AqueSys Implant

By Rohit Varma, MD, MPH

Many of the devices for microinvasive glaucoma surgery deliver on the promise of a less invasive procedure but, as of yet, without the desired efficacy. This is likely due to differences in the mechanism of action between gold standard procedures targeting subconjunctival outflow and the canal or suprachoroidal approaches.

AqueSys, Inc., has reinvented the approach to subconjunctival outflow. The company's technology is designed to provide a minimally invasive ab interno procedure while safely and significantly lowering the IOP of patients with early, moderate, and refractory glaucoma.

DESIGN

The AqueSys Implant is made of a collagen-derived gelatin. Upon implantation, the device is designed to create a diffuse outflow of aqueous from the anterior chamber into the nondissected tissue of the subconjunctival space. A well-known gelatin was chosen because it is extremely well tolerated by the human body and is noninflammatory. It is also very soft, and this pliability allows the device to conform to the ocular tissue, which should minimize many of the problems associated with synthetic materials (eg, migration, erosion, corneal endothelial damage). The gelatin material is cross-linked during manufacturing, which makes it permanent.

PROCEDURE

The AqueSys Implant (Figure 1) is placed through a small (approximately 1.6 mm) clear corneal incision via a preloaded IOL-like inserter. Using an ab interno approach, the surgeon advances the inserter across the anterior chamber into the quadrant of the eye where implantation is planned. Upon placing the inserter's tip at the desired subconjunctival location, the surgeon delivers the device in a fashion similar to placing an IOL in the bag. The AqueSys procedure is straightforward and can be performed as a primary procedure or in conjunction with cataract surgery.

One clear benefit of the AqueSys ab interno to subconjunctival approach is that it bypasses all potential aqueous outflow obstructions instead of trying to reinvigorate an already failing outflow pathway, as occurs in other approaches.1,2 The conjunctiva-sparing ab interno approach means that additional AqueSys Implants could be placed over the course of the patient's lifetime, if needed. Furthermore, unlike with more invasive ab externo approaches or implants for microinvasive glaucoma surgery that require significant retention features (sutures, barbs, etc.), the AqueSys device can be removed in a straightforward procedure with minimal ocular trauma.

RESULTS

Several multicenter studies are underway in the United States, Canada, Europe, Asia, Australia, and South America. Figure 2 shows the initial 2-year follow-up results from a multicenter study outside the United States in patients with mild, moderate, and refractory glaucoma (n = 107). The data reflect significant IOP lowering from best medicated preoperative IOPs that was sustained over a 2-year period. Follow-up for this study is ongoing.3,4

AqueSys was granted the CE Mark in Europe in 2011 for a broad treatment range for patients with mild, moderate, and refractory glaucoma. The company is currently enrolling subjects under an approved investigational device exemption for its first indication in the United States, with an estimated clearance in 2014.

Rohit Varma, MD, MPH, is a professor with the Department of Ophthalmology and Preventive Medicine at the University of Southern California, Keck School of Medicine, in Los Angeles. He is a paid consultant/advisor to AqueSys, Inc. Dr. Varma may be reached at (323) 442- 6411; rvarma@usc.edu.

  1. Goel M, Picciani RG, Lee RK, Bhattacharya SK. Aqueous humor dynamics: a review. Open Ophthalmol J. 2010;4:52-59.
  2. Gedde SJ, Schiffman JC, Feuer WJ, et al; Tube Versus Trabeculectomy Study Group. Treatment outcomes in the Tube Versus Trabeculectomy (TVT) Study after five years of follow-up. Am J Ophthalmol. 2012;153(5):789-803.e2.
  3. Gomez IK, Dick B. First results of the innovative minimal-invasive glaucoma surgery technique: AqueSys Aquecentesis Procedure. Presented at: XXX Congress of the ESCRS; September 8-12, 2012; Milan, Italy.
  4. Palmberg PF. One year results with the minimally invasive Aquecentesis procedure. Presented at: 6th International Congress on Glaucoma Surgery (ICGS) 2012; September 13-15, 2012; Glasgow, Scotland.

CyPass Micro-Stent

By William J. Flynn, MD

Designed for microinvasive glaucoma surgery, the CyPass Micro-Stent (Transcend Medical) has achieved promising early results in clinical trials. The device is implanted in the supraciliary space to establish a permanent conduit for aqueous filtration via uveoscleral outflow. The uveoscleral outflow pathway is an ideal target for therapeutic intervention for a number of reasons. Experimental evidence indicates that there is a negative pressure gradient between the suprachoroidal space and the anterior chamber, which provides a driving force for aqueous outflow.1 Clinical experience demonstrates that a traumatic or iatrogenic cyclodialysis is associated with a significant decrease in IOP, because it creates nontrabecular outflow through the uveoscleral route.2 Although uveoscleral outflow is relatively independent of IOP when pressure is at normal levels, a cyclodialysis results in a markedly pressure-dependent increase in uveoscleral outflow.3,4 Moreover, experience in glaucoma pharmacotherapy demonstrates that some of the most effective IOP-lowering topical therapies act primarily by increasing uveoscleral outflow.5

DESIGN

The CyPass (Figure 1) is a fenestrated, miniature stent made of biocompatible, nonbiodegradable polyimide material that has demonstrated a minimal inflammatory or fibrotic reaction in preclinical studies in a rabbit model.6 The device is 6.35 mm long and has an external diameter of 510 μm. The inserter for the stent consists of a handpiece and a releasable guidewire. The latter was designed to atraumatically follow the anatomical plane of the potential space between the ciliary body and the sclera.

PROCEDURE

The procedure is performed ab interno. After obtaining a view of the angle with a goniolens, the surgeon identifies the key anatomical landmark, the scleral spur. Loaded in the inserter, the CyPass is then advanced via a paracentesis or phacoemulsification incision across the anterior chamber to a position juxtaposed with the planned site of insertion. The goniolens is reintroduced to view both the CyPass and the scleral spur. The surgeon then implants the device by inserting the guidewire of the inserter just posterior to the scleral spur and advancing the stent so that nearly its entire length is in the supraciliary space (Figure 2). The implantation via the blunt, “noncutting” dissection of the guidewire creates a controlled cyclodialysis that is maintained by the CyPass.

RESULTS

Multiple clinical studies in Europe and the United States are underway or were recently completed. The reports on IOP reduction have been favorable and consistent. Ianchulev shared the first clinical results of more than 81 eyes, which achieved a reduction in IOP from 22.9 to 16.2 mm Hg at 6 months.7 More recently, Hoeh et al reported that combining the implantation of the CyPass with phacoemulsification provided a sustained decrease in IOP that exceeded 35% through 12 months, with more than a 50% reduction in medication.8 The safety data from these initial 265 patients are encouraging. There have been no incidents of erosion of the device or endophthalmitis. Nor are there reports of hypotony maculopathy or choroidal effusion. Suprachoroidal hemorrhages have not occurred, and postoperative hyphema have been infrequent, small, and brief—typically lasting less than 48 hours. Finally, the acute IOP spikes that often accompany spontaneous closure of a cyclodialysis cleft have not occurred.7,8

The current FDA study is the COMPASS clinical trial (compassclinicaltrial.com). This randomized, controlled study is twice the size of any previous microstent trials, with a total of 505 patients. Subjects are randomized either to undergo implantation of the CyPass combined with phacoemulsification or to have phacoemulsification alone. The study has a robust design, with diurnal IOP measurements at baseline, 1 year, and 2 years, all with medication washouts. The investigation will be fully enrolled in the next several months, again with follow-up for 2 subsequent years.

CONCLUSION

Supraciliary stenting with the CyPass Micro-Stent offers a number of potential advantages over canal surgeries and trabecular stents. Because the suprachoroidal space is continuous and larger than Schlemm canal, it may have a significantly higher absorptive capacity for outflow. Moreover, because there is a greater area for stenting in the suprachoroidal space, large devices can be developed. The CyPass has almost three times the internal diameter of a trabecular microstent and six times the length, allowing additional fenestrations that may further enhance outflow. Furthermore, the placement of a suprachoroidal stent at its intended site of implantation is straightforward, is easily confirmed at the time of surgery, and can be imaged postoperatively with ultrasound biomicroscopy and optical coherence tomography (Figure 3).9

The CyPass is minimally invasive, ab interno, conjunctivasparing, nonperforating, blebless glaucoma surgery. The device creates a controlled cyclodialysis cleft that lowers IOP by filtering aqueous from the anterior chamber to the suprachoroidal space. The reported outcomes data so far are encouraging in terms of a successful and sustained reduction in IOP, and the implant appears to be well tolerated by the eye. Moreover, the problems of hypotony and bleeding—so common with cyclodialysis clefts—have not occurred with the CyPass. In this author's experience, the one-step implantation technique is straightforward and easily adopted. Nonetheless, the insertion technique is undergoing further refinement for yet simpler implantation, without the need for surgical gonioscopy.10

William J. Flynn, MD, is a glaucoma specialist in private practice in San Antonio, and he is a clinical professor of ophthalmology at The University of Texas Health Science Center at San Antonio. He is a clinical investigator for Transcend Medical in the COMPASS Clinical Trial. Dr. Flynn may be reached at (210) 340-1212; flynn@rreyes.net.

  1. Emi K, Pederson JE, Toris CB. Hydrostatic pressure of the suprachoroidal space. Invest Ophthalmol Vis Sci. 1989;30(2):233-238.
  2. Barkan O, Boyle SF, Maisler S. On the surgery of glaucoma: mode of cyclodialysis. Am J Ophthalmol. 1936;19:21.
  3. Bill A. The aqueous humour drainage mechanism in the cynomolgus monkey (Macaca irus) with evidence for unconventional routes. Invest Ophthalmol Vis Sci. 1965;4:911-919.
  4. Toris CB, Pederson JE. Effect of intraocular pressure on uveoscleral outflow following cyclodialysis in the monkey eye. Invest Ophthalmol Vis Sci. 1985;26:1745-1749.
  5. Toris CB. Pharmacotherapies for glaucoma. Curr Mol Med. 2010;10(9):824-840.
  6. Nguyen QH, Ahmed IK, Craven ER, et al. Biocompatibility of a polyimide suprachoroidal microstent (CyPass) for intraocular pressure lowering in glaucoma: 6 months rabbit animal model. Invest Ophthalmol Vis Sci. 2012;53:e-abstract 3730.
  7. Ianchulev T. Minimally invasive ab interno suprachoroidal device (CyPass) for IOP control in open-angle glaucoma. Poster presented at: AAO Annual Meeting; October 18, 2010; Chicago, IL.
  8. Hoeh H, Rau M, Reitshamer H, et al. Clinical outcomes of combined cataract surgery and implantation of the CyPass Micro-Stent for the treatment of open-angle glaucoma. Paper presented at: XXX Congress of the ESCRS; September 9, 2012; Milan, Italy.
  9. Ahmed IK, Rau MB, Grabner G, et al. Use of anterior segment OCT for deep-angle visualization after microstent implantation. Paper presented at: ASCRS Congress and Symposium; April 24, 2012; Chicago, IL.
  10. Guguchkova P, Samsonova B, Topov A, Ianchulev T. Gonio-free minimally invasive glaucoma suprachoroidal microstent implantation. Paper presented at: ASCRS Congress and Symposium; April 23, 2012; Chicago, IL.

The Hydrus Microstent

By Robert Marquis MD, PhD

The obstruction of aqueous outflow may cause ocular hypertension and glaucoma. Traditional ab externo glaucoma surgeries carry significant risks, including hypotony, choroidal effusion and hemorrhage, and bleb- or shuntrelated infections, sometimes arising years after the procedure. The clear necessity for safer yet effective surgical intervention has spawned the new class of microinvasive glaucoma surgery, and the initial results of the Hydrus Microstent (Ivantis, Inc.) in studies outside the United States have been encouraging.

DESIGN

Comparable in size to an eyelash, the Hydrus is made from nitinol, a nickel-titanium alloy. Nitinol medical devices have been implanted in various anatomical locations and have demonstrated an excellent safety and biocompatibility profile. Initial studies of the Hydrus show similar safety in the eye, as discussed later. Figure 1 shows the device's dimensions and curvature, which takes the same arc as Schlemm canal.

PROCEDURE

The Hydrus is loaded inside a handheld injector. At the time of surgery, the ophthalmologist observes the nasal iridocorneal angle under direct gonioscopy. The injector's tip is advanced through a temporal corneal wound, then engaged through the trabecular meshwork and delivered into Schlemm canal by the surgeon's advancing the roller wheel mechanism on the injector with his or her index finger (Figure 2).

Outside the United States, the Hydrus is being evaluated in several studies, including comparative effectiveness research against an alternative microinvasive glaucoma surgical approach, in both phakic patients and those undergoing a combined glaucoma-cataract procedure.

RESULTS

Efficacy and Safety

More than 500 Hydrus Microstents have been implanted by over 20 surgeons in 10 countries outside the United States during the past 3 years. Samuelson and colleagues reported the 6-month results of a six-center trial of 29 patients who underwent combined phacoemulsification and Hydrus implantation.1 The average preoperative IOP was 24.6 ±5.3 mm Hg after washout from an average of 2.2 topical medications. The 1-, 3-, and 6-month data showed significant decreases in IOP, averaging 8.7 mm Hg at 6 months (Figure 3). No significant complications were observed during surgery or during postoperative follow-up visits. Remarkably, 79% of patients remained free of medication with an IOP of 18 mm Hg or less at 6 months.

In another report, Samuelson and colleagues discussed the 6-month results for an additional 40 patients who received the Hydrus as an isolated procedure (not combined with cataract extraction).2 The average preoperative IOP was 21.6 ±4.4 mm Hg on an average of 1.7 ±1.4 medications. The 6-month follow-up data showed a significant reduction in IOP to 16.9 ±3.8 mm Hg, and the number of medications needed was also reduced significantly to 0.6 (from 1.7 preoperatively). Minor complications, including transient hyphema that resolved in less than a week, were reported, but no significant complications arose.

Although both trials were limited by sample size and time of follow-up thus far, the results are encouraging and point to the need for additional studies.

Current US Investigational Trial

Presently, a 2-year prospective, randomized, controlled trial is underway in the United States to determine the safety and efficacy of the Hydrus implanted in conjunction with phacoemulsification. The control group undergoes cataract surgery alone. This study design is important to determine the effectiveness of the microstent, because it has been established that cataract surgery alone may lower IOP significantly. This trial should eventually enroll more than 500 patients at more than 30 sites.

The primary endpoint will be a reduction in IOP of at least 20% after medication washout, with results measured at the 2-year postoperative time point. The secondary endpoint will be the difference in IOP reduction between the Hydrus and control groups. Safety outcomes will include vision loss, changes found during a slit-lamp examination, endothelial cell loss, and any other complications or adverse events.

CONCLUSION

Although topical medications have improved with regard to dosing frequency and side effect profile during the past 4 decades, surgical innovations have lagged. Blebless procedures are of great interest, but an ab externo approach (as used in canaloplasty) necessarily compromises a portion of conjunctiva that may be needed for future surgery, whereas an ab interno approach preserves the conjunctiva. The Hydrus Microstent appears to offer some of the same benefits as canaloplasty: dilation of Schlemm canal, improved outflow through the collector channels, and decreased resistance to flow across the trabecular meshwork. The additional advantages of reduced surgical time, minimal postoperative complications, and efficient implantation hold great potential.

Robert Marquis, MD, PhD, is a glaucoma specialist at Texan Eye Glaucoma Service in Austin, Texas. He is an investigator for Glaukos Corporation and Ivantis, Inc. Dr. Marquis may be reached at (512) 327-7000; rmarquis@swbell.net.

  1. Samuelson TW, Lorenz K, Pfeiffer N. Six month results from a prospective, multicenter study of a nickel-titanium Schlemm's canal scaffold for IOP reduction after cataract surgery in open angle glaucoma. Poster presented at: American Glaucoma Society 22nd Annual Meeting; March 1, 2012; New York, NY.
  2. Samuelson TW, Pfeiffer N, Lorenz K. Six month results from a prospective, multicenter study of a nickel-titanium Schlemm's canal scaffold for IOP reduction in open angle glaucoma. Poster presented at: American Glaucoma Society 22nd Annual Meeting; March 1, 2012; New York, NY.

iStent Inject

By E. Randy Craven, MD

With the FDA's clearance of a trabecular microbypass stent, the surgical options for glaucoma will continue to expand as better technology is developed. Based on the 2-year data from the first-generation iStent Trabecular Micro-Bypass Stent (Glaukos Corporation), significantly more eyes in the stent group had an IOP of 21 mm Hg or lower without ocular hypotensive medications than in the control (phacoemulsification alone) group (P < .036). In addition, the IOP with one device was 17 mm Hg at year 1 and remained stable at 17.1 mm Hg at year 2. In the control group, the IOP drifted upward 0.8 mm Hg during year 1 to reach 17.8 mm Hg at year 2. These results indicate that the IOP reduction achieved with the iStent may be sustained. More patients were free of medication in the combined than the control group (61% vs 50%; P = .36.).1 This finding indicates that patients who wish to decrease their dependence on topical IOP-lowering medication after cataract surgery may want to consider an iStent. Of course, surgeons who were not a part of the device's FDA studies are just now starting to evaluate the iStent and how it works in their hands versus in a clinical trial. One of the problems that doctors have struggled with somewhat is the bidirectional movement required for positioning of the stent in Schlemm canal. First, the surgeon must use a medial-lateral movement to get the device across the anterior chamber, and then, an inferior motion is required to position the stent in the canal. A single motion across the anterior chamber in a direction toward the trabecular meshwork would be an easier option, because only medial-lateral movement would be required.

Several years ago, Ike Ahmed, MD, reported on the IOPlowering effect from the placement of more than one iStent. He found that implanting two or three stents produced a lower mean IOP than the placement of a single stent.2 Glaukos Corporation began a trial evaluating an injectable trabecular microbypass stent with two devices loaded in the same inserter (GTS 400 or the iStent Inject). This research is now a prospective, randomized, controlled, pivotal US investigational device exemption trial. The idea is to allow the surgeon to access two areas of the canal of Schlemm and to bypass the trabecular meshwork with two implants on the same inserter, using just a medial-lateral motion to get the devices into the meshwork.

DESIGN

The iStent Inject is a single-piece, heparin-coated titanium stent with a length of 360 μm and a maximum width of 230 μm. It has four outflow orifices that divert aqueous into the canal. The device can be implanted in the right or the left eye (unlike the iStent recently approved by the FDA that comes in right or left eye models). An outside area of reduced diameter, midway along the device, is designed to promote retention within the trabecular meshwork (Figure 1).

PROCEDURE

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The sterile, single-use injector system is preloaded with two stents and designed to deliver them into Schlemm canal. The surgeon traverses the anterior chamber with the injector. Its tip has a sharpened, stainless steel trocar and a stainless steel insertion tube with an insertion sleeve. The stents are aligned on the trocar and are within the insertion tube, which is contained within the insertion sleeve. The injector's housing features an insertion sleeve retraction button and a stent release button. After the trocar penetrates the trabecular meshwork, the surgeon injects a stent by pushing the stent release trigger on the inserter system. After implantation, there are several clock hours of distance between the two stents (Figure 2). The idea behind using two stents is that they will get into the canal of Schlemm and, through closer proximity, tap more collector channels. This may decrease the IOP further than a single iStent.

RESULTS

Two-year results for the first 121 patients who had a medicated IOP of 24 mm Hg or less before undergoing phacoemulsification combined with the implantation of the iStent Inject were released this year. At the time of analysis, 25 subjects who had received stents and 17 control subjects had completed 2 years of follow-up. Of those in the stent treatment group, 68% had an unmedicated IOP of 18 mm Hg or less versus 24% of the control group.3 These results are encouraging, and the technology appears to represent an advance in the options for treating early to moderate open-angle glaucoma.

E. Randy Craven, MD, is an associate clinical professor at Rocky Vista University in Parker, Colorado. Dr. Craven is a consultant to Ivantis Inc. and Transcend Medical and a stockholder in Solx, Inc. He has received research support from Glaukos Corporation, Ivantis Inc., and Transcend Medical. Dr. Craven may be reached at (303) 748-5102; ercraven@yahoo.com.

  1. Craven ER, Katz LJ, Wells JM, Giamporcaro JE. 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;38:1339-1345.
  2. Belovay GW, Ahmed II. Using multiple trabecular micro-bypass stents in cataract patients to treat primary openangle glaucoma. Paper presented at: The ASCRS Symposium and Congress; April 9-14, 2010; Boston, MA.
  3. J. Results from two years postoperative from prospective, randomized studies of second generation stents and cataract surgery in mild-moderate open-angle glaucoma. Poster presented at: American Glaucoma Society 22nd Annual Meeting; March 1, 2012; New York, NY.

iStent Supra

By Jason Bacharach, MD

It is an exciting but challenging moment for physicians who treat patients with glaucoma. Surgeons desire less invasive techniques with quicker rehabilitation times, higher efficiency in the OR, and the ability to combine glaucoma procedures with cataract surgery. Microinvasive glaucoma surgery is characterized as a microincisional technique that involves no destruction of tissue, no corneal flaps, and no disruption of the conjunctiva. On the heels of the FDA's approval of the iStent Trabecular Micro-Bypass Stent (model G-1), Glaukos Corporation has initiated clinical trials to develop a suprachoroidal device (the iStent Supra). The goal is to allow surgeons to lower IOP by enhancing uveoscleral or conventional outflow, both via an ab interno approach.

The iStent Supra is one of a few new technologies that attempt to harness a potentially vacuum-like effect of the suprachoroidal space by shunting aqueous to the area. Once in the suprachoroidal space, the aqueous exits either via a transscleral route or by choroidal absorption. Other technologies under investigation for use in the suprachoroidal space are the Solx Gold Shunt (Solx, Inc.) and the CyPass Micro-Stent (Transcend Medical). I have been a clinical investigator of and have experience placing both the Solx Gold Shunt (via an ab externo approach) and the iStent Supra (via an ab interno approach). (For more on the Solx Gold Shunt, see the sidebar by Marlene R. Moster, MD, on this page.)

DESIGN

The iStent Supra is designed to create a patent lumen between the anterior chamber and the suprachoroidal space. It is made of poyethersulfone and has a colored titanium sleeve. The device also has a proprietary heparin coating (Duraflo) and is biocompatible. It is nonpyrogenic, nonferrous (not magnetic), and terminally sterilized (irradiation). The stent is slightly curved to match the suprachoroidal space. It features retention rings to provide stability at the site of implantation (Figure 1).

PROCEDURE

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The iStent Supra can be implanted in combination with cataract surgery or as a freestanding technique. The keys to successfully implanting the suprachoroidal device are clear visibility of the angle structures and a knowledge of the angle landmarks. The surgeon views the angle through a goniolens placed on the cornea. My tips for optimizing visibility are tilting the patient's head away from the surgeon and zooming up the microscope's power (10×-12×). The stent is implanted right below the scleral spur. Next, the trocar/stent is advanced into the suprachoroidal space until approximately 0.5 mm of the sleeve is left in the anterior chamber. Then, the surgeon engages a trigger mechanism on the inserter to release the stent (Figure 2).

RESULTS

Earlier this year, Eric Donnenfeld, MD, presented the results of a prospective, single-arm, open-label study of 40 subjects (current enrollment, 37 eyes).1 The subjects had moderate to advanced glaucoma (cup-to-disc ratio ≤ 0.9) and no history of surgical intervention for glaucoma. Their preoperative IOP was 18 to 30 mm Hg on two medications (mean of currently enrolled subjects = 20.7 ±2.5 mm Hg). Baseline IOP after washout was 22 to 38 mm Hg (mean of currently enrolled subjects = 24.7 ±1.9 mm Hg). The treatment included one iStent Supra and one postoperative medication (travoprost). The study's protocol includes 2 years of follow-up.

Dr. Donnenfeld reported the status of 25 subjects through 1 year. The mean decrease in IOP at this time point was 43%, with a reduction of one medication. Ninety-six percent of patients met the primary efficacy endpoint of at least a 20% reduction in IOP. All eyes met the secondary endpoint of an IOP that was less than or equal to 18 mm Hg (the IOP was ≤ 15 mm Hg in 80% of subjects). There were no untoward adverse events intra- or postoperatively. Dr. Donnenfeld and his fellow investigators concluded that implanting the iStent Supra as a sole procedure is feasible, safe, and capable of significantly reducing IOP and the need for topical medical therapy in patients with open-angle glaucoma that was previously uncontrolled on two agents. The study is ongoing, and 2-year data are being collected.

CONCLUSION

The flipside to the excellent safety profile of microinvasive glaucoma surgery is that, in general, it lowers IOP less than more invasive procedures (ie, trabeculectomy and tube shunt surgery). An ab interno suprachoroidal shunt such as the iStent Supra may combine the best of these properties by achieving a lower IOP than ab interno stenting of Schlemm canal while maintaining conjunctival integrity.

Jason Bacharach, MD, is the director of research at North Bay Eye Associates, Inc., in Sonoma, California, vice-chair of the Glaucoma Department at California Pacific Medical Center in San Francisco, and chair of the American Academy of Ophthalmology's Practicing Ophthalmologists Curriculum Glaucoma Panel. He is an investigator for and consultant to Glaukos Corporation. Dr. Bacharach may be reached at (707) 762-6622; jb@northbayeye.com.

  1. Donnenfeld ED. Open-angle glaucoma treated with implantation of suprachoroidal stent and topical travoprost. Paper presented at: ASCRS Symposium and Congress; April 20-24, 2012; Chicago, IL.