My Canaloplasty Journey
Ab Interno canaloplasty with the new iTrack Advance is a safe and highly effective intervention in mild to moderate glaucoma
Norbert Koerber | | 4 min read
sponsored by Nova Eye Medical
I began performing ab externo canaloplasty as an alternative to trabeculectomy over 15 years ago. I ceased trabeculectomy altogether when it became clear that it was no better than canaloplasty in terms of IOP reduction. The next step was the development of ab interno canaloplasty. This procedure, which I introduced to Germany in 2014, is useful in many patients (see box), particularly those early-stage cases in whom medication is ineffective. Furthermore, ab interno canaloplasty is more efficient than the ab externo approach because of its relatively simple two-step approach: i) clear corneal incision and microcatheterisation to remove blockages in Schlemm’s canal and ii) viscodilation (24–36 clicks) to expand canal and collector channels and create microperforations in the trabecular meshwork. By contrast, the ab externo procedure involves multiple steps: creation of an outer flap, creation of an inner flap/Descemetic window, intubation and stenting of Schlemm’s canal, viscodilation (~6 clicks), suture tying and tensioning, and incision closure.
Who should get ab interno canaloplasty?
- mild-to-moderate glaucoma
- controlled or uncontrolled
- phakic or pseudophakic
- eyedrop-intolerant and/or noncompliant
Notably, the ab interno technique – unlike other MIGS procedures – does not destroy tissue or alter aqueous currents; rather, it aims to preserve trabecular meshwork physiology and therefore preserves future treatment options, too. Also, the ab interno approach is uniquely comprehensive in that it targets all resistance sites, including collector channel ostia. Finally, the new iTrack™ Advanceis more easily adopted than previous techniques, making it more accessible to surgeons and thus available to more patients.
We have now published a retrospective, single-center, consecutive case series (1) summarizing our experience with ab interno canaloplasty (iTrack) in cases of mild-to-moderate POAG with insufficiently reduced IOP and poor medication tolerance. Patients (28 eyes) underwent ab interno canaloplasty, either alone or combined with cataract surgery. Cases were grouped according to the number of medications (0–4). Four-year data are summarized in Table 1. We also now know that, at five years, all groups had statistically significant IOP reductions; the single-medication group showed a reduction in mean IOP from 88 to 37 mmHg and groups on two or three medications both showed mean IOP reductions from ~20 to ~15 mmHg.
|All eyes||Base line||12 M||24 M||36 M||48 M|
|Mean ± SD||19.85 ± 5.2||14.98 ± 2.6||15.58 ±||14.71 ± 3.8||14.56 ± 3.0|
|Stand Alone||Base line||12 M||24 M||36 M||48 M|
|23.5 ± 9.26||17.67 ± 2.3||17.25 ± 7.37||16.33 ± 4.73||17.67 ± 4.16|
|Combined with Phaco||Base line||12 M||24 M||36 M||48 M|
|19.22 ± 4.20||14.63 ± 2.51||15.27 ± 2.01||14.44 ± 3.73||13.93 ± 2.43|
Table 1. Impact of ab interno canaloplasty on IOP in eyes with open-angle glaucoma four-year data.
We are now participating in CATALYST, a prospective, multicenter, randomized clinical study that commenced in 2022. Conducted across five sites in Germany, the study compares iTrack™ Advance and cataract surgery with cataract surgery alone (2). Briefly, CATALYST will recruit up to 80 patients with mild-to-moderate, uncontrolled, primary open-angle glaucoma and randomize them between test and control groups in a 2:1 ratio. Patients will be followed for 12 months commencing. Primary endpoints will be reduction in mean IOP and mean number of medications. Secondary endpoints include adverse events, visual acuity, endothelial cell count, and quality of life outcomes. The study is expected to reinforce the known clinical utility of ab interno canaloplasty in the treatment of mild-to-moderate glaucoma.
In summary, the key feature of ab interno canaloplasty is that it can be combined with cataract surgery for early intervention in mild-to-moderate patients, in whom it controls IOP and reduces medication burden. By contrast, the ab externo approach is indicated for severe or late-stage disease, typically to avoid trabeculectomy or tube shunt procedures. Having performed close to 50 procedures with iTrack™ Advance, I can state that it has major advantages over competing systems – notably, that the simplified nature of the technique makes it a truly single-handed surgical procedure. Briefly, the surgeon uses the uniquely designed cannula to create an opening in the meshwork and then guides the microcatheter into the canal using the handpiece injector – all with only one hand. Further, the device has been designed to catheterise the full 360 degrees of the canal in just one intubation. With other devices, you can only catheterise 180 degrees of the canal at a time.
I believe iTrack™ Advance should be adopted by any practice that manages early-stage glaucoma cases, especially for patients intolerant of or noncompliant with medication.
Norbert Koerber: How I Perform Ab Interno Canaloplasty
- I make the clear corneal incision close to the limbus.
- After inserting the microcatheter, I viscodilate on the way in and out, one click per clock hour.
- Many surgeons inject viscoelastic during withdrawal of the microcatheter only, but I am of the opinion that injecting viscoelastic while advancing the microcatheter dilates the canal in front of the tip, loosening adherences and pushing herniated endothelium away from collector channels. This makes for a gentler procedure.
- Also, the viscoelastic reduces microcatheter-mediated mechanical stress on the endothelium, making endothelial damage less likely.
Watch a panel of experts discuss the iTrack Advance and canaloplasty
Learn more about iTrack™ Advance
iTrack™ Advance has been cleared for the indication of fluid infusion and aspiration during surgery, and for catheterization and viscodilation of Schlemm’s canal for the reduction of intraocular pressure (IOP) in adult patients with open-angle glaucoma. iTrack™ Advance has a CE Mark (Conformité Européenne) for the treatment of open-angle glaucoma. iTrack™ Advance is not available for use or sale in the USA.
- N Koerber, S Ondrejka, “4-year efficacy and safety of iTrack™ ab interno canaloplasty as a standalone procedure and combined with cataract surgery in open-angle glaucoma,” Klin Monbl Augenheilkdr, [Online ahead of print] (2022). PMID: 35426107.
- Nova Eye, “Nova Eye Medical launches multi-centre ‘CATALYST’ study in Europe to investigate canaloplasty with the new iTrack™ TM Advance” (2022). Available at: https://bit.ly/3UTkFWn.