This video demonstrates Baerveldt Implant surgery in a patient with advanced glaucoma. The implant was placed in the inferonasal quadrant and the tube was placed in the anterior chamber
Surgery location: on-board the Orbis Flying Eye Hospital in Hanoi, Vietnam
Surgeon: Dr. Thomas Samuelson, University of Minnesota
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Dr. Samuelson: My initial step here is to give some some subconjunctival lidocaine and I’m going to give it in the same place where my incision will be so he’ll feel a little scratchiness. This is simply 2 percent plain lidocaine. So he’s had some sedation to help but this is the only anesthesia that he’s had on the eye so far other than topical tetracaine. Now we’re going to create a peritomy inferiorly. Notice I’m incorporating the place where I entered the Conjunctiva within the incision, so I’m not violating the conjunctiva in any important area when I give my injection. So I’ve achieved down to bare sclera. And I’m going to pass more lidocaine.
This is 2 percent plain, no epinephrine, I don’t want epinephrine. And this is very consistent with the technique that Orbis teaches. We’re not passing any sharp needle back into the retro bulbar space, our chances of getting these retro bulbar hemorrhage is very very small. Then I’ll be ready for a muscle hook very soon. But I think we have enough room to place a 350. I am making sure that all the adhesions are freed up in the inferonasal quadrant, so I am passing the Westcott scissors very easily throughout the entire quadrant.
I’m going to secure the inferior Rectus first. And this is when I tell my anesthesia colleagues that the patient needs maybe a little extra help because it’s the most uncomfortable part of the procedure when we’re pulling on the muscles. Now I’m going to let my anesthesia work a little bit longer while I prepare the implant. I’ll take a 350 Baerveldt implant. So the implant comes with a suture that
holds it in place, I’m going to cut that. And then actually these don’t really need to be primed like the Ahmeds do. So I’ll take the 7-0 Vicryl needle. I’m making a few slits in the tube itself. This will help control the pressure for the first four to six weeks until the tube opens more completely.
So I’m going to place what we call a ripcord suture, it’s a suture that we can take out in clinic. I’m putting this what I call ripcord suture in the lumen of the tube. This suture only occupies about half of the internal lumen. So flow could easily pass around this suture. And next I’m going to put a ligature around it to crimp the tube down tight against the nylon so won’t allow any flow through the length of the tube, the slits that allow flow in the interim until the the tube is open. The ligature is a dissolvable vicryl suture.
So now none of these steps are necessary with the Ahmed implant. That is one reason why the Ahmed implant is popular because you don’t have to do these interim steps. The black suture inside the tube is a 4-0 nylon.
Just a bubble of fluid there, that’s fine. So I placed this implant now in the inferonasal quadrant between the inferior rectus muscle and the medial rectus muscle. Often, we will use a 9-0 prolene suture for this. This is an 8-0 nylon but it’s a heavier suture to help secure the implant. Muscles themselves will help hold the tube in place.
But it’s also nice to have the sutures to help secure it. I would say 75 percent of the tubes that I put in are in the superotemporal quadrant and maybe 25 percent are in inferonasal quadrant. So I don’t want the audience to think that all tubes are put down here. In this particular case, we’re putting it in inferiorly because of all the scarring superiorly. You can see here is the interior rectus muscle. With all tube shunt procedures, we have to worry about diplopia or double vision because these tubes do involve the muscles. In this case he doesn’t have any vision in his other eye, so diplopia is not a concern and that’s one of the reasons I made the decision to go with the large implant.
So one of the nice things about achieving this step is, most of the remaining steps are quite comfortable for the patient. So all the steps that sometimes cause discomfort are completed.
So I always rotate the knots into the eyelet hole so that there’s no chance that the knot would contribute to eroding through the conjunctiva. Now We’re going to trim the tube to size. So it is obviously much too long. So we’ll trim it so that it fits in the anterior chamber and I’d rather err on the side of the tube being a little too long and too short.
I will also trim the ripcord suture. So I’m going to put this in the subconjunctival space. This can be taken out in the clinic, if the pressure’s too high. I’m looking at my length in my tube again, what looked to be perfect length is a little bit close.
I’d like to extend a little more central so I might need to move the plate up a little bit. It’s enough, it’s just barely enough. I would like to see a little more of the length of the tube entering into the entire chamber. I’m going to put another suture to make sure that this plate stays anterior. I don’t want it to slide back at all and possibly allow the tube to exit the eye, So I am going to put a stiff suture. Again this isn’t typically necessary, I’m just doing this as a precaution to make sure that the plate does not slide posterior at all. Within a short period of time, a month or so there’ll be a tense capsule around this plate and it won’t migrate at all.
But in the meantime, I want to make sure that it’s very secure. One of the design features is to help keep it in place by because of the rectus sutures.
So the rectus sutures hold it in place so it be hard to slide it too much forward. If the eye was not phakic, it would help to just put the implant in the sulcus behind the iris, but because the eye is phakic, we can’t do that. So that’s going to be fine.
The next I will need is a 23 gauge needle. I don’t want to take out the needle until I’m ready to put the tube in. It’s going to make the eye firm and makes it easier to put the tube in. He has a narrow angle like many of the patients that you deal with. So therefore you sometimes fight synechiae as well.
It’s usually easier to get it through, but like I said, in these crowded eyes that sometimes can be more difficult, we will see just enough tube inside the eye. And then while we get that ready I’m going to put a suture to keep that tube from migrating.
Question: If you pass the needle in preparation for the tube to go in and it’s proved to be difficult or something, you cannot try it again?
Dr. Samuelson: You can. The more times you pass the needle the more you risk bleeding. But you could sure. I want to tie this such that I don’t block the tube.
Question: So now if the fenestration is behind the tying suture, how it would work for lowering the pressure?
Dr. Samuelson: That’s right. They’ll they’ll work for the next month or so until the tube opens because the ligature will dissolve. This vicryl suture will dissolve and then the pressure will come down as soon as the stitch dissolves. If the stitch is too slow to dissolve, then we can pull the ripcord stitch out.
Question: The tying suture is anterior to the fenestration that you made in the tube?
Dr. Samuelson: No, this suture doesn’t do anything other than hold the tube in place. The black suture that I just put in does not block the tube.
This is Tutoplast pericardium, you can use anything from autologous sclera if you wanted, to pericardium, to donor sclera, cornea donor cornea tissue as well.
Question: There is a proference now for the clear cornea if you have it, right?
Dr. Samuelson: I like clear cornea, cosmetically it’s really nice to help just look normal because it’s clear, but this is quite good as well we just need something to help protect the place where the tube enters the eye. There aretwo or three commercial providers of preserved cornea, glycerin preserved cornea. They just take right off the shelf and use as a patch graft. And it’s what I like the best because it’s cosmetically obviously very transparent and clear.
Question: Do you need to remove the epithelium of the cornea?
Dr. Samuelson: Ohh yes, but they do that for you because it’s glycerin preserved it kills the epithelium anyway.
The rest is pretty straightforward, putting the patch graft on and we’ll close the conjunctiva. To summarize this case, the one thing that I would do a little bit differently is I would leave a longer portion of the tube to save myself that extra step. But now that we’ve done that extra step it looks perfect.
Question: Is it correct that when you put Ahmed to the pressure goes up after one month and that it goes down again in two months. Is it correct understanding or not?
Dr. Samuelson: I think that’s generally true of most drainage devices, in most tubes the eye will form a capsule around the implant and that restricts flow for a while and then the capsule will soften over time improving the flow.
Question: Dr. Samuelson, when we see the patient tomorrow, what we’d be looking for in the clinic, first postoperative day?
Dr. Samuelson: So, tomorrow we’ll make sure that the tube is nicely positioned in the eye, make sure that the pressure is adequate. I generally tell patients that they’ll need a drop or two for their pressure until the tube opens completely.
Question: So how about the use of steroids drops after the surgery for tubes?
Dr. Samuelson: I usually use steroids every two hours while awake for the first couple of weeks and then taper over the next month or two. I don’t need steroids as long with this procedure as with a trabeculectomy. The role the steroids play here is mostly to help the redness and help the eye return to normal appearance. They don’t play as big of a role to prevent fibrosis.
Question: So we expect the bleb to be formed and functioning in how long after the surgery, Dr. Samuelson?
Dr. Samuelson: Usually four to six weeks for that vicryl stitch to dissolve allowing flow through the tube. Now if by the fifth week, if the vicryl hasn’t dissolved then I’ll pull the rip cord stitch out in clinic and once you’ve done that, then the tube is completely active.
So because we just use short acting lidocaine, will patch this eye for a couple of hours, so you can start to see something because as I mentioned his other eye has no vision.
Then will start his drops today. The conjunctival closure is one of the most important steps, if any parts of the tube or the plate become exposed it has to be covered up again with another procedure.
Question: So if you have a patient with a very high pressure and very high risk of damage to the optic nerve you still choose Baerveldt or you prefer to have Ahmed?
Dr. Samuelson: There’s one other method you can use to gain pressure control right away and that’s instead of putting a slit, I just pass a 10-0 suture, whether it is vicryl or nylon through the tube and then cut it, leave it as a wick until the tube opens more completely. Now this is the end of the 4-0 nylon over here that can be just taken out right in clinic to open up the tube any time we want. And that’s why some do like the Ahmed implant because you can put it in and gain pressure control straight off.
The studies have shown both devices work very well. The Baerveldt gives a little better long term pressure control but the Ahmed gives more immediate control. We’re all nicely covered everywhere, we’ve got a good intraocular tube segment, We’ve got the ripcord over here easily accessible in the clinic that we can pull anytime we want.
August 13, 2017