Canaloplasty Glaucoma Surgery
Intended for eye surgeons/ glaucoma specialists who want to master canaloplasty. Canaloplasty is a minimally invasive glaucoma treatment. Although technically challenging, Canaloplasty has several advantages over traditional glaucoma treatments/ surgeries, specially in its safety profile.
Canaloplasty Glaucoma Surgery
Using Mastel Instruments: Part 2 – Dissecting The Deep Flap
So now, one of the things that you can do with the Mastel diamond, with regard to creating the deep flap, is you can set it to 100 or 200 micrometers and use the guarded blade to keep you from going too deep.
Before we get to that. What I’m doing here is, with the superficial flap, I just want to keep that from drying out. So I place some viscoelastic on it and will then use the .06 to just place it underneath my bridle suture. And I like this particular type of bridle suture, which takes two bites through the cornea and comes out on either side of the anticipated superficial incision, so that I can do exactly this: I can just tuck the superficial flap underneath the bridle suture and get it out of my way.
Back to the deep flap. We’re now getting ready for the deep flap, high magnification. I actually prefer just to keep the blade fully extended and freehand it. But again, you have to be very, very careful here because, as I said, there is no real tactile feedback, and this blade is so incredibly sharp that if you put any pressure on this, you really could go right into the eye. So, it’s probably a reasonable thing to use the footplate and guard the incision to 100 to 200 micrometers, for most surgeons.
For me, I don’t like to have the footplate there while I’m making this initial outline of the deep flap. Again, here you can see, I’m just using the diamond blade itself to freehand a little edge of the flap so that I can get some tissue held by the .06 and have some room between the .06 instrument and my diamond blade, since I don’t want to take the risk of dulling this very delicate and very expensive diamond blade.
So, deep flap is actually something that’ll take a lot longer in creating than I do the superficial flap, just because it’s so easy to go a little too deep or a little too shallow.
Now, interestingly, when I used metal blades, when I went too deep, it was actually relatively hard to get the plane of the incision back up into the sclera. But I find that with this diamond blade, if I go too deep and I expose choroid, and I’m right on top of it, this blade is just so sharp all I have to do is just aim it up a little bit and I’m right back into the plane that I want to be, approximately 50 micrometers, superficial to the actual choroid itself.
And so you can see, what I’ve done is I’ve made the initial outline of the deep incision. But I do use the blade to deepen the actual what would you call those? bordering incisions. At this point I’m getting close to what I anticipate to be Schlemm’s canal. I expect I’ll be unroofing it any second here.
And so I’m just taking my time, looking for the change in the scleral fibers, change in color. I feel like I’ve probably gotten there, and so what I’m going to do now is I’m going to lower the pressure in the eye by releasing some aqueous from a previously made paracentesis. In this case, this patient had cataract surgery just prior to the canaloplasty. And I’m also going to release the traction on the bridle suture. So we’ll just release that. And now the bridle suture is just freely hanging, inferiorly.
So at this point, without the bridle suture, in order to get good exposure I will have to use the .06 on the deep flap. So now that the pressure in the eye is lower, I can just, very delicately, dissect this up and expose the canal and Descemet’s window.
All right. So, what I’ve just done is, by dissecting the edges of the flap while keeping traction on the deep flap, I’ve exposed the trabeculo descemetic window there.
So this here is an instrument called the CP manipulator CP for canaloplasty. And this is not a Mastel instrument. This is one of the instruments that’s been around for a few months now. And I’m just very, very gently creating a plane of dissection between the deep scleral flap and the Descemet’s window.
And it is very, very important to be very gentle, at least in my experience. You can actually puncture through Descemet’s, even though this instrument is not sharp, and so I just am very gentle in it. But I do want to get good dissection up and create that potential space, and the reason for that is due to what I’m going to do right now.
I’m going to actually make sure that I can get a good amount of exposure here. So I’m pulling up the superficial scleral flap. And now I’m going to really, really pull up this deep scleral flap as I dissect up along the margin here with my diamond blade. And these diamond blades just work so well when you’ve created a good potential space with the manipulator beforehand, to give you wonderful exposure.
So now I’m going to use this on the other side here, and we’re just going to watch this zip right up. And because I’ve created that potential space, it takes so little effort. And there you have it: I have a good, over 1,000 micrometers of exposure to the trabeculo descemetic window.
About the Author: David Richardson, MD
Medical Director, San Marino Eye
David Richardson, M.D. is widely recognized as one of the top cataract and glaucoma surgeons in the US and is among an elite group of glaucoma surgeons in the country performing the highly specialized canaloplasty procedure. Morever, Dr. Richardson is one of only a few surgeons in the greater Los Angeles area that performs Micropulse® "Cyclophotocoagulation" (MP3) glaucoma laser surgery. Dr. Richardson graduated Magna Cum Laude from University of Southern California and earned his Medical Degree from Harvard Medical School. He completed his ophthalmology residency at the LAC+USC Medical Center/ Doheny Institute. Dr. David Richardson is also an Adjunct Assistant Professor of Clinical Ophthalmology at Keck School of Medicine of USC. Twice weekly, he treats veterans at the VA Greater Los Angeles Veterans Healthcare System.