Canaloplasty Minimally Invasive Glaucoma Surgery. Part 7 of 12 of “What’s New In Glaucoma Surgery” Presentation, a continuing education course for Optometrists presented by Patient-Focused Ophthalmologist, Dr. David Richardson on May 20, 2015.
Canaloplasty Minimally Invasive Glaucoma Surgery
Canaloplasty is the one surgery that I truly believe enhances flow without adding significant extra risk and without having the downsides of the more traditional surgeries while still achieving pressure lowering in the range of glaucoma drainage devices. And so this is a very exciting procedure, both to perform as well as to talk about. Let me go over what Canaloplasty is.
Canaloplasty is based on an earlier type of surgery called Viscocanalostomy, which is what basically a dilation of the natural drainage system – the Schlemm’s canal. It’s essentially angioplasty for the eye.
This animation is just reviewing what we already know the ciliary processes produce aqueous fluid, it drains out through Schlemm’s canal. Now much of the literature suggests that for most open angle glaucoma patients it’s the Trabecular Meshwork that is the limiting factor. There’s something in the Trabecular Meshwork that’s blocking the flow. With Canaloplasty the flap is created and this catheter that’s the world smallest catheter- Its really cool to actually see it during surgery, is passed through Schlemm’s canal out the flap and then once it’s out, a suture is tied to the tip of that stent that stent is then brought back through it. As it’s brought back through viscoelastic – usually HEALON® or Healon GV® is used to dilate the canal. So, as with angioplasty, instead of using a balloon as you would for the heart, we use viscoelastic. And then instead of using a springy little device in the heart vessels we use this suture and we tension it. Like a hoodie. It’s pulled in, opens up the canal.
Then the question is, “Well, that sounds really cool but how well does it work and is it really less risky?” Well, it really is less risky and it does work and we’re going to go over that right now. The things that patients like about this it’s non-penetrating. You’re not making a hole lot in the eye and I can’t tell you how many patients come to me telling me that they don’t want that procedure that puts a hole in their eye and I don’t blame them. There’s no bleb. If there’s no hole there’s no bleb. Now, you’ll hear some people who don’t perform Canaloplasty say, “we have heard they end up with bleb anyway” Early on after Canaloplasty, because you are making a flap, if you get a lot of flow you’ll end up with a bleb. I do not have any patients – in the hundreds of Canaloplasty that I’ve performed that have blebs that have maintained. Just don’t. I have a couple of patients who had, maybe a low-lying, kind-of Chemosis but that’s it. And that’s probably through kind-of a transcleral process of fluid moving out.
But the key thing about no bleb is: no bleb means no restrictions on lifestyle activities. You want to go big wave surfing? Get big wave surfing. I’ve another patient who is a Llama farmer. She was told she’d have to sell her farm because she needed Trabeculectomy. She loves her Llamas. That’s her life. Fortunately she had Canaloplasty. Now she’s out in the dirt with her llamas. It’s no big deal. She’s at no extra risk for infection. Contact lenses? Not an issue. No bleb. You want to wear your soft contact lenses afterwards? Go right ahead. It’s safer than traditional surgeries (will go over that). Really, it’s the pro-active lifestyle. Patients love knowing two things.
Our modern well-educated patients like to know that they’re going to be able to maintain their active lifestyle and they like to know that what we’re doing is physiologic. Is natural. Enhancing. They don’t like stuff in the eye, on the eye, elsewhere. They don’t like things that are creating changes in our anatomy that aren’t natural. And this really appeals to many of the modern glaucoma patients.
One Year Result
The question is, does it work? Well, here we have…this is by Dr. Ike Ahmed. Again he’s just an incredibly well-respected surgeon. He’s taught me a lot. He and his, I believe, residents or fellows, actually evaluated. They took a look at patients who had Canaloplasty and compared them to Trabeculectomy with Mitomycin-C. That’s very important to note because the Mitomycin-C is really what allows Trabeculectomy to work so well and to keep the pressure lower. Well here we’ve got one year after surgery, Canaloplasty patients, 13.4 mmHg; Trabeculectomy 12.3. You might jump on that and say, “Ha! There’s an extra point of lowering.” Well, actually it turns out that this is not statistically significant. There’s really no difference but let’s say it was a millimeter difference. I grant you that. You got a millimeter of extra difference for that Trabeculectomy. Well what did you pay to get that millimeter difference? Because nothing’s for free you pay for everything. Whether you pay it with money or risk. In the case of surgery, every extra mmHg that you get from something like Trabeculectomy or tube is paid for with risk. And what are the risks that we’re looking at?
What About Loss of Vision?
Loss of vision- How about that? 2% in Canaloplasty. 16% percent in Trabeculectomy the whole point of glaucoma surgery is to save vision. What are we doing to these patients? Clearly the patients that end up with Trabeculectomy, in general, we feel, are going to lose vision anyway so we’re just trying to slow it down but still look at that difference 2% versus 16%.
I passed over this but this is worth noting too- the number of medications needed to achieve that pressure lowering after Canaloplasty 0.6. After Trabeculectomy 0.7- no difference in the number medications needed a year out. Let’s take a look at the other risks surgery.
What About Other Risks?
Hypotony. We talked about that Trabeculectomy gets the pressure down really low. That’s what everybody says, nothing else is going to get the pressure down in the single digits below 10. OK, well fine but that also means if you’re below 10 you’re pretty near that hypotony risk and hypotony can result in hypotony maculopathy. You think maybe that up to 20% risk of Hypotony maculopathy with Trabeculectomy here might be contributing to the loss of vision? How about other things that we don’t necessarily think of as huge risks but in our patients’ lives it makes a big difference to them: chronic irritation from bleb?
Well, with Canaloplasty, there’s no bleb, no irritation. I’ve actually had patients who’ve had Canaloplasty. Their ocular surface disease improves because you get them off some or all of their medications. They feel better. Their eyes are less irritated and I’ve even had patients (I don’t tell them to expect this but) I’ve even had patient whose best corrected vision improves after Canaloplasty. You’re not going to see that with a Trabeculectomy because you got this bleb, which messes up the tear film results *** irritation. Bleb leak. Again not expected with a bleb-free surgery. 4% per year of patients with Trabeculectomy with Mitomycin-C can end up with bleb leaks. And bleb leaks put you at risk for infection, put you on risk for loss of vision. Vision threatening eye infection, well, we’ve just talked about that. Not with Canaloplasty, yes with Trabeculectomy.
Cataract formation. Here’s an interesting thing: the cataract formation after Canaloplasty appears to be on par with just the natural progression of cataracts. With Trabeculectomy, one of my favorite attendees, made the statement that, “With Trabeculectomy five years out from surgery, your patients are more likely to have developed a cataract than they are to have had their intraocular pressure well-controlled.” Now, think about that for a moment. That’s a crazy statement but the literature actually supports it five years out from Trabeculectomy, 50% of Trabeculectomy will have failed. They have about a 10% per year failure rate. Whereas with cataracts 78% of your patients who’ve had Trabeculectomy will end up with the cataracts, five years out. And that kind of put you behind the *** because cataract surgery increases the risk of Trabeculectomy failure. So, you *** with Trabeculectomy with Mitomycin-C. I had another attendee who told me that is very important that academic glaucoma specialists change institutions every five years. That way you’ll never know what a failure you’ve been. If this is your mainstay of surgery – Trabeculectomy, I can understand that. So, how about three-year results? That was 1 year.
The Three Year Results
The 3-year results…people ask, “Well, okay 1 year, lots of things look good on one year. Even the iStent seem to be okay, in terms of the difference between cataract surgery and the iStent + cataract surgery, but two years out?” No significant difference. Canaloplasty 3-year data are good. Canaloplasty alone, 34% had a mean IOP decrease versus baseline here that’s a, rather, 34% decrease and there is a 50% reduction in the number of drops. Now, here’s the neat thing… Unlike Trabeculectomy, which doesn’t play so well with cataract surgery, Canaloplasty actually works better when it’s done with cataract surgery. When you combine Canaloplasty with cataract surgery, you get a 42% mean reduction in pressure. 81% mean reduction in drops. And this is really outstanding: almost 9 out of 10 patients are drop-free, three years out from Canaloplasty. Without the risk of a bleb, without the risk of infection, without chronic irritation. Almost 90% of patients who have cataract surgery and Canaloplasty are drop-free.
About The Father of Canaloplasty
So, this is Dr. Robert Stegmann. He’s the father of Canaloplasty. You know, he’s just a really interesting guy. He likes to call himself a bush doctor. He works in South Africa and he sees patients that come to him. South African patients. His patients keloid, they scar down. They do not do well with Trabeculectomy. The bleb, almost always fail. Not only that, he sees them and they go back out into the bush and he doesn’t see them for a while so follow ups horrible now and also they’re out on the bush, that’s not a good place to have a cystic bleb that can potentially get infected So, he developed this procedure and he felt very strongly…this is a quote of his, to find a safer, more predictable operation with preferably no complications at all… and he felt that Canaloplasty- and he says this, “is the closest I have ever come to that” this is a surgeon who has the most challenging patients you will ever see and he feels that Canaloplasty is the closest to the ideal that he’s been able to achieve and that really says a lot for this procedure.
What's New In Glaucoma Surgery Series:
- What’s New In Glaucoma Surgery
- Laser Trabeculoplasty ALT, SLT, MLT for Glaucoma
- Trabeculectomy Glaucoma Surgery
- Glaucoma Drainage Devices
- Cyclophotocoagulation and Trabectome for Glaucoma
- Glaukos iStent: A Quick Review and Commentary
- Canaloplasty Minimally Invasive Glaucoma Surgery
- Promising, Pending FDA Glaucoma Surgical Treatments
- Trabecular Microbypass, Hydrus™ Microstent
- Suprachoroidal Implants [SOLX®, STARflo™, iStent Supra®, CyPass®
- Subconjunctival Implants [InnFocus MicroShunt® & Xen 45 Gel Stent]
- Ab-Interno Canaloplasty: The Most Promising, FDA-Approved, Glaucoma Surgical Treatment?