Canaloplasty is a highly effective surgical technique for the treatment of open-angle glaucoma. Minimally invasive, it uses breakthrough microcatheter technology to restore the function of the eye’s natural outflow system without the need for a filtering bleb – offering an unprecedented level of efficacy and safety in the surgical treatment of glaucoma. As an added benefit, Canaloplasty can be performed at any stage in the glaucoma treatment paradigm and can be used in conjunction with existing drug based glaucoma treatments, after laser or other types of incisional surgery and does not preclude or affect the outcome of future surgery. It can also be combined with cataract surgery in order to maximize IOP reduction while also making the best use of your operating time.
Addressing the full treatment spectrum of the glaucoma disease process, Canaloplasty can be performed via both ab externo and ab interno approaches to Schlemm’s canal in order to best meet your patient’s requirements.
During the procedure, 360-degree viscodilation of Schlemm’s canal opens up the ostia of the collector channels, re-establishing outflow. Specifically, the precisely controlled delivery of Healon/Healon GV during withdrawal of the iTrack™ microcatheter separates the compressed tissue planes of the trabecular meshwork, and also triggers the withdrawal of any herniated inner wall tissue from the collector channels. The ab externo Canaloplasty procedure also entails performing a deep sclerectomy, creating a Descemet’s window and employing a tensioning suture in Schlemm’s canal to provide added longevity in IOP reduction.
ABiC, Ab-Interno Canaloplasty
ABiC™ is a new, comprehensive MIGS procedure. Performed via a self-sealing, clear corneal incision, ABiC™ conserves the clinically proven benefits of 360-degree viscodilation of Schlemm’s canal provided by traditional Canaloplasty, but with the speed and ease of implementation of an MIGS procedure. Unlike other currently available MIGS procedures, however, ABiC™ preserves tissue and does not require permanent placement of an implant in the eye. It has also been shown to be effective as both a stand-alone procedure and as a combined procedure performed in conjunction with cataract surgery.
The most defining aspect of ABiC™ is its comprehensive approach. To date, ABiC™ is the only MIGS procedure that successfully and comprehensively addresses all aspects of potential outflow resistance. Whereas other MIGS procedures treat only one aspect of aqueous outflow, ABiC™ comprehensively accesses, catheterizes, and viscodilates the trabecular meshwork, Schlemm’s canal, and importantly, the distal outflow system, beginning with the collector channels.
Another hallmark of ABiC™ is that it does not involve a permanent implant or stent. Not only does this ensure a more simplified post-operative course, along with a reduced risk of possible complications, it is also well accepted by patients.
With over 60,000 procedures performed to date, clinical studies have shown that Canaloplasty provides an improved safety profile with infrequent intra-operative and post-operative complications and does not result in bleb-related issues compared to traditional glaucoma surgery, such as trabeculectomy. During the procedure, the trabecular meshwork plates are stretched by a suture, which is tied and left in situ in Schlemm’s canal, also ensuring that the canal stays open. The canal itself is dilated over 360 degrees to more than 250 microns in diameter, which helps to pop open any previously obstructed collector channel ostia and restore the natural outflow pathways.
Restoring the Natural Outflow Pathways
Unlike trabeculectomy, which works by bypassing the trabecular meshwork, Canaloplasty specifically addresses all areas of potential “blockage” in the natural outflow system. Using the combination of a stent and viscodilation of the entire Schlemm’s Canal, Canaloplasty restores aqueous flow through the trabecular meshwork into Schlemm’s canal, and out through the collector channels, effectively restoring the normal functions of the natural outflow system.
The Importance of the Collector Channels
Canaloplasty is the only currently available glaucoma procedure to address blockages in the collector channels. Studies undertaken in human POAG eyes by Haiyan Gong, MD, PhD (University of Boston) have shown that many of the collector channels may be blocked with herniated trabecular meshwork tissue at 0 mmHg and become progressively worse as IOP rises. Cannulating the whole of Schlemm’s canal with Canaloplasty, via a process of 360-degree viscodilation, may “pop” open these herniations and enable full access to collector channel ostia for the egressing aqueous. In the case of other glaucoma treatments, where only a segment of Schlemm’s canal is addressed, or where the trabecular meshwork is targeted in isolation, any herniated tissue would most likely prevent improved outflow.
One of the most significant advantages of Canaloplasty is that it works in the absence of a filtering bleb. This leads to more predictable outcomes and easier post-operative management. Indeed, Canaloplasty provides an improved safety profile and enables surgeons to reduce or eliminate many of the intra-operative and post-operative complications associated with trabeculectomy, including ocular discomfort, bleb scarring over, not scarring enough, and infection.
With over 35,000 procedures performed to date, clinical studies have shown that Canaloplasty comprehensively opens up all components of the eye’s natural outflow system to deliver a sustained reduction in IOP*. By addressing all of the possible sites of resistance, including potentially occluded collector channels, Canaloplasty delivers a significant degree of IOP reduction and enables surgeons to obtain post-operative pressures in the range of 12-14 mm Hg, sometimes even as low as 8-9 mm Hg.
* R.A. Lewis, K. von Wolff, M. Tetz, N. Koerber, J.R. Kearney, B.J. Shingleton, T.W. Samuelson. Canaloplasty: three-year results of circumferential viscodilation and tensioning of Schlemm’s canal using a microcatheter to treat open-angle glaucoma. J. Cataract Refract. Surg., 37 (2011), pp. 682-690.
Compared to traditional glaucoma surgery, Canaloplasty offers an improved safety profile with fewer complications and less side effects*. It can therefore be offered earlier in the disease process. Unlike trabeculectomy, Canaloplasty can be performed on patients who wear contact lenses. In addition, patients who have undergone Canaloplasty can continue normal day-to-day activities very soon after treatment and with minimal post-operative follow-up.
* M.C. Grieshaber. Ab externo Schlemm’s Canal Surgery, Viscocanalostomy and Canaloplasty. Dev Ophthalmol. Basel, Karger, 2012, vol 50, pp 109–124
Canaloplasty is changing the glaucoma treatment paradigm by providing an earlier alternative to surgical intervention. Less invasive than traditional glaucoma surgeries, Canaloplasty can be performed without the risks and discomfort associated with trabeculectomy – it can therefore be offered earlier in the disease process.