Anterior segment OCT has been feasible for a number of years, but it’s been slow to achieve widespread use. During this live webinar, we will discuss its advantages, how it compares to other technologies used for this purpose, and why it’s taking a while to become popular. Pearls for surgeons who are adding AS-OCT to their list of clinical tools and what the future of this technology will lead us to will also be discussed.
Dr. Jose Mendoza, Ophthalmologist, Lima, Peru
[Jose] Thank you for inviting me, again, to give a lecture in this Cybersight webinars. Today we will talk about anterior segment and OCT. Anterior segment OCT, we have three different technologies supplied for anterior segment OCT, much the same that we have for posterior segment OCT. Regular time-domain OCT, then we have the second generation, those are spectrometer-based OCT. And then we have the third generation that’s called swept-source OCT.
If we talk just about anterior segment OCT, these are all the anterior segment OCT that you have right now in the market, including some of them that do posterior segment OCT and also anterior segment OCT. If we were talking about the technologies, the first one, time-domain OCTs, just like the Visante OCT or this slit lamp OCT from Heidelberg. Heidelberg just launched a new anterior segment OCT this year. But these two, actually, were time-domain OCTs and they worked with a wavelength around 1310 nanometers. That’s the perfect wavelength for the anterior segment. When you’re doing OCTs on the posterior segment, usually you work around a wavelength of 840, 820 nanometers. This is because retina tissue on a choroid, if you’re going to go through the retina and go through choroid, doesn’t have that much liquid consistence as the cornea or the anterior segment. When you’re doing imaging of the anterior segment, you need deeper wavelength.
The second reason for anterior segment OCT is better, bigger wavelength is because you want to go through some deep media. For example, if you want to look at the vertex of the angle, you have to go through sclera because usually the vertex is beneath the sclera. If you want to identify clearly this anatomic reference position, then you need an OCT with a bigger wavelength. I don’t want to say that OCTs with shorter wavelengths, like usually OCTs that are done for posterior segment and working with anterior segment too, will work, you will get great images. But you want to get the resolution as you will get with this. That being said, the third generation of OCTs, swept-source OCT, also work with 1310 nanometer wavelength. The Triton OCT works with 1050 nanometers. It’s an error here in the slide, but it’s almost the same. This kind of wavelength defines the quality of the image.
Also one important thing to take into account as in posterior segment OCT, is the scan speed. If you’re talking about time-domain OCT, they do 2,000, 200 A-scans per second. If we’re talking about swept-source OCTs they could do up to 100,000 A-scans per second. That’s an important point.
Here’s, again, something to think about the principles and the resolution. This is 1310 nanometers you get an actual better action of resolution than a 1050 you get a standard resolution, and at 840 you wouldn’t get that good resolution as the other two.
Talking again about resolution and comparing OCT with other imaging technologies. If we want to see the resolution of the ultrasound that we usually use for anterior segment, resolution is around one millimeter. It’s almost the same as a CT scan or MRI. If we want to see smaller tissues then we need another type of imaging technology. And here is where comes AOSLO, scanning laser ophthalmoscopes, and OCT imaging. We’re talking about a hundred micron. If we’re going to look at smaller tissue than we need, again, another type of resolution.
Resolution comes on a hand with speed of acquisition. If you want the better solution, it will take more time than if you do regular scans with regular resolution. If we compare anterior segment UBM with 50 megahertz probe versus OCT imaging, you will see the resolution of the OCT imaging it’s better. Penetration of the ultrasound, it’s more. You can see what’s going on beneath the iris and the ciliary body down here. And with regular OCTs you could not.
Here comes our first poll question. Which types of OCT technologies are available for anterior segment OCT? Here comes the results, and the results are all of the above, that’s right. You have time-domain OCTs, remember this is the first technology like the Visante OCT, spectral domain OCT’s 840, 820 nanometers. Most of the OCTs in the market do anterior and posterior. Swept-source OCT gave us the best resolution for anterior and posterior segment of the OCT because it goes deeper because of the wavelength, we talked about it. The answer is all of the above.
Here we got some of the images of things that you could do with anterior segment OCTs. With the technology being evolving and constantly evolving, you could see a lot of different landmarks, anatomic landmarks in the anterior segment. You could see here, outer limbus, corneoscleral transition/junction, trabecular meshwork, Schlemm’s canal, angle recess. You see that the angle here, you couldn’t see quite well when you’re doing a regular spectral domain OCT. If you do swept-source OCT then you could see better the angle recess and clearly the vertex of the angle. If you’re doing goniometry, when you’re doing goniometry you could measure a lot of different points in the anterior segment, you could measure ACD 500, AOD, those are apertures of the angle then the different types of distance that are between the angle and the iris and you could see if this is an angle that could be occluded with some sort of pathology. You could also see Decemet’s membrane, the Schlemm’s canal, again, trabecular meshwork, endothelium, and, of course, the iris. Depending on the different technologies you could have different angle measurements. All of these are whole metrics or goniometry. There are measurements of the anterior segment.
These measurements of anterior segments sometimes take in account the vertex of both the angle and sometimes they just need to assume this because the type of technology they’re using couldn’t measure all of these different measurements. Different OCTs have different tools to doing all these measurements but this could also help a lot in seeing different types of glaucoma.
If we compare anterior segment OCT with another anterior segment technology such as Scheimpflug images, you could see that the images look quite the same. Scheimpflug images have been used for a long time to reconstruct and do 3D models and with these 3D models, you could do measurements of different anterior segment structures. But not only like goniometrics or anterior chamber depth metrics, they could do elevation maps. Based on this technology, Scheimpflug, we’ve been a long time using it for topographic maps and elevation maps. When OCT starts evolving and we got better images like this one, the technology also evolves and let us took what we usually do with regular corneal topographs or with Scheimpflug place technology.
We could do measurements of the cornea, of course. Not only on the center but we could measure the whole cornea with different scans and then do a map, a pachymetry map. This pachymetry maps I show here. And also could do epithelial maps. And these epithelial maps will show the epithelium and the stroma separate not only on a whole map.
This helps a lot when we try to see static disorders of the cornea or if we want to see if we have keratoconus, for example. These pachymetry maps will be quite sensitive and they will show this zone where the protrusion is or the thinner cornea, in this case, of keratoconus. These types of technologies not only show us different types of maps, these types of technologies improve the resolution will give us several cuts around the cornea. You could do the first OCT let us do 12 or 16 different slice of the cornea. Now you could do hundreds of slices of the cornea and then do a 3D reconstruction map, quite the same as they do with Scheimpflug technology.
Right now we could have, also, as I told you, epithelial thickness show in different types of maps in keratoconus assessment, using not only OCT but also combinations of other technologies. For example, in this machine you could see OCT and also some topography rings plus the rings that are using it for getting the other maps of the machine.
One of the technology’s advantage since it’s very sensitive and you could get a lot of elevation from this, is getting OPD maps. In this case, we’re getting just about corneal OPD maps. You could not mesh for the whole crystalline lens and get a full OPD map or a full aberrometry map for the eye without the use of an aberrometer. In this case we’re looking at the elevation maps and with the elevation maps we could do the synechia coefficients and see all the different types of eye order aberrations and lower aberrations that are displayed in this cornea.
When I was talking about the crystalline lens, some advantages in the technology could let us measure the lens. You couldn’t get the whole visualization of the lens because most OCT technology is blocked by the pigment. And since we get a lot of pigment in the posterior side of the iris, this could be blocked, the white line could be blocked, and then you could get best imaging in the center where the pupil is and less good imaging on the periphery where you need to measure the crystalline lens. Remember less some technologies let us measure the whole lens thickness like in this example, and also the lens diameter.
Here comes our second poll question. Which of these could be achieved using anterior segment OCT? Goniometrics, corneal elevation maps, corneal topography maps, crystalline lens metrics, or all of the above. Anterior segment OCT technology could give us all of the above information: goniometrics, corneal elevation maps, corneal topography maps, and crystalline metrics. Crystalline lens metrics, again, depends on the type of OCT you’re using, depends on the penetration, that’s because of the wavelength of the OCT you’re using. But it could get some lens metrics. Actually when you’re working with swept-source OCT, you get better lens metric than with older machines. If you’re talking about, for example, biometers, and we’re talking about the IOL master, the IOL master has a version that it’s based on swept-source and gets really good measures of the crystalline lens, even the whole eye.
The technology evolves a lot. And it could do 3D reconstructions of the anterior segment. This is with swept-source OCT. With swept-source OCT instead of doing 10 or 12 or 16 different scans, you could do hundreds of scans. And hundreds of scans could do a 3D reconstruction, complete anterior segment and see different cuts in different parts of the eye. This is, again, a 3D video where you could see the reconstruction of the anterior part of the eye. You could see even the posterior part of the iris and you could do several cuts in different positions so you could go through all these 3D model of the eye.
Let’s see some cases of what you could do with the anterior segment OCT. You could do evaluation of these scans for the anterior segment. You could do three millimeter lines, six millimeter lines, 12 millimeter lines, and 16 millimeter lines. You could get the whole cornea and even part of the, you can see eyelids and some of the anterior segment accessories.
Speed. Speed is important. We talked that time-domain OCT started doing 200 A-scans per second, then 2,000 A-scans per second. Then spectral domain could do 50,000 A-scans per second and now swept-source could do up to 100,000 A-scans per second. The faster the OCT, you will get less noise in the background and you could do less ghost images. It’s better.
Then we got densitometric evaluation. This is nice because if you’re doing, for example, anterior segment OCT of the region and you’re suspecting that it could be neoplasia, then the density change could tell you which type of pathology you’re seeing. It’s like using biopsy, that’s why OCT is sometimes called in vivo or live biopsy. Also, you could see if you’re doing anterior segment OCT of glaucoma surgery, for example, a trabeculectomy, if the bleb is well toward, you could measure it or you could see if the bleb is crusty and it’s not filtrating anymore, the surgeries.
And you could get images through opaque corneas. That’s, again, due to the wavelength that most anterior segment OCTs are working with.
This type of resolution could let us even look at here, you could see where the arrows are, you could see the flap of LASIK surgery. When we started doing anterior segment OCT of different patients, here is the flap edge. When we started doing the anterior segment OCTs with LASIK patients when you perform LASIK surgery with microkeratome, these flaps are not as regular as you will see with femtosecond assisted laser. This is done with a femtosecond assisted laser, that’s why you can see it’s almost perfect.
What else you could do? You could do an evaluation of intrastromal rings. Since this anterior segment OCT could detect and gave us libation maps and several topography maps about keratoconus screening. Then when you do the treatment afterwards and you place, for example, a segment of an intrastromal ring with this technology, you could measure if the ring is in place and how near you are to the corneal endothelium because one of the complication of the surgery is obstruction into the anterior chamber of this ring. This, again, is an incision made with a femtosecond laser. You could see quite good with swept-source OCT incisions made by the laser.
Again, another intrastromal ring patient case. Now you are the whole anterior chamber, you can see here with this OCT you could see the whole crystalline lens pretty well. Here are the segments in position and this is the image of the anterior segment showing where we are doing the cut.
This is a next case that was published online in the American Academy Journal some time ago, and it shows another indication for swept-source OCT. This is a capsular distension syndrome and on an 83-year-old woman that was performed phaco surgery on the right eye. Three years after follow up, patient complained about blurred vision and they could see there was a distention of the posterior capsule. Here is the lens, you can see the IOL, and here is a lot of material beneath. They performed YAG laser capsulotomy and it resolves completely. You can see the image here again, the posterior capsule is attached to the surface of the IOL. Now this shows how anterior segment OCT could see density of different types of solutions, or particles in this case, and the change in this density will let us know what’s going on. And it’s actually gives us a map where we can perform safely any procedure that we want to do.
Another interesting thing that you could do with anterior segment OCT is measuring of the extraocular muscles. This is a study that was performed a couple of years ago and was reported on the Ophthalmology and Strabismus from the pediatric magazine. And it shows measurements of the extraocular muscles after surgery, after a strabismus surgery. And they compared three different OCTs, two of them were spectral domain and one of them was swept-source OCT. The images of the swept-source OCT are clear and they could measure even easier all of the extraocular muscles. The spectral domain OCT, we won’t show that good results but you could get some good reproducibility between these methods. When you’re doing a strabismus surgery, usually they use calipers to measure this, this is a more reliable measurement technology that you could use. Of course, it’s cheaper to use a caliper and sometimes when you’re doing a strabismus surgery, you don’t have all the resources. But if you could have some access to this technology, this will give us really good measurements and more reproducibility in this case.
There are a lot of papers that have been published about anterior segment OCT. Some of them, as I told you, measuring metrics of anterior segment, some measuring extraocular muscles, some change in difference between anterior chamber, between gonioscopy and other anterior segment OCTs. Some take in tomographic of the anterior segment and also looking at glaucoma flap morphology as we were talking about.
Now it’s time for us to our third poll question. Which are the major advantage of anterior segment OCT? Images through opaque structures, speed, multiple maps for anterior segment evaluation, high resolution compared to other anterior segment image technologies, or all of the above? Anterior segment OCT we’ve been talking about it could be used for a lot of different anterior segment metrics and assessments. We want to know which are the major advantages of anterior segment OCT.
We have the answers coming through. All of the above, that’s correct again. Image through opaque structures is really important if you’re doing metrics of the angle recess. We talk about speed, it’s really important if you want to do good images and 3D reconstructions. Multiple maps, that’s true, pachymetry maps, endothelial maps, topographic maps, elevations maps, all different types of maps. Right now with the software anterior segment OCT, and high resolution compared to other anterior segment imaging technologies. Of course, that’s true when you want to see the anterior part of the eye.
Let’s see a case. This is a patient that I found when I was doing a training session in Columbia. And we saw a biker that was driving without using a helmet. And then a bee came flying through and it sticks right here, he feels it, it hits and sticks in his eye. After some time, the vision of the eye started diminishing, he complained of a lot of pain, and decides to go to the clinic. When we see it at the clinic, there was a lot of edema in that zone. He told us it was the bee that hit him and he removed it from the eye. And the bee sting was actually, we suppose it was behind all this because we couldn’t see the anterior segment quite well. It was a huge edema in theory. We decided to do anterior segment OCT. You can see the edema was clearly because the cornea’s really, really, really thick. And here you could see part of the sting in the anterior chamber.
I have a video so you can see it better. You see, here’s the normal cornea, then it starts going thicker here at the sting coming through, and after it you see a whole thickening in the cornea. This bee sting with the toxins that it came with gave a lot of reaction. Here at the bee sting, it’s almost anterior stroma because the guy has taken the bee out of the eye. It was a lot of edema and a lot of toxic reaction here. He needs to go into the OR, the anterior segment surgeons found it and could get it out. But this is a real interesting case I like to show.
Another thing that you could do is talking about now glaucoma, evaluation of the different implants that you could do on glaucoma. We were talking about the bleb morphology. You could see the density here starts showing changes due to fibrin reaction or if there are different facets being formed. You can see the incision where it’s going to anterior chamber. And when you do all the different OCT cuts, you could see a tunnel where it’s really doing its work. If we’re talking about the implants, you could see the lumen of the valve if it’s really good or if it’s not penetrating quite well.
This is another nice case of a friend of mine, Dr. Carl Glittemberg from Austria. It’s a 68-year-old patient that using chronic sleep apnea oxygen. The mask he was using doesn’t cover quite well his nose. It wasn’t attached quite well. There was a filtration of the O2 through the mask, all the night. And the patient started complaining about some blurred vision and irritation on his eye and a lot of discomfort and a lot of epiphora. When we saw the eye, it was clearly, clearly totally inflammated. And when we do anterior segment OCT you could see here that the tear film, you could measure the tear film meniscus with anterior segment OCT. And when we go through the cornea, we could see all different ulcers in the cornea due to the air filtration that was going directly all the night. The patient hasn’t got some good occlusion of the eyelids, as you can see here in the image. It was a really chronic ulcer because of this. He changed the mask, we give him treatment, and the patient comes off really good.
You can do also metrics for measuring contact lens. And this comes really handy when you’re adapting scleral contact lenses. Scleral contact lenses are not like regular lenses, they fit and sits on the sclera and you need to measure the distance from the limbus to the sclera right here to see if it’s sitting clearly, if it’s fitting correctly. And also it’s important to see the space between the cornea, the lacrimal film, and the contact lens. It’s in the central vision, also measuring in other different positions. Adaptation of scleral contact lenses it’s another thing that anterior segment OCT help us with. As you can see different measurements of scleral contact lens.
You can do also an evaluation of the iris root. The iris root and the vertex, again, it’s better to visual when you use a swept-source OCT. If you were using a time domain OCT or a spectral domain OCT, then you couldn’t evaluate the iris root. This is another of the advantage of the technology. In this case, this is a case report measuring PAS in glaucoma.
And in the evaluation of the iris you could see also the evaluation of the posterior part of the iris. This is not usually OCT scans, but I’m showing this to talk about the improve of the technology. Usually one of the limitations when we were talking about OCT, and I started the lecture talking about it, is OCT is blocked by the pigment. And you’ve got a lot of pigment in the iris. It’s the same type of disadvantage that you get when you’re trying to get beneath the pigmented epithelium, the RP on the retina, is you see the pigment below the RP choroid is really difficult to scan. If you want to evaluate the posterior part of the iris or if you want to evaluate the choroid, it’s better OCTs with deeper penetration. That could give you a more foreseeable view of these structures.
You could evaluate on the iris, not only the iris root. You could evaluate nodules of the iris. This is some microphotography showing a lot of iris nodules. And you could look at the iris sits, you could also see the change of the density in different part, differentiation why it’s more homogeneous density inside a cyst and more heterogenic on the other one.
Now evaluation of the ciliary body. Evaluation of the ciliary body it’s usually you use UBM for these types of evaluation because OCT couldn’t see the ciliary body quite well. But this was the first time they used, in this paper report in 2018, OCT strips were supposed to see the ciliary body and the change of the ciliary body during accommodation.
Visualization and evaluation of ciliary body with OCT, it’s only possible again if you use long wavelength swept-source OCT. Here you could see quite well the ciliary body swept-source OCT the same patient. With the spectral domain OCT you couldn’t see quite well. This is because, again, the wavelength. Deeper wavelength will give us a lot of penetration in tissue. If you’re using time-domain OCT, that usually has a deeper wavelength, you could get through tissue but the scan rate is so slow and the eye could move with microsecadic movements then you couldn’t get a great image. You will get a blurred image most like the same you’d get on a spectral domain. Again, if we’re going through opaque area, it’s better bigger wavelength technology.
It’s time for our last poll question today. Which structures are not visible with anterior segment OCT? Posterior iris, ciliary body, corneal endothelium, extraocular muscles, corneo-scleral junction? I’ll give it time for you to answer. Which structures are not visible with anterior segment OCT? Posterior iris, ciliary body, corneal endothelium, extraocular muscles, corneo-scleral junction?
Here we have some disagreement. Posterior iris, you could see posterior iris with anterior segment OCT if you’re using the correct technology as well as the ciliary body, that’s true. Extraocular muscles, you could see extraocular muscles, we’ve seen a couple of articles talking about this. Corneal-scleral junction, of course, you can see the corneal-scleral junction. What you could not see with the anterior segment OCT is the corneal endothelium. The corneal endothelium is a single layer of cells and we don’t have, right now, the capacity of correct segmentation of the endothelium. You could do an automatic evaluation of the epithelium, you could get an automatic measurements of the angles, goniometry. But you could not see, right now, a single layer of cells of the corneal endothelium. Remember these are really small structures, you need a specular microscopy or another type of technology for seeing these small single line of cells.
What else is coming, what else could you do? What else is new on anterior segment OCT? This is a nice paper that suggests correlation between break up time and also the height of the meniscus, the lacrimal field meniscus. Again in different measurements of the height of the meniscus could give us a lot of information about dry eye disease in some patients.
This is evolving and now by measuring small area, right now you could do only small area of the central cornea. Hopefully this technology could evolve a little bit more and you could get a bigger picture, you could see the dynamics of the lacrimal field. This is the break up time again. But instead of using the slit lamp, you could have, over time, how the dynamic of the lacrimal film is changing. How it starts from on second one and then starts diminishing going down on the second test. This is normal but you can see a lot of changes in the first five seconds on patients that have dry eye disease.
Another new thing that is coming to anterior segment OCT is OCT-A, OCT angiography. OCT angiography, right now it’s on the beginning of the study stages. You could do images of the anterior segment base, the base cells. You don’t have the reproducibility as we would like to right now. The technology’s constantly evolving and I’m sure that we will get a lot of better images and reproducibility of this on the upcoming years. Right now we don’t have metrics, we couldn’t measure the flow. We could see zones that are not only on the iris but we could see corneal neovascularization and this is a nice preview to see coming through on the next years.
With reconstruction on these images, you could see also 3D reconstructions of pupillary block or a pupillary membrane like in this case.
This is a nice paper also that shows conjunctival and intrascleral vasculatures using anterior segment OCT and geography. These are normal eyes. As in regular OCT-A, we are doing scans on different depths of the eye. This is superficial flexus, 0-100 microns, intermediate flexus, this is 100-200 microns. These two accounts the superficial layer and then the deep layers, 200-300 and 300-1,000 microns. Here you can see different layers, all of them this is 1,000 microns depth. This is the whole scleral depth. And you will see different reds and blues showing like a doppler sign, or actually it’s not doppler, it’s a flow measurement based on the same principle of OCT-A that it’s the blood flow going through these vessels.
I’ll start answering some of your questions. Can anterior segment OCT be used to understand the integrity of the posterior capsule of the lens in opaque corneas? Yes. Anterior segment OCT can be used to understand integrity of the posterior capsule if there is something in between the IOL and the posterior capsule. If you have some sort of interface between the posterior capsule and the IOL, you could see the integrity of the posterior capsule. You couldn’t go through the periphery though. You couldn’t go only through the, if you dilate the patient you get a bigger pupil, you get a bigger view, but you couldn’t get the borders or the really ends of the posterior capsule. It will depends, actually.
Can PPC can be diagnosed on OCT? If you’re talking about anterior segment OCT, posterior capsular opacification you could see, you could diagnose that, sure.
Thank you so much, excellent presentation. Maybe, it’s possible, also. Not with anterior segment OCT. Usually meibomian gland when you want to see that, you need to use another type of light. You could have a slit lamps with anterior cameras that could do visualization of meibomian glands. We couldn’t do that right now with anterior segment OCT.
Thank you on this presentation, very informative. Does machine operation need special training? Yes. Depending on which one you’re using. Some of them are more user-friendly. Some of them are not that much user friendly. It’s like using posterior segment OCT, you do need some training. I don’t think it’s that hard, the learning curve. I do think you need some instructions prior to using it.
Is confocal microscopy the best modality to assist corneal endothelial integrity? Yes. Yes, for the endothelium, that is the best imaging technology we have right now. Not only for endothelium, you could see with confocal microscopy, the intrastromal nerves. You could see the whole stroma, you could see the cells of the cornea when they’re activated. You could see a lot of different changes at the cellular level using confocal biomicroscopy. That’s really, if you want to see the endothelium, that’s the best technology right now. Although you could do that also with regular specular microscopy. It will show you a lot of resolution of the endothelial cells if you just want to look at the endothelium.
Can we say which layer of tear film is sufficient on an OCT? No. You couldn’t say which layer of the tear film is efficient on OCT. You do need another type of studies for that.
Can anterior segment segment OCT replace gonioscopy? Well, that’s an interesting question. Usually on gonioscopy you get a direct visualization of what you’re seeing. Anterior segment OCT with goniometrics information won’t show you the direct visualization of the structures that you use for goniometry. For gonioscopy, I’m sorry. Goniometric measurements got a good reproducibility. You could rely on them most of the time. But I don’t think any technology right now will change the way that we do clinic. I do think these are imaging diagnostics that will help us assess in difficult situations. For example, patient with a cornea, an opaque cornea, or with synechiae, or things that didn’t show us as direct visualization. If you want to have metrics you want to have good way or good tools to measure anterior segments. I don’t think it will replace goniometry or gonioscopy any time soon.
Can I see the angle that it’s supposed to said, the inclination of the bolt? You could see the bolt with this, yes, you could.
Are goniometrics affected by skilled pressure measurement them or is it objected down by the machine? Dependent again on the OCT you’re using. Some of them do automatic metrics, some of them have manual metrics. It is effective on the person doing the metrics and it’s effective on the live search, it’s a lot easier doing the metrics. It’s not the same having a live bolt on or off during this because of the iris movement and the changing of the anterior segment.
Can anterior segment OCT be done for puncta also? Yes, you can do any type of implant or anterior segment implant. You could move anything that go in through the eye, can go in through the eye lid or any type of implant, the technology could give us this.
Are the drawings were taken from the CASIA 1000. No. Some of them were from the CASIA 1000, some of them were from the CASIA 2. Most of them were from the Triton. Triton is a swept-source OCT also, 1050 nanometers. And it gives good penetration in anterior chamber and also in the posterior segment. Some of them through the 3D reconstructions and the 3D movies, they were from the CASIA.
What are the disease best diagnosed by anterior segment OCT? Diagnosed? Well, you could diagnose corneal ectasia, keratoconus, or ectasia post LASIK surgery. You could diagnose the anterior chamber or recess of the angle. I don’t want to see acute glaucoma because you don’t need anterior segment OCT with acute glaucoma. But you could see if the angle is prone to be closed. That’s another thing that you could diagnose with anterior segment OCT. You could see the density of the crystalline lens sometimes. You could diagnose cataracts, uveitis, certainly with anterior chamber reaction. There’s a lot of different pathologies that you could diagnose with anterior segment OCT.
Corneal epithelial thickness and keratoconus early detection? Of course. Corneal epithelial thickness you could do, keratoconus early detection is almost the same as shine flow images and technology.
Perfect, thank you guys. Again, sorry for the signal drop at the end and I hope we see you soon. Bye bye.