Surgery: Boston Keratoprosthesis + Extracapsular Cataract Extraction

This is a 49-year-old lady with bilateral alkali burns and this is the eye with greater potential. A Boston Keratoprosthesis and an extra capsular cataract extraction with IOL implant was performed. Posterior pressure was felt while extracting the lens, so a peripheral iridotomy was performed. The Boston KPro was carefully sutured.

Surgeon: Dr. Mark Mannis, University of California Davis


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DR MANNIS: This is a 49-year-old lady with bilateral alkali burns. This is actually the eye with the greater potential, and we’re going to do a Boston keratoprosthesis, extracapsular cataract extraction, lens implant. So our plan now is to… We’ve measured 8.5 millimeters as the size of the donor carrier. And momentarily, we will assemble the prosthesis prior to opening the eye. So I’m now cutting an 8.5-millimeter carrier donor. This does not have to be a high quality endothelial donor, since the cell count is unimportant. Now I will take the Boston keratoprosthesis and the dermatologic punch. So we now have the cornea with a hole in the center. 3-millimeter opening. Okay. Sorry about that delay. We had a little problem with the derm punch not going all the way through. The keratoprosthesis is in three parts. The central optic, which you see here, and the optic — the carrier cornea fits over a column of the optic, like so. And then over the back is the posterior plate. We have a small wrench that puts that unit together. So there you can see the unit put together like so. We notice that it looks very nice from the front. I’ll show it to you under the microscope in a moment. So here you can see the entire unit put together. The carrier cornea on the front. The central optical plate. And on the back is the locking ring. To ensure that everything stays in position. So now we’ll make a trephine opening and prepare to do the extracapsular cataract extraction. You may notice that — I’m not sure if you can see it on the screen, but there are sutures here, previously a circumferential suture, which was done to put amniotic membrane on the eye. So the Barron trephine is designed to be… To give you very good control. Each quarter turn is 66 microns. So we will start 250 microns anterior to the corneal surface. Suction on. One, two, three, four. That puts us at the corneal surface. Five, six, seven, eight. We’re now about 250 microns into cornea. I’m gonna go another 120 microns. One, two. We can expect some bleeding, because she’s highly vascularized. One of the things we can use — we don’t have it available today — but if you can use topical thrombin, neurosurgeons use it all the time. 1,000 units per CC will stop this bleeding altogether.

>> Sir? There’s a question that if we use topical epinephrine, would it also work with the bleeding?

DR MANNIS: It’ll help a little bit. The problem with topical epinephrine is that it, number one, doesn’t work as well, and number two, it can be problematic for the anesthesiologist. So we prefer not to use topical epinephrine. She has a reasonably clear lens. But, of course, we have to take the lens in order to put in a prosthesis. I’m going to leave the cornea hinged. So we’re going to do an extracapsular extraction. First we’ll do a small anterior capsulectomy. So there is a little bit of posterior pressure here. And there comes our lens. Can you give me the lens loop, please? There’s our lens. Lights down. Simcoe needle, please. Now, to remove the cortex, we’re going to use a Simcoe needle, which is a very simple irrigation-aspiration device. Let’s have fluid, please. Since we’re doing this open sky, of course, you have a very flattened capsule. So you have to be extremely cautious not to pick up a capsular remnant and rip the capsule. There’s always more cortex than you think there is. So I’m just going to expand the capsule with a little bit of Healon. It’s not going to expand it too much, because there’s not very much room. So this is a single piece PMMA lens. And we need to insert this horizontally. In this case, it’s probably gonna go into the sulcus, although I’m trying to get it into the bag. Scissors to the right, and Colibri. The reason I leave the cornea hinged is that if there is a choroidal hemorrhage, I have something to help cover the eye. Okay. Healon, please.

>> Excuse me, Dr. Mannis. So do you do PI or not?

DR MANNIS: I normally do not. But you certainly could do that. If I do that, I’ll do an inferior PI. Perfect. That’s it. Oh, oh, oh. Stop, stop, stop. As you can see, we have a prolapse of the lens. Take a Weck sponge and just hold that there for me, please. Can we have next stitch, please? Hold it there. We’ll finish the first stitch in a minute. Let’s take this one next. Okay. So that changed our plan a little bit. Because of the posterior pressure, I’m going to put in the… Straight 0.12, please. The four cardinal sutures. Then we’ll look to the peripheral iridectomy after that. In a situation in which you have posterior pressure like this, it’s important to repressurize the chamber as your first responsibility. Then you can go back and do the regular steps of the procedure. So I saw from the beginning that we had some posterior pressure. And decided to hold off on the PI. Then the lens was pushed out. The lens was put back into position. Once we’ve got the cardinals in, we can go back and do a peripheral iridotomy. The suturing here is a little bit different from doing a PK. The sutures are actually harder to get into position.

>> How about using the patient’s own cornea (inaudible)?

DR MANNIS: The patient’s own cornea? The problem with doing that is that you have to leave the eye wide open for a long time. So you could do that. But in this situation, as you saw, there was a lot of posterior pressure. And I would not have wanted to leave the eye open. In addition, I usually oversize a little bit, to make it easier to suture. And, of course, you can’t oversize when you use a patient’s cornea. It’s forehanded. I wanted it backhanded. So the next two need to be backhanded. Okay. Now, before the next suture, I would like a curved McPherson. Curved tine forceps. And the Vannas scissor. So I’m gonna make that little peripheral iridotomy now that we’re closed. Okay? I can reach in and do that now. I couldn’t really do that before, because of the pressure. You can’t pick up the suture on top of the polymethylmethacrylate. See? It won’t pick up. You have to move it over to the tissue.

>> So, Dr. Mannis, we have a question here. How long do you keep the patient on the steroids after the KPro?

DR MANNIS: Probably at least a year. And that’s topical steroid, beginning at four times a day, and usually by about 4 months, we’re down to two or three times a day. Healon, please. And BSS intraocular. So now we’re in pretty good shape. We have the nice deep chamber. We have the intraocular lens in good position. We have a red reflex. We have a peripheral iridotomy. Life is good. So you know you have a good chamber, because when I lift this up, see how nice and deep the chamber is. That’s a very good sign. So this lady should do very well. This should be the last suture, unless we break one. Let’s have the SuperBlade and the conjunctival forceps. I’d like to take the ring off now. Then we’ll deal with the corneal sutures. Oh, see that? You’ve got to be very careful not to leave those. BSS intraocular, please. I think maybe that one needs to be replaced. I need one right-handed stitch, please. She will be able to see tomorrow. You’ll see. It’s pretty amazing, actually. Actually, this one looks like it’s sticking up a little bit. So we’ll move that. Is it leaking a little bit? I’m not too worried about that, actually. I think once the tissue de-swells, that will stop. See, this is all a big, rigid piece. So there’s always a little bit of leakage. But when the swelling stops, that will go away.

July 21, 2017

Last Updated: October 31, 2022

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