Lecture: Using the Slit Lamp Microscope to Visualize the Ocular Structures

During this live webinar, we will provide techniques to aid in the usage of the slit lamp microscope to effectively visualize the ocular structures. We will discuss the examination of the anterior segment as well the use of both fundoscopy and gonioscopy lenses. Questions received during registration and during the webinar will be discussed.

Lecturers: Dr. Rachel Brackley, OD, FAAO & Dr. Stephanie Leburg, OD, Salus University, Pennsylvania, USA


[Rachel] Good morning, I’m Dr. Rachel Brackley. I’m here in Philadelphia, just outside of Philadelphia at the Pennsylvania College of Optometry, Salus University to speak with you today about using the biomicroscope to evaluate the ocular health. I’m an assistant professor here at the college and I teach in both the didactic and the clinical program. [Stephanie] My name is Stephanie Leburg and I am also clinical faculty. I also teach in the didactic program here at Pennsylvania College of Optometry. And we’re excited to speak with you guys today and hopefully have a good discussion at the end with some questions that you guys might have. Think we can get into it. [Rachel] We want to start by telling you that we have no financial interests to disclose here. We would like to thank Volk for their commitment to worldwide vision in the presentation today. Let’s get started by talking about what is the slit lamp biomicroscope. Many of you have access to one. I’m sure all of you have used one or will use one shortly. What is it, what does it do? It gives us a slit beam of light and allows us to cross-section imaging of layered tissues. What are those tissues we can layer that we can look at with it? We can look at the cornea with it, we can look at the lens, and of course you know that using different lenses we can also look at the retina. We can look at all layers of the eye if we use a slit lamp. It can give us an ocular health assessment. Of course when we look at the fundus with it, we’ll be looking at the optic nerve, at the macula, we can look at the peripheral retina if we use a lens. We also know that with it we can get variable heights and widths, we can get different brightness and different magnification. So if we see something and we want to see it larger, of course, we would use a slit lamp. We do this each and every day in our clinical practice when we look at the cornea, when we start with the lower magnification we go to a higher magnification. We know that this allows us to see things that you can’t see with the naked eye. Also available on slit lamps are filters, you might see a blue filter, many of us use a cobalt blue filter to do tonometry. We might use a red-free filter to look at the retina. In addition, slit lamps, as many of you know, have cameras. We can put the Goldmann tonometer to it. And in some situations there’s teaching tubes that can be used as an adjunct to the slit lamp in order to teach others. Why are we using this? Of course, the number one reason that we use a biomicroscope is to do a routine ocular health assessment on each patient that we see. We also use it when we prescribe contact lenses to make sure that contact lenses fit properly. We would use it, of course, in emergency care in order to assess the ocular health. In addition to just looking at the structures of the eye with the biomicroscope, we also can use ophthalmic lenses and devices with more advanced skills to get more details and more about the ocular health. What are those different lenses we might use? We might use gonioscopy lenses, we might use a 3 mirror or 4 mirror. We might have to remove a foreign body from the cornea. How do we get that magnification to remove it? We do it behind the slit lamp. We might need to epilate a lash. We might need to look at the fundus. Of course there’s various lenses that we can use, different magnifications that we can have when we use a fundus lens. And we also know that there’s a 3 mirror lens, and we’ll talk about those different lenses and what the uses are throughout this presentation. And then of course, as we said, you can do Goldmann tonometry with the biomicroscope. If you’ve had access to a biomicroscope, what you know is that there’s different designs. And when you look at the designs and the name, they’re named really based on brand, as you look at them. There’s the Haag style slit lamp, that’s the newer style slit lamp. With that the lighthouse is positioned above the microscope. The microscope of course being ocular so you can see here in this picture that that lighthouse is above and that would be your Haag style slit lamp. You also have an older style which was the Zeiss style and their exposition below the microscope. Different practitioners prefer different biomicroscopes. Really once you can use a biomicroscope I like to always say it’s like riding a bike. Once you can use one you will be able to adjust to another. What we want is to have access to our biomicroscope in our ocular exam. Let’s talk a little bit about the illumination system. Here we have a picture of the Haag style slit lamp. And what we can see with those illuminations is that there’s variable apertures. We can change different things on here. We can change the slit height, we can change the beam width, we can make it wider, we can make it narrower. We can change the brightness. We can also change the orientation from vertical to horizontal. If you were to take that lighthouse at the top and you were to change that, you can make it vertical, you can make it horizontal, you can make it at any angle. And there might be times that you actually want to manipulate the slit lamp. Of course most of the time you’re going to see that we work in a vertical faction and we keep that light nice and straight. But there will be times that you want to change into different views. Just a little bit more details about those different things. You can see here that we have a picture of what you might see at the top of your microscope. And you can see that the letters correspond to what they do. You have your open, your fill intensity. You have a neutral density, your gray filter, that can help diffuse the light. Your red-free filter which can help in the visualization of blood in the retina or blood in any kind of part of the eye. It can help us, as well, when we evaluate choroidal nevuses. You can also have optional filters. I’ve worked with slit lamps that have yellow filters in order to decrease the amount of exposure of light to a patient and make a patient more comfortable. Different slit lamp you are able to put in different filters. You’ll see there’s a fixation star that can help with where the patient will be looking. And then the next thing that you’ll see at the top of that area is that you will see aperture sizes as well as a sliding slit beam scale. So that you can change the height of your slit beam. This comes to be really important too. Let’s say you have a corneal ulcer and you want to say how big is this because I’m going to see it today and then maybe I’m going to see it tomorrow and I want to make sure that that ulcer has not gotten larger, but it has actually improved. I can take that millimeter measurement, I can take my slit beam and I can make it really small and check horizontally, I can flip it, check it vertically, right, or horizontally and then vertically. And I can make that measurement and I can put that in my chart to check it the next day. That feature with the beam height and that ruler can be a great diagnostic tool. As well there’s a cobalt filter, of course, we use that in Goldmann tonometry or any time that we use fluorescein dye in a patient. Let’s talk about the illuminations that we have in a slit lamp and what we can do. And we’re going to start by talking about an optic section. An optic section sections tissue so it allows us to see different layers. What it is is the thinnest and the brightest beam of light that you can get. We’re talking width here. You want to use whatever your adjustment tool is for width in order to do this, get the smallest width you possibly can. You also have a maximum beam height. There’s slit lamps that allow you to go to eight millimeters, there’s slit lamps that allow you to go to 10, others 14, whatever that maximum beam height is, will allow you see more of the ocular tissue. When you are looking at a tissue with an optic section, you want to have your lighthouse at an angle. Rather than have everything straight, you want it to be angled. If everything’s straight, I’m not sectioning the tissue. I can’t see the layers. But if I take that lighthouse and I angle it, I can see the layer. If you look at this picture here, what you’re seeing is you can visualize the epithelium. You can visualize the stroma, you can visualize the endothelium. You can section that tissue and look at what structure has been affected. When you do this, you really can use any magnification. You could use a low magnification of 10, you can use a high magnification of 16. This is really going to show us the structural detail. And you can use this to section the cornea, you can use it to section lines as well. What we’re going to do here is actually show you an optic section scan of the cornea. In this, what I’m really seeing is is the cornea healthy? Can I see all the tissue, is there clarity, is there a scar on the cornea? And I just slowly take that optic section and scan that cornea and you can see in this video that we have a very healthy cornea, there’s no opacity. I could look in that stromal area and say is there any place that is more opacity than another? So many there is a scar at the cornea and I could visualize that using an optic section. Here are a couple pictures of optic sections and uses for other reasons. You can see here in the one picture that the optic section isn’t regular. It’s very irregular. As we go from superior to inferior there’s a part where you see thinning. This is a patient who has had corneal surgery and in that surgery the cornea was not regular at the end and you can see right where the incision scar is. You can see that the optic section isn’t regular. This tells us something about the cornea and helps us to visualize that the stroma endothelium is very different in that area of the cornea as opposed to the superior cornea. In this other picture you can see an optic section of the anterior lens. I could continue with that optic section and not only look at the anterior lens, but go through the nucleus into the posterior lens in order to look at the clarity of the lens. You’ll see in that optic section, I always like to say that’s a white-black-white. That is showing me the anterior lens capsule right in here. So I can see that and continue through. As we’re giving you these tips and tricks, I just want to remind you this is what we have learned. This is in our experience a way to teach. There are other ways to teach this as well. We just want to make you aware of really what has helped us and helped us and guided us as we’ve taught many students. As we move from an optic section, we move into a parallelepiped. If you look at this parallelepiped of the cornea, what you can visualize here is that the epithelium and the endothelium. What we’ve done here is we’ve widened that slit lamp beam. We’ve made the epithelium equal to the endothelium and gotten rid of the stroma. I can no longer see the stroma. If I have something on the endothelium, let’s say I have a keratic precipitate on the endothelium and I really want to be able to visualize that. Then I can use this technique in order to do this. Right here I would be able to see the endothelium. This beam is, again, at an angle. It’s not straight. That slit lamp lighthouse is at an angle so that I can see both the epithelium and the endothelium here. The wider I make that angle, the more epithelium and the more endothelium I would see. If I were to continue to change my width of that beam here, what would happen is I would go into diffuse illumination. When I go into diffuse illumination, I’m going to see more epithelium than endothelium. If you want to be able to visualize that endothelium, really using an optic section would give you a little bit of that endothelium. And using this parallelepiped at an angle will allow you to visualize the epithelium and the endothelium. From here what we’re going to do is present a few cases to you and explain to you what we would do based on the case history and based on the clinical finding. Our first case here is a 55-year-old Hispanic female who presents with intermittent episodes of eye pain and nausea worse in dim light. After taking the history your leading differential diagnosis is intermittent angle closure. What techniques are you going to use to confirm your diagnostic assessment? The first thing we’re going to need to do is we’re going to need to evaluate the narrow or closed anterior chamber angle. There are three techniques you can use in order to do that. You can do a penlight angle, you can use the Van Herick technique, as well as perform gonioscopy. What are we doing here when we’re looking first for a penlight angle? What we want to do is we want to see is that angle open or is that angle closed? What we see right here, of course, our anterior chamber angle is right in here. We have the ciliary body, we have the trabecular meshwork, we have the scleral spur, we have Schwalbe’s line. All of that is part of the anterior chamber. And here what we can see is the iris is nice and flat and the angle is open. If we do a penlight angle, and what we’re going to do in a penlight angle is we’re going to come in temporally, keep it parallel to the iris and look for a shadow on the iris. If it’s open, you’re going to see a shadow between the cornea and the iris. If this iris is bowed forward, you are no longer going to see as wide as a shadow, you will see a minimal shadow between the cornea and the iris. Here are some visual depictions of what you might see. You can see here in this picture you have your penlight right parallel to the iris and you see a nice big shadow over that no shadow over that iris, and here in this picture you can see this shadow easily over the iris saying that your angle is not wide open. Again here are other pictures that you might see. So you can see here at this top picture a nice wide open angle and here in the bottom picture you can see how there’s a shadow being cast over the nasal iris saying that your angle isn’t wide open and you need to be concerned that your patient has a narrow angle or an angle closure. Another technique that you can use in assessing the anterior chamber angle is a Van Herick angle and I think most of us do this quite often. And of course we use our slit lamp to do this. What is a Van Herick angle? It’s a qualitative measurement that estimates the depth of the anterior chamber. What we do here is we compare the depth of the peripheral anterior chamber to the thickness of the cornea at an angle of 60 degrees. That 60 degrees is extremely important here. Because if I’m not at 60 degrees, I’m not going to be estimating the Van Herick angle, I’ll be doing something else. If my lighthouse was at 30 degrees, I’m not going to get the correct estimation. What do you have to do here? First of all, you need to make that crisp, clear optic section. You have to have that beam as thin as possible. You want a full beam height here and you want the angle of the lighthouse to be at 60 degrees. You want the brightness to be full. I always think when I’m using an optic section it’s a very thin beam so there’s very little light coming through. I need that high intensity in order to fairly see. What am I going to do, how do I measure the Van Herick angle? What I do is I get that optic section and I have to obtain the first full optic section of the cornea after the sclera. I move from the sclera to the limbus, onto the cornea and when I first see all the layers of the cornea, the epithelium, the stroma, and the endothelium, I know that I can estimate my Van Herick angle. The way that I estimate is I compare the width of the corneal optic section to the width of the shadow. That width of the shadow will be the thickness of your anterior chamber. When you do a Van Herick, this can be done temporally, it can be done nasally, it can be done superiorly, or inferiorly. So you don’t just have to assess one and that’s where you make your determination. You might need to assess all four depending on your patient. Here is a visual depiction of the optic section as to the shadow. So you can see here in this picture, here’s where you have your optic section and your shadow here is very small. If we magnify that more you can see here’s your optic section and here’s your shadow. And we‘ll talk in a moment about how to measure that. But I think all of us can appreciate that our optic section here is wider than this shadow. If we move over to this picture, we have our optic section here, followed by our shadow, and we can appreciate here that our shadow is larger than it was in the other picture. That is telling us that our angle is more wide open and again, we’ll talk about the grading scale here in a couple of slides. I like this picture to help you visualize what does it look like when the shadow is narrow as opposed to open. This here is a picture of a patient who has an iris cyst. What you can see here is the shadow superiorly here is very thin. As we go down more inferiorly this shadow is much wider. This is the shadow we’re talking about, this is what we have to compare. If we look right here at the top, this shadow is less than a quarter of the width of this optic section. If we look here at the bottom, this shadow I would say is about ¾ maybe even a little bit more, it’s not quite an equal width of the optic section, but it’s definitely much closer than up here. What is the grading scale that we use? This is an internationally accepted grading scale that eyecare professionals throughout the world use in grading a Van Herick angle. If there’s no shadow between your corneal optic section, then it’s a 0. If you have a shadow that is less than a ¼ of the corneal thickness we would grade that a grade 1. That means that the angle is extremely narrow. If your shadow is a 1/4 of the corneal thickness, we would grade that a grade 2. And that means that your angle is narrow. If it’s greater than ¼ to ½ the corneal thickness, you would grade it a grade 3 and it is open. And if the shadow is greater than the width of the corneal optic section you would grade it a grade 4 and you can call it wide open. Of course we use this as eye care professionals often in determining if we should dilate our patients. If a patient has a grade 3 or a grade 4 Van Herick, we don’t worry that when we dilate our patient the angle will be occluded. As our patient’s angles become narrower to a grade 2 or a grade 1, we want to be concerned that if we dilate our patient, we might send them into angle closure and maybe we need to do a procedure prior to dilation. Of course, how do I make that final decision of whether to dilate? I’m not going to just do that based on my Van Herick. If I have the opportunity to do gonioscopy, that’s what I’m going to do to make the final assessment of the anterior chamber angle and make the decision to dilate. If we go back to our case, this is what would happen. We would take a look at it. We have a grade 2 Van Herick. The Van Herick here is narrow. Again, aiding in our diagnosis of intermittent angle closure, you need to be concerned. Once we determine that we have this small angle, we’re going to go ahead and do gonioscopy. Gonioscopy is a hard skill to learn. Once you are proficient at it, it is much easier. But I think gonioscopy first of all, putting the lens on can be difficult, but also understanding where to look in the lens to visualize the anterior chamber angle can be difficult to understand. What are the different types of lenses we can use? We say do gonioscopy and you could say there’s five different lenses I could use. You could use a 1 mirror, 2 mirror, 6 mirror. There’s all different types of lenses. There’s also lenses that have flanges. There’s lenses that don’t have flanges. There’s a handle, there’s no handle. So what lens do you use? Any of these lenses will work as long as you know how to use them. When we’re looking at 1, 2, 4, or 6 mirror lenses, all of the mirrors in those lenses are used to assess the anterior chamber angle. When you look at a 3 mirror lens, a 3 mirror has three different mirrors. So you can assess both the anterior chamber angle in the angle mirror as well as the retina in the other mirror. We will talk more about a 3 mirror further in the presentation. Here’s more on different types of lenses and what they look like when they’re in the eye so you can see here what a 2 mirror gonioscopy lens would look like. Here you see a 6 mirror. The advantage to a 6 mirror is that there’s less rotation. The less lenses you have the more you have to rotate the lens in order to get different angles. With the 6 mirror, you have minimal rotation in order to view the anterior chamber angle 360 degrees. This is more on the 3 mirror and what a 3 mirror would look like. Of course you have the three different mirrors: the angle, the peripheral, and the equatorial. We can also view the posterior pole with this. In the equatorial mirror we would look at the equatorial retina, the peripheral mirror we would look at the peripheral retina. And then you can use the angle mirror to view the ora serrata, the far peripheral parts of the retina. When we’re putting a gonioscopy lens on the eye, we need to understand what’s happening. When we put this lens on the eye, light is being reflected from the anterior chamber angle into the indirect gonioscopy lens and is reflected by a mirror. The structure you’re viewing is 180 degrees from the mirror. If you placed a mirror temporally, you’re viewing the nasal angle. If you place the mirror inferiorly, you’re viewing the superior angle. Just make sure that you’re aware of which angle you’re looking at, so where your mirror is and what angle that is so you make sure that you assess properly. How do we actually do this? What do we do in order to put this lens on an eye? First of all, we disinfect the lens. The next is, of course, for patients this isn’t the most comfortable procedure for patients. In order to make them comfortable we’re always going to instill an anesthetic so that that can be comfortably placed on the eye. When we do this, we do this with a patient in the upright position and we do it in the slit lamp. If you’re going to use a lens with a flange, you need to make sure that there is some type of conditioning solution in the lens. If you don’t use a flange, there’s no solution necessary. Why might you use a flange as to a lens without a flange? Really a lot of it is practitioner preference. A flange is much more stable so if you put a flange on the eye and you hold it there, it’s going to stay a little bit more steady. Without a flange, there’s more of a chance for the lens really to move about on the eye and it might be a little bit more unsteady. That being said, when we have a flange, we cannot do indentation gonioscopy as without a flange we can do indentation gonioscopy and many practitioners prefer a 4 mirror without a flange due to the ability to do indentation gonioscopy. How do we actually insert the lens? I always like to say if you’re going to do gonioscopy be ready so that this can be as quick and efficient as possible for the patient. Make sure you prepare the slit lamp. When we talked about optic sections and we talked about parallelepipeds, we talked about our lighthouse being out of alignment. Here the lighthouse needs to be in alignment. Your slit beam is going to be about 3-4 millimeters wide. That could vary depending on your preference, but that’s what I prefer to have. Your slit height is going to be 6-8 millimeters high. Again, that can differ depending on your preference. By not using a full 14 millimeter beam what I’m doing really is decreasing the amount of light getting to the patient, making the patient a little bit more comfortable and that’s why I would use that slightly smaller height. My brightness, again, is going to be moderate. Again to keep patient comfort. When I hold the lens, and you’re going to see here in just a minute, we’re going to put up some videos. I like to hold that lens between my index finger and between my thumb. I’m going to place that lens directly on the eye. And my tip here really to being steady in gonioscopy is that as a female, I don’t have a long arm. I actually can’t rest my elbow on a slit lamp. What I have to do is I actually, as you’re going to see in these videos, that I take my middle finger, my ring finger, my pinky and I grasp the forehead rest, I hold the lens here between my index finger and my thumb and that helps me keep steady. All of my strength is in these fingers here in order to keep my hand steady and do the procedure. Right here you’re going to see a video of how we would insert a 4 mirror lens. You can see I’m just inserting it right there onto the eye. You do this with the lens nice and straight. In the video what you see is I like to tilt the lens up toward the patient, just bring it right there flat on the eye and hold it in place. If you were going to use a 4 mirror with a handle, here’s how I would suggest that you do it. You can see here in these two pictures how you would hold that handle and place it on the eye. Some people find it a little harder to use a 4 mirror with a handle. You have to be a little bit more steady, be a little more proficient with your technique. Here you’ll see us using a 4 mirror with a handle. You can see in that bottom how we’re putting that right on the eye. And then what we’re doing is going right into the slit lamp and viewing it and then removing it. You’ll also see, one of our hints here for using a 4 mirror with a handle is those handles can be unscrewed. If you’re more comfortable actually holding it with your index finger and your thumb, than with the handle, then you can unscrew that handle and go ahead and place that on the eye without the handle. You can also really hold the top and the bottom part of the lens and let the handle fall in your hand if that’s easier for you as well. And what do you see when you do 4 mirror? What happens in the slit lamp? You’ll see here what’s happening. We have the slit lamp lined up, we’re going to push the slit lamp in in order to visualize the central lens. The pupil should be in the center of the central lens, that’s going to help visualize the angle. You can scroll up, move right up into the superior mirror or the inferior angle and scan it. You can move into the superior angle, inferior mirror and scan there. And then you can move into your nasal and temporal angles as well. Again, you’ll see we’re going back to that central lens and refocusing the iris. If you ever lose your focus as you’re going through this and can’t find the angle, what I would suggest you do is go into that central lens, make sure the lens is centered just right, the pupil’s in the middle of that central lens, and then go back to the mirror that you’re looking at and try to visualize that. Once you’re in that lens, what do you see? You see the anterior chamber angle. What does that consist of? That consists of the iris, the ciliary body, the scleral spur, the trabecular meshwork, and Schwalbe’s line. And then you’ll be able to see the posterior corneal surface. When we look at in a lens, it’s a little bit more difficult. What do you look at? You have this lens, you have 100% of the image. And what we’re asking you to do when you’re doing gonioscopy is actually just look at 5% of everything that you see. If you see the iris right here, right at the edge of the iris, you can see in this lens, the ciliary body. You can see a white line here, a very thin white line, that’s your scleral spur. And you see a little bit of pigment here in the trabecular meshwork as well as Schwalbe’s line. What you want to look at is just that crescent right there. Everything else in the lens has to be there because it’s on the eye and you’re viewing it, but it’s not important. What you need to do in gonioscopy is really train your eyes to look just at that little slit and that slit is your anterior chamber angle. What if you can’t see the angle in the mirror? What are some things that could happen? First, you could get bubbles. Bubbles often happen because there’s pressure. You’ll often see that that lens has to be held nice and flat and flat up against the eye. If you start to drift one of your hands, so maybe your thumb starts to come toward you and your index finger goes toward the patient, a bubble will get in. If you see a bubble I would really encourage you to make sure that that lens is nice and flat. You might see corneal folds. That means you’re pressing too much, let go of a little bit of the pressure. One of the biggest struggles that people have when using a gonioscopy lens, of course, is glare. What can you do to relieve the glare? Our best tip for you is to tilt on the access you are not viewing. If you’re looking at the superior or the inferior mirror, tilt the lens nasally or temporally. So that would be tilting toward nine o’clock. Tilting toward three o’clock. And then you would do that opposite if you were looking at the superior or the inferior mirror. I always like to think if I have glare, I tilt the lens. If the glare gets worse, I tilt the other way. If you’re in that lens and all you see is the iris, what you need to do is tilt to where you’re looking. Let’s say you have a grade 4 Van Herick angle, you know that you should probably see the ciliary body or the scleral spur and you’re not seeing it. You just see a bunch of iris in that lens. Tilt toward where you’re looking, meaning if you’re in the superior mirror, tilt up toward 12 o’clock, just tilt that lens. Don’t move the lens up, tilt it. If you only see sclera, you need to move opposite. You tilt away from where you’re looking. If you’re in the superior mirror, and you just see a bunch of sclera, tilt towards six o’clock and you should be able to do the. In this picture here what I like to show you, this is the slit beam of light. We had a vertical slit beam of light that’s 3-4 millimeters wide. When you’re actually in the slit lamp this is what you’re going to see. Pictures often, as in my last picture, I illuminated the whole entire angle, that’s not what we see when we do gonioscopy. We move our light up and we just see this little slit. Right there, that would be my angle and I could move my lighthouse, with the joystick move right and left and be able to visualize the whole anterior angle if this was the superior mirror. Why do we do gonioscopy? We need to determine if the angle is open or if it’s closed. We need to determine if there’s any pathology, whether there’s neovascularization, is there synechia, is there angle recession? All of those things can be found using a gonioscopy lens. So if we went back to our patient here, what we’d see is that their angle is really narrow. We can also see that the iris is bowing forward. If we’ve determined that our angle is narrow, we might not want to dilate our patient. We might want to get further testing before we actually go ahead with dilation and if the angle is closed we might want to have a procedure prior to dilation. What you’re going to have to do here is undilated slit lamp ophthalmoscopy. I like to do undilated 90 so that’s why I say that. You could also do direct ophthalmoscopy. I prefer undilated 90. What are you going to do here in order to undilated 90 because undilated 90 takes time. It’s something that takes time to become proficient. Your illumination here would be moderate. The height of your beam should be smaller than the size of the pupil. And the reason I say that is the less light that’s going into the eye, the larger the pupil is going to be. If we’re going to work with an undilated eye, we want to have the pupil as small as possible. The width of my light 3-4 millimeters, maybe even a little bit narrower depending on the size of the pupil. As I do this, what I like to do, when you’re talking about doing slit lamp ophthalmoscopy, there’s really two techniques that practitioners would use. They might focus on the cornea and pull the slit lamp back. There’s other practitioners that like to start with the slit lamp closest to them and then push in. With undilated, what I do is I focus on the cornea and I pull back. I’ve done dilated slit lamp ophthalmoscopy enough that I have a general idea of how far I have to pull that slit lamp in order to get focused on the retina. If I’m doing undilated and I’m all set up so I have that light right centered over the pupil, I’ve gone ahead I’ve put my lens in place and I pull my slit lamp back, and I’m at the point that I know that I should see retina, but I don’t see anything. What I will do is make very small micromovements with my lens. Up, down, right, left. And see if I can find the red reflex. And normally at that point I find the red reflex. When I find that red reflex I hold that lens as steady as possible and move the slit lamp either in or out to visualize the retina. Here you’re going to see a video of undilated ophthalmoscopy. We’re going to do it here with three different lenses. Here we go, you can see us actually setting it up. You’re going to see how we hold that lens between the thumb and the index finger, so the same way I hold a gonioscopy lens is the way that I hold these lenses. You’ll also see that I put my fingers at the top of the slit lamp the same thing. Because again, my arm isn’t long enough. I could get a rest to rest my elbow on, that’s something I could do. But if I don’t have one, I can go ahead and put that lens right in place. You’re going to see I’m going to pull back that slit lamp and I get to the point that I should have something. I don’t. So I start making small micromovements. With those micromovements I was able to find the red reflex and there I go, I can visualize the retina. I have the optic nerve there and then I can examine the superior retina here, you can get the inferior retina and move over to the macula. You’re going to see in these videos there’s a lot of glare. There’s often glare when you do one of these procedures. What you have to do as the practitioner is learn to avoid the glare but also really zero in on the areas that don’t have glare. There’s glare there but the glare, this here is using a Super Pupil, the glare doesn’t get into the way of the view of my retina so I can ignore that glare and just really focus on this part of the retina. And then here’s my last view and we will use these same lenses dilated later in the presentation and talk more about them so you can just see again another lens. There’s various lenses you can use in order to do undilated ophthalmoscopy. [Stephanie] All right so let’s get into the second case here. This case we have a 66-year-old African American male who was previously working in a garage and he presented to our clinic with an ocular emergency. His left eye had become red and painful and he was very light sensitive. And this has been going on for about two days since he had been working at a garage. When we get into some of his history we perform a review of symptoms. Some other ocular symptoms that he was noting he mentioned that he had the eye pain, the redness, but he was also tearing quite a bit. He said that he had a headache and he definitely felt a foreign body sensation all in that left eye. Just some additional questions that we thought were pertinent to ask based on his initial presentation, we asked him if he had any history of muscle weakness or joint stiffness and to those things he said no. And he was not having any flashes, floaters, or loss of vision, common things we would ask on any patient. How should we proceed with our slit lamp exam at this point? We have to make some decisions. With every patient that comes in through emergency, you’re not necessarily going to evaluate the eye in the exact same fashion. Sometimes patients are so uncomfortable based on the presentation that they’re coming in with that if you were to evaluate the eye with a full beam maxed out brightness, you’re not going to be able to evaluate the eye. They’re just not going to be able to tolerate that sort of illumination. We have to think about how wide should we make our beam, should we start with an optic section, or maybe start with a more diffuse light? How should we start with our beam height, what magnification should we use? In general a good rule of thumb would be to start with lower magnification and then work your way from there. There really is never a situation where we’re going to jump right in the highest magnification possible until we’ve found something worth looking at. How bright are we going to have our illumination? That really depends on what you need to see, what you’re suspicious of, and also what the patient can tolerate. Specifically in our emergency service, a lot of times we will try to make an evaluation without instilling any anesthetic first but if the patient is really in so much discomfort that they’re unable to tolerate our evaluation, you may have to instill a drop of anesthetic so that you can use the light illumination that you need to to properly evaluate the eye. And then secondly, what fundus lenses should we use? Specifically in the emergency service too, it’s really important to think about evaluating the eye in its entirety, all the way from anterior to posterior. Even if you think you see something that is excluded to just the anterior surface of the eye, you cannot rule out posterior segment problems so you have to think about the eye as a whole, every time. With this patient who came in feeling like he had gotten something in his eye, with further questioning he felt like maybe there had been some sort of a high projectile foreign body while he was grinding metal. Any time that we have a question of a foreign body, we’re definitely going to want to perform a Seidel test. And so what a Seidel test is, a Seidel test will let you detect a perforation or a wound to the anterior chamber of the eye. And how we do that is we take a fluorescein strip, you can get that fluorescein strip wet either with saline or anesthetic. And then what you’re going to do if you have an area of suspicion on the cornea that you think might have been affected, you’re going to apply that fluorescein strip to that area. And what you might see if you might see that fluorescein having diluted stream to it and what that diluted stream is indicating is actual aqueous coming out through that wound. If you do see a diluted stream of fluorescein, like you do in this picture, that would be a positive Seidel sign showing that there has been some perforation to the cornea. Interestingly with our patient here, he did not have a positive Seidel test. I wanted to show you what one looked like. But when we performed a Seidel test on our patient, he was Seidel negative, there was no aqueous stream that we were able to see. But because we had such a suspicion for a foreign body, we continued on with our evaluation. Wanted to evaluate the entire eye. It’s really important, any time you’re questioning some sort of inflammation or trauma that you evaluate the anterior chamber. And how we evaluate the anterior chamber and just as a reminder that anterior chamber is that optically empty space, or it should be empty, it’s the space between the cornea and the anterior lens that is filled with aqueous humor. How we perform this anterior chamber assessment is we want to shorten our parallelepiped beam, we usually use a parallelepiped. We shorten it down so that it fits inside the limits of the pupil and we start focused on that cornea. After we are nice and focused on the cornea, we then move in and focus on the anterior capsule of the lens as you can see in this picture here. Once we are focused nice and tightly on the anterior lens capsule, we then pull our focus back just a little bit and then you can see that both of the structures are blurry. Here’s our out of focus corneal beam and here’s our out of focus anterior lens. If they are both blurry, you are now focused in this really dark black anterior chamber. And if there’s no inflammation in the anterior chamber, this empty space will appear optically empty, it will be black. You should not see little particles floating in it. If there has been something that has caused inflammation though, you might see some very, very small white particulates, white blood cells. They might also be pigmented if there has been some sort of pigment released from that trauma incident. These little spots that you see here, this is really an over representation, they’re going to microscopic, so you really need to be at a higher magnification. You will not see these tiny little individual cells on low magnification, let’s say 10 or 16. Up to 25 or 40 is really the magnification that you want to be at. And there’s a couple other really important things that we need to think about here in terms of our brightness and then our room situation. You’re looking at this dark optically empty space, you need to yourself, the doctor, be adapted to a very dark room. All of the lights in the room really should be off. If you have monitors behind you casting off some light into the room, they should be off too. As best you can, you want all of the lights in the room to be off so that you can properly adapt to this dark light and then you need the brightness on your slit lamp to as bright as possible so that it will reflect off these tiny, really really really small white blood cells in that anterior chamber. And so when we evaluated our patient’s anterior chamber he did indeed have quite a prominent anterior chamber reaction indicating there was probably something that really did happen during this trauma event. Because we didn’t see a Seidel positive sign, we aren’t done. We still need to look at the fundus and be suspicious. He was working in a garage grinding metal, there’s a high likelihood that maybe he had some sort of metallic foreign body penetrate the eye. We’re going to use different fundus lenses and which lens you choose is really provider preference. But some of them are a little bit better suited for certain things than others. All of our fundus lenses though are convex lenses. They converge light. And what they do is they cause images to be magnified. You can see here some of the more common lenses that are used in primary care as well as emergency practice here. I have a little bit more familiarity with some of the Volk lenses because that’s what I was using as a student and we use what we know. There are some very nice specialty lenses that different manufacturers provide for some speciality situations. I would say that the most common lens would probably be the 90 and all manufacturers make a 90 diopter lens. But there’s some very nice specialty lenses for certain situations. I really like, on my undilated patients with very, very small pupils, I really like my Super Pupil lens because it really allows for you to see a really large field of view with an undilated eye. You could use it on a dilated eye as well, but it just allows you to still see a lot of the retina, even if you have a very, very small pupil. An interesting relationship here that is just good to be familiar with, is that as the diopter power increases, the magnification actually decreases. With a 60 diopter lens, compared to a 90, the lower diopter powered lens actually has the bigger magnification. What do you do if you’re in the slit lamp and you’re trying to get a view with one of our fundus lenses and you just can’t? You think you have your alignment just right. There is one little tip that you can try in addition. You want to make sure that the light coming out of your slit lamp is reaching through the pupil. What you can do is move your head outside of the slit lamp. As you see in this first picture here, it does not look like the light is passing through the pupil in comparison to the second picture here you can see his actual crystalline lens glowing within his pupil. Then you know that your light is passing through the pupil and you should have a view. From that point then you have to try to just keep things steady and find where your retina image is going to show up. And now here we have a video of what a dilated slit lamp exam might look like here. You’re going to see in the bottom screen there our hand placement. We’re still bracing our hands on the outside of the slit lamp. And here we are now focused on the optic nerve, we’re scanning nasally and temporally. You don’t have too much glare, here we’re focused on the macula. And now we do have a full beam height here because this is a dilated eye. We really want to see as much retina as possible. Moving on now to the Super Pupil lens, you can really see that you have quite a big view in addition, even though the magnification is a little bit less. You’re really able to see a lot of the retina, especially with this Super Pupil lens. I’m a big fan of it, some people have different preferences. This now is the Digital Wide Field lens. I really like this Digital Wide Field lens because it allows me to see the biggest field of view. If I had a really, really nice dilation, I’m probably going to choose to use the Digital Wide Field lens. I can go at least six disc diopters nasally and as far out temporally, way past the equator. This is just a comparison here of what some of your still shots might look like with your magnification of your different lenses. The 90 diopter and the Digital Wide Field, pretty similar in magnification. It’s just with your Digital Wide Field you’re really going to be able to go out quite a bit further in your scans. And with your Super Pupil, the magnification is less but the field of view is going to be more. What are some of the struggles with these fundoscopic lenses? We know that reflections are really the bane of our existence. It takes the most time to find these little tips and tricks that are going to work for you. And really, experience is probably the biggest benefit here. But reflections can really be a problem, they degrade your image quality. One of the biggest advantages that’s come out in recent years are the anti-reflective coatings that manufacturers have started putting on their lenses to help reduce some of these reflections. And now back to our case with the foreign body. As I said, he did have a sealed cornea. He did not have a positive Seidel sign but when we looked fundoscopically we were able to see that he had a foreign body retained in his retina. I just wanted to show you this little video. This was actually at the retina surgeon and this is a video courtesy of one of our colleagues, Dr. Jeff Nyman here. And so here the retina surgeon has located the foreign body, just superior there to the optic nerve. And what he’s going to start doing is sealing off this foreign body here because he knows when he removes this foreign body he’s going to cause a retinal detachment. He wants to seal down the area of the retina before he removes it. Getting on to our third case here then. We have a 23-year-old Asian American female she presents for a comprehensive eye exam. She had blurred vision in her glasses and her contacts but her prescription was a little outdated. She denied any eye pain, redness, any of those symptoms but she did have some headaches and eye strain. And she did have some new flashes and floaters from about a month ago. All of her entrance testing was normal. She did pinhole down to 20/20 and you see in her refraction here, she did have quite a myopic shift from her two year old glasses in each eye. She’s quite myopic. And when we did her dilated fundus exam, the right eye was normal but as you see here in this left eye, we do have this large area of lattice with quite a large hole inside of it. We had some different lenses that we used to evaluate here. We had a 90 diopter lens that we would use off axis with and then 20 diopter lens was what we used with our BIO. And then to really better evaluate the traction in this area, we used a 3 mirror gonioscopy lens. What’s interesting here about 3 mirror gonioscopy is that you can really look at all of the different areas of the retina. This is just us inserting the 3 mirror lens here. We start by having the patient look down, then the patient looks up, and that 3 mirror with the flange is inserted right against the front surface of the eye and then the patient looks straight ahead. Just very important that the eye is anesthetized beforehand or else the patient really wouldn’t sit through this procedure here. And then now here is our 3 mirror exam. We’re rotating the lens, there are different mirrors. You can evaluate the posterior pole through this central lens. And then you can evaluate different areas of the retina: peripheral, equatorial, or the far anterior retina. As long as you’re in the right mirror. In each mirror you have another pupil through which you can push your light and view the retina. Here I believe we’re in the angle mirror of viewing the far peripheral retina here. And then we just performed an OCT on that same area to show that there was some traction in this area and that definitely warranted a referral to our specialty retina service. [Rachel] And with that that ends our presentation. We’d be happy to answer any questions. Thank you for joining us and we hope that our tips and tricks help you in your clinical practice. In regards to the, do you have any thoughts on this? I don’t have much thoughts on the cup-to-disc ratio within the Zeiss model of the slit lamp. Dr. Leburg, do you have any? [Stephanie] Not any different than the Haag model as well. Just as a general thing where you know the beam height of your slit beam based off of the metric ruler up top. If you know that you have, let’s say, a 10 millimeter height beam, you could then turn that beam horizontally and see if that can help you actually perform a little bit of a metric conversion there. [Rachel] The next question is, how long would a slit lamp take in minutes for white light assessment in a normal exam without presenting any complaints. I think that really is patient dependent. Some patients are very sensitive to light and as soon as you put that light in there, they get very upset and squinty and really you can’t do much of an evaluation as opposed to some patients who can sit for a long amount of time. How long does it normally take? It’s really going to depend on the examiner and how fast they can go. I think most of us do it within a couple of minutes but if it takes you 10 minutes to examine the anterior surface of the eye, it’s not going to cause any permanent damage. [Stephanie] How do you make retroillumination with the slit lamp? That is a separate illumination technique. What you need to do is first focus on the tissue that you are interested in evaluating with retroillumination and you can evaluate different tissues, you can evaluate the cornea, the iris, the lens. Focus first on the tissue that you want to evaluate using retroillumination and then it’s really pretty simple, actually, as you just reduce the angle of your lighthouse. Reduce your beam angle until it’s almost in click. Your lighthouse might be swung out to 30 degrees, you’re just going to reduce that beam angle almost until it’s in click and right on either side of it being in click is where you should see that red retroblow. It’s just really important to know where you’re focused first, depending on what you’re trying to evaluate. [Rachel] And then the next question is how do I know the layer of the lens when viewing through the slit lamp? The most important part, of course, would be to know your layers of your retina and really be visualizing that. I often think of it, I’m assuming most of us know what an M&M is here. I think about the lens is an M&M with a capsule and a nucleus. The nucleus is the chocolate, the capsule is the shell. If I were to take the M&M and look through it through the side, if I were to cut it in half and look through the side, I would have the capsule, I have the part that the colored candy, I have the chocolate in the middle and then I have the colored candy in the back. The lens, when we’re looking at it with a slit lamp, is really the same idea. I’m just taking a light and then slicing it through. You can visualize that optic section that we had of the anterior lens, so that white-black-white. You can also get that optic section of the posterior lens. You can do that white-black-white and it almost looks yellow. Often looks yellow in a lot of patients as they age, but we’ll see that white-black-white again. If you section through that and go from the anterior to the posterior just like with the anterior chamber, saying the area in between it is the aqueous, here the area in between that is the nucleus. Just understanding the anatomy of the lens as you push back can really help you to understand where you’re looking at in the lens when you’re in a slit lamp. [Stephanie] Question here about is the illumination 60 degrees or is range 45-50? That’s a good question but it depends on what you’re looking at. There are some certain illumination techniques like performing the Van Herick angle assessment where that’s a definition. It really should be at 60 degrees in order to perform an accurate Van Herick angle assessment. But there are different scans where you don’t necessarily have to be all the way out to 60 degrees. A good range for all of your anterior structures, the lids, the lashes, the conj, the cornea, somewhere between 30-50 degrees is really a good zone so that you’re really seeing all of the layers to some of those tissues. [Rachel] There’s questions on cleaning a gonioscopy lens and how we would go about doing that in order to make sure that we don’t scratch the lens. Hot water, dish soap, a mild detergent. It’s good to keep your lenses clean. And disinfecting, a dilute bleach solution and dilute hydrogen peroxide solution will kill anything that might possibly get on the lenses when you put that on the patient eye. As for cleaning, cotton cloths. 100% cotton. If you have an old T-shirt that you’re not wearing any more and it’s 100% cotton, cutting that up and cleaning any of your lenses with that will really help to prevent scratching. You want to be really careful with lenses, of course, with microfiber cloths. The AR coating can be ruined in those microfiber cloths. 100% cotton, I really think an old T-shirt cut up is a great way to clean your fundus lenses, your gonioscopy lenses. [Stephanie] How do we see tobacco dust with a slit lamp? This is a really important skill to have. What we start with is a really, really bright optic section. The brightest, thinnest beam you could possibly make. You’re going to cross your beam through the lens. So you’re going to start anterior lens, move through the cortex in the nucleus, land on the posterior lens capsule, and then you’re going to continue to push back a little bit further into the vitreous. Once you’ve passed the posterior capsule of the lens, we also have our beam out at an angle so we’re looking at a cross section through this tissue, once you know that you’re in the vitreous and you have a really bright light, if there are small little tobacco dust is really the term for pigmented cells that have been released from a retinal detachment or a retinal hole. If you were to have any of those little pigmented cells in the vitreous as long as your light and your illumination is really bright you should be able to reflect light off of them and see them. [Rachel] There’s also a question about consideration of a patient’s myopia, hyperopia, when I need a lens for examination. I never think about what a patient’s refractive error is because what I know is I’m going to move my slit lamp in and out. And based on where I put that slit lamp it’s going to focus the retina. I never use a different lens depending on refractive error. [Stephanie] How is it possible that the patient had a retinal foreign body without a sign of entry point in a negative Seidel test? Yes, I would love to explain this more. If the foreign body was at such a high projectile and in such small size, it’s very possible that a little bit of time had passed. The foreign body did enter through the cornea and so right after that happened there might have been a positive Seidel sign. But with a little bit of time the time that it took from the patient to get from where he was to our emergency clinic, during that time aqueous is still being produced within the anterior chamber. And that force of the aqueous restored the pressure within the eye and basically sealed that wound. It just came down to the internal pressure from the anterior chamber of the eye sealing that wound. It’s not that the wound isn’t still there, but it’s not allowing aqueous to escape out anymore. When to use the green filter? The green filter is really helpful. I prefer to call it the red-free filter because that’s a little bit more accurate. What is it doing, is it’s blocking out all of the red noise or the red distraction from your view. It’s really helpful. You can use it in the front of the eye, you can use it in the back of the eye. In the front part of the eye if you were to put on the red-free filter, it’s really going to make other things that are red pop out black. If you have a lot of injected really bold blood vessels they’re actually going to show up a little bit more black. If you have a little hemorrhage of the front surface of the eye that’s really going to make it stand out as well. In the back of the eye, it really as I said, it blocks out some of the other red distraction of the rest of the retina. If you have certain pigmented lesions in the back of your eye, you could use this red-free filter to distinguish what layer they are in. We have pigmented tissues both in the choroid as well as the retinal pigment epithelium. If you have a lesion that you’re seeing in the retina, and you throw on that red-free filter, if that pigmented lesion disappears, then you know that it’s in the choroid. But if that pigmented lesion still stays in your view and it’s still nice and sharp and black, if it stays in your view then you know that it’s in the retinal pigment epithelium. [Rachel] There’s also a question about describing sclerotic scatter. sclerotic scatter whenever I do this I use a parallelepiped. I take my parallelepiped, I’m at an angle of light and I take my parallelepiped and I go to the limbus. And then what I do is I come out of the slit lamp. What I’m trying to do is look and see, is there an opacity in front of cornea. I come out of the slit lamp, what I’m going to see is I’m going to see a ring of light around the cornea, 360 degrees, and the cornea is going to be illuminated. If there’s any type of opacity in the cornea I’m going to see it. If your patient has a corneal ulcer and you do sclerotic scattering, you look from the outside and that ulcer is big enough no matter how big it is you should be able to see light. There’s something that’s decreasing the clarity of the cornea and that’s really what you would use sclerotic scatter for. [Stephanie] How far can we see by Super Pupil lens comparing to a wide field lens? Actually the field of view I think is pretty similar between the two of them. The really big differentiating feature that I like between these lenses is one is really best suited, I think, for when you have a really, really small undilated pupil. Think of our much older patients with diabetes and their pupil, even dilated, is still really only two or three millimeters. That’s when I’m going to use my Super Pupil lens so that I can still get the same big field of view through a very, very, very tiny pupil. Whereas a Digital Wide Field or there’s several other variations of wide field lenses, those I really feel, you can use them on dilated but I think they’re best suited for when you have a really nice wide dilation and you’re really trying to be as efficient as you can and see as much in a very short amount of time. Very similar field of views it’s really more on when I would choose to use one versus the other. Super Pupil I would use undilated and a Digital Wide Field I would use on a nice, big dilated eye. [Rachel] Next there’s a question about how to perform applanation tonometry in a slit lamp. I’m just going to quickly say that there’s a lot to that and a lot of things and pictures that I would use in order to talk about how to do applanation tonometry. A couple of things here and another question about the role of cobalt blue filters. I’m going to put those together. First of all we use cobalt blue filter when we use fluorescein. We use fluorescein in order to do Goldmann applanation tonometry. If we talk about fluorescein we might look for an epithelial defect with that, we put the fluorescein strip in and look to see if there’s any staining on the cornea. Staining, of course, is a brighter area of green or yellow than you would see if you didn’t have staining. That’s really what we’re using a cobalt filter for, it checks the front surface of the eye, it makes sure that the ocular health is okay, that there’s no breaks in the epithelium. If you have some type of break on your conjunctiva, if you have a conjunctival erosion, it will also stain the conjunctiva so you could use the cobalt blue to visualize that staining. With Goldmann tonometry what you’re really doing is you’re using some type of fluorescein in order to get the image. You also want to use an anesthetic. Whether you use something like a Fluress that has both an anesthetic and the fluorescein in it, or if you use just a fluorescein strip and paracaine or any type of topical anesthetic, you can do the procedure. Then what you’re going to do is take a tonometer tip and you’re going to applanate that tonometer tip onto the eye and with that you’re going to see something we always call as mires and they’re two semicircles. There’s one of the top and one at the bottom and we have to line those up. In your view they should be aligned vertically and horizontally so I should have two half semicircles. And then I use the pressure drum in order to get them so that they just touch in the center. The inner edges are just touching. When those inner edges are touching is your measurement. If they’re like this or they’re like this, they’re not right. If there’s a big gap, again, not your measurement. It’s when they’re just touching. Of course when you’re doing Goldmann I always say be really careful, you really want to have control of that slit lamp. Make sure your hand is on the joystick so that you can easily move this slit lamp away and not push into too much. If you push in too much you can cause a defect to the cornea. That’s just a brief how do I do Goldmann, there’s a lot more that we could talk about in regards to that. [Stephanie] The conical beam question there. Most slit lamps, I guess all slit lamps, back to that millimeter height ruler that you have up top, 14 millimeters would probably be the highest. Most of them have an even smaller section if you scroll all the way down past the one millimeter you might find a 0.2 setting and that would be your conical beam. It is a little bit more difficult to know exactly where you’re focused with that conical beam. And we have pretty limited use for that, that’s really for evaluating the anterior chamber for cells and flare and most of us prefer to use a little bit taller parallelepiped. But it is possible to use the conical beam as well. In terms of measuring the growth on the conjunctiva using the slit lamp, we did reference this really briefly that you can change the height of your beam, you could also change the orientation of it. In general, we like to make measurements both horizontally and vertically. And we can adjust that millimeter height up top to actually take that measurement. You find the lesion, once your silt beam is on it, then just adjust the height and just read right off the instrument up top in millimeters what that measurement is. And then you can turn the entire slit lamp or turn the entire lighthouse horizontally to create a vertical beam of the light and then again shorten that down and take your measurement that way. There was one here about how do you assess the fundus of a patient with anisocoria. Not really any different than somebody without anisocoria. If you have the option to dilate them, we’re going to dilate both eyes, even somebody with anisocoria it’s very likely that both eyes are going to dilate equally. There can be sometimes where this is complicated, maybe somebody has had some sort of trauma and they have a fixed pupil or that pupil has been synechiaed closed to the anterior surface of the lens. In which case dilation probably isn’t going to work on that eye. But if they have physiologic anisocoria it’s very likely that both eyes, both pupils are still going to dilate equally. We would assess it just like we would the other eye. [Rachel] Another asked about magnification in the slit lamp for the use of both lenses. It is going to be easier at first to use a lower magnification. If you start with 10 it might be easier to get the fundus and get that image and really use any magnification from there. Of course the higher the magnification it’s going to be a little bit harder to get the image. But often what I will do is I’ll start with 10x and then if I want to see something with more detail I’ll mag up into whatever magnification I want. When you do get up into those high magnifications like 40, it is really hard to keep your image clear. 25, 16, it’s going to be a little bit easier. But you could use any magnification on the slit lamp with the fundus lens. [Stephanie] In what conditions do we see cells in the anterior chamber? Any time that there’s inflammation. Inflammation could be from a rheumatologic condition, it could be from infection, it could be trauma. Anything that can cause inflammation to any part of the eye would cause potentially some breakdown of the blood aqueous barrier and then you might have some white blood cells leaking in the anterior chamber. And that’s what we call cells, those white blood cells. [Rachel] In regards to the high mag ocular lens as to the Wide Field Volk, I actually really can’t speak to that. I’m not as familiar with all of that with those lenses, so I apologize but I’m not sure we can address that question well. [Stephanie] Applanation tonometer in an uncooperative patient? That’s a good question. Takes a lot of practice. Thankfully though in this day and age we do have alternatives while Goldmann tonometry is the gold standard for measuring pressure, depending on how uncooperative your patient is, you might decide to use a different alternative measurement such as NCT or an iCare if you have access to those. If you don’t have access to those, it’s just going to take some work between you and your patient trying to hold the lids yourself as opposed to just trying to ask their patients to hold their eyes open. Sometimes just holding the lids is enough to be able to take your measurement. But you just want to make sure that you’re not pushing on the eye to falsely induce a higher pressure. [Rachel] I’m not sure if it was on my end or another end but I guess the specular reflection didn’t quite hear the answer so let me just quickly go through that again. I use a parallelepiped. I take that parallelepiped to the limbus and then I come out of the slit lamp. When I come out of the slit lamp I’m going to see a glow around the cornea at 360 degrees. [Stephanie] For specular reflection. [Rachel] Oh, I apologize. I apologize, I read it wrong, sorry, guys. [Stephanie] For specular reflection that was with a parallelepiped beam. I don’t believe we had a picture of this in our slides. But I think if you have access to Google you could look up specular reflection of the corneal endothelium. That would be something that you would be able to actually see a picture of what we’re talking about. It’s a little bit difficult to describe without something to look at. But the starting point is a parallelepiped on the cornea. And then every slit lamp instrument causes these reflections to be present on what you’re looking at. And so you’re going to find that small little area of where that LED light is causing a little reflection on the eye. You’re going to bring your parallelepiped over to that reflection and then you’re going to see this textured surface show up on the back half of your parallelepiped which would then be your endothelium. And that’s a little bit more of an advanced technique but we use that for looking at the individual cells of the corneal endothelium for diagnosing things like Fuchs’ endothelial dystrophy or polymegathism. [Rachel] How do you assess the vitreous with the slit lamp if your patient complains of floaters? This is where that slit beam comes into play. What I would do is I would actually use a parallelepiped. I would move that parallelepiped back behind the posterior lens capsule because I know that’s where the vitreous is. I like to make sure I’m at just the right angle so sometimes I have to play with my angle just right in order to really visualize that vitreous. And then I like to have a decent amount of illumination so I might increase my illumination a little bit so I really can look at the fibers in the vitreous and that’s what I would do in order to look at the vitreous with the slit lamp. [Stephanie] Which is better for fundoscopy, 90 or 60? It’s personal preference. Your magnification is going to be higher with a 60 diopter lens. If you need to see something with a little bit more magnified view, then the 60 is going to help. I think that it’s a little bit better to pick your lens based on the magnification rather than just increasing the magnification on the slit lamp itself. 90 is just a really nice middle point for most things that you need to see. If you don’t have additional lenses, if you don’t have a 78 or a 60, you should be able to accomplish everything you need to with a 90 diopter lens. [Rachel] Another question about assessing the retina for a retina hole versus a peripheral retinal degeneration. The retina is going to look different in a retinal hole. Of course in a retinal hole the sensory retina is going to be missing so the color is going to be different. One of the things when I’m assessing the retina that I look at is color. If something is dark and pigmented that means that there’s pigment. It means that there’s probably some type of degeneration as opposed to something when I see red. When I see red I know that the retina is clear. If I see red what’s happened is I’m actually visualizing the choroid. In order to determine what I’m looking at, whether it’s a degeneration, whether it is a hole, I’m looking at the color. I’m also looking to see if there’s any elevation, of course, because I’m looking for subretinal fluid. Degenerations you’re not as likely to see, you shouldn’t be seeing any elevation, everything should be on the same plane. And something like a tear or a hole you’re going to see that the retina has possibly been elevated if there’s any of that detachment of the retina. You’ll be looking at that plane as well. [Stephanie] Can you use a Digital Wide Field lens on an undilated eye? Absolutely. How to check for cells and flare? We did go over that in the presentation, I don’t think we necessarily need to talk through that again, but please review that little section there where we talked about where to focus and what you’re looking for afterward. How can you grade cells and flare in the anterior chamber? There is a standardized criteria that you could reference. It’s called the SUN criteria. It’s the standard uveitis nomenclature that came out of that study. There is a grading criteria that you can look up on Google for that as well. It comes down to how many individual cells you see within your one millimeter by one millimeter square beam in the anterior chamber. That’s how we really should be grading. It is based off that standardized criteria. But if you just want a qualitative measurement you can use that little bit taller parallelepiped beam just to see if there’s inflammation or is there not? If you want to grade it, you really probably want to stick to one of those grading criterias. [Rachel] I’m visualizing the posterior lens and the vitreous in an undilated pupil? Obviously it’s not as easy as it is in a dilated pupil and it’s all going to be dependent on how big your undilated pupil is. I would say one thing I do when I’m going to the posterior lens or the vitreous is that angle of light is a little bit different. If I have that wide angle of light and it’s a 40 degree angle of light and it’s just going from the anterior lens to the posterior lens I have a harder time visualizing it. I will decrease that angle of light a little bit so I can visualize a little bit more of the posterior lens and the vitreous. But it really is going to be dependent on your patient. You will see the posterior lens but the degree of what you see is going to be limited in an undilated pupil just by the nature of what you’re looking at when you’re looking undilated. [Stephanie] Unfortunately I don’t think either of us are equipped to answer that Hruby lens question. I do remember learning something about that as a student first year but we don’t use them clinically in our practice. I’m sorry but I don’t think either of us can answer that one. [Rachel] As for illumination and magnification when looking at stages of a cataract, I always say to students, one thing that has to happen is you have to see a lot of normal. And once you see a lot of normal, then you can begin to really figure out what abnormal is. What do I use in order to assess it? Some of it, of course, is all this data out there in the reading and the research that I’ve done. Some of it is that I’ve seen enough patients I know what normal is and then I know what abnormal is so I figured out what an S1 is, I’ve figured out what an S2 is based on looking at patients. A lot of it is clinical that is going to occur. With illumination and magnification here, I think a moderate illumination is often what ends up happening. My magnification, I normally start with 10-16. I normally don’t go into a high magnification when I’m looking at lenses. I tend to go with a 10 or a 16. I also think when you’re looking at cataracts if you’re able to dilate that patient, that can really help you because if I dilate that patient I can visualize more of the lens and get a better idea of what that cataract really looks like. [Stephanie] Any techniques in how to view flares? I’m thinking that means cells and flare or any posterior chamber pathology. Really it just depends on what you have at your disposal. If you only have, for example, if you only have access to a slit lamp and a 3 mirror lens, you can really do a full retinal assessment. You can look at the posterior pole, all of the different areas of the retina all the way out to aura if all you have at your disposal is a 3 mirror lens. If you have access to a binocular indirect ophthalmoscope, that’s the head set with the 20 diopter lens, that’s probably going to be your preferred choice as you’re going to get a much clearer, sharper image and you have definitely some practice to get proficient at that. But it really depends on what you have at your disposal. Not everybody is going to have access to the same lenses and the same equipment and it’s just what you become familiar with. [Rachel] Here’s a question on seeing flare in posterior lens. The question’s gone, sorry guys, I can’t see it anymore. But with flare, just one thing I always have to remember. When I think about cells and flares, just so you know, I’m sure all of us have been at a place where we’ve seen some type of video projector. And if you look at that video projector in a dark room you see dust and you see fog. That’s kind of what the anterior chamber is, that’s what I always think. The dust is the cells and the fog is the flare. I think it can be really helpful to see post surgical patients. Post surgical patients are normally going to have cells and flare because they’ve just had a trauma, that’s what surgery is. They have inflammation. I think if you can see those then you can begin to, again, see what abnormal and normal is. [Stephanie] Which lens should we use? That’s a good question, can’t answer that for you. It’s personal preference, it’s what you need to see, it’s what you have access to. You’re going to make the best use of whatever access you have. Lots of personal preference there. [Rachel] I think there’s a little bit of a question about, I think there’s a question about the inferior angle and the superior. I think what you’re saying is it’s easier for you to view, you put your 4 mirror on, it’s easier for you to view the inferior angle than it is superior angle. I think that’s true for everyone. That’s very common. What can you do? A couple things I would say, that’s where rocking I think could come into play if you’re only seeing scleral, rock for 12 o’clock, if you’re only seeing iris, rock towards six o’clock. Make sure that your lighthouse is just right and also make sure you’re holding that lens nice and straight. You might want to come out of the slit lamp and even though there’s a flange, you might think that you’re straight but maybe you’re tilting the lens a little bit. Maybe the top is going a little bit towards your patient and the bottom is coming a little bit out towards you. Make sure that your hand is nice and straight, the front of that lens is really flat. That might also help you do that a little bit better. [Stephanie] When I’m also teaching, I always like to tell my students to that yes we are looking at the mirrors in the 4 mirror but really it’s that center lens that I feel is the most important because your contact with that cornea is going to really determine if you’re going to have good views in the mirrors are not. I really encourage my students to spend the most amount of time in that center lens making sure that they have a steady view and that the pupil is smack dab centered right in the middle of that centered lens before trying to go to one of the mirrors to get a view. And then once you’re in one of the mirrors, then we’re tilting on the opposite axis to avoid glare, we’re rocking along that same access like Dr. Brackley was saying to try and see more of those angle structures. How do I know that I am looking at the vitreous? Say, for example, vitreous detachment or floaters in the vitreous. There’s a couple different ways to assess the vitreous. The first way, moving anterior to posterior. The first way that I would assess the vitreous would be with a very bright, sharp, clear optic section. Once I know that I’ve pushed past the posterior capsule I know that I’m in the vitreous. You’re going to start to see some of these collagen sheets and a little bit of some cloudiness to that vitreous.You can ask the patient while you have a nice view in that vitreous if the patient is dilated you could ask the patient to look up and then when they look straight ahead you’re then going to see this what we call the ascension phenomen of the vitreous. You’re actually going to be able to see movement. That can be a little bit helpful if you’re wondering if maybe there’s some clumpy floaters that the patient has been noticing. But you can also look at the vitreous and assess for a vitreous detachment using one of your fundoscopic lenses. Let’s say you have a 90 or a 78, once you have found the view of the retina, let’s say that we start focused on the optic nerve, you’re then going to bring your focus back out into the vitreous so then the optic nerve is going to become blurry. Once you have pulled your focus off the retina you are now in the vitreous and you can scan around and see if you can see a clumped up Weiss ring or some other floaters that have condensed there. [Rachel] I know there’s a question about the torch light examination of the angle. I believe what you’re asking about is the penlight angle. I wish I had a transilluminator or a penlight on me right now so I could do it, but I don’t actually have one. What I do have though is a pen. What I’m going to do here is show you guys. Let’s say this where my light, this is my light. I would come in and I would bring my light right parallel with the iris. By doing that what I’m going to see is I’m going to see either a no shadow or a shadow over the iris. If it’s nice and illuminated and nice and bright there, there’s no shadow, that means that angle is wide open. If I look, the shadow is going to start nasally, my light’s temporally so it’s going to be nasally. If I see a shadow, so a darkness over the temporal part of that iris, excuse me, I apologize guys, over that nasal part of my iris, if I see that shadow, then my angle isn’t as wide open. I hope that explains that. Again, wish I had my penlight but I don’t have it on me. And then I think the question of which gonio lens gives the best view of the angle, the number of mirrors? Again that comes down to you and the examiner’s preference. I will say something like a 4 mirror or a 6 mirror you really can do nasal, temporal, superior, inferior with it so you will have less rotation. Some people prefer to do the rotation. If that’s your preference is to rotate, then use a 2 mirror or a 4 mirror, whatever really is your preference. What I will say is you have never used a 3 mirror and you look at an angle, the view of an angle with a 3 mirror is beautiful. You really can get a lot of fine detail with that 3 mirror. But again, as a practitioner, how many of us are going to routinely put a 3 mirror on to do just gonioscopy to make sure an angle is open, probably not many of us. But it is an option if that’s what you prefer. I think really with all of these lenses as we talk about it, it really comes down to examiner preference from what you’re familiar with. And a lot of times I think it also comes down to what you were taught on and what you first used ends up being your preference.

Last Updated: December 29, 2022

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