This talk will discuss more advanced gonioscopy techniques; techniques for when obtaining a view is difficult – or when the findings are hard to interpret. The corneal wedge and indentation gonioscopy will be emphasized.
Lecturer: Dr. Wallace Alward, University of Iowa, USA
DR ALWARD: Hi, everyone. I’m Lee Alward at the University of Iowa, and I’m going to be talking to you today about gonioscopy, and techniques for difficult angles. I have no conflicts to report regarding this lecture. I have written a book and I have a website regarding gonioscopy. But remarkably, I don’t get any income from either of those. And also, I’m gonna talk about lenses that I use, but I have no financial relationship with any lens manufacturers. So my department buys my lenses for me. I don’t have the sense that any particular brand of lens I use is superior in any other way to any other lens. It just happens to be the one I have in my white coat. Really, gonioscopy is a really important tool for us all to know how to use. It allows us to look directly at the pathology, and to see what’s going on. And I’m hoping that by the end of this lecture, you’ll be excited about gonioscopy. You’ll want to grab your lens and go look at things. You know, you can see great stuff with gonioscopy. This is a patient who had intermittently blurred vision, and we could happen to catch him right at the time where we could see him bleeding from his old cataract wound. It’s a pretty cool video. A patient with angle recession — you guys had a lot of questions about angle recession. And I’ll show more towards the end. But what’s really great about this video is this patient has so many iris processes that you can actually see where the angle recession starts and where it ends. Because here there are no iris processes, but as I come around, you will see where the processes start up. Right there. A patient with neovascularization. One of your questions was: How do you know what’s neovascularization? New vessels will cross the scleral spur and will branch on the other side of the spur. So these are clearly not physiologic blood vessels. A patient with red eye and big vessels. And when we put on the gonio lens, you can see clearly blood in Schlemm’s canal. The patient has unilateral glaucoma. The eye looks okay until you lift the lid. It looks a little less okay now. And this is an eye that has the angle completely full of melanoma. So we’re gonna talk about indirect gonioscopy today. And specialize on techniques for difficult angles. So there are two main types of indirect lenses. There are the Goldmann-style lenses, as you can see on the left, and the 4-mirror-style lenses. The old prototype was the Zeiss lens. It’s really not made anymore, but you’ll see it crop up in my talk periodically. So there are advantages and disadvantages to both of these. And I think that it’s important to understand those. Because actually, I think it’s really useful to have both lenses available. The Goldmann-style lenses are, I think, easier to use. And the view is spectacular. The Goldmann-style lenses are the lenses that you’re gonna use for photography or for laser treatment. So those are the advantages. And I think that if you’re looking at a four-mirror lens and you really just want a better view, I wouldn’t hesitate to pull out a Goldmann-style lens to give you a different view. The downsides of the Goldmann lens is it’s more inconvenient, because you need to use a coupling solution. Because it has such a big area of contact, you can’t indent easily with this lens. And the last point there is clinic flow. So in my clinic, patients come in, they have their vision and pressure checked, and we would do an exam, and then send them off for visual fields, and maybe OCT or photography. But if they have coupling fluid, if they have methylcellulose on their cornea, then the photographers and the perimeters are not gonna be happy with you. You’re not gonna get good results. You can do 4-mirror gonioscopy without messing up their photography or their field, So the clinic piece is a big piece of this. And if you have a 2 or 3 mirror lens, it’s the short mirror used for looking at the angle. The other mirrors are designed for peripheral retina. This is a lens called a Magna View lens. If you’re at either of my websites, almost all of my movies were done with this kind of a lens. It has only one mirror, but this mirror has a little bit of magnification. Like 1.1x. It’s not a big magnification. But it’s a lens that I like. There are special lenses like the Ritch lens and the Latina lens that are designed for laser treatment, and there are many, many more. The four mirror lens has the advantage of being convenient. And anything that’s convenient you’re gonna do more often. It’s much easier to see the whole angle. You don’t need to rotate the lens very much. I think a big key here is it’s great for indentation. And we’re gonna emphasize indentation in this lecture. It’s harder to master. So I think when I watch my residents use the four mirror lens, they’re often pushing way too hard. So it requires a very light touch. So corneal folds should not be part of your normal exam. So if you have a really strong grip on the lens and you’re pushing hard, trying to keep up with the patient who’s moving around, you’ll see corneal folds, and that means you’ll never see a narrow angle in your life. So the touch with the four mirror lens should be very, very light. And I know that when my residents watch me through the side scope, it’s a little irritating for them, because there’s often air flashing underneath the lens. Because I’m trying to hold it just so delicately that I’m not accidentally indenting all the time. But you could see with just one mirror, without moving the lens, you can see most of the angle. If you just rotate it a few degrees, you can pick up what’s in these areas here. So it can be very fast. So there’s a Posner-style lens, and then there’s a Sussman-style lens. They’re both four mirror lenses. They’re both excellent. I use a Posner lens. Most of my partners use Sussman lenses. I think it’s just whatever you’re more comfortable with. I do think that if one has shorter arms, the Posner lens is probably easier to use. Than the Sussman lens. And alternatively, if you’re very, very tall, this might be easier to use. I would try both of them. See which is most comfortable for you. Somebody asked about — and by the way, thank you for all the great questions that you guys sent in. Somebody asked about the six mirror lens, and there is a six mirror lens. I have tried it. I don’t personally like it very much. Because each of the mirrors is so short. But I don’t see any real disadvantage to it either. So people ask what I use. This is what I use. I don’t think this is necessarily better than lenses by Volk or any other manufacturers. But several people wanted to know what I have in my pocket, and this is the lens I have right now. I’m gonna talk a little bit about general techniques. Of how to do gonioscopy. You get to meet my daughters through this. I set up the patient so that they are at the canthal mark. I’m gonna go back, because I think people don’t pay attention. This mark should be lined up with the lateral canthus. Because you need the full excursion going up and back. This is a little bit older video. This is a Zeiss lens. Again, that’s a Sussman lens. The Zeiss lens is great, but very fragile. This is the Posner. There are four mirrors, as I’m pointing out here. For some reason, I’m pointing it out twice. And then this is just showing that the Posner/Sussman/Zeiss lenses are smaller. The area of contact is a lot smaller than with the Goldmann lens, and that’s important for indentation or dynamic gonioscopy. It’s very hard to indent with the Goldmann lens. So this is me continuing the exam. You can see she’s a myope, and her angles are open. And I can just go around. Since this is a young woman, her angles have almost no pigment in them. The dark band you see there is the ciliary body band. And notice I have my three fingers against her cheek, and the lens being held gently between my index finger and thumb. And here I’m just indenting, just to show how to indent. But it’s important for you as the examiner to be still. That means I’m braced against the patient’s face. And my elbow is on the table. If I’m doing a Goldmann-style lens, it’s important to fill the lens concavity with viscoelastic. And that viscoelastic — using methylcellulose — you need to do that without bubbles. So either start a stream on a tissue and move it over, or I usually just break that little dropper cap out and just dump it in. But it’s important that there are no bubbles in there. And I put the bottom of the lens in first, and then flip this up. And I’ve trained myself to hold the lens with three fingers, so that I don’t ever have to use my other lens, my other hand, and bring my other hand around, to help with this. So it’s good to learn this technique. Two fingers against the patient’s face. The other three fingers are rotating the lens. I see some iris processes here. Someone asked about iris processes versus PAS. So iris processes should follow the concavity of the angle. And they shouldn’t pull the iris up. Like in PAS, peripheral anterior synechiae, would do. So I’m just turning this lens, and then obviously my other hand is on the slit lamp controls, because you have to keep up with the lens. And I do think this is a better view with the three mirror lens. It but I don’t think it’s enough better view to make me want to use it routinely. And if it doesn’t come off, I usually push against the globe to break that seal. One of you asked: How much illumination is advisable when doing gonioscopy? Is it best done in a dark room? You certainly don’t want to flood the eye with light, but it doesn’t need to be a totally black room. It doesn’t need to be totally dark. The exception would be when we talk about the corneal wedge. And when you’re doing the corneal wedge, it’s really good to have a dark room. We’ll get to that. So don’t worry about it being totally dark. Just dim. So when I came to the University of Iowa, I discovered all these paintings by this incredible artist, Lee Allen. And life would be easy if everything looked like this, right? But a lot of times, it’s hard. A lot of times, a lot of times, gonioscopy is hard for me. And especially it would be nice if they came with labels like this. And so I’m gonna talk — the thrust of what we’re gonna talk about today is: What to do if the view is difficult. And so I’m gonna talk about these five techniques. But I really want you to leave here this hour together trying the corneal wedge. Some people call this the parallelepiped. I could never spell that, so I call it the corneal wedge, because that’s what Lee Allen calls it. And indentation gonioscopy. So when I start gonioscopy, I always look at the inferior angle. That means I’m looking in the upper mirror. Because the inferior angle is the deepest. It’s the most pigmented, because of gravity. And it’s easiest to use the corneal wedge in the upper and lower mirror. So I always start looking in the upper mirror, at the lower angle. Once you get your bearings, once you know where all the structures are, because it’s so nicely pigmented down here, you can figure out the rest of the angle. You don’t need the pigment so much anymore. Somebody asked about using the corneal wedge in the lateral mirror. So the temporal and nasal mirror are much harder to use. Is it possible to do the corneal wedge in those mirrors? It is. You have to actually tilt the illumination part of the slit lamp. It requires a lot of gymnastics. I never do it. I wouldn’t really recommend trying it. But it is possible. Again, if you use the wedge, which we’re gonna do next, you can identify the angle structure. Schwalbe’s line is right here. Then I can take that knowledge and transfer that knowledge to the rest of the exam. So start off in the upper mirror. So what is a corneal wedge? The corneal wedge is a way of identifying Schwalbe line. The anterior border of the trabecular meshwork. And so to do this, again, it’s good to have a room that’s pretty dark. Offset the ocular… Ocular is going straight ahead. The light source is offset. Just like you’re doing a van Herick test, and when you do that, it breaks the light up on the cornea. So you have a beam on the inside and a beam on the outside. So the one on the inside is usually very crisp and sharp, and the one on the outside is sort of fat and fuzzy. And they illuminate the front and back of the cornea, until they run out of cornea, and then they illuminate the interface between cornea and sclera, and it comes back and they join Schwalbe line. So this is a great technique. I will admit at the front it’s a hard technique. But if you are struggling with where Schwalbe line is, this is the way you do it. And this is the kind of eye that you struggle with. I struggle with. Right? This is a 15-year-old person. They have zero pigment in their angle. How do you find where the trabecular meshwork is? In Lee Allen’s paintings, he always makes Schwalbe line look like something. It rarely looks like anything, but by using the corneal wedge, we know that this is Schwalbe line right here. Let me show you a video example. This is a young boy, 14-ish. Zero pigment in his angle, right? But you can see this inner crisp beam and this outer fat fuzzy beam, and they come together right there. So that tells me that’s the beginning of my trabecular meshwork. Without this, without the corneal wedge, I would just be guessing at where his trabecular meshwork is. So again, you’re using a light that’s offset from your oculars. A narrow, bright beam. And in a pretty dark room. Because the darkness does help with this. But I think this is a great example of finding the corneal wedge. And finding Schwalbe line in somebody with no pigment. And it can be just as big a problem if you have too much pigment. Right? Like this eye. I had no idea what’s going on here. Lots of pigment lines. Which one is the pigmented trabecular meshwork? Where is Schwalbe line? And again, I follow these two until they join right about there. So this is a Sampaolesi line. Another example. I have no idea what I’m looking at here. But this is the anterior border of the trabecular meshwork right there. So this is the meshwork. Some of these are really, really hard. Fat, fuzzy, sharp. Come together right there. And that’s the anterior border of my meshwork. This is a little bit offcenter. Sorry about that. But this is an angle that’s very narrow, and the beams come together just barely above the iris. So this is an angle that’s very, very narrow, but not closed. And this is an angle that’s closed. The inner and outer lines on the cornea run parallel like railroad tracks. And they never come together. So this is what the corneal wedge would look like in somebody who has a closed angle. So tip number one… I struggled with this. In fact, when Mr. Allen, the guy who did all that great artwork, was alive, I asked him how he always found a corneal wedge. Because it’s always in every one of his paintings. And what he told me to do was just hugely helpful. It’s to have the patient look slightly away from the examining mirror. Right? People in the questions that you sent in were asking about looking over the hill. Which used to be part of this lecture. Because in the past, when we had people on pilocarpine, they would have some relative bombe, but their angle wasn’t closed. You had to kind of look over that bombe to see the angle. So to do that, you would have them look into the mirror. So by having them look into the mirror, I’m now looking up over that hill into the angle. Since we have virtually nobody on pilocarpine anymore, I kind of dropped that from this lecture. But it’s the same concept. In this case, you want to look more into the angle. To do the corneal wedge, you really want to look more onto the cornea. So have the patient look just slightly away from the examining mirror, and that will put you up on the cornea, and suddenly it will appear. Tip number two. Please don’t wait ’til you need this to start dusting this off. If you have a clinic that’s slowing down, you have a few minutes, do gonioscopy on one of the patients and find the corneal wedge. Do this on dozens of patients until you realize that you can find that wedge. Don’t wait until you have that patient where you can’t see the meshwork. And figure it out now. You really have to practice this technique. The other thing I want you to go out of this talk with is indentation gonioscopy in your pocket. Some people call this dynamic gonioscopy. Manipulative gonioscopy. Other things. It doesn’t really matter. The concept is that you have a lens with a small area of contact. And then when you… So this is an angle that’s closed. Right? So when I indent, this side remains closed, because it’s got a peripheral anterior synechia, this side opens up, because it was just in bombe. It’s important to know that. So synechia there, wide open there. You need a lens with a small area of contact. Again, this is the Zeiss lens, Posner lens, Sussman lens. Any of these lenses would be great. And you can see here that these lenses, the four mirror lenses, have a much smaller area of contact. So some people say they can indent with a Goldmann. I find it very difficult. And what I’m doing here is I’m just pushing gently. I don’t have to push hard. I just push gently. And I can just watch the iris move back. And again, practice just doing gonioscopy. Consciously move the iris around, so you get good at this. Don’t wait until you have someone where you’re trying to sort out whether they’re in bombe or synechially closed. So this is an angle in which we see no structures. When I indent, there’s a trabecular meshwork. You see all these corneal folds. The corneal folds, again, should not be part of your normal exam. They should only be seen when you’re intentionally indenting somebody. This is a patient — very narrow. I don’t know what this is. I don’t think it’s trabecular meshwork. But I’m gonna indent and see what I find. As I indent, that’s clearly meshwork back here. That was just a Sampaolesi line. Opens beautifully when I release the pressure. All that goes away. And now I can see the meshwork again. You would assume — I would assume — that this is somebody, if I did an iridotomy on them, they would do — that angle, I would hope, would open up nicely. I like this video. This is an angle that doesn’t look that bad. So I would say that looks like meshwork, scleral spur, I’m gonna do laser trabeculoplasty, blast along here, but when I indent this eye, that was not the trabecular meshwork. That was the Sampaolesi line. That’s what I thought was meshwork and spur. That’s actually trabecular meshwork there and scleral spur there. So I would have just welded the angle together if I hadn’t done indentation and determined where the actual trabecular meshwork was. This is a patient who has synechiae on the right side, open on the left. Just a video example of the same thing. So I’m indenting here. You can see the left side of the image stays closed. And the right side opens up. When I release the pressure, it just all looks closed. When I push, it opens on the right, and again, I’m showing the corneal folds here, because you just want to be careful you don’t see those all the time. This is a lower mirror, upper angle. Same thing. There’s a lot of synechiae there, and parts that do open up with indentation. The other situation in which I find indentation to be really, really helpful is for plateau iris syndrome. You can do microscopy to make this diagnosis, but you can also make it with your gonio lens that you have in your pocket. This is somebody with a very anterior ciliary body, and it gives them an angle — the anterior chamber looks deep in the center but drops off markedly in the periphery. If we do a Van Herick test, which we’re gonna talk about in a minute, it would show us that the anterior chamber looked pretty normal. The anterior chamber depth would look pretty normal, so it would miss plateau iris. And what do you see when we indent? You can see we have the ciliary body holding everything up here, we have the lens holding everything up here. If you just push down on the iris, it would drape over the lens and drape over the ciliary body and give you this sort of sine wave or double hump pattern. If instead you indent, and instead of the iris going back like this, the iris has this ridge or lump in the periphery. Then you should be thinking plateau iris. So here’s a patient… Central chamber is pretty deep. Periphery is pretty narrow. And when I indent, I can see this hump in the periphery. This iris roll. I can see the meshwork a little bit. Show a few video examples of this. As I push here… You can in your mind’s eye see that something is holding the iris up here in the periphery. That there’s a lump under there. Like something under the carpet. When I release, it goes away. And then when I push again, you can imagine that there’s something out there, holding this iris forward. Just another example of the same thing. Kind of a steep dropoff in the periphery. And when I indent, you see the corneal folds. And this one, you really clearly see that there’s something there. There’s something beneath the iris. So I find this technique to be incredibly valuable for the plateau iris diagnosis. Van Herick technique — Van Herick was invented many years ago, when the only kind of gonioscopy was direct gonioscopy, where you had to lie the patient down in a separate room and use a ceiling mounted slit lamp to do gonioscopy. So this was a way Van Herick came up with to estimate the anterior chamber depth by slit lamp exam. It’s not a replacement for gonioscopy. As we showed with plateau iris syndrome, you miss plateau iris for sure with this. But it’s a great adjunct. I always do a Van Herick whenever I look at anybody. I’m just unconsciously trying to figure out how deep the angle is. So this is my myopic daughter. And as I bring this lens or the light beam into the very periphery, I use the thickness of the cornea as a ruler and compare that to the chamber depth. And you can see she is deeper than her cornea is thick. This is a recessed angle. Hugely deep. This is a very narrow angle. Way less than the corneal thickness deep, and there are even areas here where the iris is touching. And then this is just flat. So you basically the corneal thickness as a ruler. Any chamber that’s deeper than the cornea is thick is quite deep. Once you get down to half corneal thickness or less, then that’s a pretty narrow angle. And again, I would never replace — gonioscopy is so easy to do, once you have that four mirror lens in your pocket. But this is a way, if you have, say, an angle that’s very poorly — unpigmented, and you can’t tell if it’s wide open and you’re looking at unpigmented trabecular meshwork, or it’s closed and you’re just looking at cornea — obviously the corneal wedge, but if you can’t get the wedge to work, the Van Herick might help you with that. So it’s just a gross estimate of the angle depth. Examine the other eye. If my residents come up and say: We have this patient. The pressure is 50, the cornea is cloudy, I can’t see the trabecular meshwork, can’t do gonioscopy, I always ask them two questions: What’s the patient’s refractive error? Because if they’re a myope, then I’m less likely thinking that they’re in acute pupillary block angle closure. They should be hyperope or emmetrope. And the other is: What does the other angle look like? You’re not gonna do gonioscopy on this eye very easily. But if they’re phakic in both eyes, the other angle should be pretty darn narrow. Right? If the other angle is very deep, then you have to rethink your diagnosis. This is a patient who has… We see pigmented trabecular meshwork here. Scleral spur. Really wide ciliary body face. So do they have angle recession? Or are they just a myope? It helps to look at the other eye. And so when you look at the other eye, you can see that the ciliary body is lighter on this eye. And that’s because we’ve torn into the ciliary body. And there’s less ciliary body between you and the sclera. And so usually in angle recession it’s lighter in color. Like we see here. Weirdly, sometimes, it’s darker. Don’t ask me to explain that. I don’t understand that. And you see iris processes in this uninvolved eye and there’s none left in the involved eye. A lot of questions about angle recession in the questions you sent me. So these are the things that I’m looking for. If they’re iris processes, they would be broken. The scleral spur is usually brighter, because there’s nothing on top of it anymore. And the ciliary body face is usually lighter in color. So these are some of your questions. I think I answered the first question. How much is significant? Any amount of angle recession is significant. So the angle recession doesn’t hurt the eye at all. What the angle recession is telling you is this eye has had bad trauma. Right? It has torn the iris, torn into the ciliary body face. And so the degree of angle recession is really not associated with the risk of glaucoma. The degree of angle recession is kind of meaningless. But if there is angle recession, like if there’s a sphincter tear, or if there’s a ring, those are signs of bad trauma, and that’s a sign of why this patient has glaucoma. Just another angle recession, since there were so many questions about it. You can see the wide ciliary body face that’s light in color. And these are actually little dried up balls of old blood. That are also helpful in making that diagnosis. And this is one where you can actually see a radial tear. So let me go through a few of your questions here. I hope that’s been helpful to you. These first two have to do with how do you grade things. And so there are several grading systems. There’s the Spaeth, the Scheie, Shaffer. I really like the Spaeth system. Beyond what I can talk about in this lecture. But if you go to my curriculum website, there’s a gonioscopy talk. And I go through the Spaeth system. But the Spaeth system describes not only the width of the angle, but also the height of the iris insertion, and the shape of the iris. So I think it’s harder to learn. But it’s really useful. How does anterior segment OCT fit in my practice? I don’t really use it very much. I use anterior segment ultrasound biomicroscopy more often, because that lets me look beneath the iris. The OCT doesn’t show me much that I can’t see with my gonio lens. Somebody asked about manipulation versus indentation. In my mind, those are the same things. Dynamic or manipulative indentation. And we talked about how you differentiate normal vessels. Those are usually circumferential. Neovascular vessels typically cross the scleral spur and branch as we saw in that video at the beginning. Congenital glaucoma — usually you would be using a direct lens. Like a Swan-Jacobs lens or Koeppe lens with the operating microscope to do an exam in congenital glaucoma. But in answer to the second question, can you do it with a surgical microscope and a four mirror lens? Yeah, you can. It would be a little bit more awkward, but I don’t know why you could not do that. Can you do indentation in acute attack? You can actually break an attack of glaucoma by pushing on the cornea with something small. Like a four mirror lens and an applanating tip. People have described doing that. But it’s pretty hard to see the angle if they’re in acute attack. Partly because of the edema. And can you break PAS? No. I don’t think — a true PAS is pretty tough to break with indentation. Intraoperative gonioscopy is kind of beyond this talk. How do you teach gonioscopy? Not to advertise, but I have two websites. Gonioscopy.org and Iowa Glaucoma Curriculum. Gonioscopy.org is just designed to teach gonioscopy. So you could send them there. We talked about edema. Iris strands and peripheral anterior synechiae. How do you differentiate them? Iris strands should follow the concavity of the angle. And they shouldn’t pull up the iris. Right? Synechiae bridge the angle. Often there’s pigment anterior to the synechiae. And they distort the iris. And again, I wouldn’t worry about the nasal and temporal angles. You can make a slit, but it is gymnastic and not worth the effort. So figure out the anatomy by looking in the upper and lower mirrors. And then just use full field illumination to look in the lateral mirrors. I wouldn’t worry about doing a slit in the nasal-temporal mirrors. What does a ciliary body look like on gonioscopy? You know, when gonioscopy was first discovered by Trantas, he was trying to look at the ciliary body, and accidentally discovered that he could see the angle. We don’t usually see the ciliary body doing gonioscopy. And I always tell my residents that if you see the ciliary body, something is wrong. You may not know what’s wrong, but something is wrong. This is a patient who had — was pseudophakic and had a tube shunt done, as you can see there. And fell and ejected their iris out of their phaco lens. But it gives us an excellent view of the ciliary body. The ciliary body in a normal eye is hidden by the iris. So you would see it, and this is traumatic aniridia, of course. You can see it in congenital aniridia. This is a spectacular view. This is somebody with neovascularization of the angle. Iris and angle. And it’s pulled the iris up and out. And that allows you to see the ciliary processes there. But I would say any time you put on a gonio lens and you see the ciliary body, you should be wondering why and what’s wrong, that’s causing you to have this view. You have a big round lens like in spherophakia, sometimes that will let you see the ciliary body, but in a normal eye, you won’t see it. So two websites that you may or may not have discovered already — gonioscopy.org has been around for 15 years or so. Strictly hundreds of movies of gonioscopy. So if you just want to watch a lot of gonioscopy, I would recommend that. My newer website, which is now five years old, is the Iowa Glaucoma Curriculum. And that is 50 lectures. One of which is on gonioscopy. And really covers a lot of what we covered here today. Also covers everything about glaucoma. This is payback. This is my daughter, who I was doing all that gonioscopy on, who is now a glaucoma specialist, and got to do gonioscopy on me. I have some examples here, but let me look at the questions and answers, and see if there’s anything here that we should answer before I move on. Let’s see. During gonioscopy, how visible is neovascularization? It’s quite visible. I think that you need to pay attention. I’m a little red-green colorblind, so I have to pay a lot of attention. But you should be able to see it. I think we answered that question. Is it possible to treat nystagmus? I don’t know why that would have anything to do with gonioscopy. If the patient has nystagmus, gonioscopy can be a challenge. How much offset is needed for the corneal wedge? Just a little bit. 20 degrees or so. I don’t think there’s any magic number. Just so you have… That you find enough to give you two different beams when you do that. Edematous cornea is hard. You can use topical glycerin. As I said before, sometimes if both eyes are phakic, sometimes looking at the other eye is gonna tell you a lot of what you need to do or what you should be seeing. But an edematous cornea is hard. In the operating room, sometimes I’ll scrape the cornea. But you obviously don’t want to do that in the clinic. Is there a digital non-invasive way to perform gonioscopy? Not that I’m aware of. You can use anterior segment OCT to garner some information about the anterior segment depth. Although in a study looking at people with narrow angles predicting who would develop pressure rise, actually anterior segment OCT was less effective than gonioscopy. And the disadvantage — I love anterior segment OCT. I think this technology is spectacular. But you can’t see pigment, for example. So making a diagnosis of pigmentary exfoliation would be much harder. Do we need anesthetic? Yes, you do. Absolutely need a drop of anesthetic to do gonioscopy. Does the coronavirus affect the work of the ciliary body? Absolutely no idea. I don’t know that at all. Do we need to do gonioscopy only in glaucoma suspect patients? So anyone who… I only live in a glaucoma clinic. But we use gonioscopy for other things. I would say just a routine person who comes in for a refraction, has nothing else going on, I bet they don’t have gonioscopy performed. Any glaucoma patient absolutely needs to have gonioscopy performed. And in a study that was done by Paul Lee, they reviewed charts of people who had a diagnosis of glaucoma, only half of them had had gonioscopy. That’s ridiculous. So anyone with a diagnosis — who is coming in, being evaluated for ocular hypertension or glaucoma — definitely needs to have gonioscopy performed. And certainly anybody who is diabetic, somebody who has vein occlusion, who is at risk for neovascularization, I gonio every diabetic every year. Another question about classification system, Spaeth system for sure, for me. Harder to use, but it gives you so much more data. So one question about a glass four mirror lens. I love the Zeiss lens, which was glass, on the handle. The problem with the Zeiss lens was that the mirrors were not attached as well as the plastic lenses now. And so the mirrors would often start to fall off. And they really had a short lifespan. But they were great for everything else. The view was great. Indentation was great. Why does angle recession have a paler ciliary band? Because you’re looking at the ciliary body, and the ciliary body is between you and the sclera. If you tear into the ciliary body, you have less tissue between you and the white sclera. If you tear the ciliary body completely off the scleral spur, then that’s a cyclodialysis cleft, and it’s white. You’re looking right at the sclera. How do you sterilize gonio prism? That’s a great question. You can use peroxide. I wipe mine with alcohol swab and let it air dry. How do you examine the ostium after trabeculectomy? Just with the gonio lens. Should it be done routinely? I don’t. If the pressure stays up even after suture lysis, I’m wondering if maybe iris or something, fibrin, is plugging it. So then I would do a gonioscopy at that time. What is goniosynechialysis? It’s a surgical technique where one breaks anterior peripheral synechiae, but that’s a little beyond the scope of this lecture. Is it better to do gonioscopy in dilated or non-dilated? Definitely better to do it non-dilated, before you dilate the patient. Because dilation moves the lens-iris diaphragm back. Are there contraindications apart from corneal surface disease? I can’t think of any. Can you perform gonio with a soft contact lens instead of anesthetic? I guess so. I’ve never done that. I guess I really don’t know that. And what do you think is a likely cause of blood in Schlemm’s canal? That would be… Either there’s a high episcleral venous pressure. So thyroid eye disease, sinus fistula, or there’s very low pressure inside the eye, like a hypotonous eye. Any time the balance between the episcleral venous pressure and the intraocular pressure is… Where the intraocular pressure is lower than episcleral venous pressure, then you’ll see blood in Schlemm’s canal. So it’s usually high episcleral venous pressure. Let’s see. Since pilocarpine can worsen pupillary block and cause iris bombe, why is it often used in angle closure? So it can pull the iris out of the angle. The pilocarpine can. But it’s sort of a two edged sword. It moves the lens-iris diaphragm forward, but also pulls the iris out of the angle. It’s not a good long-term solution for people with narrow angles, for sure. So pediatric patients. A couple questions about pediatric patients. You know, I’ve done kids in my clinic as young as four and five years old. But that’s unusual, that they’re that mature and they let you do that. Most pediatric patients you need to do in the operating room. In an exam under anesthesia. Let’s see. I think I’ve answered most of these questions. So I have a few more… Since we have a few minutes… Maybe there are more questions here that I missed. Let’s see. Do I use pilocarpine prior to SLT? I do not. Difference between plateau iris and grade one to two angle? Basically plateau iris, you would have that roll. In the far periphery that we described. How is slit lamp grading and gonioscopy grading different and which is most dependable? They’re rarely different. As I said, in plateau iris, sometimes slit lamp says the angle is open when it’s very narrow. If you had to choose one, clearly gonioscopy is better. Someone asked to demonstrate Van Herick again. I would ask you just to go to the Iowa Glaucoma Curriculum website. And it’s right there. So let me show you a few more examples. I guess I have about 6 or 7 more minutes. This is somebody with Cogan-Reese syndrome. So you see with people who have ICE syndrome, these really tall anterior peripheral synechiae. This is Cogan and Reese’s original drawing. So if you have ICE syndrome like this, it’s easy to make the diagnosis. But if you have ICE syndrome like this, it’s much harder. Somebody thought this was angle closure, did an iridotomy, but if you look, they have irises distorted down here inferiorly. And if you ever see this… Where the iris comes up onto the cornea, you should be thinking ICE syndrome. Because the cornea can’t stick — the iris can’t stick to the cornea unless there’s a defect in the cornea. If you have a flat chamber after trabeculectomy, it’ll stick to the paracentesis site. But if you just have angle closure, it will only stick up as far as Schwalbe line. But if you have synechiae that comes way up like that, you should think about ICE syndrome. And this is that patient’s specular microscopy. This is a great — this is a patient with aniridia. Again, for people wanting to see the ciliary body, so what you see in aniridia is a stub of iris. This person has a cataract and pannus. Everyone always guesses that this is silicone oil. But it’s in the wrong place, right? This is in the inferior angle. Not the superior angle. So this is perfluorooctane that was used for retinal detachment. Somebody with a volcano. This would be a high myope with angle closure, which would be spherophakia. And this is then dilated. Axenfeld-Rieger syndrome. This is the circle of the iris, really prominent here, and these are iris processes, up to… This ring of collagen in the periphery… Another Axenfeld-Rieger syndrome. Young patient with kind of a scary-looking lesion on their iris. 17-year-old girl. When you do gonioscopy, you can see that it not only goes into the angle, but extends pretty far around the trabecular meshwork. Really cool pigmentary glaucoma picture. Shows the pigment in the angle. And the Scheie stripe. The backbowing here. And really prominent Scheie stripe here. Particularly in countries where patients are really darkly pigmented, this is a great technique, finding the Scheie stripe to make the diagnosis of pigmentary. This is somebody with diffuse iris melanoma. Somebody had an intraocular foreign body. You can see a defect in their iris. They had a vitrectomy, lensectomy, they developed cirrhosis, and found a piece of lens that had been left behind. Which looks really cool on gonioscopy. Exfoliation syndrome. Frosted zonules. So again, I’m gonna stop there. Because the time is almost up. I really appreciate everyone sending such great questions. And paying attention. I hope this has been helpful to people. And everything that’s on here, that I’ve talked about, all these videos, are on these two websites. So feel free to check in there. That may answer any questions that you have. Very good. I will leave it there. Lawrence, should I just sign off, then?
January 20, 2021