Surgery: Deep Anterior Lamellar Keratoplasty (DALK)

DR LEHMANN: Hi. My name is Dr. James Lehmann, and I’ll be narrating this DALK surgery, done by Dr. Menen, from Addis Ababa, Ethiopia. Here Dr. Menen is passing an episcleral bite to suture down a Flieringa ring, in case the surgery has to be converted to a PK. Here she’s marking the geometric center of the cornea from the limbus. Which you premeasure, after measuring the corneal diameter. This is an optical zone marker, used to aid in trephination. And then that’s a paracentesis, and now some injection of viscoelastic into the anterior chamber. This would firm up the eye and help with trephination. You can see the pupil getting slightly bigger there, indicating the AC was deepening. In this technique of DALK, Dr. Menen is going to do partial trephination, in order to dissect off the free cap, before making the big bubble. So she’s doing some quarter turns on the trephine here, and then after achieving adequate depth, she’s gonna remove it. And then investigate how deep she made the cap. It looks like it was maybe not deep enough on the right side there, so she’s going to do a little more hand trephination. And then using a crescent blade and 0.12 forceps, you can see the full dissection of the cap. And you can see the rough underlying stroma. Now she’s gonna attempt to remove some of the viscoelastic and inject some air in there. So if there’s air in the anterior chamber, it aids you when you make the big bubble to make sure that you’ve bared Descemet’s membrane, and the bubble is still intact. So using a cannula, she’s injecting air now. Into the stroma. And it looks like we’re getting a mixed bubble here. Probably a type II at first. And there’s an area of type I there, where she’s touching with the Weck-Cel at this point. Trying to get a little more peripheral extension of the dissection, and now removal of the cannula. So the next step here is gonna involve doing the brave slash. And she’s gonna try to decompress the anterior chamber a little bit, get the eye a little bit softer. And then there’s some viscoelastic she’s putting over the stroma to help slow the egress of air once the brave slash is made. And you can see that area decompresses rather quickly. Now she’s using a cannula and injecting viscoelastic to create some space to extend that initial incision. This can be done with scissors also that are blunt on the bottom side, so that you don’t cut Descemet’s membrane, and it’s always good to keep refilling that potential space with viscoelastic, so that you’re creating enough space, where you don’t cut Descemet’s membrane. She’s extending this, and the idea here is to cut the posterior stroma into four quadrants, so that you can excise them from the area that was trephinated. Here she’s using viscoelastic to fill up that area, and now a dissecting spatula, to help extend that dissection into the area of trephination. So it’s a very nice technique here to extend the area of dissection. Gently. So that you can cut it at the area that was trephined, and it’s not smaller or uneven at the trephine edge. So these are those type of scissors that are blunt on the bottom, and a little longer on the bottom as well. And she’s cutting these lamellae into quadrants so they can be removed. Real care is taken here not to cut Descemet’s membrane, always improving the view by removing some of that viscoelastic, and always using a little more viscoelastic if needed. Push posteriorly that Descemet’s membrane/Dua’s layer complex. So it looks like she almost has it in the four-petal pattern here. Extending it all the way out to that area of trephination, which is most likely about 8 millimeters. And now she’s gonna extend it inferiorly. With care, as always. It gets more delicate as you get to that area, because that’s where there’s still less dissection. And now, using scissors to remove the four lamellae at the site of trephination, so again, she’s removing the petals from the area of trephination there, and this is the last step there. You can see how clear the underlying Descemet’s is there. It’s probably a type II bubble. And here she’s putting the donor lamella there. The Descemet’s membrane has been removed from that. It’s kind of set into position, and then using Pollack forceps, she passes half thickness through the donor, and then 90% thickness through the recipient, coming out just short of the limbus in a very nice pattern there. After suturing that 3-1-1, the most important suture, as we know, she sutures the inferior one the same way. Half thickness through the donor. 90% thickness through the recipient. Then the video is fast-forwarded, and she’s done 16 nice radial sutures. With a nice depth and symmetry to all of them. You can see they’re very nice radial sutures. This last step just involves injecting antibiotics and steroids. So great surgery there. Thank you very much.