 This is a standard B-scan probe which is used in most ophthalmic ultrasound machines. It's a 10 megahertz probe which is a higher frequency than is used for other parts of the body. And the reason is we can use high frequency around the eye because the eye is small and also it's full of fluid. So sound penetrates very easily whereas the abdomen or other parts of the body we have to use a lower frequency because the penetration is less with high frequencies. So we can use this around the eye for the 10 megahertz as I mentioned. The B-scan that we use, almost all of them, have a little mark on the probe. So there's often a white mark, in this case it's a little silver streak. And that is there to orient the probe position. When the machine is turned on there's a transducer inside of this which is going back and forth. And it's about 15 to 20 times a second. It's oscillating back and forth. And that mark indicates the direction of oscillation. And that's important because of probe position. When you're looking at different lesions we need to analyze a lesion in different directions. And that allows us to do that with that orientation of the probe. I usually put a drop of anesthetic in the patient's eye and have the eye open during the procedure just for better orientation and better sound penetration. And we put kind of a gel on the probe. In this case we use ones that are safe for the eye, artificial tear solutions of different kinds, methyl cellulose which is what I'm using now. So totally safe for the eye. So I'll demonstrate a couple of things here. So one is probe position. We use two major positions that we examine with. One is called the transverse position. And in that position we hold the probe so that we're parallel to the limbus. So if the limbus is here, here's the cornea limbus, I'll put the probe like this and the mark is here, the transducer is going back and forth like that. That's called a transverse position. Whenever I'm parallel to the limbus, whatever position I hold the probe in, if I'm parallel that's called the transverse position. So here I'd be inferior pointing towards the superior part of the globe. Here I'd be at the nasal part of the globe pointing temporally. Here I'd be superiorly pointing inferiorly. But every position I'm holding that mark is such that the transducer is parallel to the limbus. If I turn the probe so that the mark is now perpendicular, like in this case here, that is called a longitudinal position. And that gives us a little better peripheral examination of the eye. So I usually use both positions as I go around. Each sweep of the probe gets about 60 degrees of the globe. So if we go around in six different positions we're going to capture the entire 360 degrees of the globe circumference. So I will do that and demonstrate how we do that. So I'm placing the probe here inferiorly around the 6 o'clock limbus and the mark is towards the nose so it's going back and forth. This is a parallel limbus position. So I'm in this position, I am in a transverse probe position. And the screen shows that. So here is the retina, the back of the eye. Here's the front of the eye. And in this technique where we're touching the eye, we lose information in the front of the eye. We can't really see the cornea, the anterior chamber of the limb because they're all kind of meshed together in the initial signal. There is a way to show that with an immersion technique, which I'll demonstrate later to actually back the probe away from the eye and show anterior structures and separate them out so we can see them. But in this position here, I'm looking at the superior globe. So here's around the 12 o'clock equator. And I kind of gradually angle the probe like a lever. I'm going back and forth here. I'm going further and further out peripherally. So I'm getting very peripheral here towards the partial plana. As I angle the probe this way back towards the back of the eye, I'm getting more posteriorly towards the posterior pole. So that is a 12 o'clock position. To look at the superior temporal globe, I put the probe at around the 4 o'clock position. And again, the marker is such that I'm going parallel to the limbus in the transverse position. On examining now, this would be superior temporal globe. So I'm here in this area here, be around the 11, 10 o'clock position. As I angle the probe more and more, I'm getting more and more peripheral. If I put the probe exactly at 3 o'clock, I'm getting a temporal position. So this would be the temporal part of the fundus. So again, here's retina. This is orbit behind it. This is inside the eye in the vitreous cavity. And then look down slightly for me. And this would be the inferior position I'm putting the probe superiorly. But I'm looking at the inferior globe because the probe is right here, going through the vitreous, hitting the back of the eye here. So this would be an inferior position looking at the 6 o'clock area. And so I can do that all the way around the globe for 6 positions. Once I've done that, I can then do longitudinal positions where I put the probe so that the marker is perpendicular to the limbus. And this way I'm going more peripheral. I'm able to get way out to the periphery, which I can't do as well with the transverse position. So this would be the superior fundus here, very peripheral towards the parts plana. And again, as I go around different positions, same thing. I'm maintaining myself so that I'm perpendicular with that marker. So the sound beam is going back and forth this way in a perpendicular position to the limbus. Here's the temporal fundus. So I'm going across the globe here, temporal fundus looking at the retina and examining that. Now a major landmark that we use for pro-position is the optic nerve. And to see that the best, I find the position where I put the probe so the marker isn't fairly nasally. So I'm kind of pointing towards about 5 o'clock. And if I do that, the nerve just usually kind of will just pop up at me right there. You see a shadow as I went by there. And here's the optic. Here's the globe here, front of the globe, back of the globe. And here's the optic nerve shadow. It's kind of a V shape sometimes, other shapes. But when you see this darkness here, that means you're at the optic nerve. And that's a good landmark, because that'll orient you where you are in respect to other parts of the globe. So that's the basic B-scan examination. So again, using a 10-maker Hertz probe, I've gone around the eye in six different positions, both in a transverse position, being parallel to the limbus, and also longitudinal, being perpendicular to the limbus. And I've examined the entire globe that way. By doing that, we pretty well see everything. We see all the way to the paris plana. What we don't see would be the ciliary body and the space behind the iris. And again, that's where the immersion technique comes in, which I'll demonstrate in a few minutes. So that's the basic position. What I'm watching for as I do this, I'm watching for any regularity of the fundus, any little bumps, elevations of it. I'm watching the vitreous cavity for anything in the vitreous, such as a posterior viscous detachment. And look straight ahead again. So right here, we see a few vitreous capacities right here. And that would be consistent with little floaters. Most patients have those, little specks that float around. The ancient Romans called them muscay volatantes, which was Latin for moving flies. People, thousands of years ago, had little flies in their eyes floating around. They called them muscay volatantes. But most of us have those. We can see them if you look at a bright light or against a clear sky. You see little tiny threads kind of floating by. That's very normal. If there's a sudden change in floater, if you suddenly see a lot more than usual, bigger floater is more than usual, that can be an indication of a vitreous detachment, which most of us go through as we get older. But as that vitreous detaches, it can sometimes tear the retina. It's a torn retina, detached retina. So we always examine for that carefully. So looking here again, we have some vitreous opacities, which I would probably just call vitreous enteresis. I don't really see a posterior viscous detachment, but I see little dots in the vitreous, which are very typical for most people. Now that's the B-scan technique.