Dr. Radcliffe: This is a pleasure for me, to speak today about anterior segment imaging in my practice. It's--really allows me to showcase the work of a lot of my colleagues. So, many of what I'll be showing you, although I had involvement with all the patients, maybe their surgeries were not done by me. The concept here, though, is that shortly after we got our Cirrus and were using the anterior segment module, we just discovered a variety of things that we could look at and visualize. And the evolution continues to this day. I just actually added a new slide five minutes ago that's something new, a new use that we've found. And I'll show a little bit about Visante as well

So, with that, I'd like to first acknowledge my colleagues, whose patience and whose hard work is going to be demonstrated here. I'm at Cornell, Weill Cornell Medical Center in New York City. We're on the Upper East Side, and we have about 16 faculty in the department. We have a rather robust corneal service. We even have a--an optometrist who does a lot of prosthetic ocular surface ecosystem work, and I'll be demonstrating some of that to you, as well as a retina practice as well.

So, just sort of going back to the beginning, where things started with Cirrus was really with anterior segment imaging. And the first two things that were looked at were the cornea and the angle. You have several different modes that you can collect data in. You can either get a cube of data, that's the 512 by 128 scan, or you can get a high-resolution five-line raster, and there's a caliper as well. So, you can see here a corneal thickness measurement being taken with the Cirrus OCT.

In looking at these images, again, this is with the Cirrus, the definition is amazing. You can determine where the epithelium is, where Bowman's is, and where the endothelium is as well. And I'll show you some examples where that becomes clinically relevant.

Of course, angle structure can be identified. Schlemm's canal can be seen maybe half the time. It depends a little bit and it depends how many images you want to look at, but oftentimes Schlemm's canal can be visualized. But, this shows you a wide-open angle here

And do I have a laser pointer? Yeah, but that'd be hard for me to use, right? See if I can figure out how to make this work. Oh, there we go. Oh, I'm advancing. Sorry. Okay. Well, it's not going to work. It's not going to project well up there. In any case, this is a wide-open angle. You can see the trabecular meshwork, which is just adjacent to Schlemm's canal. Here's one of my patients. Again, with an open angle, you can not only see Schlemm's canal but you can see some of the collector channels a little bit distal to that.

Here is a patient with a narrow angle. So, a couple things become apparent to you when you start using Cirrus to look at the angle. One is that patients can see this and understand their anatomy. And I think that that--the value of that is actually quite high. So, showing a patient their own Cirrus and that they've got narrow angles helps them understand the disease

Additionally, you see things like angles that are maybe a little bit narrow will suddenly become a little bit closed. Looking at this image here, where the iris is in contact with the corneal endothelium, I think you can see that there is some thickening of that endothelium there. So, you get the sense that this angle has probably been even more closed than we're visualizing here. Of course, we can do the Cirrus in light and dark as well. So, this is a patient who needs a laser iridotomy, and I think the patient will understand that after seeing the picture.

In addition to measuring corneal thickness, you can measure the--in some cases, how deep the anterior chamber is. So, this is that same patient, a very shallow anterior chamber depth. That could be measured with the caliper tool. You can confirm the patency of iridotomy, and you can also go back after performing iridotomy to confirm that the angle is opened

Some other features, as you begin looking at more and more patients with angle closure, include iridolenticular synechiae. And I’m wondering--this didn't show up. Is that right? It sort of disappears when I get on the screen. Yeah. Okay. But, you can see there iridolenticular synechiae and you can also see, again, iridotrabecular or actually irido-endothelial, irido-corneal touch from a narrow angle.

In this patient with iridolenticular synechiae, you could also see with Cirrus a anterior polar cataract. Just hang on to that image. It may not seem that fantastic because, of course, we can visualize a lot of the pathology I've been showing you with the slit lamp. But, here you have an anterior polar cataract that you can see with the OCT.

You know, this was a patient who had had radial keratotomy and presented, and his scars actually weren't that easy to see. And I think you can get a sense for why. He has a very smooth epithelium and the--but, you can see how deep the keratotomy incisions went, and those were just nicely visualized. You can also see the effect, actually, that those incisions have had on the curvature of the cornea here. We've also used the Visante at Cornell. And I'll give you some examples of those images and just getting a different perspective. Ultimately, anything that can be visualized with the Visante can be visualized with the Cirrus and vice versa, but there are going to be differences in terms of the resolution and in terms of the type of view that you're getting

So, you get a much larger view of the eye, so measuring things like the white to white is going to be feasible with the Visante. Here is an open angle. Anterior chamber depth measurement is also very easy with the Visante. You can use other tools to quantify, you know, how many degrees the angle is and the anterior chamber depth and so on.

So, this is a special type of patient that we care for at Cornell who has really just had a lot of trouble. And, you know, when you look at this, you can sort of start to piece together what happened to this eye.

So, you see a anterior chamber intraocular lens which really is quite anteriorly positioned. You see a tremendous amount of fibrinous material that just sort of locked that anterior chamber IOL to the iris. You see a very small anterior chamber. And then, superficial to that, you see the patient has had a corneal transplant. There's actually a little bit of epithelium--does that show up? Yeah. So, you can see a little epithelium growing in there between the graft-host junction. And then, what we're looking at here is a--this prosthetic lens. And these are designed to have a very large vault for people with bad ocular surface disease with the concept of providing a smooth refracting surface and also getting over a lot of this pathology.

Well, what type of pathology? Here is a patient with pellucid marginal degeneration. You can sort of see this beer belly appearance to the ectatic cornea. And while it seems like this lens may be vaulted a tremendous amount, it's necessary in this case in order to accommodate the profoundly ectatic cornea. This patient actually had keratoconus. And again, just looking at the signal, you can see they'd had some hydrops and they have a little bit of scarring at the apex there as well.

Going back to that patient that I showed you who had that little bit of epithelium growing into the graft-host junction, you can see a rather large bullae. And you could see how this type of bullae, this epithelial bullae would interfere with vision. It creates obviously a tremendous amount of disruption. But, by creating a sort of prosthetic surface, we can cancel out some of the effects of that bullae on the refractive medium of the eye. Whether it's a large bandage contact lens or whether it's this PROSE lens, a lot of patients with multiple eye problems will have undergone tube shunt surgery. And one of the things we worry--we become concerned about is whether the contact lens is going to erode and cause an erosion over the tube.

And this is an area where OCT has been very helpful, because it helps to take a look at how much healthy tissue there is over the surface of the tube or between--how well the contact lens is fitting over the tube. And you can actually monitor the thickness of that over time and make sure that things aren't trending in the wrong direction.

OCT, and I think I'll switch back to the Cirrus on this case, but it can be used to help with preoperative planning. So, here we have a, you know, typical patient who presents to my practice, anyway, in glaucoma at Cornell. And this is a patient who has an anterior chamber intraocular lens, and they had a surgery where vitreous loss was present. You can't really appreciate it, but there is a little bit of vitreous here between the peak pupil and the wound. And again, just looking at this eye with the Cirrus, you can see a lot of the pathology. So, here we see the corneal incision, vitreous gaping right up to the wound. And you can see that it's had some contact with the anterior chamber intraocular lens there.

This was a fascinating case of angle closure that presented to me. The right eye had a normal pressure, maybe about 18, and the left eye had a pressure of about 50. And you can actually see there is just a little bit of edema. But, what isn't as apparent from this photograph is there is no anterior chamber in the left eye, so all this iris is atrophic iris which is completely in touch with the corneal endothelium. I'll show you some examples. So, I'm showing you the better eye. This is the right eye, another anterior polar cataract there. This is the left eye. This is the anterior chamber, actually, this fine little line right there. It's, you know, less than a micron in depth. This is--you can see the epithelium, corneal stroma with a little bit of edema, and then this is the iris signal right up against the endothelium.

I had assumed when I initially saw this patient that the material here was fibrin and that right behind it was the lens. So, this would be a bombe iris acute angle closure glaucoma. The lens comes forward with the iris. I did obtain ultrasound biomicroscopy and actually, oddly enough, confirmed that the lens was in the normal anatomic position and that the iris was actually--this is the iris signal right here. Because, if you look, there is--we go right from zonules to what looks like endothelium, but we can determine that this is the iris up against the endothelium.

Going back now to the OCT, you can see that the normal lens shadow that we're seeing in the right eye really wasn't present in the left. And it's possible that that was blocked by the signal, but I think it's more likely that we didn't see any lens signal there because it's a posterior chamber without any lens behind it.

Here's a patient who's undergone two tube shunts. You see one here superotemporally and another superonasally. His tube shunts, one is in the iridociliary sulcus between the lens and the iris, and another one is in the anterior chamber. And if you look at series of eyes that have had two tube shunts, the likelihood of corneal decompensation is about 50 percent in those--in that population

So, the second you're putting a second tube in, your main concern really is as much the cornea as the--as it is the glaucoma. This patient had a patent iridectomy that can be visualized quite nicely. But, just wanted to show you I was happy to see that the tube is really lying perfectly flush against the iris, so offers some reassurance, you know, in this patient that I'm doing my best to keep the tube out of his corneal endothelium. And I'll show you some examples of what can happen if you can't achieve that. Here is--again, this patient had a sort of uveitic glaucoma, had some high peripheral anterior synechiae. And here's what a filtering bleb looks like with OCT. And while in general you can get a sense of how well a bleb is looking by inspecting it, I have had a few patients who had unexplained great IOP reduction, maybe after a phacotrabeculectomy where there did not appear to be much of a filtering bleb. And in some of those cases, you'll see some of this organization in the conjunctiva addition--in addition to other signs that there may be filtration.

So, there's a very robust corneal service at Cornell, and I have the pleasure of caring for the glaucoma that's associated with a lot of corneal disease. So, here is a patient who presented with--it was a traumatic corneal rupture and had a rather urgent penetrating keratoplasty with pretty poor apposition seen here with the Cirrus.

In addition, patients undergoing Descemet's stripping endothelial keratoplasty can be followed with OCT. So, here we see the DSEK button. It's not opposed well to the corneal stroma and there is resulting epithelial edema. And the vision was obviously very bad here.

The next slide I'm going to show you is this same patient after things got better. And you may not believe it, but this is the same eye. It's the same area. So, you can track the resolution. And of course the way it works is the--you know, the graft gets better opposed to the corneal stroma and then the bullae go away.

Here is a patient who had DSEK but really never had much of an anterior chamber, developed iris synechiae that came from behind the DSEK and actually pushed--sort of held the DSEK in place. But, again, you can see here some subtle signs of corneal lack of functioning with some bullae. And that graft, although in good position, isn't going to do well.

Here is a patient with fibrinous uveitis, synechial uveitis. It's really tough to see, but there's actually a tube right there. The patient kept developing repeating bouts of angle closure requiring fibrinolysis to the tube ostium. In any case, eventually it occluded with fibrin and the treatment was to just entirely remove the intraocular lens, so this patient is now aphakic. And you can see the tube here sitting and you can see that the graft looks very clear.

So, I was worried that the tube was a little anterior and so I got an OCT. And as I said, this was a--someone who is prone to form synechiae. So, I was sort of concerned that there were some synechiae right here. And I'd also like to just point out the health of the endothelium looks pretty good through the signal. But, sure enough, couple months later, synechiae is pulling the tube more anteriorly.

There's contact, presumably, between the tube and the endothelium. And I'm not entirely sure whether this is decompensated corneal endothelium or whether this is this, you know, fibrinic membrane that's starting to slowly grow over the entire eye. But, in either case, I could quantify a change in the distance between the cornea and the tube with OCT. And it just confirmed my clinical impression that this tube had indeed shifted. So, at least I don't have to worry that I put it in the wrong position initially, if that's going to make me feel any better. Here's a patient who really didn't know their history that well. It was obvious they had had some corneal surgeries. You can see there's a failed graft and band keratopathy. Also, a glaucoma tube shunt, of course. I was interesting--interested to see how band keratopathy looks with OCT. So, you see some high areas of reflectivity there.

And now let's look at the rest of the cornea. Well, you look at this slide and you're starting to suspect there's been a DSEK performed. But, this right here tells it all. The patient's had both a penetrating keratoplasty and a DSEK. And that history was nice to know, as this patient ultimately underwent keratoprosthesis surgery. And I'll show you a few examples of that in a minute. You can use OCT to look at how much fluid there is over a tube to get a sense of whether this is an obstructed tube or whether it's a so-called primary tube failure where encapsulation has occurred and there's just not enough filtration around the tube. And then, there are keratoprostheses. So, in these patients that have shown you--with severe corneal disease, some of them have undergone eight corneal transplants between their two eyes. And at point, it's unlikely that another graft is going to work. So, the keratoprosthesis is--it's a hybrid. It's a prosthesis that's nested in a cornea and then sewn into place as a--almost in the fashion of a standard PK, although you don't have to worry about astigmatism because ultimately the refractive media has been determined. Here is what the keratoprosthesis looks like with the Visante. So, this is the graft-host junction right around here. And the keratoprosthesis is this all the way back. And this is a so-called pseudophakic keratoprosthesis, so you see an IOL behind it. As often as not at Cornell, when we're doing a keratoprostheses we'll remove whatever IOL was in there, because inevitably there is a tremendous amount of retained lenticular material. So, we find it's best to just get all that proinflammatory media out and then put in a lens that's powered for aphakia.

Here's Cirrus looking at keratoprosthesis. So, you may not get as broad a view, but you can get a nice view of the anatomy. This patient has a bandage contact lens, so here is the tear film. This is the anterior surface of the keratoprosthesis and, you know, we're seeing some interesting things. Epithelium does migrate up along the keratoprosthesis. And in some patients, they'll actually have intact corneal epithelium in front of the keratoprosthesis. So, there's some integration that's occurring. Here again is that graft-host junction in an eye with a keratoprosthesis. But, it's really less important how well that's opposed, as ultimately the cornea isn't going to be contributing to any irregular astigmatism or anything like that.

As I said, you know, I do get concerned about tube erosion in some of my keratoprosthesis patients. They have to wear a bandage contact lens, or at least they should if they can, because that presumably will decrease their likelihood of having a leak or an infection.

But, you can get the sense here that this bandage contact lens is really rubbing against the tube and is potentially going to lead to exposure. So, again, something I can monitor. Bandage contact lens, conjunctiva, tube, I can least monitor and see how well that's staying stable.

De la Cruz and Garcia have published on the use of Visante in anterior segment OCT, but here what you're looking at is, up top, anterior segment OCT of a keratoprosthesis and, down bottom, ultrasound biomicroscopy. And I think the point, each has its place. I use ultrasound biomicroscopy particularly for things that are behind the sclera, on the back surface of the iris, anything relating to the ciliary body. OCT currently isn't giving us the images there that we'd like to have

But, when it comes to things that can be seen, that light can get to, the resolution and the clarity of OCT, in my opinion, is just superior. So, I think this image of the keratoprosthesis gives a pretty good sense of that.

Okay. So, I think those are the cases that I had to share with you. You know, in summary, the applications for anterior segment OCT are just expanding, and I think rather dramatically. And we're probably just at the beginning of this. So, you know, corneal thickness measurement, angle assessment, sure

One thing I didn't--I thought I had a slide in there on but I guess I left out, assessing the tear film. And maybe it's not just measuring the tear film, measuring how big it is, but maybe we'll be able to get some information about the quality of the tear film from the OCT signal.

I've shown how you can use anterior segment imaging to look at contact lens fit, to evaluate patients who have had a variety of different corneal procedures, obviously to quantify things like corneal edema but also to understand what surgery has been done on these corneas. Of course, intraocular lens position, malposition, vitreous visualization, wound construction could be easily seen. And of course, in glaucoma, narrow angles, synechiae, anterior chamber depth, the success and educational value of anterior segment OCT in iridotomy and iridectomy, I think, is a great value.

And the difference between taking a few minutes to show a patient their anterior segment OCT and not doing so really changes, for me, the doctor-patient dynamic with narrow angle patients. It's been a blessing. We can, of course, look at our tubes, tube plate position, and conjunctival thickness over the tubes, and of course some other things with cataract as well.

And that's it. Thank you very much.