This video demonstrates a surgical technique for combined cataract extraction, IOL implantation and MMC trabeculectomy.
Surgeon: Dr. Ike K. Ahmed, University of Toronto, Canada
DR AHMED: This video describes combined phacotrabeculectomy here. It’s a two sided approach here, we’re using. This is the right eye. We’ll make a standard paracentesis superiorly, being aware to avoid conjunctiva with the incision. And then proceed with our standard temporal approach. Here we’re using a soft shell technique, with a dispersive under the endothelium first. Into the anterior chamber, followed by a cohesive. And we’ll make our standard temporal clear corneal incision using a limbal incision here into clear cornea, as a standard approach. The capsulorrhexis is performed as per usual with a sharp tipped Utrata, and hydrodissection is performed here with a Chang cannula, to ensure adequate mobility and dissection and delineation of the lens. Here this moderate lens is being chopped using a horizontal chop and hemi-flip technique, to remove the endonucleus, followed by epinuclear flip, as we see here, to remove the remaining epinuclear shell. We’re keeping the chamber formed, prior to removal of the phaco handpiece, and here cortical removal is occurring. And also here in this case, the cohesive viscoelastic is used prior to removal of the I/A handpiece, to prevent anterior chamber collapse and shallowing. This will prevent potential risk of choroidals, and these patients who are predisposed, particularly with longstanding glaucoma. Once the IOL has been placed in the bag, in this case, a three-piece lens has been used. The temporal incision is sutured, which is a bit of a departure from the standard clear corneal phaco. To ensure these wounds remain stable for the postoperative period. Before locking the knot, the anterior chamber is pressurized to a normal pressure, to provide tension for the suture, which is not excessive, but just enough to close the wound. This prevents excessive astigmatism created by the suture. The suture is then locked, and hopefully placed in a fairly astigmatically neutral tension. Now we can rotate the scope here, after the knot is rotated here, superiorly. This doesn’t add much more time to the case. And we’re gonna inject with lidocaine here, just over the superior conj area, into the fornix. This conj incision is made, as you’ll see here, 1.5 millimeters back from the limbal insertion. This basically leaves a lip of conjunctiva attached to the limbus here, which we’ll suture back. This is a fornix-based flap, of course, and here you see we’re making this incision about 4 millimeters or so here, and basically elevating the conjunctival flap. You can see now we’re grabbing both Tenon’s and the conjunctiva to create a plane that will be placed just over the sclera, and the blunt tipped Westcott scissors here are used to mobilize that flap. Now, this basically is — the dissection is done primarily to mobilize the flap. The effort here is not necessarily to bluntly dissect posteriorly excessively, for risk of bleeding. Furthermore, I’m not of the opinion that further dissection posteriorly enhances posterior flow, as this is a potential space in which fluid flow will occur posteriorly, naturally. I think it’s more important for the mitomycin to be applied over a reasonable area. We’ll switch hands here and dissect here, in this case, into the slightly superotemporal quadrant, to again ensure that we have adequate mobility of the lens. Here are some corneal protectives, placed in the cornea here, and we will then use a 22-gauge pencil tip cautery, to provide hemostasis. I do like to ensure that we avoid any charring. I also like to ensure that those vessels around where the flap will be made are cauterized sufficiently, to prevent bleeding. It’s better to cauterize them now than during the flap creation, as doing it later may create everted edges, and potentially difficult closures. Again, very light here. This is linear cautery. And here, a corneal light shield has been placed on the cornea. That cautery, again, was basically very light and linear. Linear control. Here you’ll see we’ll grab the sclera here to the left of the conjunctival peritomy, and we’re gonna make our scleral flap here. This scleral flap in our trab dissection here is basically about 3 millimeters or so, by 2 millimeters, as we see here. The radial incisions are basically not into clear cornea, but they’re basically up into that blue zone. The idea is not necessarily to make these incisions too anterior, but just enough to allow the flap to be raised. And we like this flap — this posterior edge here — to be dissected fairly deep. This flap ideally will be anywhere from 1/2 to 2/3 thickness. I think one of the key points of trab surgery is to ensure that we have adequate thickness. Here a diamond SuperCrescent blade is used to create the lamellar dissection. I like to tunnel first here, as you see here, basically consistently staying at that plane, as we dissect forward, and visualizing every so often, as we see here, to ensure that we have maintained that plane. This is very important, of course, to ensure that the depth is maintained. To create a sufficient flap. But once we basically get into that blue zone, we just slightly angle up, without lifting up on our blade. We simply angle up to slightly modify our angle here, of course, with the change in the radius of curvature. The conj-limbal remnant here is basically now placed down, so we can adequately visualize the tunnel of the flap being made with the diamond blade very nicely and smoothly, because it’s a diamond. And we now have reached into that clear corneal region, and we can now stop the progression of the flap. Notice the flap is hung up on each side, again. The idea is that we’ve tunneled forward, past the radial incisions, with the radial incisions, again, being there to help visualize the posterior flap. Now, the conj flap is grabbed here with a curved tier. Being careful to evert the edges, while mitomycin is being placed. This is a half cut Merocel sponge here, with 0.2 milligrams per cc of mitomycin. And you see here we’re ensuring that the edge of the conjunctival flaps are kept away from the mitomycin. Here using a Weck-Cel, and we’re basically placing the mitomycin sponge here, just at the posterior edge of that scleral flap here, to provide the effect. I’ve found generally speaking that this sized Merocel sponge is adequate. There are some who advocate placing more sponges more posteriorly, and I find that’s not quite necessarily, as this sized flap — which is basically about 6.3 — this size of sponge, which is basically 6.3 millimeters — it provides good broad mitomycin coverage and really helps to create diffuse blebs. After two minutes, in this case, we will then remove the mitomycin sponge. In this case, this patient was at high risk for fibrosis, so we’re in fact actually gonna place a second sponge here. And my feeling has generally been: If we go more than two minutes on the sponge, we typically replace it, considering that the tissue saturation of mitomycin has basically reached its limit. And if we do want to get more effect, going for more time is helpful, but placing a second sponge here for an additional minute can be helpful. Again, at the same concentration of 0.2 milligrams per cc. Again, be very careful to ensure that we avoid any contact with the cut edges of the conjunctiva. And using that Weck-Cel here, to clear away any potential mitomycin that may have touched the edge of the conjunctiva. Again, this is placed just at the posteriors of that flap, and you see that scleral flap is slightly lifted under the mitomycin Merocel sponge. We’ll remove that corneal light shield prior to irrigation, and then now remove the mitomycin. You see, before I do remove it, I kind of push it back into the posterior dissection of the conj flap, move it around a bit, and then bring it out, and here we’re gonna now irrigate the field. Most of the mitomycin has basically been bound at this point, but we’ll irrigate particularly under the flap and prior to making an insertion into the eye. And ensure we basically just irrigate around the area, around the conjunctival flap, to ensure that we’ve freed potentially any — cleared any potential mitomycin, although again, most of this is really bound, at this point in time. Here you can see, prior to the incision through the flap into the anterior chamber, we’re gonna place a bit of Miochol here. Keep in mind that the viscoelastic has remained in the eye at this point, and has not been removed, to keep the chamber formed, prior to the sclerotomy being made. Here we’re gonna use a ZAP knife, or any sharp keratome can be used here, to advance — following — maintaining that plane that was initially made. Once we get to the anterior extent, we’ll basically dive down into the anterior chamber, left and right, to make that incision into the anterior chamber, and this is the Descemet’s punch, which is now gonna be used in a bevel fashion here. You can see hooking the posterior, lifting up 45 degrees, and then coming down the punch. I look to the specimen here. And now we can visualize the sclerotomy being made here. Of course, it’s being made into peripheral cornea. The limbus. And you can see we see a little bit of the iris. The idea is not to make this a very posterior bite, but more anterior, and you can see that it’s somewhat beveled. And this is the ideal position. The viscoelastic that’s remained in the eye, which is cohesive, of course, has prevented the chamber from collapsing at this point in time. And we really don’t need to make an iridectomy in this case. As long as the scleral flap sutures will be made at each corner of the rectangular flap. We have a slight bias to place these a bit on the radial side, to ensure we keep that flow going posteriorly, and suture down that radial side. And potentially — in most cases here — we basically place two. I’m using 10-0 nylon here. We’re gonna pull it all the way along here, until we essentially have enough to then make a second throw here. And the second throw is made again here on this temporal side of the corner of this scleral flap here. And of course, the thickness of the flap, as well as the suture tension that’s gonna really regulate the flow postoperatively, which we’re gonna take effort to titrate intraoperatively, as we’ll see shortly… Ensure these passes are made fairly long. This will help to rotate the knot easily, and also will help to visualize sutures for potential postoperative suture lysis. And you can see here we’ve got full thickness in the scleral flap and partial thickness through the posterior sclera. Now we’re gonna use the slipknot here, using a pair of curved tiers and straight tiers. Slipknot here, again, here, two throws in a single direction, done separately, will allow the knot to be slipped, and then can be tightened or loosened, if necessary. We’ll then also do the same for the second suture. And in the vast majority of cases here, we typically place two sutures at each corner. Sometimes, occasionally, a third is required along the posterior edge, and very rarely there are requirements along the radial edge of the flap. And again, because we didn’t cut the radial edges of the flap all the way forward, we do have good protection on our anterior flow, radially. Because of that nice closure there, along the sides of the flap. At this point now we can remove the viscoelastic. We do this simply by irrigating and burping out the cohesive viscoelastic through the main incision. Ensuring that we get all or at least most of it out, pushing on the lens, to get it out of the capsular bag, while irrigating. And at this point now, we can check the flow. Sometimes I do irrigate under the flap as well, to ensure there’s no viscoelastic trapped underneath. But you can see that the flap tension is fairly good. There’s a small trickle of fluid coming through the flap, and it’s important when we check for flow we also check for the pressure in the eye. We want to ensure that the pressure in the eye is at adequate tension to see flow. If the pressure is very low, of course, there will be no flow, and if the pressure is very high, there may be excessive flow. So we’re basically looking for a pressure here running into the high teens, ideally, on palpation. You can palpate with such sensitivity. But approximately, at that level, I hope to see just a little bit of flow here. You see that after a little bit of pressure here, the flow is minimal, and at that point, I’m happy. We will then lock the suture, using a reverse throw here, and of course, we do like to tie the sutures somewhat on the tight side, and always perform suture lysis later on, and we really want to prevent a clot in the early — in this case, this patient actually was a fairly high myope, and this is particularly important to prevent any early postoperative hypotony. We’ll rotate the knot. We like the knot to be rotated here into the scleral flap, avoiding it to be placed within the actual outline of the dissection here, but just under the scleral flap here, as you see here. At this point in time, we’ll just check again for flow here, and you can see that there’s just a little trickle of flow there, with a pressure here probably in about the mid-teens or so, as I palpate on the cornea with a second instrument. This is 9-0 vicryl on a VAS100-4 needle. It’s a special design from Ethicon, and we’re gonna do a horizontal mattress suture here. And notice we’re gonna start on the left hand side here. This needle itself is a spatula design, but not a normal spatula. The wings of the spatula needle are cut off to avoid having an excessively large needle hole or suture tract, to prevent leakage. We’ll at this point now tie the suture to itself, at this point, on the left side here, just a standard triple throw, and I typically do 3-1-1, and then I add an additional 1, as you’ll see here, just to ensure we have good tight closure. And you see here on my left hand, I basically have a straight tier. In my right hand, I have a needle driver, a fine microneedle driver here, to do the work of the conj suturing. And this is again — and then we’ll cut that short end. Now, this is here why we’ve left the conj flap. We’re suturing conj to conj. What we’ve left — this is a fornix-based flap, but we’ve left the small 1 1/2 millimeter conj-limbal tag here. And it’s that tag that we’re gonna use to suture the conj flap to. Typically, we only really need anywhere from 3 to 5 throws here. You can see this is the second throw here. And we go again back and forth in a horizontal mattress fashion. It’s important not to make these throws too close to each other. Really about a millimeter or so apart is all that you need. And you can see we’re going conj to conj. Now, it’s important when we cinch this down that we pull the suture toward the patient’s feet. In that direction. To avoid any cheese wiring through the somewhat thin limbal flap side. You can see here actually this is a fairly nice small conj peritomy that was made actually slightly under 4 millimeters in this case. And really we only required four passes here, or three passes, after the initial knot. We’re gonna leave the remaining loop here at the end. And then do a slipknot again here, to tie the suture to itself, prior to locking. And this is basically — this horizontal mattress suture, when it’s tied to itself, will create an accordion effect of tissue. Again, the slipknot being performed here, and we basically will pull it. So it’s important, very important, to prevent that loop from twisting. Otherwise, we cannot slip it. As we just saw here, that was a single throw, and we just slipped it forward. Usually you need to put two throws in, to ensure that knot stays put, and then you slip it forward like this, as you see here. But it’s very important — it usually is the inside sutures. You see, I’m grabbing there with my right hand. That allows me to slide the knot. And it’s important, very important, again, to prevent twisting of that knot. Or else the suture may not slide adequately. And I like to see this accordion-like effect, the tissue coming together like that, right at that anterior aspect of that flap. Typically that’ll create a nice fine scar in that area, and will of course still maintain adequate flow posteriorly. Once the sutures are cut, we will inject some BSS into the anterior chamber, to evaluate for any leaks, and if there are, we can place individual or mattress sutures where they might be leaking. Again, checking the pressure in the eye here, and looking for the bleb to be raised. It does help sometimes to push at the posterior edge of that flap to see a bleb raised, and there we go. Again, checking for wound leakage, we see a nice bleb form. At this point, now, the surgery is concluded, and the patient will start frequent steroids and antibiotics on the same day. We typically don’t patch our patients. The corneal suture incision — the corneal suture on the temporal incision may be removed about a month postoperatively, and of course, the vicryl suture will resorb after about 4 to 6 weeks. And this is our technique for combined phaco and trabeculectomy procedures. Two-sided approach. Again, here you leave the viscoelastic in the eye until after the scleral sutures have been placed.
December 18, 2019