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Subspecialties Glaucoma, Business and Innovation, Cornea / Ocular Surface, Cataract, COVID-19, Practice Management

iStent inject Outcomes

sponsored by Glaukos

Imran Masood, Consultant Ophthalmic Surgeon, Birmingham and Midland Eye Centre, UK, talks about his experience with the iStent inject®.

How important is early intervention with trabecular micro-bypass in glaucoma?
Extremely important! Minimizing topical medication helps improve quality of life (1). Moreover, as eyedrops can lead to ocular surface disease (OSD), reducing their use leaves you better placed for subsequent complex glaucoma surgery involving the conjunctiva – such interventions are more successful in patients using fewer eye drops (2).

How does treatment burden affect compliance and outcomes?
Eye drop application is difficult, especially for elderly patients. Significant force is required to expel the drop from the bottle and even competent patients often miss the eye (3). Errors due to these kinds of administration issues can be exacerbated with increasing polypharmacy (4). Finally, OSD caused by eye drops further inhibits compliance – another reason to reduce treatment burden in glaucoma patients. The disease itself is largely asymptomatic; let’s not cause symptoms by treating it!

In terms of outcomes, it’s clear that eyedrop-associated OSD has a negative impact; it can cause chronic, irreversible periocular changes that may prevent invasive glaucoma surgery. Fortunately, however, OSD doesn’t affect angle surgery or iStent technology surgery, unless damage to the eye is so severe as to cause tight eyelids and scarred conjunctiva. Also, we occasionally see patients with tight orbit syndrome – where over-medication causes melting of orbital fat, resulting in the eyeball sinking into the orbit; in these rare cases, angle surgery also may be contraindicated. But in the vast majority of patients, OSD won’t prevent iStent technology implantation.

What is your experience of iStent technology outcomes in glaucoma patients?
Having started iStent procedures in 2011, I now have patients who were implanted eight or nine years ago and still maintain good IOP control, stable visual fields and visual function – without any further intervention. One case that comes to mind: a patient with early cataract, raised IOP and OSD who had been offered a trabeculectomy in another practice. Instead, we performed sequential cataract and iStent inject surgery; subsequently, with only two medications, her IOP remained low and visual function stable. She so nearly had a trabeculectomy, with all its attendant problems – yet we managed her disease with trabecular micro-bypass and cataract surgery alone. I can also cite patients on two eyedrops who ceased medication altogether after cataract and iStent inject surgery – this combination really puts patient benefit first. I’ve also seen iStent inject provide excellent results in patients with far more complex conditions (see sidebar: “Life- changing outcomes with iStent inject)*.

Could you share any iStent inject case studies?
One of my patients was monocular, highly myopic, with pseudoexfoliation syndrome, IOP ~24, with a dense cataract and severe OSD. They were on four medications. After a combined phaco and iStent inject procedure, his vision improved from 6/60 to 6/12, with stable IOP and vision at five years postop.

Another patient, who had previously undergone trabeculectomy surgery, was monocular, with severe OSD and dense cataract. Following a “grand round” meeting with 10 consultants, I offered phaco and iStent (1st generation). Three years postop – the disease remains stable with a vision of 6/12.

Who is the ideal iStent technology patient?
I would recommend iStent technologies for mild to moderate glaucoma patients. As a rule, if glaucoma patients are having cataract surgery, I believe they should have iStent technology at the same time (provided they meet the official indications). In mild and moderate patients, iStent inject has been shown to reduce the treatment burden and therefore reduces the risk of OSD (2). Increasing numbers of surgeons I know and work with are sometimes using iStent inject in advanced patients, even though it isn’t licensed for use in advanced cases. In brief, for patients with IOP of less than 30, on one, two or three medications, I believe that phaco and iStent technology is a reasonable approach.

Do you see any advantages to using the iStent inject during and after the pandemic?
In the past few months, I have had patients who were unable to attend their appointments and procedures as they were shielding or they were afraid to come to the hospital, even though their IOP became unstable. With trabecular micro-bypass surgery, the risk of complications is very low (5), which means that patients are much less likely to have to return to the OR for further interventions. Postop follow-up is also not as intense as for more complex glaucoma procedures, which also reduces the number of necessary visits and helps keep patients safe at home. Additionally, some patients whose cataracts might have gotten worse in the first months of the pandemic, when cataract procedures were cancelled, have noticed their visual function deteriorating, at a time when they rely on their vision for tasks that keep them occupied at home. Combined cataract and iStent inject surgery has allowed me to improve those patients’ vision at the same time as getting their pressure under control, preventing deterioration of their glaucoma, and improving their ocular surface, which has been very welcome by my patients.

*results may vary


Karsten Klabe, ophthalmic surgeon at Breyer, Kaymak & Klabe Augenchirurgie in Düsseldorf, Germany, has been using iStent technologies for over six years, starting with the first-generation device, progressing through iStent inject, and now switching to iStent inject W. He describes his experience of long-term safety and efficacy outcomes with iStent devices.

Why iStent technologies?
Perhaps the major advantage of iStent technologies is that it allows us to offer both a cure for cataracts and an effective glaucoma treatment within a single surgical episode. That’s important, because about 10-15 percent of our cataract patients also have glaucoma. Furthermore, the benefits are stable over four to five years, as shown by our own results with iStent inject (6) and with the first-generation device (7). Finally, the iStent inject W represents a further improvement in that the new design enhances visibility which helps to facilitate seamless implantation.

Is the iStent inject W easy to introduce into the clinic?
Overall, the procedure is relatively straightforward for cataract and glaucoma surgeons, and the short learning curve simplifies adoption – you feel comfortable after 10-20 surgeries. As noted, it also combines elegantly with cataract surgery – the only additional requirements are viscoelastic and a gonioprism. You don’t need another assistant, nor additional sophisticated devices – you just put a gonioprism on your operating table, and that’s it! Also, the time demands of the procedure are acceptable.

Has the iStent device range changed glaucoma outcomes?
In glaucoma patients, stand-alone cataract surgery is followed, as you would expect, by increased IOP within two years (8), likely necessitating a return to eyedrops. By contrast, most iStent inject patients are medication-free at five years (6)! This outcome is excellent – it bypasses the medication adherence issues that we see in up to a third of patients (9, 10), particularly the elderly. This is a critical point – poor medication adherence results in IOP fluctuations and glaucoma progression. With iStent technology implantation, however, if the patient experiences IOP and medication reduction that results in no further need for medication, the patient will therefore not suffer eyedrop side-effects. So iStent technologies are designed to stabilize glaucoma and can also improve quality of life. It is an excellent option for patients whose glaucoma could be controlled by medication, if only they took it…

What difference does the iStent inject’s safety and efficacy make during and after the COVID-19 pandemic?
The high safety profile and the low complication rate together with the high predictability of the IOP lowering effect are key parameters in treating glaucoma patients with the iStent inject during this pandemic.

The need of fewer postop checkups (on day one and week four in our clinic) and less frequent routine glaucoma examinations benefit especially our elderly patients, help reduce contact, and prevent possible infections.

Any final thoughts?
In summary, my experience is that iStent inject is more straightforward to learn, simpler to apply, less time-consuming, and more predictable than other MIGS-based glaucoma management procedures. It significantly lowers IOP in most patients (6, 11) and enables most of our cataract patients – including the elderly – to reduce eyedrop medication to nearly zero for years after surgery (6, 12). It provides excellent outcomes, including improved quality of life, with a very low complication rate (11). With iStent technologies, the patient’s burden of glaucoma control via medication adherence is replaced by the skill of the surgeon – it’s good for everybody. 

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  1. LM Nijm et al., Asia Pac J Ophthalmol, 9, 481 (2020). PMID: 33323704.
  2. JA Schweitzer et al., Ophthalmol Ther, 9, 941 (2020). PMID: 32789800.
  3. E Mehuys et al., Eye, 34, 1392 (2020). PMID: 31690823.
  4. NBA Hussein et al., J Ophthalmol, 234157 (2015). PMID: 26167292.
  5. M Kozera et al., Clin Ophthalmol, 15, 473 (2021). PMID: 33603321.
  6. K Klabe, Poster presented at the 38th Congress of the ESCRS; October 2-4, 2020.
  7. TH Neuhann, J Cataract Refract Surg, 41, 2664 (2015). PMID: 26796447.
  8. G Vizzeri, RN Weinreb, Curr Opin Ophthalmol, 21, 20 (2010). PMID: 19829115.
  9. CMG Olthoff et al., Ophthalmology, 112, 953 (2005). PMID: 15885795.
  10.  JE Stryker et al., J Glaucoma, 19, 66 (2010). PMID: 20075676.
  11.  M Popovic et al., J Curr Glaucoma Pract, 12, 67 (2018). PMID: 30473602.
  12.  R Lindstrom et al., Clin Ophthalmol, 14, 71 (2020). PMID: 32021070.
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