Surgery: Trabeculectomy with MMC

This video demonstrates trabeculectomy surgery with mitomycin, a fornix based peritomy and a rectangular scleral flap. At the end of the surgery, the anterior chamber is perfectly formed and the wound is secure.
Surgeon: Dr. Thomas Samuelson, University of Minnesota


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DR SAMUELSON: This is a trabeculectomy with mitomycin. I’ve given the patient topical anesthesia, but they’ve not had any retrobulbar block. This is a mixture of mitomycin and lidocaine that we’re injecting. So this will serve as our anesthetic, as well as our antifibrotic agent. It’s a 50/50 mixture of mitomycin 0.4%, and it’s mixed with 2% lidocaine, with epinephrine. It’s very apparent — you can see how thin the conjunctiva looks — you can see the bubbles very easily, through the thin conjunctiva. So we have to be very careful. So we do our fornix-based peritomy. And I try to minimize my disruption of the conjunctiva. I don’t do a lot of undermining, posteriorly. I don’t want to generate inflammation. I want this scleral incision to be about 3/4 depth. This is a 67 blade. And now I’m dissecting forward. Making sure that I’m not too deep or too shallow. The more anterior I can make my dissection, the less likely I’ll get bleeding with my punch. And, see, I’m well up onto the clear cornea here. Now I’ll make my paracentesis. So before I enter the eye for the trabeculectomy, before I enter underneath the scleral flap, I like to pre-place my sutures. It’s far easier to control these things now, when the eye is still formed and the pressure is still normal. I also like to make sure I have complete hemostasis. I’m gonna enter the eye very anterior. Now, with these narrow, crowded eyes, we have to do an iridectomy, if they’re phakic. And I lift the iris out of the wound, and make a clean cut. It’s not uncommon to get some — just a little bit of bleeding. Nothing significant here. Now, it’s far better to have the sutures in place already, so all I have to do is tie now. Much more difficult to pass the sutures when the eye is very soft. I tied that first suture down, but I did not lock it yet. This one I’m locking. Quite often, it’s helpful to release the traction suture, but so far I haven’t — that hasn’t been necessary. If the iris prolapsed, or there was signs of too much pressure on the eye, I would release the traction suture. Now I’m gonna go back to this stitch and tighten it down. It broke, like sometimes happens. So I’m gonna replace that one. I’ll take 10-0 again. It’s always a good idea to rotate the knots. Now, in phakic eyes that have narrow angles, it’s important not to allow overfiltration. I’ve got a nice, firm pressure it doesn’t take much to — watch out just gentle pressure will cause the flow more aggressively. But I like the amount that we have right now. I try not to undermine too much, because I don’t want to generate a bleeding vessel way back here, where I can’t easily cauterize it. Now, this closure is with an absorbable vicryl suture. I like to place the sutures so that it buries the knots as much as possible. I like the vicryl, because it dissolves, and there’s no need to remove the stitch. But now I just simply run this. Because there’s no inflammation, the bleb will be diffuse and migrate posteriorly. Remember, we injected the lidocaine, which lifted the conjunctiva up as well. There should be no barrier to flow, posteriorly. As I’m closing, I’m watching the anterior chamber, and I’m watching the pressure. I don’t want it to be too soft. I’m wondering if I want to put a 10-0 nylon right here. And also, I’d like to encourage flow back here. Through the back part of the… To get a more posterior bleb. I don’t want a lot of flow anteriorly, in this location. As a rule of thumb, it’s better to have the pressure be too high in the first few days than too low. Especially in a phakic eye. So I always try to bury this last knot. It’s sometimes hard, but I always try. And before I tie it down, I cinch up the entire wound, to make sure it’s as tight as I can. I pull on both sides of this loop. So I just want to check the pressure. So I can generate — if I push hard enough, I can get a little leakage right here. So I have to decide: Do I want to put another stitch there? And the conjunctiva is so thin, I think that that could do more harm than good. It’s just a very light area that only leaks if I push it. And even now there, just a little bit. So I like that. That’ll heal fine. You can see a nice bleb. The pressure is not too soft. It’s probably mid-teens. Maybe slightly less. But the anterior chamber is perfectly formed. The wound is secure.

June 15, 2017
Last Updated: October 31, 2022

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