This lecture will discuss some Minimally Invasive Glaucoma Surgeries (MIGS) including iStents, Hydrus, and Xen gel stents. Why choose one over the other? The pros and cons of each procedure will be presented as well as surgery videos and case presentations to help attendees understand MIGS.

AMEN 2021: While It Is Day

<p>This lecture will discuss some Minimally Invasive Glaucoma Surgeries (MIGS) including iStents, Hydrus, and Xen gel stents. Why choose one over the other? The pros and cons of each procedure will be presented as well as surgery videos and case presentations to help attendees understand MIGS.</p>

<p>Free sharing permitted under the Creative Commons <a rel="license" href="http://creativecommons.org/licenses/by-nc-nd/3.0/us/">BY-NC-ND 3.0 (US)</a> license.</p>

Adventist Medical Evangelism Network (AMEN)

Peter Blackburn

Optical

Small Differences with Big Consequences: A Story of Underrated Maladies

Paul Chung

Understanding the Changing Options with MIGS Part 1

Understanding the Changing Options with MIGS Part 2


I did want to mention to the optometrists in this group that even though this is not, my lecture here is not COPE approved, so you can't get credit for it. But this is a series of lectures, This is just 2 hours of lecture in a six-hour series that Pacific Cataract and Laser Institute did for optometrists in Oregon, Washington, Idaho, Montana. And they did get COPE approval for it. But I don't think it's available yet, but our PR person said that within a month it'll be available. So you could go online and choose that lecture and just go to the end and you'll be able to answer the questions from what I told you.

So I don't know if you saw my email address at the beginning, But it's basically my first name dot last name at PCLI.com. Paul.Chang at PCLI.com. And if you email me, then I can send you the information when it's available. So you can actually get credit for this lecture. Okay, so I think we're being recorded.

And it looks like we drove out all the non-I related people. I don't know. There's still 1 person. I don't know what you do with eye care, but I figured out who everyone else was. Are you in eye care?

Oh great, oh yes. Hi Sandy. All right. Okay, so we'll continue on with our minimally effective glaucoma procedures, but it's actually minimally invasive glaucoma procedures because XenGel stents, I think, does work really well. I started doing xangel stents probably 4 or 5 years ago.

I used to do plenty of trabs. I've been a glaucoma specialist for 25 years now. Trabeculectomy was the main surgery I was doing. I know there's some people who prefer tubes over traps, But I find that I get good results with my traps. But it's very tedious surgery, time-consuming, and there's also potential for complications.

And the Zen gel stent can give you the same bleb and low pressure. And it's such a simple procedure. I mean less than 10 minutes if everything goes well. So the Zen gel stent basically goes in through just either through TM or just above it. This arrow should be higher and then into the sub-conjunctival space.

So when it was first FDA approved, it was approved as an ad internal approach. So, you have to go in through peripheral corneal incision and then come out to the superior angle and find the area just anterior to the iris with this inserter that's basically a needle, 23 gauge needle I believe. Once you're in the subconjunctival space, there's a slider that pushes the xangel stent out. It looks like curved here, but it's not. It's a stiff porcine collagen stent that gets pushed in the subconjunctival space so that a millimeter of it stays in the anterior chamber, 2 millimeters in the sclera, and then 3 millimeters in the subconjunctival space.

But as soon as it gets wet, it becomes like a wet noodle. So it becomes more flexible. So this is basically the end result of it. Sometimes you can see the anterior chamber portion on slit lamp exam. Other times you have to gonio them if the sclera or the limbus is further anterior.

It's a 6 millimeter gelatin tube with a lumen diameter of 45 microns. On gonio, this is what it looks like. This 1 is a little more posterior than it should be. When you go to posterior, when you stick it in, you can hit the blood vessel and they can bleed. So that's why you want to go either through TM or more corneal.

I think this might have been 1 of my earlier ones. So in the subconj area you can see this sort of yellowish stent and this looks pretty flat. So this may not be working properly. All right, so here's the surgery. So it started off FDA approved as ab internal, but some surgeons came up with another idea thinking okay, why don't we do it, try going ab external, coming in from the outside.

I found it to be much easier doing it this way, than going ab internal, where you make an incision down here, go across, and then going to insert it somewhere here. Okay, so this is the actual surgery. I put a corneal traction suture and this is caliper set at 3 millimeters so I'm trying to figure out where 3 millimeters is here and then another 3 and then another 3 because I want to go in around 7 or 8 millimeters back so that the stent will end up here, but my needle hole will be way back here, so it's not going to leak out through the needle hole. I was just checking to make sure that there is a stent there before I go in. So I expressed the stent out a little bit, and then I just pushed it back into the needle.

So now I rotate the eye down, and I'm trying to find the area where there aren't too many blood vessels. And You just go through. Initially I want to go into tinons, but then I want to become more superficial. It's sort of hard to do, to figure out exactly what level you're in. But once you get about 2 to 3 millimeters from the limbus, you inject Pierce Disclera and you want to try to stay parallel with the iris and that needle tip should end up between the iris and the cornea, preferably right in the middle, bisecting that angle.

And so as soon as I can see the needle tip, then I advance the slider forward and I'll see the stent coming out. And once the stent is actually in the anterior chamber, if you keep on advancing the lever, the needle retracts back into this inserter. So you're less likely to hit a blood vessel. I guess it didn't retract all the way. So that's why I hit a blood vessel.

So it's bleeding now, but that's okay. As long as the stent is in place, yeah, It'd be nice if it didn't bleed because then you can see better. But you can barely see the outline of the stent here. If too much of the stent is in the anterior chamber, you can grab it and pull it out a little. So you only have about 1 millimeter in there.

It's hard to tell on this two-dimensional video, but this conjunctival tissue is actually ballooning up because the fluid from the inside is coming out. The other way you can tell is just by pressing on the eyeball and it's getting softer. Now I'm using a gonio lens and I'm looking at this mirror and there's the stent. I was just checking to make sure the stent's in the right position. Now injecting mitomycin C going from a different location and coming across and injecting into this subconscious space.

When we first started doing trabeculectomies, we were so afraid of mitomycin C. We would apply it for 30 seconds to a minute and then we'd irrigate it out. But as we used it more and more we realized it's not that toxic. So now we're actually injecting mitomycin C into the area where you want the blem to form and just leaving it there. Right, oh, yeah, so for those that don't know what mitomycin C is, it's an anti-cancer medicine and it kills fibroblasts and it helps to prevent scarring after the stent is in.

Because the number 1 reason for these glaucoma procedures to fail is wherever you make the, where you put the stent or made a new drain, it can scar over. Now I'm just injecting dexamethasone in the inferior cul-de-sac just to help prevent inflammation and scarring. So they've got a nice bleb or elevation of the conjunctival tissue there. So I'm just drawing around there. I remove the traction suture.

Then, yeah, Usually I'll check the needle tracks, the holes, too, to make sure it's not too big. I did have, I think, 1 patient where The tissue is just so fragile. Anywhere I put a needle in, they had a big hole and I had to suture it. Okay, so we talked about that already. Ab interno versus ab externo.

Yes? The needle what? Uh-huh. Right, so I believe it's 23 gauge and the retina doctor will say if you poke even if you poke the sclera with a 23 gauge, you don't usually suture that, right? Yeah, So the conch, if you can get deep enough so that you're not just subconch, but you're subtenons also.

But then by the time you get closer to the limbus, you want to be more subconch. But the tenons will help to plug up the needle hole. It rarely leaks through that. Just that 1 patient I told you about, he was leaking the next day, So I had to take him back to the OR and suture it. Okay, so who do we do Xen-Gel-Stin on?

So Xen-Gel-Stin is indicated for all glaucomas, mild, moderate or severe. So that's the nice thing about the Zengelstin. It has the potential to get the pressure really low, like low teens. I've had some patients even in the single digits. But basically it's almost as effective as a trabeculectomy.

But the trabeculectomy can be more effective in some patients because you just you can make a larger opening. You can let more fluid come out and avoid the scarring that comes when just a little bit of fluid is going out. If you look at the ganglion cell complex, the red means the layer is thinner, meaning a lot of nerve tissue has been damaged and gone. This would be a severe opening glaucoma patient. There was a study that looked at Zen Gelstead.

185 patients that had Zen. 169 that had trabeculectomy with no prior filtering surgery. So there's no scar tissue in the superior conch and there's 35% reduction from pre-surgical medicated pressures and That was what they're looking for. 80 percent of the patients needed fewer topical meds postoperatively at 1 year. When they compared the 2 groups, they were about the same.

Since I started doing this Zen gel stent about 4 or 5 years ago, I think I've only done about 2 or 3 trabs. I'll do a second Xangel stent before I do a trab. Okay, so the post-op care is very similar to a trabeculectomy post-op care. We have to see them at least once or twice a week for the first 4 weeks. Antibiotic drops for 1 week, slowly taper over actually 3 to 4 months.

Initially, they're on steroid drops every 2 hours. Maybe at around week 3 or 4 we can go to every 3 hours and then at about a month, month and a half, go to 4 times a day. So just very slow taper. Because I've had patients where if you taper it fast they get inflammation and the bleb scars and doesn't work anymore. When I did trabeculectomy, sometimes we would do digital massage to get more fluid to come out and try to spread the blood out more.

I tried that initially with a Zen gel stent and the stent broke. So I learned that you can't really do that. It's such a small opening that even if you press on the eye, you're not getting a lot of fluid to come out immediately. It just slowly trickles out. So, you wouldn't do digital massage.

This is the 1 big thing about the XenGEL stent. Even though it's a very easy procedure to do in the OR, the post-op care is more, because about a third of these patients will start scarring around the stent. So we do bleb needlings where at the slit lamp I go in with a needle, a 27-gauge needle, and basically come across from a distant spot, come over to the bleb while I'm moving the needle up and down to try to cut the scar tissue around the stent. And then I try to go in front of the stent, behind the stent, just to clear away any scar tissue. Oftentimes we can save the blood that way.

So yeah, up to a third of the patients need it. Then at the slit lamp and I also inject 5-fluorouracil which is another, it's a less potent antifibrotic agent than mitomycin, and that will help to make the blood function better. But unfortunately, the 5-FU leaks out through the needle hole and sometimes can compromise corneal epithelial health and they can develop sterile ulcers or get really dry. So they have to use artificial tears a lot. Even though Xenjiao stent has less complications than a trabeculectomy, sometimes the pressure can go really low.

There's great variability in how thick the congen tenons is. Some elderly patients can, it seems like they barely have any tenons and the congen is very thin. And I have had patients where the pressure goes down to 2 and stays around 5 or 6. Then they can get corotofusions in the back. There's a B-scan of that.

But most of the time they resolve on their own. Eventually the pressure comes up and the corotofusions disappear. There was 1 patient where I put in a stent and as I was trying to manipulate it, it broke. So the anterior chamber portion is still in there, but the subconch portion, there's only like half a millimeter there. And I thought, oh this may not work.

So I put in a second stent and that was a mistake because he had hypotony and he developed corotofusion. So I had to eventually take him back to the OR to drain the effusions. I think he's got a little bit of hypotony maculopathy too. I wish you were nearby. Yeah, so even though all the corotofusion is gone, his pressure's about 10 now.

He's got a really nice blab, but his vision is still a little blurry. So I'm hoping it'll still clear up. So this, here's a patient that, where the stent, the anterior chamber portion is a little bit long. But as long as you have at least 1 or 2 millimeters in the subconscious space, it'll still function. So sometimes you can get localized blebs like this.

The idea with the Zen gel stent was because the opening is almost 4 or 5 millimeters away from the limbus that you should get more posterior, more broad blebs. But, depending on the direction that it went in, ideally you want it to come straight in. But, if there's scar tissue from previous surgery or their angle anatomy is different, I think most likely this is probably a right eye. You have the nose here. You have to come in from temporal side, and that's probably why it's angled like this.

If the tip is very superficial, then sometimes you can get a very thin avascular bleb. Here's 1 that looks a little better. The bleb is much more diffuse, but this is the 1 where the pressure went really low and had the corotofusions. And had the corotofusions. And here's a patient where you have, it looks like almost 4 millimeters in the subcons space, but the bleb is more posterior.

I don't know if you can tell, but there is some elevation there. So here's a patient. This is 1 of my earlier surgeries where I went, you know, I'm just trying to stay away from the iris because when I was injecting, sometimes I'd end up behind the iris and then I'd pull back. Here's 1 that was too corneal. Then he started getting fibrosis around there.

But so far the cornea has still been okay. So we haven't needed to remove it. Alright. We're just about done for this part. When you refer patients for a glaucoma surgery, just communicate the severity, progression, compliance, send visual fields.

This is talking about the other mixed devices. We went over last hour the iStents and Hydris. And then we'll decide based on their glaucoma status which stent they should get. All right, Do you have any questions? Because if not, then we'll go to more fun things.

In your previous talk, you showed yourself watching and putting the set. Do you hold that yourself or do you have an assistant? Oh yeah, so I'm holding it myself with my left hand and then I'm going with the right hand. There are some gonio lenses that are free-floating that you can just put on their disposable gonio lenses and then But yeah, so that that was 1 of the hardest parts of doing this procedure To learn how to how much do you tilt the head, hold this in place, hold it still, and then bring this in. And then you have to, you know, the trabecular meshwork is really thin.

It's probably like a quarter of a millimeter. So you're trying to get the the choke card to hit just there. And I remember the very first time I put in the eye stent. We did a wet lab the day before and it was pretty easy. But then when I got into the eye, as soon as I got close, my hand was shaking.

So then I pulled back, and then I said, OK, I'll try it again. Shake again. Then I said, OK, I'm going to hold my breath and try. So probably the first 5 or 10 cases were tougher, but then you know everything the more you do the easier it gets And now you just go in and put it in. So for right eyes, I sit at the head.

I'm right-handed, so I can do a temporal clear corneal incision and operate with my right hand. But for left eyes, I was trying to do it left-handed, but I broke capsule and I felt like, okay, I should stop doing that. So now I sit on the temporal side. We have surgeons with MPCLI that do left eyes left-handed, right eyes right-handed, because they don't want to keep moving the chair back and forth. They just want to sit at the top.

But the eye stents you pretty much have to go straight on. The hydra stents, if it's right eye, I do a right temporal incision and then I'll place it inferiorly. So I just go in through the CCI and place it from 6 to 3 o'clock. So the stent is still in the infranasal quadrant where you have more collector channels. Whereas the left eye, I'm sitting temporally and I do my surgery this way, but then I'll make a paracentesis at 01:00 to insert the hydrus at the 09:00 position going down to 6.

So it'll still be infranasal, but the opening will be at 09:00, whereas for right eyes the opening is down at 06:00. I think, well, so when I first started doing it, I used to, for right eyes, I would make a 05:00, no, 07:00 paracentesis and then go in and put it at 03:00 and go up to 12. But then that ends up in the supra-nasal quadrant. And I'm glad you asked that because there's been a few cases where I couldn't put it in. I think the superior canal is thinner than the inferior canal.

Studies have shown that there's more collector channels inferiorly. So I think it's better to put it in the infranasal quadrant. Though I asked the hydros rep, because the way they tell people to do it is it ends up in the supra-nasal quadrant for right eyes and infra-nasal quadrant for left eyes, if they're right-handed. But if they're left-handed is opposite. And I asked if there was any difference in the 2 eyes in their studies, and he said they didn't see any difference.

So I don't know. Okay, so I think we're gonna stop recording now. And Yeah, so those that want COPE approved credits, just email me paul.chang at pcli.com and then I'll let you know when it's available and you can go online and get it. Okay, we're signing off now. Or if you

Back to Menu

Series

Optical

Understanding the Changing Options with MIGS Part 2

Description

Parent Series

Parent Conference

Sponsor

Recorded

Other Teachings in Series

Small Differences with Big Consequences: A Story of Underrated Maladies

Understanding the Changing Options with MIGS Part 1

Understanding the Changing Options with MIGS Part 2

Sound Doctrine