This video demonstrates surgical technique for iris cerclage, one of the more challenging techniques in eye surgery. This patient presented with an atonic pupil, secondary to trauma and with significant light sensitivity.

Surgeon: Dr. Ike K. Ahmed, University of Toronto, Canada

Transcript

DR AHMED: This patient’s had a traumatic subluxed cataract with an atonic dilated pupil. And we’ll first start by making three incisions. Notice these incisions, where they’re placed. There are three incisions we’ll be using primarily for the iris repair. And they’re equidistant apart. Three incisions. Left, right, and then nasally here, for access. Some lidocaine is injected into the anterior chamber. And then some dispersive viscoelastic is used to fill the anterior chamber, particularly in the area of the dialysis. Now, the cataract procedure will be performed through a temporal clear corneal incision, which is made here, and as you can see here, in this case, a toric IOL is used. A capsular tension ring has been placed in the capsular bag as well. And because we’re gonna be doing a pupilloplasty here, we’re gonna remove viscoelastic from behind the IOL manually, using a 27-gauge cannula. It’s important to do this prior to the repair of the iris, as it may be difficult to access the viscoelastic behind the lens. And this is done manually here, and carefully, to remove all the viscoelastic from behind the IOL, to ensure the toric lens stays in position, to prevent rotation, as well as to reduce the likelihood of a potential postoperative intraocular pressure spike. Here we’re injecting some BSS as well, under the capsule, to ensure that all the OVD has been removed from behind and around the IOL. And we can see the capsule come up. It shows now that the OVD has been removed. Keep in mind that the viscoelastic is still retained in the anterior chamber, to prevent AC shallowing, while it’s been removed behind the IOL. Miochol is placed directly over the iris and swept centrally here to try to achieve some pupillary constriction, which is minimal. And then we use a pair of micrograspers to grab the pupil edge, to bring it forward, see how much tissue is there, look at the distensibility of the tissue, and usually there’s quite a lot of tissue that we can work with. And even with a long-term chronically dilated pupil, we can actually get a significant effect. Now, here’s a 10-0 prolene on a curved CI-4 needle, placed through the nasal paracentesis. The micrograsper is used, and we’re going straight down through iris tissue here, directing the needle into the central anterior chamber space. Notice the direction of the needle during our initial placement, and then we will direct the needle in this case toward the nasal quadrant. For the pupillary cerclage, we take multiple bites through the iris tissue around the pupil. These bites should be as close as possible, and you can see the micrograsper here is being used to hold the iris tissue, to pass a needle through. The suture technique is essentially a running baseball-style suturing technique. You can see the bites here, again, are just literally about a millimeter or less than a millimeter from the pupil edge itself. And it’s important to note that both the suture needle itself is maneuvered into the anterior chamber, and importantly, the micrograsper here presents the iris tissue to the needle, to facilitate its passage. It’s very important, of course, as we work in this closed space, to use the incisions as a fulcrum, to prevent corneal striae and rotation of the needle. And the control here is afforded by these microinstruments. Once we’ve gotten through here, this amount of tissue, as we see, we’re gonna inject a little bit more viscoelastic to preserve the anterior chamber space, as well as remove some of that pigment that’s in our view. And we continue along here, marching toward that superior incision, which in this case is to the left side of our view. And we’re gonna try to grab as much tissue as we can, as we comfortably can here, and notice we’ve changed the trajectory, the angle of that needle, heading toward that superior paracentesis. And particularly toward the end of the needle pass here, most of the work is being done by the micrograsper. Pushing along the iris tissue, along the needle itself, to give us more room at the tip, to pass the iris tissue. Here you can see why it’s helped to grab the needle here, very close to this wedge, to allow enough needle length itself to be placed in the anterior chamber, to grab as much iris tissue as possible. And usually toward the end of this first pass — this is the most challenging aspect here, to prevent a rotation of the needle or iridodialysis. At this point, we’re gonna come out through that superior incision, docking the needle to a 27-gauge cannula, and then pushing and pulling the needle out through that paracentesis. It’s also important to ensure to watch for excessive traction on the iris tissue, as we can see, very diligently and carefully pushing that needle forward. We then remove the needle again, with the needle driver, following the natural curve of the needle. We avoid pulling the needle with the docking needle. It’s much more controllable by using the needle driver itself to pull the needle. And we’re basically gonna pull the needle with some countertraction with a Kuglen hook, following the natural curve of this gently curved CIF-4 needle. And now we’ve made our needle pass to approximately one third of that nasal and superonasal iris. We’re now ready to make our second pass for our pupillary cerclage, and you can see where the iris has entered initially. We’ll recognize that point, as our next pass will be made just adjacent to it. This is double armed 10-0 prolene, with these two CIF-4 curved needles. We’re gonna now go through the same paracentesis we initially came from. And now, using our left hand to hold the needle driver, we will then grasp a needle — again, close to this wedge — and place the first pass very close and adjacent to the initial pass that was made with the first nasal pass. Again, in this case, going through the main incision with the micrograsper, directing the needle toward the main incision, we will then continue the baseball running suture technique here, with the assistance of the micrograsper, to present the iris and actually push the iris through the needle. So you can see in this case, again, the needle is fairly stationary, and the iris itself is being manipulated to bring it to the needle tip as well. This is a bit more controlled. It’s often difficult to control that needle in the anterior chamber, moving it back and forth, without coming out of the previously passed tissue. We’ll switch hands here now, using our right hand to grab the needle, and injecting some more viscoelastic as we approach the temporal incision. You can see now we’ve used our superior incision with the micrograsper to have a better approach, grabbing that iris, and bringing it to the needle tip. So using multiple incisions, really working out what the best angle to use our microinstrumentation is helpful here to be able to access the entire iris and pupil edge for 360 degrees. As well, using both the right hand or left hand, depending, again, on which area of the anterior chamber we’re working in. It’s helpful as you grab that needle. Here again, at the very end of this passage here, this is usually the most challenging part. Important here again to keep that needle as steady as possible, holding with the right hand here, and trying to grab as much tissue as we can, until we get under that temporal incision. Again, using a 27-gauge docking needle, to dock the needle, to ensure we don’t grab any corneal tissue. It’s very important to pass that needle freely through that incision. And that’s why a docked needle helps. Once you get the needle tip through that incision, though, it’s important to release the docking needle, and then pull the remaining needle through the incision, using a needle driver, to allow it to gently follow the curve of that needle, preventing any torquing or any tension on the iris tissue that could inadvertently cause more trauma. Again, countertraction can be used with the Kuglen hook to pull the suture through, and then we’ll evaluate again where that last pass was made. We have to remember that, in terms of where we’re gonna initially be going through. It helps to again get more of a loop into the eye, so we can see where we’re coming from. Now, in this case, we’ve determined that it would be an easier approach to pass the needle through an inferior paracentesis, so we’re actually gonna take that needle that has come out through the temporal incision, dock it through the inferior paracentesis, and pull it out, so we can then — and reenter the eye through the inferior paracentesis. You can see this will give us a much better approach, as we head toward the superior paracentesis. Again, highlighting the importance of using the right incision and the incision placement, as we do the pupillary cerclage. This is now, with our right hand, holding the needle itself, and again, using the same baseball running suture technique here. Micrograsper holding the iris, to pass along. Notice again that we’ve taken multiple bites, probably anywhere from 10 or more bites along each side of the pupillary cerclage. In this case, we divide it up in three. We place our micrograsper through that superior paracentesis, to provide the best access. And we’re almost toward the end of the cerclage here, very patiently and diligently trying to suture the pupil margin here, in a pursestring manner. And you can see we’ve taken note where that last pass was made, along the superior side. Injecting further viscoelastic, to see if there’s still remaining tissue left. It’s important not to try to finish off too early here. If we do, then there can be a little notch that forms there. Which isn’t the end of the world. We can always place an additional simple suture in that area, but it’s nice to be able to get it done here with one suture. Now we’re ready to dock the needle here. Docking with a 27-gauge cannula. We usually place the cannula in viscoelastic, so we can inject into the eye, if need be. And then we’ll gently push and pull. Again, primarily pushing here with the needle driver, releasing from the docking needle, and then pulling the needle completely out. So now we have both ends of the suture out through that superior paracentesis. And we’re now ready to plan on tying the suture. We’ll then use a Kuglen hook to identify both suture ends in the anterior chamber. We’re gonna now cut the needle off both ends of the sutures. And this technique here we’re gonna use — we’re gonna actually bring both of the suture ends out through the main incision. And this will allow us to tie the suture in a modified McCannel technique, and we find this to be usually the easiest and the most titratable and controlled way to tie the suture. There are many ways to tie the suture. It’s very important to control the tension here, as we tie the suture. And therefore we like using combined external/internal technique, as we’ll show here. Other techniques, including the sliding knot, can be used as well. We have a short end and a long end, and we’ll identify here both ends here, along the temporal side of the eye. The long end is grasped with a traditional straight tier, while we have the microtier here being used to loop around itself with the long end of the suture. Grabbing the short end, and then cinching the knot to form a tighter knot, as we bring it into the anterior chamber, and then we’re gonna slide the knot with the pair of the micrograspers into the anterior chamber, and this is where the micrograspers can be very helpful, either through the main incision or through a side port, to pull the short end into the eye, bringing that knot toward the pupil margin, and then tightening it. We’re gonna tighten that suture here to about a 3.5 millimeter pupil size, which is usually our planned aperture. This usually gives us the best balance between reducing photophobia and allowing adequate visibility of the posterior segment, and in the mesopic light setting, for cosmesis. Identify the long end and the short end here. We pull the short end out of the eye, and it’s important to keep that short end relatively short. This allows easy maneuverability into the anterior chamber. So we just trimmed it a little bit there. Almost the length of a corneal diameter. Again, doing a single throw in the reverse direction, to lock the knot here. Using that microtier here to bring that knot into the anterior chamber, pull it tight, to lock that knot onto the pupil edge, where the initial triple throw was made. And this, again, done with the exquisite control of using microinstrumentation, to bring the knot into the eye. This is what we’ve termed the modified McCannel technique, or someone described it as the McAhmed technique, which combines the benefits of the McCannel external suture throwing with the internal aspects of the microtier within the anterior chamber for adequate control. The final throw is made to confirm the knot, and then a microscissor is used to trim those suture ends here to adequate size. Note at the conclusion of the case the pupil has come down quite nicely. Of course, it won’t dilate more than it is right now. But this will significantly reduce the amount of photophobia and glare this patient has had with an adequate cosmesis result in this traumatic subluxation of the lens and atonic pupil. Pupillary cerclage here is probably one of the more complex procedures we do in the eye. And can be done under topical with intracameral lidocaine or retrobulbar block, if necessary.

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December 17, 2019

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