Surgery: Deep Anterior Lamellar Keratoplasty (DALK)

She has lattice dystrophy. You can see the central cornea is very cloudy. It’s not easy to appreciate the lattice-like changes, but you could see them when we were at the slit lamp. It wasn’t severe. It was more like some subepi scarring, almost like a combined type of endothelial dystrophy with some stromal changes. So what we’re gonna do is we’re gonna attempt to do a DALK, and if we’re not successful, we’ll do a PK. I’m just marking the center of the cornea. I’ll take that optical zone marker. So that’s 8. We’re going to a 7.5 graft, so we’re gonna go inside of that. So what we’re doing now — so there’s different ways to do DALK, okay? The most popular way is the big bubble, where you do some partial trephination and then you inject air into it. The way I learned is called the Melles technique, and it seems to have served me well. You can still perforate, and you don’t get bare Descemet’s membrane, but you get good results, and at least in my hands, it’s kind of what I always did. Now, what we do in this technique is we want to create a scleral tunnel here. You can burrow into clear cornea and then do a lamellar dissection. Okay. So what we’re gonna do is we’re gonna make a scleral groove here. Now, how deep do you want to go? You want to go about half scleral thickness, around 400 or 500 microns. And how do you know that? Well, you start to see a little bit of the bluish tint of the choroid underneath. So that looks maybe a little bit too superficial. Now I’m good. Now you can see I have enough depth where you can see the blade here. Okay? But there’s some thickness to it. You’re not just about to perforate, like you would if you’re too thin. Okay? So I’m flat here. And now I’m burrowing up into clear cornea. You can see that, passing the limbal vessels there. That’s about as far as I need to go. Now when I need to go back, I cut going backwards, like this. So that I stay in the same tunnel. So now I always go back in the same groove. So I fixate the eye here. I enter again here. And in my same groove, and then I’m cutting as I go back, and then I wiggle forward just a little bit, always keeping in the base of that, and I come back, and I wiggle forward a little bit. I can tell I’m at a good depth here, because I’m pretty deep in the cornea. Maintaining a nice plane. So now we have our plane of dissection. Okay? And so this is what that spatula looks like. It’s called a Morlet spatula. It’s made by Duckworth and Kent, and there’s two sides to it. There’s this side, that has a little more of a cutting blade, and you can kind of enter with this and gauge the depth, and then this is what you use for dissection, and you can see it can reach across the cornea, and it has a little bit of a curve to it. Now, before I do this, what I have to do is I have to put air in the anterior chamber so that the eye is firm. If I try to do it with a soft eye like this, Descemet’s membrane is more likely to bunch up and then tear. Okay. So where do I make this incision? We’re gonna fill the AC with air. So I want to make it inferiorly. So I’m gonna rotate the eye down a little bit, and I make a little stab incision at the limbus. So now I’m in the eye. Okay. I’m letting aqueous out. So now I get a bubble. Okay? Now, you see how the bubble wants to escape? I need to put a suture through that, so it stays closed. Okay. Now we need to put that air bubble and make it full now. So now we’re pretty firm. So I’ll take the Morlet spatula back, and then we’re gonna put some viscoelastic on, and that helps to keep it a little smooth. And then this part is just real tedious. So now you see I’m in the right plane, and I’m just dissecting like that. And it’s fairly easy. You can see how nice it moves. It’s very smooth. And then here you’re just making little micromovements. And you’re kind of watching to make sure the pressure stays high. The trick here is you’ve got to keep this guy — has to stay flat. And you have to respect the curve of the eye. If you start to lift up this, then you’re pushing down here, like a pedal, and you end up getting a perforation. And so we’re about halfway through with the dissection. You can see I’m crossing the half cornea there. Doing the dissection. Everything is going fine. You’re just calm. Doing the same thing. Reach in. I want to reach across to get to that edge of that mark. That’s the trick. Once you’re over there, you can stop. Make sure you’re on the right side. So the dissection right now is about this area. I haven’t reached that completely. But I think I’m gonna be okay. Because I don’t really have — that’s fairly close to the limbus, and we’re gonna be half a millimeter inside of this. So I think I have enough dissection there. Now we need to dissect this area over here. So I’m gonna put a little more viscoelastic. A DALK over a PK is very helpful, because less chance of rejection. Less chance of post-op problems. So I got close to my incision here, and I let some of the air out through the wound there, so now I touched the eye and it’s kind of soft, so I want to put a little more air, and then we’re just gonna dissect. All right. That’s nice and firm. That’s this last part here. So we’re good. I’m gonna soften the eye. So I’m gonna go back in my wound here and I’m gonna take out that air. That worked. Okay. So now we have a lamellar dissection of the cornea. And then there’s a bubble in the AC. And the chamber’s flat. So her orbit’s kind of small. Palpebral fissure, small. So there’s some posterior pressure. That’s why that bubble came out so fast. So what we’re gonna do is inject some Healon into that potential space we just created. You see that bubble move? That tells me that the Healon has filled all this space. Except right here, because the bubble hasn’t gone right there yet. Now, the reason she’s squeezing a little bit is why I can’t deepen the chamber so much. So I’m gonna open the speculum a little bit. And now we’re able to push that bubble all the way to the edge of the dissection. So there’s a big space here. We’ve pushed posteriorly what we dissected. So now when we trephinate here, we’re not gonna hit that area. How far do we want to go? We don’t want to go that far. Her cornea is probably 400 microns, so we want to go maybe 300, something like that. Okay. We’ve got good suction. I’m right on the dot. You can see that there, guys. And so I haven’t hit the epithelium yet. Now I just hit it. So then every half turn is about 60 microns. So we’re about 60 there. That’s 120. That’s 180. About 250. About 325, about 400. Now I’m gonna move real slowly. One more. One more quarter turn. Now we’re gonna enter that potential space. And where do I want to enter? I want to enter at about 11:00 here. If I go in here, that’s where the dissection is the least done. Right? Here you know that because of the wound, it’s most filled with Healon. So I grab this, and I pull it to the middle, so I can expose that area. And then you see the viscoelastic come right there. So now I know I’m in the right space. Okay? So now I’ve got to get these forceps in, so I’ve got to go in like that. And then be real gentle, okay? So you can see the dissection isn’t complete there. I’ll end up cutting this in two parts here. I’m gonna remove this in a little bit with a different dissection. Almost done, guys. And then I just need to dissect that little ring off, and I’ll be good. The depth is beautiful. We can see the depth is great. But this ring is not ideal. Okay? So how do we fix that? I’m gonna put some more air in. So what I want to do is kind of just dissect this a little bit more. And that’s creating a little more gap under here. I don’t even have to dissect it any more. It’s gonna create some overlap, so that I’m able to leave that little rim of tissue and just suture into it, and it’ll be fine. Because it’ll get pushed back into that space I’m creating, like a little bit of a tuck. So this is a 54-year-old donor. And what we have to do is we have to remove Descemet’s membrane, now that we’re gonna do a DALK. We’re staining Descemet’s here, so we can peel it off. I just mashed on it a lot, and now there’s gonna be some little marks. You see? All those marks, they wouldn’t be there if I didn’t just mash on it. Okay? So now what do we have to do? We’re gonna use the crescent blade here to strip it off. You can see here this is where the scleral spur right here is. You see how you can start there, and you can peel it way from that. That’s where the neural crest cells in the ectoderm start. And then we’re gonna do the same on this quadrant. Strip it down. So that’s all coming together here. We got that Descemet’s. Okay. So we got the little circle to help us. And then that circle we got right here — that’s helping me to see this rim. So I can center it better. You want to see a little bit of purple all the way around. It looks good. And then we’ve got the same size, 7.5. Spin it. Make sure it’s okay. And then lift, and then we’ve got us a cornea there. Just a little bit of some arcus here. I don’t love that. So I want to put the arcus up here on top, so it’s covered by the patient’s lid. So you see the depth is 50% there. You see that? 50%. And then into the recipient. And we’ll go full thickness, or close to it. I’ll go just right here, and then out at the limbus. So watch how much I tie this here. See how tight it is? And then I lock it forward like that? It’s so tight that you can see the tissue getting white. What I want to do is I grab it here. And I look to see where the bend goes on this, and I pretend where I’m gonna put it, and see if the same distance is on each side there. So this looks pretty good. And then I go half thickness. This is the most important suture. So when I place it, I want to make sure the gap is the same. That’s too much to the right. That’s too much to the left. So that’s just right, right there. And so I normally do 8 interrupted sutures and a 16 running. So that’s what I’ll do. And see how it gets in a nice position like that? Tie it and then lock it. Rotate it back. Okay. So now we just need these two. So you kind of do that. Where does it want to go? It wants to go right there. So you get it nice and tight like that. And then lock. And you tie it without disturbing that knot there. The difference between the second four sutures and the first four — the first four, you’ve got to tie them as you go, so it’s down nicely now. We can pass a few, and it’s faster, because we can tie them afterwards. So again, we want to crank them down, and we’re gonna have eight interrupted. So these are all interrupted. I want to put one more through the scleral tunnel and one to close the conj, and then we’re gonna use a running suture to finish it off. So you can see it’s kind of hard. You’ve got to learn to be able to crank them down and use locks effectively, where they don’t open. Okay. So we’ve got all our interrupteds here. There’s a little bit of a gap there, but otherwise it sits nicely. But you see we need more sutures. We couldn’t just have this. Rotate the knot. And then where do I like to leave the knots? I like to leave the knots inside the donor graft, just inside. To me, they’re easier to take out that way. I kind of want to put one more suture right there. Okay. And now I’m gonna close the conj. All right, so the last suture I’m gonna place is just gonna be a running. So when you do a running suture, we’re gonna do the same. 50% through the donor, 100% or 90% through the recipient. Kind of just radially, two between every suture. So we adjust the tension by getting the loose slack out of the line. I’m just cleaning it off, that blood, and a little trick is to put some viscoelastic right here on the knot, so you can bury it a little easier. So what you do is you get a little slack here. I’ve got some slack. Get some slack. Some slack here. There’s slack, you see? And you grab here and you put it under, and then you can add the slack again. A little bit more. Get all that… There we go. Perfect. And now she has a bubble in the AC. You just leave that. That’s gonna help to make the Descemet’s adhere, but she doesn’t have to position tonight. But we’re all done. Got a nice graft there. So it should be good. Thank you. Okay. Thanks, guys.