Navigating the Canal
What is canaloplasty’s place in the glaucoma treatment algorithm?
| 4 min read
sponsored by Nova Eye Medical
We have many MIGS options for treating glaucoma – but where does canaloplasty sit in this array of interventions? The answer becomes clear when we consider the canaloplasty technique and its associated benefits: in brief, this approach catheterizes and viscodilates Schlemm’s canal, thereby restoring natural aqueous flow while preserving trabecular meshwork and other aspects of ocular anatomy. Being stent-free, canaloplasty has no safety issues regarding long-term consequences of implant placement. The technique therefore closely approaches the MIGS ideal: namely, a safe approach to restoration of natural physiology with minimal tissue damage.
That said, different patients have different needs, and surgeons must match the intervention to the individual accordingly. Relevant factors include disease severity, medication load, target pressure, comorbidities, history, and need for cataract surgery. In general, however, canaloplasty is ideally suited for i) reduction of IOP and medication burden in mild-to-moderate uncontrolled patients (both phakic and pseudophakic), and ii) reduction of medication burden in non-compliant individuals, and cases of symptomatic OSD. The suitability of canaloplasty for early-stage patients is a consequence of the mechanism behind elevated IOP in glaucomatous eyes. Briefly, diseased trabecular meshwork accumulates extracellular matrix proteins, which trigger chronic inflammation and fibrosis. In late-stage disease, meshwork sclerosis becomes irreversible; at this point, dilation of the canal is ineffective, and bypass procedures may be the only option. In early-stage disease, before fibrosis has become unmanageable, dilation of the canal can improve outflow. Canaloplasty is a far better option for these patients than decades of eyedrops which – even if effective and well-tolerated – cannot interrupt meshwork fibrosis. In summary, fibrotic progression will ultimately result in non-responsiveness to IOP medications and at the same time make the eye refractory to canaloplasty – so early canaloplasty makes sense.
MIGS procedures, categorized by anatomical site
- Schlemm’s canal:
- dilate Schlemm’s to restore natural outflow pathway
- stent through meshwork
- ablate or excise meshwork
- Supraciliary space:
- stent to bypass obstructed outflow pathway
- Subconjunctival space:
- stent to bypass obstructed outflow pathway
- form a bleb
“The iTrack Advance really is an advance – it’s not just a name.”
The new iTrack canaloplasty device, known as iTrack Advance, has a number of advantageous features, including a spatulated cannula (which assists intubation of the microcatheter into the canal and can also be used to incise the trabecular meshwork tissue), and a slider that helps control microcatheter movement. Moreover, the method has been significantly improved; previously, surgeons needed to make an incision, use forceps, apply a blade to open the meshwork, and then insert the microcatheter. With the Advance, these steps have been eliminated or simplified. After making the incision, the surgeon simply pushes the microcatheter through 360 degrees of the canal and back out again. Importantly, the illuminated tip of the microcatheter visually confirms its location as it traverses the canal – and this is a key point because, if we can continually track the passage of the device, we can ensure it doesn’t end up in the wrong place. As it is withdrawn from the canal, the iTrack Advance employs pressurized injection of hyaluronic acid (HA)-based OVD to stretch the inner canal wall, thereby clearing collapsed regions of the canal and opening collector channels. This also has the mechanism of stretching the trabecular meshwork, to create a more porous structure. Note, too, that iTrack Advance is designed to be equally suitable for both left- and right-handed surgeons.
In conclusion, canaloplasty is a safe and effective intervention suitable for a broad range of glaucoma patients, particularly early-stage cases. These patients can expect reductions in IOP and medication burden via canaloplasty-mediated restoration of natural outflow, without undue ocular trauma. The iTrack Advance is an excellent device for achieving these aims. From a surgeon’s perspective, it is a very easy and convenient technique. Finally, it’s a very efficient procedure – iTrack Advance is the MIGS equivalent of a hot rod!
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