Canaloplasty: Maximal Impact, Minimal Trauma
How can you look after the corneal health of your glaucoma patients?
David M. Lubeck | | 5 min read
sponsored by Nova Eye Medical
Since the Cypass supraciliary stent was withdrawn from the market in 2018, we’ve become more aware that the corneal endothelium can be damaged by even minimally invasive procedures. Nevertheless, we need to remember that anti-proliferative medications, preservative-containing eye drops, and glaucoma surgical procedures also have deleterious effects on the corneal endothelium, which is already compromised by the direct effects of elevated IOP. How can we mitigate endothelial cell loss (ECL) while effectively managing glaucoma?
One factor under our control is choice of intervention. Ideal approaches minimize corneal trauma by i) avoiding stents and the associated potential mechanical damage to the endothelium; (ii) restoring natural outflow, thus avoiding endothelial trauma associated with artificial flow at isolated points; and iii) preserving meshwork, thus eliminating post-operative inflammation and consequent endothelial trauma. Canaloplasty meet these criteria; for example, canaloplasty works with patient physiology, not against it, to restore aqueous outflow. Not only does it preserve the trabecular meshwork, but it aims to reestablish the function of the trabecular meshwork and, in doing so, help to reset the physiological mechanism of the trabecular meshwork in counteracting IOP fluctuations and elevations. Furthermore, it is an implant-free procedure.
But does canaloplasty really result in improved outcomes? To answer this question, we instigated a study assessing ECL as a measure of canaloplasty safety using the iTrack canaloplasty device (Nova Eye Medical) the results of which will be presented at ASCRS 2023.
Canaloplasty and endothelial cell preservation: study overview
- Prospective multicenter registry study in USA, commenced 2019
- Inclusion criteria: patients undergoing ab interno canaloplasty combined with cataract surgery
- Outcome measures: endothelial cell density and loss, IOP, medications, BVCA, visual field, optic nerve measured with OCT
- Methods: specular microscopy at 0, 6, 12, and 24 months
- Recruitment: 46 patients, 77 eyes (mean age 74.5)
- Controls: age-matched patients undergoing cataract surgery only
The results were extremely striking; mean ECL was only 100 cells per milliliter at 12 months, while mean IOP was reduced by around 20 percent. We found no significant difference in ECL between mild-to-moderate and severe cases (around 3.5 percent loss in each). Similarly, mean IOP dropped from ~17.9 to ~15 mmHg in mild-to-moderate patients, and from ~17.5 to 14.4 mmHg in severe cases (12-month readings); IOP reduction was more significant in uncontrolled than controlled cases.
Thus, our study shows that canaloplasty does not cause significant ECL. By contrast, trabeculectomy ECL rates are 9.5–28 percent at 1–2 years (1, 2, 3, 4, 5), and tube shunt ECL rates are 8–24.6 percent at 2–4 years (6, 7, 8, 9). Further, when we compare our study results against other MIGS devices and procedures, canaloplasty presents as one of the safety MIGS available. Indeed, iTrack is probably the safest MIGS procedure available in terms of corneal preservation.
PQ: “iTrack is probably the safest MIGS procedure available.”
In conclusion, ab interno canaloplasty is a gentler, safer alternative to stent-based or ablative glaucoma surgery, being expressly designed to restore the conventional outflow pathway without inserting implants or otherwise damaging tissue. This comprehensive approach targets all outflow resistance sites, including collector channel ostia, and it is suitable for both phakic and pseudophakic mild-to-moderate cases. The iTrack has been in use in the USA since 2008. More recently, the iTrack Advance has been introduced as the next generation canaloplasty device, combining the tried and trusted iTrack microcatheter with an easy-to-use handpiece. The iTrack Advance is easily adopted by anyone interested in angle surgery. Furthermore, it is a very efficient procedure – advancing through 360 degrees of Schlemm’s canal is easily achieved. I recommend that surgeons consider iTrack Advance when planning management of glaucoma patients.
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
- S Arnavielle et al., “Corneal endothelial cell changes after trabeculectomy and deep sclerectomy,” J Glaucoma, 16, 324 (2007). PMID: 17438428.
- N Nassiri et al., “A comparison of corneal endothelial cell changes after 1-site and 2-site phacotrabeculectomy,” Cornea, 27, 889 (2008). PMID: 18724149.
- T Storr-Paulsen et al., “Corneal endothelial cell loss after mitomycin C-augmented trabeculectomy,” J Glaucoma, 17, 654 (2008). PMID: 19092461.
- J Konopińska et al., “Prospective randomized study comparing combined phaco-ExPress and phacotrabeculectomy in open angle glaucoma treatment: 12-month follow-up,” J Ophthalmol (2015). PMID: 26137318.
- Y Buys et al., “Prospective randomized comparison of one- versus two-site phacotrabeculectomy two-year results,” Ophthalmology, 115, 1130 (2008). PMID: 18171584.
- E Lee et al., “Changes in corneal endothelial cells after Ahmed glaucoma valve implantation: 2-year follow-up,” Am J Ophthalmol, 148, 361 (2009). PMID: 19505676.
- K Kim et al., “Changes in corneal endothelial cell density and the cumulative risk of corneal decompensation after Ahmed glaucoma valve implantation,” Br J Ophthalmol, 100, 933 (2016). PMID: 26508781.
- A Tan et al., “Corneal endothelial cell loss after Baerveldt glaucoma drainage device implantation in the anterior chamber,” Acta Ophthalmol, 95, 91 (2017). PMID: 27495264.
- N Tojo et al., “Baerveldt surgery outcomes: anterior chamber insertion versus vitreous cavity insertion,” Graefes Arch Clin Exp Ophthalmol (2018). PMID: 30171351.