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Subspecialties Glaucoma, Cataract, Business and Innovation, Practice Management

Beyond Comparison

sponsored by New World Medical

Mario Economou, Consultant Ophthalmologist at Queen Sofia Hospital and Praktikertjänst in Stockholm, Sweden, and Achyut Mukherjee, Consultant Ophthalmologist at Oaks Hospital and East Suffolk and North Essex NHS Foundation Trust, Colchester, UK, describe their experience with the Kahook Dual Blade® (KDB) and offer a comparison with the iStent inject®.

Mario Economou is an experienced cataract and glaucoma specialist, who treats both medical and surgical cases. He moved into private practice around 18 months after 17 years at the University Hospital in Stockholm, Sweden. Economou is also affiliated with the prestigious Karolinska Institute, where he has been involved in both research and teaching.

Achyut Mukherjee is a dual fellowship-trained corneal and glaucoma surgeon who treats a high proportion of complex anterior segment conditions and secondary glaucoma, as well as transplant-related glaucoma; however,  the majority of his glaucoma patients have primary glaucoma.

Economou started using the KDB and iStent inject in 2016 and has since incorporated them in his clinical practice, using both regularly in combination with cataract surgery or as a standalone procedure. He says: “I use both the KDB and the iStent for ocular hypertension and mild to moderate glaucoma patients. I have also successfully used the KDB in advanced glaucoma when a trabeculectomy is not an option for various reasons. I think that canal-based procedures, such as KDB goniotomy and iStent inject, are safe and effective options for managing glaucoma and should be offered as a first option in appropriate patients. They can produce sufficient IOP reduction for a large portion of glaucoma patients and/or reduce the number of glaucoma medications without compromising safety. I would say that surgical glaucoma treatment needs to become more stepwise, allowing an early intervention with the canal-based procedures that would allow for a more optimal IOP level for a longer period of time with less dependence on drops.”

Mukherjee was one of the first surgeons in the UK to integrate the KDB into their practice back in 2016, and has since used it in a wide range of open angle glaucoma, primary angle closure, and secondary glaucoma patients. He comments: “I have developed a modification to the KDB procedure using indirect gonioscopy to extend the treated area, which my team has called KDB-XL, and which enhances the effect of the KDB procedure.” He has also been using the iStent, starting with the iStent inject and more recently moving to the iStent inject W.

Hard data

Economou and Thorsteinn Arnljots recently published data retrospectively analyzing the results of procedures using KDB or iStent inject as a standalone procedure or in combination with cataract surgery with two years of follow-up (1). He comments: “Both the KDB and the iStent, when combined with cataract surgery, showed to be effective in reducing the IOP by more than 20-30 percent while also reducing the number of glaucoma medications. The KDB as a standalone procedure reduced the IOP by 28 percent, which is very useful information when offering a new surgical option for patients who are already pseudophakic and have uncontrolled IOP. The study also showed that the KDB had a good effect on eyes with pseudoexfoliative glaucoma, which is often considered to be more difficult to treat. Both the KDB and the iStent inject proved to be very safe procedures. IOP spikes were very rare, while hyphemas self-resolved within a few days.”

Mukherjee’s group recently published clinical results of an extended ab interno trabeculotomy using the KDB, and found that 77 percent of all eyes treated with phaco KDB achieved IOP-related success and reduced medication, compared with 5 percent of eyes treated with just phaco (2).

Patient selection

Mukherjee sees the procedures using the KDB and the iStent inject as appropriate to different patient groups, based on several important differences. In his experience of working with both devices, the KDB lowers the IOP with a greater effect. He uses it up to a 180 degree angle (using indirect gonioscopy with extended KDBXL), whereas his iStent procedures are usually limited to 40-70 degree angles. In terms of corneal opacity, the KDB requires a good angle view, whereas iStent can be safely performed when the cornea limits the view. The risk of hyphema is, in his experience, greater with the KDB, but hyphemas usually resolve spontaneously. The iStent has a shorter operative time – a few seconds in many cases – whereas with the KDB it is longer, which may be problematic in less cooperative patients.

From one surgeon to another

Economou asserts that his experience with the KDB and the iStent inject is very positive. He elaborates: “Since the introduction of these devices, my clinical and surgical armamentarium has been enriched and I can now offer these two options to my patients with ocular hypertension, mild to moderate glaucoma who also have cataracts and have either a suboptimal IOP or are on glaucoma drops that give them negative side effects or compromised compliance.”

Mukherjee concludes: “In my experience, the KDB is highly efficacious in a wide range of glaucomas. My clinical experience is that the IOP lowering effect is greater than that of trabecular bypass stents.”

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  1. TS Arnljots, MA Economou, Clin Ophthalmol, 15, 541 (2021). PMID: 33603332.
  2. M Hamza et al., Medical and Research Publications (2021). 
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