Trabeculectomy


OK. So I’m going to talk about how we do a trabeculectomy with mytomicin-C. The first thing to say is there’s lots of ways of doing trabeculectomies. And this is just one technique that I use. So this is a corneal traction suture. I tend to use a 7-0 vycral so that the superior conjunctiva. You want to go sort of half to two thirds thickness and fairly long so you’ve got a nice secure suture in the superior cornea. I tend to use peribulbar block, pull the eye down, secure it. And here, I’m giving a bit of subconjunctival lignicane. And I’m just massaging it down. And with the vannas scissors, I’m cutting at the limbus, just cutting the conjunctiva. Not really cutting Tenon’s at this stage. Just making a nice clean incision there. Extending a little bit on that side. And then I change to the Westcotts. And I really want to try and get into that space between the sclera and the Tenon’s. So the sub Tenon’s space with some blunt dissection. Sometimes you have to do a bit of cutting to get rid of the Tenon’s. And you really want to make sure you’ve got a nice clean pocket. And you can see me spreading there and making a nice area where the mytomicin-C will go later. Do some cautering now. Some diothermy. Again, you don’t want to do too much of this, but not too little either. It’s a judgment. So too much, you get too much fibrosis. Here I’m using the Tookes knife just to clean away some of that episcleral tissue. So we’ll have a nice clear sclera. And then with a blade, it’s a beaver blade, I’m making an incision sort of about half to two thirds scleral thickness. And with a crescent knife, I’m making a little pocket dissection into the sclera. And I’m aiming to go really quite close to the limbus but not entering the AC. Some side cuts there. And just make sure that the flap is fine. OK. So now we’re going to put in the mytomicin-C. So this is the conjunctival Khaw clamp, named after Peng Khaw. So you grab the conjunctiva. And then with the [INAUDIBLE] I’m placing some mytomicin-soaked sponges into that space that I created earlier. And I’m very careful not to touch the conjunctival edge or the limbus. But you can see me using the MQA to dab away some of that mytomicin-C. Putting in another sponge there. Pushing it as far back as I can. Again dabbing away the excess. And I tend to put one sponge underneath the scleral flap. And you leave this there for about two minutes. But you can make it more or less, depending on various factors such as age of the patient and previous surgery. So leave that for about two minutes. And then take the sponges out. Best to count them, just to make sure you don’t leave one behind. And then with some normal saline, wash out. You just give it a good wash in that area. So what I’m doing now is making a little incision in the peripheral cornea because I’m going to put two releasable sutures here. So sort of half thickness incisions, not all the way through of course. Then a 10-0 nylon backward mounted. And you go in, as you can see, through that little slit that you’ve made. Turn the suture around. And go in again through that pocket. So you’ve made a little loop in that pocket. And you want to come out about halfway through that scleral flap. Pull it through. And again secure that corner. Try not to lift the flap because if you do, then you may find the corner is not opposed. Whereas if you just lie it flat and sort of place it in there as I’ve done, you’ll find that the flap maintains the same configuration and doesn’t alter the tension in the scleral flap. So now we’re doing the same thing exactly on the other side. Now some people don’t put two of these. Some people don’t use any. Or they use one. So you know, that’s just one of the many variations of trabeculectomy technique. So I’m doing exactly the same on the other side, pulling it through so you can see, in that little corneal slit, you’ve got the little loop of the 10-0 nylon. And later on post-operatively if you want to remove that release vault, you can pull on that little loop and the suture will unravel. So I’m not tying them at this stage because I haven’t made the sclerostomy yet. But I’m just keeping it to one side. And then you cut those needles off. And now I’m doing a paracentesis. And so it tends to adjust on the side there. Putting in some miostat or miochol just to constrict that pupil a little bit. Now you don’t want to pull down too much on the cornea now. Because now we’re going to enter the eye. And if you pull down too much, it will flatten. So again with the beaver blade, I sort of make a decision where I’m going to go middle third, full thickness incision. And then with a Kelly punch, make a nice hole there. I’m just pressing down on the flap so the AC doesn’t shallow too much. And then again with the vannas and the calibri, I’m pulling that iris and doing the iridectomy. Cut it flush to the surface. And with the BSS, I’m just giving it a little squish there. And now I’m going to tie those pre-placed releasable sutures. So grab one end. Do three or four throws. Grab the loop. And just pull it secure. Obviously not too tight because you want some flow. But not too loose either. A lot of trabeculectomy is judgment call. So I just filled up the AC a little bit more there because it was a bit shallow. And then I’ll do the same on the other side. One thing you should always be aware of. If you’re handling conjunctiva, best not to use toothed forceps. Always use some blunt forceps like the Pierce Hoskins, for example. Now I’m just checking the flow. It’s always good to have a little bit of flow but not too much. OK. Then you just cut of those suture ends there. The AC is deep. It’s not shallowing. So I’m reasonably happy with that. And now it’s about conjunctival closure. So again with some non-toothed forceps, I’m manipulating the conjunctiva, just sort of putting it back into place. Just check the AC there to make sure it’s reasonably firm. And so again with the 10-0 nylon, I’m going right into the corner there, making a fairly secure suture into that cornea. So it needs to be a good bite of some solid tissue, not sort of episcleral tissue. Sort of pull it through and then you go back. And now you’re going in, out, pull it through. Some people do this all in one stage. And then I’m going to do another in and out. Just to get that sort of tension right. So again from out, in, and then out again. Pull that through. And now you’re going back in. So reverse mounted. And here you can see that white Tenon’s is there. And you really want to make sure you can grab that Tenon’s. OK? So you pulled it through. And then you tie that. Sort of three, one, one. A nice secure tie. And when you tie this, try and do it so you can bury the knot underneath the conjunctiva as you can see me doing there. So sort of lie it flat. Three, one, one. And then cut that so just one end is secured. Then we’re going to do exactly the same on the other side. Nice firm bite into that cornea. And now you have to sort of judge the tension a little bit. So you want to sort of pull it across. OK, where do I need to go? So I’m just doing one in and out procedure there. And then I’m just going to go straight back in because we didn’t need to do two as we did on the other side. So back in again. You can see I’ve grabbed the Tenon’s, the white Tenon’s there underneath the conjunctiva. And again three, one, one. And you try and bury the knot underneath the conjunctiva by lying it flat like that. So now we’re pretty secure. Some people leave it at this stage. But I always put in some limbal mattress sutures just to make sure that that limbal area is secure. Because you really don’t want to have any leakage of aqueous from that limbal area. So here now, that incision into the cornea and then out through the conj. Now if you notice, I’m really trying not to touch the eye as much as possible. It’s almost like a no touch technique. Because you’re almost done now. And if you start pressing on the eye and shallowing the AC because you’ve pressed on the bleb, it can be very difficult. So you can see I’ve grabbed the Tenon’s again. And pull it through. And I tend to do two, one, one here. And I try not to tighten this too much. So you just want a firm apposition of that conjunctiva and Tenon’s to the limbus. And again, try and bury that knot underneath the conj. So don’t pull it too tight. If you pull it too tight, you can sort of alter the tension in the scleral flap. And you can also cause astigmatism as well. So just cutting that flush. And then again this one can be a little bit tricky, as well. So you try not to touch the eye too much. So you can see, I’m just gently lifting the conj. And then I’m not really touching the eye, just a little bit there perhaps. And then pushing it through very, very carefully. Because you really don’t want to disturb that flap. And again backwards through that conj and Tenon’s. And two, one, one firmly apposed but not too tight. And then sometimes at the end, you may want to just check to make sure there’s no ooze from that limbal site. Check the AC is deep. It’s not shallowing. And then you’re pretty much done. Subconjunctival injection of dexamethasone in theory is what I tend to give. Post-operatively I give two hourly Pred Forte, and three hourly levofloxacin. And then we see them, of course, the next day. And we can tailor the frequency of the of the anti-inflammatories according to how they’re doing. So just check on the AC there. And then just give it a little bit of dexamethasone at the bottom of the eye. And then some topical antibiotic drops at the end. And the operation is finished. Just when you’re finishing, be careful when you take off the speculum just to make sure you don’t flatten the AC.

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