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Digital Supplement | Sponsored and Supplied by Glaukos

Demystifying iStent inject® W for Glaucoma Surgery


Glaucoma is the largest cause of irreversible blindness globally.1 To prevent vision impairment, timely diagnosis and effective treatment are required. Prior to the advent of MIGS, glaucoma treatment relied upon decreasing intraocular pressure (IOP) through filtering surgery (that accounts for 48% mean IOP decrease),2,3 medication (18-35% mean decrease),4,5 or laser (25.6% mean decrease).6 More important than IOP, however, we should focus on surgical success,7 quality of life,8 and complications. Classical glaucoma surgery has a steep learning curve9 and presents a risk of potentially blinding complications,10-12 which triggered the development of microinvasive glaucoma surgeries (MIGS).13 iStent® technologies (Glaukos) are the most well-studied of the MIGS procedures. Nevertheless, many myths exist regarding this surgery; we intend to demystify them using scientific evidence.

Myth 1: My patient doesn't need an iStent inject® W—he's fine with eyedrops

Though medical treatment may suffice for many patients, we must be vigilant regarding quality of life, adverse effects, compliance, and glaucoma progression.

Quality of life (QoL) is low in advanced and mild glaucoma.14-16 Unfortunately, medical treatment also significantly decreases QoL,17,18 namely when the treatment is not tolerated8 or complex, when there are adverse effects, when patients have difficulty applying their eyedrops,19 when they cause ocular surface changes (OSC),20 and even sometimes when the eyedrops are tolerated.17,21 There is ample evidence of the multiple adverse effects of glaucoma medical treatment.8,22-25 Even when the eyedrops are tolerated, they can cause OSC, decreasing QoL,17,21 and eventually impairing surgical results.26 Filtering surgery failure risk increases with hyperemia and chronic preservative use.27-29 To further aggravate the problem, glaucomatous patients are frequently non-compliant with their treatment30 (nonadherence varying between 5% and 80%),30,31 particularly if not tolerated, provoking glaucoma progression and further QoL impairment.

In conclusion, the quality of life of glaucomatous patients is low,14-16 and it can be further decreased due to medical treatment; consequently, we should consider alternatives such as laser or surgery. Selective laser trabeculoplasty (SLT) may increase QoL; some studies affirmed finding higher QoL after laser but didn't measure QoL in a validated scale,30,31 while others didn't identify significant improvement (as the EQ15 score in the LIGHT trial).34,35 SLT's IOP-lowering effect usually declines through the years.8,36 Classical filtering surgery decreases QoL in the early postoperative period and sometimes later with bleb-associated complaints.37,38 Isolated phacoemulsification surgery in glaucomatous patients may increase QoL,31 but may also cause IOP spikes,39 previous trabeculectomy failure,40,41 and does not address the real problem of glaucoma progression. Phacoemulsification may decrease IOP, but temporarily,42-44 unlike phacoemulsification with iStent®.45 As for combined phacoemulsification and glaucoma surgery, many studies failed to identify differences in QoL,46,47 except for Samuelson et al.48

Samuelson et al48 performed a posthoc analysis of the iStent inject® pivotal trial (comparing phacoemulsification with phacoemulsification + iStent inject®) focusing on QoL. While both groups increased QoL, interestingly, the phacoemulsification + iStent inject® group showed a higher increase. More specifically, there was higher QoL in the categories of driving (49.0% vs. 28.8%; P < 0.05), ocular pain (59.3% vs. 47.2%; P < 0.05), and general vision (71.8% vs. 60.0%; P < 0.05),46 perhaps due to decreasing medication need.

These arguments favor the use of iStent inject® W with phacoemulsification for glaucoma patients.

Myth 2: MIGS are minimally effective

iStent® technologies are very effective for glaucoma surgery,49-51 even with high baseline IOP, as found by Singh et al.50 In patients with preoperative IOP of ≥ 30 mm Hg, 74.4% remained medication-free 24 months after phacoemulsification + iStent inject®, as opposed to 33.3% in the phacoemulsification group (P < 0.05). Multiple iStents decrease the IOP more than a single stent;52,53 a meta-analysis identified a mean IOP decrease of 9% with phacoemulsification and one iStent®, and 27% with phacoemulsification and two iStents.54 Studies show continued effectiveness up to 8 years postoperatively.45,55

Myth 3: iStent® technologies are not safe or well known

The iStent technologies are currently the smallest devices in the human body, approximately 360 μm in length. Unlike trabeculectomies, the iStent inject® procedure’s learning curve is short. This device has a low rate of complications, comparable to cataract surgery.52,53 It is the most well-studied MIGS device56 with over 250 articles published and 1 million devices implanted. As mentioned before, it has had no severe adverse effects.

Myth 4: For a patient with advanced glaucoma, just operate on the cataract

Isolated cataract surgery in glaucoma patients may cause postoperative IOP spikes,39,57 which can cause fixation loss58 in advanced glaucoma patients. Combined phacoemulsification with iStent inject® W is a safe approach, allowing better IOP control due to its micro-trabecular design (postoperative surveillance is needed in all patients, and an IOP spike can happen even in combined surgery, namely with steroid response). Fortunately, there are no reports of fixation loss with iStent and no reports of serious adverse events,49,50 even in advanced glaucoma.51 And, since they are small and usually implanted nasally or inferiorly, iStents do not preclude a future trabeculectomy.

In conclusion, iStent inject® W is safe, effective long-term, easy to learn, and improves QoL. We should carefully choose the most appropriate treatment for each patient in a multifactorial decision, considering not only glaucoma staging, progression, and IOP but also the patient's age, daily tasks, ability to drive, eye comfort, vision stability, and QoL.

1. Quigley HA, Broman AT. The number of people with glaucoma worldwide in 2010 and 2020. Br J Ophthalmol. 2006;90(3):262-267.

2. Musch DC, Gillespie BW, Niziol LM, Cashwell LF, Lichter PR. Factors associated with intraocular pressure before and during 9 years of treatment in the Collaborative Initial Glaucoma Treatment Study. Ophthalmology. 2008;115(6):927-933.

3. Kirwan JF, Lockwood AJ, Shah P, et al. Trabeculectomy in the 21st century: a multicenter analysis. Ophthalmology. 2013;120(12):2532-2539.

4. van der Valk R, Webers CAB, Schouten JSAG, Zeegers MP, Hendrikse F, Prins MH. Intraocular pressure–lowering effects of all commonly used glaucoma drugs: a meta-analysis of randomized clinical trials. Ophthalmology. 2005;112(7):1177-1185.

5. Li T, Lindsley K, Rouse B, et al. Comparative effectiveness of first-line medications for primary open-angle glaucoma: a systematic review and network meta-analysis. Ophthalmology. 2016;123(1):129-140.

6. Woo DM, Healey PR, Graham SL, Goldberg I. Intraocular pressure-lowering medications and long-term outcomes of selective laser trabeculoplasty. Clin Exp Ophthalmol. 2015;43(4):320-327.

7. World Glaucoma Association, In: Shaarawy T, ed. Guidelines on Design and Reporting of Glaucoma Surgical Trials. Amsterdam: Kugler; 2009.

8. European glaucoma society terminology and guidelines for glaucoma, 4th edition-chapter 2: classification and terminology. Br J Ophthalmol. 2017;101(5):73-127.

9. Ge J. [The importance of learning fundamental techniques and contemporary progresses in trabeculectomy]. Zhonghua Yan Ke Za Zhi. 2009;45(1):3-4.

10. The AGIS Investigators. The Advanced Glaucoma Intervention Study (AGIS): 11. Risk factors for failure of trabeculectomy and argon laser trabeculoplasty. Am J Ophthalmol. 2002;134(4):481-498.

11. Alemu B. Trabeculectomy: complications and success in IOP control. Ethiop Med J. 1997;35(1):1-11.

12. Alwitry A, Rotchford A, Patel V, Abedin A, Moodie J, King AJ. Early bleb leak after trabeculectomy and prognosis for bleb failure. Eye (Lond). 2009;23(4):858-863.

13. Ahmed IIK. MIGS and the FDA: What's in a Name? Ophthalmology. 2015;122(9):1737-1739.

14. Lester M, Zingirian M. Quality of life in patients with early, moderate and advanced glaucoma. Eye (Lond). 2002;16(1):44-49.

15. Okamoto M, Sugisaki K, Murata H, Hirasawa H, Mayama C, Asaoka R. Impact of better and worse eye damage on quality of life in advanced glaucoma. Sci Rep. 2014;4:4144.

16. Miguel A, S.J., Azevedo L, Henriques F, Andrês R, Lopes N, Rito F, Loureiro AR, Quality of Life in Glaucoma in Portugal. Oftalmologia. Suppl – Vol. 36: pp.33-40, 2012.

17. Pastore MR, Milan S, Agolini R, et al. How could medical and surgical treatment affect the quality of life in glaucoma patients? A cross-sectional study. J Clin Med. 2022;11(24).

18. Quaranta L, Riva I, Gerardi C, Oddone F, Floriani I, Konstas AGP. Quality of life in glaucoma: a review of the literature. Adv Ther. 2016;33(6):959-981.

19. Miguel AIM, Fonseca C, Oliveira N, Henriques F, Silva JF. Difficulties of daily tasks in advanced glaucoma patients—a videotaped evaluation. Rev Bras Oftalmol. 2015;74:164–170.

20. Bonniard AA, Yeung JY, Chan CC, Birt CM. Ocular surface toxicity from glaucoma topical medications and associated preservatives such as benzalkonium chloride (BAK). Expert Opin Drug Metab Toxicol. 2016;12(11):1279-1289.

21. Zhang X, Vadoothker S, Munir WM, Saeedi O. Ocular surface disease and glaucoma medications: a clinical approach. Eye Contact Lens. 2019;45(1):11-18.

22. Ophthalmology, A.A.o., Basic and Clinical Science Course. Section 10: Glaucoma.: p. 192-220.

23. Potop V. [Glaucoma treatment and adverse effects]. Oftalmologia. 2013;57(3):19-22.

24. Mirza SK, Higginbotham EJ. Iatrogenic glaucoma therapy failure: the adverse effects of topical antiglaucoma medication treatment outcome. Expert Rev Clin Pharmacol. 2009;2(1):87-99.

25. Camras CB, Toris CB, Tamesis RR. Efficacy and adverse effects of medications used in the treatment of glaucoma. Drugs Aging. 1999;15(5):377-388.

26. Baudouin C, Kolko M, Melik-Parsadaniantz S, Messmer EM. Inflammation in glaucoma: from the back to the front of the eye, and beyond. Prog Retin Eye Res. 2021;83:100916.

27. Chamard C, Larrieu S, Baudouin C, Bron A, Villain M, Daien V. Preservative-free versus preserved glaucoma eye drops and occurrence of glaucoma surgery. A retrospective study based on the French national health insurance information system, 2008-2016. Acta Ophthalmol. 2020;98(7):e876-e881.

28. Thieme H, van der Velden KK. [Preservatives from the perspective of glaucoma surgery]. Ophthalmologe. 2012;109(11):1073-1076.

29. Boimer C, Birt CM. Preservative exposure and surgical outcomes in glaucoma patients: The PESO study. J Glaucoma. 2013;22(9):730-735.

30. Schwartz GF. Compliance and persistency in glaucoma follow-up treatment. Curr Opin Ophthalmol. 2005;16(2):114-121.

31. Skalicky SE, Goldberg I. Adherence and persistence: the challenges for glaucoma medical therapy. Asia Pac J Ophthalmol (Phila). 2013;2(6):356-361.

32. Keyser MD, Belder MD, Groot VD. Quality of life in glaucoma patients after selective laser trabeculoplasty. Int J Ophthalmol. 2017;10(5):742-748.

33. Todorovic D, Vulovic TS, Sreckovic S, Jovanovic S, Petrovic N. The effect of primary argon laser trabeculoplasty on intraocular pressure reduction and quality of life in patients with pseudoexfoliation glaucoma. Acta Clin Croat. 2021;60(2):231-236.

34. Yong MH, Hamzah JC. Selective laser trabeculoplasty vs. topical medications for step-up treatment in primary open angle glaucoma: comparing clinical effectiveness, quality of life and cost-effectiveness. Med J Malaysia. 2020;75(4):342-348.

35. Gazzard G, Konstantakopoulou E, Garway-Heath D, et al. Laser in glaucoma and ocular hypertension (LiGHT) trial. A multicentre, randomised controlled trial: design and methodology. Br J Ophthalmol. 2018;102(5):593-598.

36. Eckert S. [Effectiveness and relevance of laser trabeculoplasty: treatment of open-angle glaucoma]. Ophthalmologe. 2010;107(1):18-21.

37. Barton K. Bleb dysesthesia. J Glaucoma. 2003;12(3):281-284.

38. Sartor L, Northey LC, Wells M, White AJ. Management of bleb dysesthesia following subconjunctival micro-invasive glaucoma surgery by revision with fibrin glue. Clin Exp Ophthalmol. 2022;50(4):463-464.

39. Seol BR, Shin JY, Choi S, Kang TG, Jeoung JW, Park KH. Intraocular pressure (IOP) change and frequency of IOP spike after cataract surgery in normal-tension glaucoma: a case-control study. J Glaucoma. 2019;28(3):201-206.

40. Swamynathan K, Capistrano AP, Cantor LB, WuDunn D. Effect of temporal corneal phacoemulsification on intraocular pressure in eyes with prior trabeculectomy with an antimetabolite. Ophthalmology. 2004;111(4):674-678.

41. Derbolav A, Vass C, Menapace R, Schmetterer K, Wedrich A. Long-term effect of phacoemulsification on intraocular pressure after trabeculectomy. J Cataract Refract Surg. 2002;28(3):425-430.

42. EGS, European Glaucoma Society Terminology and Guidelines for Glaucoma, 5th Edition. 2020.

43. Committee, A.A.o.O.P.P.P.G., Primary open-angle glaucoma Preferred Practice Pattern 2020.

44. Canadian Ophthalmological Society Glaucoma Clinical Practice Guideline Expert, C. and S. Canadian Ophthalmological, Canadian Ophthalmological Society evidence-based clinical practice guidelines for the management of glaucoma in the adult eye. Can J Ophthalmol. 2009;44 Suppl 1:S7-93.

45. Ziaei H, Au L. Manchester iStent study: long-term 7-year outcomes. Eye (Lond). 2021;35(8): 2277-2282.

46. Janz NK, Wren PA, Lichter PR. The collaborative initial glaucoma treatment study: interim quality of life findings after initial medical or surgical treatment of glaucoma. Ophthalmology. 2001;108(11):1954-1965.

47. Garway-Heath DF, Lascaratos G, Bunce C, et al. The United Kingdom glaucoma treatment study: a multicenter, randomized, placebo-controlled clinical trial: design and methodology. Ophthalmology. 2013;120(1):68-76.

48. Samuelson TW, Singh IP, Williamson BK, et al. Quality of Life in Primary Open-Angle Glaucoma and Cataract: An Analysis of VFQ-25 and OSDI From the iStent inject® Pivotal Trial. Am J Ophthalmol. 2021;229:220-229. doi:10.1016/j.ajo.2021.03.007

49. Samuelson TW, Sarkisian SR, Lubeck DM, et al. Prospective, Randomized, Controlled Pivotal Trial of an Ab Interno Implanted Trabecular Micro-Bypass in Primary Open-Angle Glaucoma and Cataract. Ophthalmology. 2019;126(6):811-821. doi:10.1016/j.ophtha.2019.03.006

50. Singh IP, Sarkisian S, Hornbeak D, et al. Treatment Success Across Different Levels of Preoperative Disease Burden: Stratified Two-Year Outcomes from the Pivotal Trial of iStent inject® Trabecular Micro-Bypass in Primary Open-Angle Glaucoma and Cataract. Clinical Ophthalmology. 2021;Volume 15:3231-3240. doi:10.2147/OPTH.S316270.

51. Ansari E. 5-year outcomes of single iStent (G1) trabecular microbypass implantation with phacoemulsification in moderately advanced primary open angle glaucoma. PLoS One. 2021;16(9):e0257015. doi:10.1371/journal.pone.0257015

52. Lavia C, Dallorto L, Maule M, et al. Minimally-invasive glaucoma surgeries (MIGS) for open angle glaucoma: A systematic review and meta-analysis. PLoS One. 2017;12(8):e0183142. doi:10.1371/journal.pone.0183142

53. Gillmann K, Mansouri K. Minimally Invasive Glaucoma Surgery: Where Is the Evidence? Asia-Pacific Journal of Ophthalmology. 2020;9(3):203-214. doi:10.1097/APO.0000000000000294.

54. Malvankar-Mehta MS, Chen YN, Iordanous Y, et al. iStent as a Solo Procedure for Glaucoma Patients: A Systematic Review and Meta-Analysis. PLoS One. 2015;10(5):e0128146. doi:10.1371/journal.pone.0128146.

55. Salimi A, Watt H, Harasymowycz P. Long-term outcomes of two first-generation trabecular micro-bypass stents (iStent) with phacoemulsification in primary open-angle glaucoma: eight-year results. Eye and Vision. 2021;8(1):43. doi:10.1186/s40662-021-00263-1.

56. Nichani P, Popovic MM, Schlenker MB, et al. Microinvasive glaucoma surgery: A review of 3476 eyes. Surv Ophthalmol. 2021;66(5):714-742. doi:10.1016/j.survophthal.2020.09.005.

57. O’Brien PD, Ho SL, Fitzpatrick P, et al. Risk factors for a postoperative intraocular pressure spike after phacoemulsification. Can J Ophthalmol. 2007;42(1):51-55.

58. Bhadra T, Ghosh R, Saurabh K, et al. Prospective evaluation of wipe-out after glaucoma filtration surgery in eyes with split fixation. Indian J Ophthalmol. 2022;70(10):3544. doi:10.4103/ijo.IJO_501_22.

Ana Miguel, MD, PhD, FEBO
  • Fellowship: Glaucoma and Advanced Anterior Segment Surgery, Prism Eye Institute and Toronto University, with Ike Ahmed, MD FRCSC, Canada
  • Opthalmologue de l’Hopital Prive de la Baie, Avranches, France
  • Glaucomatologue au Centre Hospitalier et Universitaire de Caen, France


INDICATION FOR USE: The iStent inject® W, is intended to reduce intraocular pressure safely and effectively in patients diagnosed with primary open-angle glaucoma, pseudo-exfoliative glaucoma or pigmentary glaucoma. The iStent inject® W, can deliver two (2) stents on a single pass, through a single incision. The implant is designed to stent open a passage through the trabecular meshwork to allow for an increase in the facility of outflow and a subsequent reduction in intraocular pressure. The device is safe and effective when implanted in combination with cataract surgery in those subjects who require intraocular pressure reduction and/or would benefit from glaucoma medication reduction. The device may also be implanted in patients who continue to have elevated intraocular pressure despite prior treatment with glaucoma medications and conventional glaucoma surgery. CONTRAINDICATIONS: The iStent inject® W System is contraindicated under the following circumstances

or conditions: • In eyes with primary angle closure glaucoma, or secondary angle-closure glaucoma, including neovascular glaucoma, because the device would not be expected to work in such situations. • In patients with retrobulbar tumor, thyroid eye disease, Sturge-Weber Syndrome or any other type of condition that may cause elevated episcleral venous pressure. WARNINGS/ PRECAUTIONS: • For prescription use only. • This device has not been studied in patients with uveitic glaucoma. • Do not use the device if the Tyvek® lid has been opened or the packaging appears damaged. In such cases, the sterility of the device may be compromised. • Due to the sharpness of certain injector components (i.e. the insertion sleeve and trocar), care

should be exercised to grasp the injector body. Dispose of device in a sharps container. • iStent inject® W is MR-Conditional; see MRI Information below. • Physician training is required prior to use of the iStent inject® W System. • Do not re-use the stent(s) or injector, as this may result in infection and/or intraocular inflammation, as well as occurrence of potential postoperative adverse events as shown below under “Potential Complications.” • There are no known compatibility issues with the iStent inject® W and other intraoperative devices. (e.g., viscoelastics) or glaucoma medications. • Unused product & packaging may be disposed of in accordance with facility procedures. Implanted medical devices and contaminated products must be disposed of as medical waste. • The surgeon should monitor the patient postoperatively for proper maintenance of intraocular pressure. If intraocular pressure is not adequately maintained after surgery, the surgeon should consider an appropriate treatment regimen to reduce intraocular pressure. • Patients should be informed that placement of the stents, without concomitant cataract surgery in phakic patients, can enhance the formation or progression of cataract. ADVERSE EVENTS: Please refer to Directions For Use for additional adverse event information. CAUTION: Please reference the Directions For Use labelling for a complete list of contraindications, warnings and adverse events. Glaukos®, iStent®, iStent inject®, iStent inject® W and iDose® are registered trademarks of Glaukos Corporation. All rights reserved. ©2023 PM-EU-0267