Dietlein TS, Jordan JF, Schild A et al.(2008) Combined cataract-glaucoma surgery using the intracanalicular Eyepass glaucoma implant: first clinical results of a prospective pilot study. J Cataract Refract Surg 2008; 34(2):247-52.

Donnenfeld ED, Solomon KD, Voskanyan L, et al.(2015) A prospective 3-year follow-up trial of implantation of two trabecular microbypass stents in open-angle glaucoma. Clin Ophthalmol. 2015;9:2057-2065. PMID 26604675

Eldaly MA, Bunce C, Elsheikha OZ, et al.(2014) Non-penetrating filtration surgery versus trabeculectomy for open-angle glaucoma. Cochrane Database Syst Rev. 2014;2:CD007059. PMID 24532137

European Glaucoma Society Terminology and Guidelines for Glaucoma, 4th Edition - Chapter 3: Treatment principles and options Supported by the EGS Foundation: Part 1: Foreword; Introduction; Glossary; Chapter 3 Treatment principles and options. Br J Ophthalmol. Jun 2017;101(6):130-195. PMID 28559477

Fea AM, Belda JI, Rekas M, et al.(2014) Prospective unmasked randomized evaluation of the iStent inject ((R)) versus two ocular hypotensive agents in patients with primary open-angle glaucoma. Clin Ophthalmol. 2014;8:875-882. PMID 24855336

Fea AM, Consolandi G, Zola M, et al.(2015) Micro-bypass implantation for primary open-angle glaucoma combined with phacoemulsification: 4-year follow-up. J Ophthalmol. 2015;2015:795357. PMID 26587282

Fea AM.(2010) Phacoemulsification versus phacoemulsification with micro-bypass stent implantation in primary open-angle glaucoma: randomized double-masked clinical trial. J Cataract Refract Surg 2010; 36(3):407-12.

Ferguson T, Swan R, Ibach M, et al.(2018) Evaluation of a trabecular microbypass stent with cataract extraction in severe primary open-angle glaucoma. J Glaucoma. Jan 2018;27(1):71-76. PMID 29194199

Food and Drug Administration(2018) Directions for Use/Package Insert: Glaukos Corporation iStent® Trabecular Micro-Bypass Stent System. n.d. Available online at https://www.accessdata.fda.gov/cdrh_docs/pdf8/p080030c.pdf. Accessed April 17, 2018.

Francis BA, Minckler D, Dustin L et al;(2008) Trabectome Study Group. Combined cataract extraction and trabeculotomy by the internal approach for coexisting cataract and open-angle glaucoma: initial results. J Cataract Refract Surg 2008; 34(7):1096-103.

Francis BA, Singh K, Lin SC et al.(2011) Novel glaucoma procedures: a report by the American Academy of Ophthalmology. Ophthalmology 2011; 118(7):1466-80.

Galal A, Bilgic A, Eltanamly R, et al.(2017) XEN glaucoma implant with mitomycin C 1-year follow-up: result and complications. J Ophthalmol. Mar 1 2017;2017:5457246. PMID 28348884

Gonzalez-Rodriguez JM, Trope GE, Drori-Wagschal L, et al.(2015) Comparison of trabeculectomy versus Ex-PRESS: 3-year follow-up. Br J Ophthalmol. Dec 16 2015. PMID 26674779

Grieshaber MC, Pienaar A, Olivier J et al.(2010) Canaloplasty for primary open-angle glaucoma: long-term outcome. Br J Ophthalmol 2010; 94(11):1478-82.

Grover DS, Flynn WJ, Bashford KP, et al.(2017) Performance and safety of a new ab interno gelatin stent in refractory glaucoma at 12 months. Am J Ophthalmol. Nov 2017;183:25-36. PMID 28784554

Hengerer FH, Kohnen T, Mueller M, et al.(2017) Ab interno gel implant for the treatment of glaucoma patients with or without prior glaucoma surgery: 1-year results. J Glaucoma. Dec 2017;26(12):1130-1136. PMID 29035911

Hoeh H, Ahmed II, Grisanti S et al.(2013) Early postoperative safety and surgical outcomes after implantation of a suprachoroidal micro-stent for the treatment of open-angle glaucoma concomitant with cataract surgery. J Cataract Refract Surg 2013; 39(3):431-7.

Katz LJ, Erb C, Carceller GA, et al.(2015) Prospective, randomized study of one, two, or three trabecular bypass stents in open-angle glaucoma subjects on topical hypotensive medication. Clin Ophthalmol. 2015;9:2313-2320. PMID 26715834

Katz LJ, Erb C, Carceller Guillamet A, et al.(2018) Long-term titrated IOP control with one, two, or three trabecular micro-bypass stents in open-angle glaucoma subjects on topical hypotensive medication: 42-month outcomes. Clin Ophthalmol. Jan 31 2018;12:255-262. PMID 29440867

Koerber NJ.(2011) Canaloplasty in One Eye Compared With Viscocanalostomy in the Contralateral Eye in Patients With Bilateral Open-angle Glaucoma. J Glaucoma 2011.

Kotecha A, Feuer WJ, Barton K, et al.(2017) Quality of Life in the Tube Versus Trabeculectomy Study. Am J Ophthalmol. Apr 2017;176:228-235. PMID 28161049

Kurji K, Rudnisky CJ, Rayat JS, et al.(2017) Phaco-trabectome versus phaco-iStent in patients with open-angle glaucoma. Can J Ophthalmol. Feb 2017;52(1):99-106. PMID 28237158

Lewis RA, von Wolff K, Tetz M et al.(2007) Canaloplasty: circumferential viscodilation and tensioning of Schlemm's canal using a flexible microcatheter for the treatment of open-angle glaucoma in adults: interim clinical study analysis. J Cataract Refract Surg 2007; 33(7):1217-26.

Lewis RA, von Wolff K, Tetz M et al.(2009) Canaloplasty: circumferential viscodilation and tensioning of Schlemm canal using a flexible microcatheter for the treatment of open-angle glaucoma in adults: two-year interim clinical study results. J Cataract Refract Surg 2009; 35(5):814-24.

Lewis RA, Von Wolff K, Tetz M et al.(2011) Canaloplasty: Three-year results of circumferential viscodilation and tensioning of Schlemm canal using a microcatheter to treat open-angle glaucoma. J Cataract Refract Surg 2011; (in press).

Mansouri K, Guidotti J, Rao HL, et al.(2018) Prospective evaluation of standalone XEN gel implant and combined phacoemulsification-XEN gel implant surgery: 1-year results J Glaucoma. Feb 2018;27(2):140-147. PMID 29271806

Minckler D, Mosaed S, Dustin L et al;(2008) Trabectome Study Group. Trabectome (trabeculectomy-internal approach): additional experience and extended follow-up. Trans Am Ophthalmol Soc 2008; 106:149-59.

Minckler DS, Francis BA, Hodapp EA et al.(2008) Aqueous shunts in glaucoma: a report by the American Academy of Ophthalmology. Ophthalmology 2008; 115(6):1089-98.

Minckler DS, Vedula SS, Li TJ et al.(2006) Aqueous shunts for glaucoma. Cochrane Database Syst Rev 2006; (2):CD004918.

Mosaed S, Dustin L, Minckler DS.(2009) Comparative outcomes between newer and older surgeries for glaucoma. Trans Am Ophthalmol Soc 2009; 107:127-33.

National Institute for Health and Clinical Evidence (NICE).(2011) Trabecular stent bypass microsurgery for open angle glaucoma. Available online at: http://www.nice.org.uk/nicemedia/live/13157/54571/54571.pdf. Last accessed April 2012.

Netland PA, Sarkisian SR, Jr., Moster MR, et al.(2014) Randomized, prospective, comparative trial of EX PRESS glaucoma filtration device versus trabeculectomy (XVT study). Am J Ophthalmol. Feb 2014;157(2):433-440 e433. PMID 24210765

Ozal SA, Kaplaner O, Basar BB, et al.(2017) An innovation in glaucoma surgery: XEN45 gel stent implantation. Arq Bras Oftalmol. Nov-Dec 2017;80(6):382-385. PMID 29267575

Perez-Torregrosa VT, Olate-Perez A, Cerda-Ibanez M, et al.(2016) Combined phacoemulsification and XEN45 surgery from a temporal approach and 2 incisions. Arch Soc Esp Oftalmol. Sep 2016;91(9):415-421. PMID 26995503

Samuelson TW, Katz LJ, Wells JM et al.(2011) Randomized evaluation of the trabecular micro-bypass stent with phacoemulsification in patients with glaucoma and cataract. Ophthalmology 2011; 118(3):459-67.

Schlenker MB, Gulamhusein H, Conrad-Hengerer I, et al.(2017) Efficacy, safety, and risk factors for failure of standalone ab interno gelatin microstent implantation versus standalone trabeculectomy. Ophthalmology. Nov 2017;124(11):1579-1588. PMID 28601250

Shingleton B, Tetz M, Korber N.(2008) Circumferential viscodilation and tensioning of Schlemm canal (canaloplasty) with temporal clear corneal phacoemulsification cataract surgery for open-angle glaucoma and visually significant cataract: one-year results. J Cataract Refract Surg 2008; 34(3):433-40.

Spiegel D, García-Feijoó J, García-Sánchez J et al.(2008) Coexistent primary open-angle glaucoma and cataract: preliminary analysis of treatment by cataract surgery and the iStent trabecular micro-bypass stent. Adv Ther 2008; 25(5):453-64.

Spiegel D, Wetzel W, Haffner DS et al.(2007) Initial clinical experience with the trabecular micro-bypass stent in patients with glaucoma. Adv Ther 2007; 24(1):161-70.

Tan SZ, Walkden A, Au L.(2018) One-year result of XEN45 implant for glaucoma: efficacy, safety, and postoperative management. Eye (Lond). Feb 2018;32(2):324-332. PMID 28862254

U.S. Food and Drug Administration. FDA Executive Summary, Glaucos, Inc. iStent Trabecular Micro-Bypass Stent. http://www.fda.gov/downloads/AdvisoryCommittees/CommitteesMeetingMaterials/MedicalDevices/MedicalDevicesAdvisoryCommittee/OphthalmicDevicesPanel/UCM220398.pdf. Accessed July 7, 2015.

U.S. Food and Drug Administration.(2012) U.S. Food and Drug Administration. FDA Summary of Safety and Effectiveness Data. Available online at: http://www.accessdata.fda.gov/cdrh_docs/pdf8/P080030b.pdf. Last accessed August 3, 2012.

Vlasov A, Kim WI.(2017) The efficacy of two trabecular bypass stents compared to one in the management of open-angle glaucoma. Mil Med. Mar 2017;182(S1):222-225. PMID 28291477

Vold S., Ike I., Ahmed K., et al.(2016) Two-year COMPASS trial results: Supraciliary microstenting with phacoemulsification in patients with open-angle glaucoma and cataracts. Ophthalmology 2016;123:2103-2112.

Wagschal LD, Trope GE, Jinapriya D, et al.(2015) Prospective randomized study comparing Ex-PRESS to trabeculectomy: 1-year results. J Glaucoma. Oct-Nov 2015;24(8):624-629. PMID 24247999

Wang X, Khan R, Coleman A.(2015) Device-modified trabeculectomy for glaucoma. Cochrane Database Syst Rev. 2015;12:CD010472. PMID 26625212


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