Lecture: The Critical Lens Technologies and Techniques (Gonioscopy, SLT, ALT, and MIGS) to Diagnose & Treat Glaucoma

In this interactive webinar, Dr. Cvintal will review the key lenses and steps that can be used to best recognize and diagnose glaucoma patients. Practical clinical pearls will be emphasized throughout the webinar. The lecture will then move into the crucial techniques to visualize the angle for both treatment with lasers and micro-invasive glaucoma surgeries (MIGS). Gonioscopy is one of the most important diagnostic steps for evaluating glaucoma patients in the clinic, but it is also often the least done because ophthalmologists may not always be comfortable or clear on how to best do this exam. These techniques and tips become even more important when ophthalmologists want to perform laser or MIGS treatments to the angle. (Level: All)

Lecturer: Dr. Victor Cvintal, Ophthalmologist, IOTC, Brazil


VICTOR CVINTAL: Hello, everyone, welcome to the Cybersight webinar. It’s a delight to have you here on a Monday morning or Monday afternoon, wherever you are. I would like to thank Cybersight for the invitation, thank you for having the time to listen to me. We are going to go into methods of diagnosing and treating glaucoma. If you have any questions, please write in the Zoom message down on the bottom. So I have no financial interest here. However some of the images were provided by Volk. By the end of this lecture, we are going to understand and master the use of different lens for clinical exam. We are going to talk a little bit about fundus exam, the gonioscopy exam, and how to use lenses for treatment, so lasers and surgical gonioscopy. The first question for the poll is, for diagnosing glaucoma, which are the first two exams that you should perform first? OCT and visual fields, eye pressure, IOP, and visual fields, IOP and OCT, or the fundus exam and gonioscopy. Say what you usually do. Don’t say what you think is right. Then we can have a better understanding of what’s happening around the world. Remember, you are listening from all over, so we have people from Africa, people from Europe, people from South America. So we are going to talk from basics to very advanced. Here we have the first polling. We get most of the people, 40% fundus exam and gonioscopy. OCT, 10%. And IOP and visual fields, 40%. Great. That’s a great answer. We are going to talk a little bit now in the lecture. Okay. So when you see this, what’s the million dollar question when you see a picture like this? Is this a man or a woman? Victor, what are you going to be? We’re in a formal lecture, what kind of question is this? I know by your answers some people see OCT first, some people do visual field first. Nowadays we have a lot of technology and some people prefer doing OCT instead of fundus exam, because fundus exam is not easy to perform. There are many details to see, and some patterns are difficult to see. And what we know from some studies, that you can predict sex from retinal fundal photographs. What I want to say is that deep learning can recognize patterns that we humans can’t. And that’s why it’s so important, the fundal exam. It can give you much more characteristics of the disease than we still think. So fundus exams is still a major glaucoma exam. It may predict the future of the disease. It may be key for treating communities. And you should master it. We are going to help you to do so today. What’s the importance? Fundus can set the stage of the disease. And by comparing one exam to one few years after, you can define how aggressive your treatment is going to be. And another very important exam is gonioscopy. Why? Because gonioscopy is going to define the condition. Remember, the glaucoma is some kind of pipe disease. For some reason there is an imbalance between production and drainage of aqueous, so the pressure goes up. So it’s a pipe problem. And if it’s a pipe problem, we have to seek which pipe and how we can fix these pipes. And the pipes here basically is the trabecular mesh work. How do we do the gonioscopy exam? We have you, the light source, the slitlamp, the condensing lens, and the patient’s eye. How does it actually work? During the exam, you hold the condensing lens just before the eye. And this condensing lens is going to stay a few millimeters, we’re going to see it just soon after, away from the eye. And the purpose of this lens is to gather the light from the corneal eye, a divergent light due to the power of the cornea and the lens. And this lens is going to present a real image. However, this real image is going to flip. It’s going to invert to the other side and the opposite direction. How does it work? It gives you a real inverted image. And how does it work for you to understand what you’re seeing? So this is the starting image, the real image in the retina. So you get the image inverted. So if here is 12 and here is 6, the 12 goes downwards and the 6 goes upwards. However it also gets reversed. So it goes from 3:00 here and the 6:00 to the other. And what you get is a completely indirect image. It’s completely the opposite. So in the real world, what do you see? If you see left, right, up, down, you are going to see down, up, go by the color, right, and left. And it’s difficult to see and to actually write down what you’re seeing. So one way I find very easy is to draw. And how you’re going to draw? This is what we use to make easier. We have a drawing, a setting. And this is dividing to ten little squares. Why ten little squares? Because then you can draw and go from zero to 10, like the cupping ratio that you have in the clinics. And you’re just going to draw whatever you see. And see, it’s upside down. Why? Because if you draw what you’re actually seeing and then you just flip the paper, you’re going to get the real image. So this can be tricky. So let’s take this as an example. You can see here the paper, right? OS. Instead of looking like this, you’re going to flip, and you’re going to draw. By drawing what you’re seeing, once you finish, you can flip the paper, and you get the real image. The same image you can compare to your drawings. You can compare to your pictures. This really helps. And what kind of lenses do you have of condensing lenses? You have many kinds of lenses. And what’s to differentiate one from the other is the field of view, the magnification you get, and the working distance. So here we have some difference between them. So here are the lenses that I usually use in clinics. So you can see I use one that can take a wider field of view and one can give you a bigger magnification. And you are going to see the details in one minute. So here comes the second question. What slitlamp fundus lens promotes the higher magnification of the image and has a correcting factor of 1? The 20, the 66, the 78, or the 90 diopters lens? So here it’s for you to say what’s right, not what you use. Okay. We are getting the questions, the answers. Oh, that is really interesting. So basically, I’m not sure if you can see the results, we have a draw here. Basically all of them gives you one factor and have the same magnification. So the lecture today is for you. We are going to understand what is happening. Okay. So what is magnification? Magnification is how much the image you are seeing gets bigger, gets magnified. So if magnification factor is two times, as you’re going to see, it means that the image that is in the retina gets two times bigger when you see it. So the higher the magnification, the easier it is to see the optic nerve characteristics. On the other hand, the field of view is how much you see from the retina. So the wider the view, the more you can see. And this is very good for seeing retina and for seeing scars in the retina. The difference is that the one which gives you the wider view, you can do with an undilated pupil. The one that gives you bigger or higher magnification, sometimes you have to dilate the pupil. Basically I have shown the ones that I use, the digital wide field, the 78, and the super 66. What’s the difference between them? If you see here, the higher the power, or the higher the diopter, the less the image magnification, or in other words not so big. The less the working distance, but the wider the field, as you’re going to see in a minute. And the super 66 has the higher magnification, 1, on the other hand the least field of view. And this is good for glaucoma. Why? Because here I can see all the characteristics of the nerve, while here you can see but not so much. So let’s compare. Here I’m seeing the same nerve with different lenses. Okay. For some reason it’s — okay. Sorry about that, it’s not — so here you can see — it was a video, but you can compare the three differences between what you’re seeing of the nerve. So see here, the 66, here’s the 70 one, and here the wide field one. With one you can see more of the characteristics, and there you can see more of the field. Does it make a difference? It can make a difference, especially if it’s not dilated. It can make a difference to see some of the nerve characteristics. And what you see when you see a nerve, to see it better, what you can also use is to use the magnification factor of your slitlamp. In case you’re using 90 diopters lens, for instance, you can just increase the magnification here and you get increased image. However, the higher you increase here, the more light you need to see the nerve. And this can be troublesome for some patients because you need a lot of light, the bigger the magnification here. So you really have to, during your practice, see what works best for you. Okay. So here we are going to see the slitlamp magnification. So here are some differences between them. Here you can see the difference between this first lens, which is the 90 lens, then to compare if the 78, you can see that the 90 one gives you a much bigger field of view. So how to perform the exam? First of all, we’re going to put some numbing drops. Why numbing drops? We’re not touching anything. But by putting numbing drops, take out the reflex of the eye and the patient won’t feel much. You start with the low light. You put a very narrow slit of light in front of you. Then you’re going to place your fingers — I prefer to place the fingers in the slitlamp and in the forehead and just hold the lens like this. Why that? Because I’m going to take like a model, for example, if you place here, you know if the patient’s going backwards or is staying in the right place. The patient can feel your hand, so it’s kind of, he feels safer if he places his hands, if you place your hands on his forehead. And you can actually have like a more stable lens for you to do the exam. And then you’re going to increase the light very slowly, and ask the patient to look to your nose. So always point to where he has to look. Therefore you can find the nerve better. Dilate, should you dilate? It depends. I usually dilate in the first exam when you’re getting to know the patient. Why? So you can see the whole retina. I personally use my 20 diopter lens in general for seeing the whole retina, and a 66 lens to see the details. Why? Because I live in a poor country. In a poor country, you have a lot of toxo and sometimes patient can have toxo scars. If they have a scar close to the macula, it can give you some kind of things that may look like glaucoma. So remember, the slitlamp, even the [indiscernible] doesn’t replace the 20 diopter exam. How to conduct the exam? Some pearls. First of all, there is always a correct side. Some lenses, there is like a white stripe here. When there is a white stripe, it should be facing the patient. This one doesn’t have a white stripe, so you use the V of the Volk, it’s like an arrow, it should be pointing towards the patient. Always rest your arm, don’t stay like this with your lens, because you won’t have too much balance. I personally use the box to make it stable. You just flip the lens like this. So sometimes you can have glare. Just keep doing like this, and the glare will go away. So what we realized from Covid is that people are wearing masks. And when they wear masks, you might have some humidity here. So what you can do, you simply place your finger on the mask, and this will avoid the respiration coming up, and you will have a clear view. When you use more than one lens, it’s very helpful, we still have different colors for each lens. So having each color for different lens like I have here, you know which one is which, it makes it quicker to do the exam. This is simple but it helps doing the exam. But how to see the size of the nerve, so you are going to put like a very slight thin slit of light. And by using this part of the slitlamp, you can actually measure the beam. It’s going to increase and decrease, and you’re going to see what number you have here. So you can actually measure as you can see here. And by measuring, then you need to correct this factor. So let’s take an example. If you’re using a 78 diopters Volk lens, you’re going to multiply whatever you see by 1.1. So if you see a 1.4 millimeter nerve, you are going to multiply by 1.1, if using a 78Volk lens. If using a 90 diopter one, you multiply by 1.3. Why is this important? Because different size of nerves give you different cupping. So what we know is that everyone has the same amount or almost the same amount of cells. If you have a bigger eye, if you have 100 cells, and you have a big eye, you are going to have a normal excavation, a bigger excavation. However if you have a small eye, all the cells, the cupping should be smaller. The first thing is to initial and to know if it’s large or small disc because this can vary according to the cupping. Then you are going to evaluate the differences between the nerve. And to actually know what you are seeing, what I suggest is to read the five rules to evaluate the optic disc, or see another Cybersight webinar from Paulsing where he explains each very nicely. This is very difficult. It needs times to have to see. The more you see and the more you draw, the more you get used to it and the more details you’re going to realize with time. So what I usually do, all the things I have to see, I have written down in one paper. Why? Because once I draw, I can see what I’m seeing, and then I can write down. And by the end, I know everything that I have seen. Sometimes it can be kind of troubleshooting, by the time you go to your records, you won’t remember. And one thing is very difficult and you should with green light, is to check the iron and felt. The Hoyt, it means it’s darker. This is very difficult to see in real life, even if we’re using the green light. So this is even better, if you take pictures afterwards. And why are fundus exams important? Because you can compare with time. So this is a 2005 picture, it’s still printed on paper. And this is a newer one from 2022. So here you can compare if it has progressed, it has progressed or not. Different from OCT. OCT is good, yeah, it’s great, but sometimes, after ten years, after 15 years, the technology changes completely and you can’t compare one exam to the other. So fundus exams and pictures are still very important. And more important than that is that Maderos in one study from pictures, he could estimate the iron and felt thickness. See how AI is helping us in fundus exam. And more than that, nowadays we have some handheld devices which can take pictures. What you can do, you can do a screening in your practice, and when the patient comes, you can have the picture and compare to what you see and what’s different. A picture is great because it’s there, but when you do this exam, you can actually see in 3D. So you can see if it’s tilted, if it’s not tilted. You can see better the vessels. So you can complement what you see to the picture. So take the picture and write on top of it what you see in real life. And more than that, in some distant or isolated populations, you can use it as a screen tool. So I’m from Brazil. In Brazil we have many places which are in the middle of the forest. And using such devices can be very helpful, and especially nowadays. So this is a program from Volk. You can take the picture with the machine and the picture goes straight to a place with experts and the experts can review the picture that someone has taken, like a technician, for instance, and they can write down, for instance, if it’s glaucoma, if it’s not, if you should treat, if you should not. And more than that, I don’t know if you know, but Cybersight has a great program for undeveloped countries, or if you live in undeveloped countries, it’s an AI-based program which you can upload the fundus image. And this AI program in seconds is going to tell you if the fundus is subnormal or if it’s not abnormal. If it’s glaucoma, if it’s not glaucoma. It’s still under development, but it’s great, especially for distant places. So now we are going to the second part of the lecture, which is clinical gonioscopy exam. So here comes the third question, which is, which of the following lens is most used during dynamic gonioscopy? The Goldmann lens, the four-mirror high mag lens, four mirror flanged lens, or six mirror? I’ll give you a few minutes. Okay, great. So here we have a very interesting result, which 45% say the Goldmann lens, and 35% say the four mirror high mag lens. So this lecture is for you. And we are going to talk about it. So why is gonioscopy important? If you don’t pay attention, you may think this is the trabecular mesh work. However, if we indent using the gonio lens, we’ll see the trabecular mesh work is actually hidden from what we’re seeing. And what’s the problem? Because in surgery you could place a stent in a wrong position. So let’s take this as an example. So knows what’s happening here. I’m pressing using a four mirror one, I’m pressing so much I can actually see the corneal folds. When I press it, I see that there is a nice tandem. This was put not in a wrong position but it shouldn’t have been put because it’s actually blocking the eye stem. When you see corneal folds and you press hard, you press hard to see the angle, so this shows the eye stent which was hidden in a closed angle. In clinics, before surgery, always write down or take the picture of the nasal view of what you see during the gonio exam. Surgical gonioscopy is key for surgical success. If you master it, you can do any kind of MIGS surgery. Then you’re going to tell, I only do trabs, I don’t do surgery at all, why do I need to know all that? Because you may encounter these situations. What should you do in these situations? We are going to talk about it. You may go for laser, you may go for surgery. And how can you define if this is open, this is closed, if it has abnormalities, and how you’re going to follow the treatment? So you should master gonioscopy even if you don’t do surgery or even if you are a general ophthalmologist. So for gonioscopy, you have two key concepts. Location, where the trabecular mesh work is, and organization. The good thing is to find where the white part is and where the trabecular mesh work is. There are many courses you can do on the web, you can do the World Glaucoma course on the website, you can go to AAO and actually see it with more details. But basically, how does gonioscopy work? So you do have a lawsuit coming — why can’t you see, like you don’t see in a fundus exam? Because the light which comes from the image gets totally reflected from the tear film. This is called total internal reflection, which the light reflecting off the junction hits the tear field. And that’s why you need a lens. By touching the cornea, the light won’t get totally reflected and you are going to see. So the lens overcomes the total internal reflection and redirects the eye from the angle to the observer eye. So this is a direct gonioscopy. A direct gonioscopy is a steeply convex lens which the light exits the eye closer to the perpendicular at the interface. On the other hand, the indirect gonioscopy lens will use mirrors to overcome the internal reflection. And this you’re going to sit up here to see. So when using the indirect view, you’re going to sit in front of the lens. And that’s why you’re going to see reflected or inverted, while the direct view one, you can’t use it in clinics because see how the light will come up? You have to stay down here. And that’s why, one of the reasons why a direct lens is used during surgery. However, even the microscope has to be tilted. And that’s why you have all this preparation to do MIGS surgery, for example, and now we understand why you have to tilt the eye to one direction and the microscope to the other direction. And that’s why when you use during surgery an indirect lens, it’s very difficult to see. You can actually see it in a good position, you don’t have to tilt, as you know. But all the image is going to be inverse. So how do you see in gonioscopy? And that’s very difficult. And this is one of the most important parts of the lecture today. So it’s different from what you see in fundus exam. So here is your starting image. Here is your image, it’s inverted. This is what you see in gonioscopy. Different from fundus image, you have 6:00 and 12:00, but the 6 — the 9:00 stays, and the 3:00, stays in the original position. In this sense, if you make these marks on the drawings, what you’re going to see in the mirror here is actually like this. So when it’s exactly in the opposite direction, it stays the same, just inverted, or flipped. But the image here stays the same. Here, here, here, and here. What this means is, so here I’m using a four mirror lens. So the ease of this is because you don’t have to rotate the lens. So let’s see here how it works. So if you’re looking sideways here, you’re looking here, 1, 2, 3. However, if you rotate a little bit, what actually happens is this. 4, you’re going to see in the other direction. 5 goes just after 4. And 6. So see, when you follow here, it doesn’t go like you expected, like here. But it flops from here to here. So this is very important when doing laser, for instance. So when you’re doing a laser, the laser goes like this, and then you rotate, and it goes like this. So in this situation, you may overtreat or even miss someplace here. So what types of lenses do we have to use in the daily routine? You have the three mirror ones which is the most traditional one, the four mirror ones and the six mirror ones. Here you have to rotate, because you only have one working mirror. Here you have four, so you sometimes do have to rotate, but just very slight. And the six mirror ones give you a whole idea of the angle. So the three mirror ones is one of the oldest and most traditional one, is used to see into the chamber. It has three mirrors. But only one mirror is made to see the angle, which is the small one. So if you need a smaller mirror, this is the one which sees the gonio exam. And you have to rotate to see different places. And this is also known as the Goldmann lens. So here are some differences between some three mirror lenses. The one I’m showing to you is the three mirror ANF plus. This is a very nice lens. It gives you a magnification 1.06. And this is — you don’t need to put a coupling agent. But it’s good to put a little bit to make it easier and make it a nicer view. Most of them have a compact diameter, wider compact diameter, that’s why you need a coupling agent. This can give you a good image but can be sometimes not so easy to use, and for some eyes can be difficult. This is another lens which is the four mirror lens, which older mirrors angle at 64 degrees. This is only made to see the anterior chamber. And you just need very little rotation, sometimes you can go from one mirror to the other, making life much easier. And it’s also known as the Sussman lens. And this is one of the key aspects here. This is the lens when it doesn’t have a flange that you use for dynamic gonioscopy. And what is dynamic gonioscopy? It’s when you can indent. We are going to talk a little bit about it. So here, it doesn’t have a flange. And some people like to use the handle. Some people doesn’t like to use the handle. I personally don’t like to use the handle because then I can rotate in my hand and I feel much safer doing this, it doesn’t fall down. The difference between the flanged and no flanged is because the flanged one, you do have to put a little bit of coupling agent here which can be a gel. But this one, you cannot indent because it’s resting in the whole sclera and the whole cornea, while this one is not resting. Let’s see the difference here. So here I’m using a very small eye, this is a plus 14 patient. See how difficult it is to place a three mirror lens, because it’s a much bigger diameter eye, while on the right hand side it’s a four mirror lens, which is much easier to place the lens. And see here, the difference here, I’m putting a flange four mirror one, it stays very nicely and gives you a very nice view. However, it does need as well some coupling agent. When it does need a coupling agent, sometimes it can have bubbles in it. If you do have bubbles, tell your patient to move up and do this movement and the bubbles will come out. And the no-flange one gives you less stability. The flanged one sticks to the eye. The nonflanged one doesn’t stick to the eye. You have to be careful, you just have to really hold your position there. And why is the four mirror so important? Because you can do dynamic gonioscopy. You can do indentation. Why do you do indentation? Because of angle-closure glaucoma. What is angle-closure glaucoma? Here you produce your aqueous humor. It goes all the way between the iris and the lens, through the pupil, and it gets drained by the trabecular mesh work. When you have some kind of angle enclosure, something is happening that this aqueous can’t get here, and the main reasons for that is the pupil, what we call pupil block, it has this concave shape. You can have cataract or increased lens or even the ciliary block can be anteriorized. Here is what we usually see. Here you have pupil block, plateau iris, the lens, and even posterior causes. Here we are seeing the scleral spur, the trabecular mesh work, which is the pigmented and nonpigmented, and here the Schwalbe’s line. So this is very important. When you do your exam, one of the first things to do is try to find the two lines of the cornea, the anterior and the posterior line of the cornea, because where they meet is where Schwalbe’s line is. And this is important because sometimes, like in the previous example, you may think it’s the trabecular mesh work. So how do you do the indentation? You may press a little bit, and when you press a little bit, all this is going to go down and you’re going to see the angle. Or some people I advise just to move the eye or the lens up or down. But when you’re doing that, you’re not actually indenting, you’re just seeing a different perspective. And that’s why it’s important to have always straight, because if you have straight, what you see, it’s the reality. If your lens is not really straight, sometimes you can call an open angle a closed angle. So here is another example of where the two corneas meet. So here you can see the two lines. And the two lines are meeting here. This is Schwalbe’s line. You can see the depression here. This is the depression. It has some kind of plateau iris in here. Maybe the ciliary body and the crystal in the lens. In the indentation gonioscopy, what do you do? You press. And when you press here, see what’s happening? The angle opens. You can actually see behind the iris all the trabecular mesh work. This can be done by pressing the lens or even by switching on the lights. So careful when you do your exam, because if there are a lot of light, the pupil will constrict and then you get an open angle. Seeing the ciliary body, how it’s anteriorized, and a bigger lens. This double hump, and now you understand what you’re seeing in the gonioscopy. Like in this example, what happens if I indent, I don’t see the trabecular mesh work? This means it’s closed, it’s totally closed, and different from the other examples, here you may have to go straight to surgery. On the other examples, if you indent and you can see the trabecular mesh work, you may go to surgery, you may go to laser. Why all the films I’m showing are you so dark? Because gonioscopy has to be done in the dark. And why? See this film here? See what happens when I switch on the light? When I switch on the light, all the angle opens. This the UVM. As you can see here, when the light comes, the pupil constricts and the angle opens. As I told before, if you can’t really do it or sometimes you don’t have a Sussman lens, you can ask the patient to look a little bit towards one of the mirrors and then you can see an open trabecular mesh work. How do you write down? There are many ways to write down, as to space classification, as to EGS classifications. What you have to see during the exam is these five characteristics. And write down the way you think is best for you, where the iris is implanted. When you do indentation, if I can only see strobus line, if I indent, can I see the trabecular mesh work? Yes, I can. So you write it down like this. Why? Because it means you can do laser iridotomy. You can say how much the angle is formed. You can say the configuration of the iris, if it’s concave, if it’s flat, if it’s plateau. You can see the pigmentation. Sometimes when you have too much pigment, three plus, four plus, it usually has some kind of disease and extra findings, vascular, and you can actually draw what you see. So here are just some examples of what you can see in your daily practice. Write down all your findings, because it makes life much easier for you. Some suggestions foregone gone, do gonioscopy in dim light. Use anterior and posterior slit to see Schwalbe’s line. Beginning, three mirror, afterwards change to four mirror ones. Follow the iris, the angulation, and then do the indentation. Now we’re going to go to the second part of the lecture, it’s much quicker now, don’t worry, and we’re going to talk about laser procedures. And here comes poll. According to the representation, what is the most likely laser to be performed? The iridotomy, the iridoplasty, the SLT, or the ALT? That’s a tough question. But I’m sure you can answer it. Okay. So most people, 58%, say it’s the SLT. And a few of them it’s iridotomy. So we’re going to go through it. I’m going to talk a little bit more about the SLT than the others. The whole idea of this presentation is for you to make a screenshot. So do a screenshot, and carry it with you, whenever you have to do a laser, you already know and you have all the cheat sheets to use. So basically here is where the drainage is from the trabecular mesh work, remembering that here, glaucoma basically is a clot in the pipes, right? The SLT is going to clean all these pipes here. And the more you clean, the more it’s going to work. That’s what we see here. If you do a 360 degrees, it’s actually as good as a [indiscernible]. So SLT is the first line treatment for open angle glaucoma. Why? Because you have 100% adhesion to the treatment. You can add a drug or substitute one drug if the patient has dry eyes. Especially if the patient is going to start glaucoma treatment, always try to start with SLT. Why? Because it’s much easier for the patient, and easier for you because you know the patient will be using — will be treated. Remember, patients, 50% of them use drugs, the other 50 lie about using drugs. So do the SLT. 100% of them, they are [indiscernible]. How does SLT work? Basically use an indirect gonio lens. And you’re going to do one shot right after the other. So it has to be one, then the other, then the other, then the other. This is going to make some kind of inflammation in the trabecular mesh work which is going to call for mastery sites which are going to rearrange the mesh work, which is going to unclog the mesh work and then it’s going to drain much better. It’s very different from the ALT. So the SLT is kind of a fixed spot which will go above the iris, take in the whole thing right here, and you’re going to go one right after the other, while the ALT on the other hand is a mechanical — you make like a mechanical hole. So here you have disruption. Here you don’t have disruption. It’s a reorganization. And that’s why we prefer nowadays SLT. So here is the difference. Here you see no difference in the mesh work. So probably it’s reorganized. Here is the ALT, a hole. The more holes you make, the more scar you’ll have and probably in the future it won’t work as good. SLT, on the other hand, can be repeated. We know it can last for five years. So it can be repeated. How do we do it? First of all, we are going to prepare the patient. And to prepare the patient, you use pilocarpine, brimonidine, and IOP before. Do one laser after the other, trying to make 360 degrees. And you have to titrate your energy. In the beginning, what we used to do is to go just below threshold. What is the threshold? Threshold is the bubble, is the small bubbles that you can see. The bubble means that the energy — the pigment is kind of taking the energy of the laser and making a bubble. So when it makes a bubble, it’s too high. You want to go one, just one level down. So what do you do? We see a few bubbles, we go down, three or four shots, go up again. If we see more bubbles, then you go a little bit less then. And you keep repeating. Some people, they just start with 0.8, 0.7, and go 360. Here, as you can see, I’m using a rapid lens, I just go in the four quadrants. After one hour, usually measure diopter and tell the patient to use NSAIDs two times a day for two days. As you can see in the movie, you don’t see much bubbles, but you saw one little bubble down here, and this little bubble was a little bit big, and it just stayed in place. Why is that? Because it was too much energy. If your bubble stays and it doesn’t do like this, then it’s way too much energy, you have to titrate your energy for a lower level. And if you have too much pigment, then you have to start with very low energy, not 4, not 5, just do 180 degrees. So here is the lens I was using, which is the rapid SLT lens. The advantage is you just go from one mirror to the other. As you can see in the video, it makes life easier. And here is the thing that we’re talking about. So remember, this is the single lens one which I have to rotate. In this case, I may misplace or even overtreat. By having one lens, which I can see more, I can just do more sequential way, and it’s easier to use. So now we are going to talk very quickly about ALT. ALT, as I’ve told you, is a mechanical rupture, a small spot size of 50micra which you’re again place between the pigmented and nonpigmented trabecular mesh work. Iridotomy, when do you do it? When you do your gonioscopy exam you have to ask yourself is the trabecular mesh work visible? If it’s not visible, why? Because it has a pupil block or because of the ciliary body that’s anteriorized? If it’s a pupil block, you do iridotomy. If it’s because the ciliary body is anteriorized or the lens hole is way too big, you can go straight to phaco or iridoplasty. How does it work? Here are some examples. So here is one example, a very, very narrow anterior chamber. You can see by Van Herick or even by the indentation as we saw in the previous slides. So here, when you indent, you can see the trabecular mesh work. What does it mean? That I have to break down this pupil block. I do the iridotomy and choose where the iris is thinner, then I do a shot, two, three shots. And see here, this is what you have to see. When you do a shot and it opens like that and you see fluid coming out, it means you broke down the pupil block, you see the aqueous coming out. Here, on the other hand, what you see is bleeding coming out. When you have bleeding, that’s the advantage of using iridotomy lens. Some people don’t use iridotomy using lens. But if you have bleeding, you just press down with your lens and this is going to terminate the bleeding and the bleeding will stop. Iridotomy should be done as much to the periphery as possible. And see what’s happening here? The magnification lens is displaced to the periphery and it gives you a 1.7 magnification of the laser beam. And see here what happened? Here it was too thick, the iris, so I have done ALT before to thin the iris, then the iridotomy on top of it. So this, it could open like that. How to see if it’s open afterwards? You can see the hole, actually the whole illumination. Sometimes to see a hole, but it’s not complete, like you saw in the first video when I did the first shot. It seems that it was open, not open enough. So if the angle doesn’t open here, what am I going to do? I’m going to do iridoplasty, which is done basically one shot after the other, leaving a space between them. About four shots per quadrant. See here what’s happening? When I do the shots, the actual iris kind of does this movement, it shrinks. It shrinks, it’s going to open the angle. This is not usually done anymore. And why? Because we can do phaco straits. Now we’re going to talk very quickly about laser suture lysis. When you do some kind of trab or any kind of glaucoma surgery, and you have a high IOP, you have to check if the otomy is open. If it’s open, then it means the suture that is done is too tight. So you have to make a suture lysis. If it’s not open, then you’re going to do a gonio puncture. And to do the suture lysis, you do the Blumenthal lens. The Blumenthal lens, it has to be used, for instance, for me. Why? Because it’s going to magnify here. And see here, he has a very congested eye, has a lot of vessels. But when you put the lens here, all becomes white, blanched, and you can see much nicer the suture. And then you just shot it, and it’s going to disperse the nylon. Now we are going to talk about gonio puncture. Gonio puncture, when do you do? Here is the hole for the trab, the otomy. Sometimes this can be stuck because it has scarring here or sometimes because you have herniation. And in these cases, you’re going to make a shot here using Yag. For this one, use the Yag laser and you shot right on the hole. So if you think it’s more a scarring issue, you go just a little further. If you think it’s more because of herniation, then you bring your machine towards you. Now we are going to go to the last ten minutes or eight minutes of the presentation. And we are going to talk about surgical gonioscopy. What statement is not true? I don’t need to tilt the microscope to perform surgical gonioscopy. Clear cornea incisions may help surgical gonioscopy instead of near clear incisions. Surgical gonioscopy lens should be held with your dominant hand. And the best way to practice surgical gonioscopy is after routine cataract surgery. This is a more tough question. Most of you just chose — let’s see. Yes, 30%, I don’t need to tilt the microscope to perform surgical gonioscopy. And surgical gonioscopy lens should be held with the dominant hand. That’s a tricky question. Okay. For surgical gonioscopy you have two key concepts. Location, as I’ve told, and visualization. As we’ve seen before, the position of the microscope and the head are essential for a good gonial view, because you have to seat temporal to the patient and you have to get used to the microscope tilt. And this will change according to the microscope you’re using. Some microscopes you have to tilt more, some microscopes tilt less. And the more you tilt the microscope, the less you have to tilt the patient head. So get to know your microscope. In those newer microscopes, it can tilt as much as they can, just make a dot in the microscope to make it easier for your technician. And why should I seat temporal? Because I’m going to work right opposite to me. I know that most of the collector channels are nasal and interior to the eye. If I can seat temporal, I can get more easily to them. And the head tilts easier sideways. Okay. So you have to seat temporal to the patient, get used to do the microscope tilt, tilt the patient to the opposite direction, and the microscope towards you. And this can make 15 degrees to the microscope and 35 to 45 degrees. About ergonomics, always use coaxial light. When you tilt, the distance between and you the patient becomes greater, is out of to adjust and get used to this. Choose the beds that have a smaller place to place the head, so you stay closer to the eye. And keep the arms close to you, in this sense it’s easier to do the surgery. So about ergonomics, tilt the head 35 degrees. And then tilt the microscope towards you. Notice when you do that, the ocular becomes lower, and if the ocular becomes lower you have to adjust your sitting position or it’s going to very difficult for you to work. I think I’m having some kind of technical issue here. Lawrence, you may want to come in. >> Sure, Dr. Cvintal, if you want to stop your screen share, I can do that for you if you want to try and reshare your slides. >> VICTOR CVINTAL: Okay. >> If you have trouble, I can bring up your slides for you, if you can remember the slide number. >> VICTOR CVINTAL: Yes, that’s the one, 106, please. You can go forward. So here, what’s happening? He’s positioning the lens, but he cannot see the angle very well. So in this case — go one more — if he tilts a little bit more the head, it becomes much clearer. So sometimes if you don’t see the angle, just tilt the head a little bit more. One more. So here — you can go all the way down, please. How to use the lens. Clean the surface using BSS on the finger. One more. You have to fill the AC with cohesive. One more, please. And always, to clean the lens, you’re going to take the lens like this, take your finger and just clean like this, okay? If you leave your OVD vertically, all the bubbles will come up and you’ll have a much clearer view. One more, please. Some surgical tips. One more. When you begin doing MIGS surgery, try to do low volume peribulbar block to have more control of the eye. If you do, use the Honan balloon and use mannitol for the pressure. The deeper the chamber, the better the view. One more. So first thing is to check visualization. What you see is what you got during clinics. One more. So try to compare the pigment pattern to the blood reflex. See if you really can see the trabecular mesh work. One more. You can use indirect lens, but indirect lens are troublesome. Don’t try to use them, if you go up, you actually go down, if you go right, you actually go left. One more. When you’re making your incisions, don’t do like I’m doing here, try to do clear cornea. Why? Because you have bleeding, and this bleeding is going to mix with the OVD and is going to make much worse view. One more. So what’s the problem here? With this lens, I’m pressing too much the eye. And the incision is too short. So I lose anterior chamber. If I lose anterior chamber, I have too much bleeding. For these eyes I have to make a longer incision or use lens that doesn’t press too much the eye. One more. When that happens, I can make a stitch or — one more — can you press play for me, please? Or you can use this lens which has this mechanism that doesn’t allow you to kind of press the eye. So see here, it’s very gentle to the eye. One more. So here, this is a premium surgery, I’m doing a toric lens, I check to see if I can see the angle first. After checking the angle, I can place, after doing the rhexis, I can place the lens. I tilt the head, I clean my lens, my gonial lens with the finger here, just showing you how this mechanism works. See that I can’t see much, so I have to tilt a little bit more the eye. I tilt a little bit more the eye. Once I put the lens, I can see perfectly the view, as you’re going to see right here. So here you can see much nicer. You can see almost all the angle. And just to compare, a very nice lens, see, you can adjust the lens and the angle to you, and it gives you a slight different image from the other lens. The other ones is also Volk lens, but I personally prefer the Hanson because it doesn’t press the eye. See why it’s essential for all MIGS procedures. You can go one further. Okay. If you don’t see the angle, as you can see here — one more — and how to hold the instrumentation. Always hold the lens with your nondominant eye because your dominant eye is going to hold the instrument. And according to the lens, some have the handle for both left and right-handed and some has a little bit tilted, like bent handle. One good thing about that lens that I show you, you can adjust the lens to the handle. So you can do like this. And another answer from the poll is, if you don’t have to tilt the head. Actually if you tilt the head 90 degrees, you can see the angle, but it’s not [indiscernible] for the patient. We are just finalizing. Next one, please. How to practice? Just after cataract surgery, just go with any kind of [indiscernible], train the distance, how to position the lens, and try to touch the trabecular mesh work with any kind of hooks. Another one, please. So in conclusion, gonioscopy is essential for MIGS surgery. It depends on finding trabecular mesh work and having a good view. Tilt the microscope and head. Care is anesthesia, the OVD used, and practice at the end of your cataract cases. I would like to thank you. I think I talked a little bit too much. Sorry about the technical issue, I’m not sure what happened to my computer, but I think you could see. If you have any questions, if we have any time, I’m free to answer. >> Perfect, thank you, Dr. Cvintal. We have questions, if you have maybe ten minutes. >> VICTOR CVINTAL: Sure, I have as much as you want. Here a doctor from Uganda. So thank you so much for the presentation, I work in Uganda, similar to Brazil, there is a link in resource setting therefore this means at times you get high patient loads in such a setting. Is there a screening or recording too that can be used during the sedating a patient with the tool including IOP, fundus, gonioscopy, OCT findings, without missing — okay. That’s a very good question. So yes, in high screening, in places where you have a bigger population and you need to do a screening, and this was really used during the pandemic, especially from the Swedish, they did a lot of programs using virtual examinations. So in such places, you can take handheld devices, such as the one I showed you, the prestige, this handheld machine, where you can take pictures. You can go to distant places, take these pictures, use some kind of tono, we know it’s not the best ones, but you can use it, you can record. And gonioscopy, gonioscopy is the only exam that you actually need to do it, okay? Nowadays there is one machine that does it, but it uses a lot of light and, and it’s going to open. So yes, you can do all these exams with handheld machines. And as I showed you, you have some software like the Volk software, it goes straight to one place, gets analyzed from a resource center, and you can get back with the results. And the doctor is also asking, why can’t I do indentation with Goldmann? So remember, the Goldmann lens, which is this lens, has a very wide contact place. So this is going to rest on the whole eye. Here you’ve got the eye. It’s going to stay on all the cornea, the limbus, so you can’t actually press it. To press the lens, you need a lens which has a smaller diameter. If you have a smaller diameter, smaller than the cornea, you press it, and when you press the center, the periphery opens. That’s a very good question. Dr. Abdul, in prophylactic laser iridotomy, patients with positive synechiae that is not broken with medical treatment, the [indiscernible] is under control and — so to do any kind of surgery or procedures, the uveitis needs to be under control, usually six months before doing any surgery. If it’s under control, you can do the surgery. So if it’s not broken, if the laser, if you have synechiae, if you have synechiae, is it going to help the laser? Not that much. Why? Because the synechiae is going to — sticks the iris to the angle. So the channel that you make won’t open the periphery. So these cases, with extensive synechiae, you can do either a phaco, but the result varies a lot, or you can go straight to any kind of glaucoma surgery as a trab. Remember, a trab cuts the iris and makes a whole between the anterior chamber and the [indiscernible] space so it won’t matter if you have synechiae or not. Oh, that’s a very good question. What’s the logic, Dr. Tolika is asking, what’s the logic of using numbing drops for 78 or 90 exam. It’s true, you don’t touch the eye, in theory you don’t need numbing drops. But I prefer, because it sometimes can take more than 20 seconds, 30 seconds. Patients that have glaucoma, they use a lot of drops, glaucoma drops. If they use glaucoma drops, most of them have dry eye. If you have dry eye and you have a lot of light coming from the slitlamp, sometimes can be very uncomfortable for the patient to hold the eye open. And by placing numbing drops, it’s much nicer for the patient and for me because I don’t have to keep opening the eye for the patient. Which lens is used for the SLT and coupling agent? Good question. The one I showed is the rapid SLT, the lens which has four mirrors. So if you have four mirrors, like the one I just had here, you can go from one — so, here. This is the rapid SLT lens. You have four mirrors. You can go from one to the other to the other to the other. It’s easier. And sometimes if you are not sure, you just turn this light a little bit. On the other hand, if you’re using a three mirror lens, you have to keep rotating, rotating, rotating, rotating. You have to rotate 360. And this sometimes is not nice for the patient, if you have to rotate too much. The coupling agent, you can use from gonio cell which is OVT that we use in Brazil and probably in Africa as well, or any kind of gel. Remember, to do SLT, there is specific lens for SLT, like this one, like one mirror lens. Don’t use normal three mirror lens for two reasons. One, the magnification is different. If the magnification is different, the energy that you are giving is different from the energy that you should give. And second, a normal lens is not prepared for laser so you can actually make some scratch or kind of won’t be good for the coating. Okay. So Alicia is asking if I use a triple [indiscernible] for your Yag, I don’t use. I try to use just one shot. I put in a higher energy like 6 or sometimes even 7, and I try to do the least shot that I can, because I can control. Sometimes if you’re doing more than one place, the focus of the machine is different from what you see. It’s very hard to calibrate them. So sometimes the actual shot is just before, just after the focus, because it’s not calibrated well. So sometimes what you have to do before initiating, you’re doing a paper, see where the shot is and then do in the eye. Then when you’re doing the eye, your first shot is the shot to calibrate, to see where your actual energy is going to. If you do a three-shot and you’re in the wrong position, you’re going to do three shots in the wrong position. That’s me. Oh, sorry about that. Someone asked what MIGS stands for. MIGS is minimally invasive glaucoma surgery. My fault, I should have written. Those neo-surgeries, where it’s very similar to a cataract surgery, you use the same incision as a cataract surgery and you work in the trabecular mesh work, most of them. So it’s very friendly to the eye. And you don’t open the conjunctiva. Because you work inside the eye, you need some kind of gonial view. Any tips to avoid overtreatment or undertreatment if the gonial lens I have available in a single — okay. So George made a very good question. How to avoid overtreatment in a single lens, single mirror lens. This is a — this is a three one, but you can imagine it’s a single one. If it’s a single one, some of the single ones, they have on the opposite direction, a mark. And you can follow this mark. So do five shots, again you rotate, and the mark will go from one place to the other. Then you just follow the mark. So try to always do something consistent. So always go, if you go to a single mirror one, take the middle of the mirror and do five shots, like one, two, three, four, five. Then turn a little bit, then continue, one, two, three, four, five. Then can you do overtreatment? You can. It’s not guaranteed. But I would do that way. I used to use a single mirror in the beginning. Okay. And Alicia, thanks again, how often do assorted patients needs review after procedure? That’s a very good question. It varies between doctors. So SLT is still in debate. Every school does differently. As I told you, personally I use MS8 for two days, and most people don’t do any kind of medications afterwards. Some people do steroids for a week. So I usually see the patient one hour after to check for the IOP, especially if they have a lot of pigment. So remember, the higher the pigment, the more energy used. So the chance of having a spike is bigger, is higher. So I see — for these patients which have a more pigmented — which have more pigment, I see one hour after, one day after, two weeks after, and six weeks after. For normal patients I only see two weeks after and six weeks after. Why six weeks? Because the laser — remember, SLT is a metabolic reaction. It needs time to rework the trabecular mesh work. And why we know it takes four to six weeks to lower as much as it can the pressure. And after four to six weeks, I can see if I’m going to re-treat or not. So if a patient comes, and I didn’t get the [indiscernible] that I wanted, so after this I repeat the laser. That’s me, not everyone does it. So I think these were all the questions. Oh, sorry, there is one last question from Marius. Thank you for your question, Marius. Does using steroids after SLT reduce the effects? Very good question. Do you only use NSAIDs and for how long? That’s a very good question. As I just told you, some people do use minimal steroids after SLT. Some people use three times a day for five days. I personally don’t, because what I think, because it’s inflammation and the metabolic reaction that you want, I will then use steroid. So I prefer to use NSAIDs the least I can, for two times a day for two days. Some people don’t use it at all. But there is no right or wrong answer for this. Thank you, very good question. Thank you all for watching. Sorry for the technical issues. And sorry for some videos, for me they were not playing here.

Last Updated: March 5, 2024

4 thoughts on “Lecture: The Critical Lens Technologies and Techniques (Gonioscopy, SLT, ALT, and MIGS) to Diagnose & Treat Glaucoma”

  1. I attain the recorded webinar.it was so much informative.
    When i am trying to joined the online webinar it can’t open.plz told the webinar time according to Pakistan.

    • Dear Anila Batool,

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