How has the focus on glaucoma disease progression changed over the past few years?
Robert Petrarca, MD, FRCOphth, MBBS, MCOptom, BSc (Hons): Reducing disease progression to prevent functional blindness in the patient’s lifetime has always been the aim of glaucoma treatment. What is different, however, is the available treatment options. Newer surgical interventions such as MIGS procedures provide a different balance of safety and efficacy compared with traditional filtering surgery.1
Regarding disease progression, we tend to think about the more severe end of the glaucoma spectrum. Are MIGS procedures suitable in patients with advanced glaucoma?
Dr. Petrarca: Over the past few years, the MIGS category has grown vastly. Even within this category, there is a lot of variation in the efficacy and safety of the devices. I don’t believe that MIGS is a replacement for filtering surgery, but some procedures within the MIGS category such as trabecular micro-bypass, for example iStent inject® W (Glaukos), have an excellent balance between safety and efficacy.2 As a result, they can be used much earlier in the disease process, such as in patients with mild to moderate glaucoma, when we might not be comfortable performing a trabeculectomy.
What are the benefits of early intervention with iStent inject® W?
Dr. Petrarca: This question has two parts.
No. 1: What is the benefit of early intervention? Due to improvements in technology, we can diagnose glaucoma faster than ever before. Additionally, the population is aging; around 27% of people in western Europe are aged over 60 years, and it is estimated to grow significantly over the next 5 years.3 The costs of treating glaucoma increase as visual impairment and blindness increase. As more patients are diagnosed with glaucoma, we need to intervene as early as we can to delay disease progression and prevent visual impairment and blindness.
No. 2: What is the benefit of early intervention with iStent inject® W? I favor iStent inject® W for early intervention because it has an extremely high safety profile, similar to cataract surgery.2 I feel comfortable using the device even in the mildest disease, when the patient is having their cataract removed anyway. Apart from patients presenting with glaucoma late, one of the biggest challenges we have in terms of disease progression is patient adherence to medication.4 iStent inject® W improves natural flow of aqueous and works continuously,5 providing surgeons with reassurance that the IOP can be controlled throughout the day.
Is medication reduction the main goal with procedures such as iStent inject® W?
Dr. Petrarca: No, the goal of any glaucoma treatment is to reduce IOP. This is still the only modifiable risk factor. Reducing medication burden and improving quality of life at the same time are additional benefits, but the primary goal has to be to reduce IOP.
What is body of evidence for iStent inject® W in terms of IOP reduction and disease progression?
Dr. Petrarca: iStent technologies have been available for more than a decade, and more than 1 million devices have been implanted worldwide. Between the various iStent devices, there has been more than 250 peer-reviewed publications. There is a high degree of consistency between data from randomized controlled trials (RCTs), real world studies, and even meta-analyses.6 Not only does the data show powerful IOP reduction and a very low degree of visual field progression over the long term (between 5 and 8 years),7-11 but they demonstrate that iStent inject® W may also delay the need for secondary surgical interventions.12
What is the future of MIGS?
Dr. Petrarca: There are many exciting developments in the pipeline, both in terms of glaucoma devices such as iStent infinite® and drug delivery devices such iDose® (Glaukos). In the immediate future, I think we will see iStent inject® W taking its place as a bona fide treatment for mild to moderate glaucoma—not just a way to reduce drops or ocular surface disease but to actually slow disease progression.
The safety data behind iStent inject® shows a low rate of postoperative complications such as peripheral anterior synechiae (PAS) development2 and endothelial cell loss13 that is comparable to cataract surgery in the immediate postoperative period and over the longer term. This gives surgeons the confidence to intervene early.
1. Saheb H, Ahmed IIK. Micro-invasive glaucoma surgery: current perspectives and future directions. Curr Opinion Ophthalmol. 2012;23(2):96-104.
2. Samuelson TW, Sarkisian SR Jr, Lubeck DM, et al. Prospective, randomized, controlled pivotal trial of an ab interno implanted trabecular micro-bypass in primary open-angle glaucoma and cataract: two-year results. Ophthalmology. 2019;126(6):811-821.
3. 2021 Market Scope Glaucoma Surgical Device Market Report.
4. Nordstrom BL, Friedman DS, Mozaffari E, Quigley HA, Walker AM. Persistence and adherence with topical glaucoma therapy. Am J Ophthalmol. 2005;140(4):598-e1.
5. Data on File (Glaukos).
6. Healey PR, Clement CI, Kerr NM, Tilden D, Aghajanian L. Standalone iStent trabecular micro-bypass glaucoma surgery: a systematic review and meta-analysis. J Glaucoma. 2021;30(7):606-620.
7. Berdahl J, Voskanyan L, Myers JS, Katz LJ, Samuelson TW. iStent inject trabecular micro‐bypass stents with topical prostaglandin as standalone treatment for open‐angle glaucoma: 4‐year outcomes. Clin Exp Ophthalmol. 2020;48(6):767-774.
8. Hengerer FH, Auffarth GU, Conrad-Hengerer I. iStent inject trabecular micro-bypass with or without cataract surgery yields sustained 5-year glaucoma control. Adv Therapy. 2022;39(3):1417-1431.
9. Ferguson TJ, Mechels KB, Dockter Z, et al. iStent trabecular microbypass stent implantation with phacoemulsification in patients with open-angle glaucoma: 6-year outcomes. Clin Ophthalmol. 2020:1859-1866.
10. Ziaei H, Au L. Manchester iStent study: long-term 7-year outcomes. Eye. 2021;35(8):2277-2282.
11. 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 Vision. 2021;8(1):1-12.
12. Barton K. A UK cost analysis of trabecular micro-bypass stents in patients with primary open-angle glaucoma NHS commission perspective. Poster presented at: 9th International Congress On Glaucoma Surgery; September 6–8, 2018; Montreal, Canada.
13. Ahmed IIK, Sheybani A, De Francesco T, et al. Long-term endothelial safety profile with iStent inject in patients with open-angle glaucoma. Am J Ophthalmol. doi.10.1016/j.ajo.2023.02.014
iStent inject® W IMPORTANT SAFETY INFORMATION
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-0234