Lecture: Pushing the Limits in the Surgical Correction of Keratoconus

During this live webinar, an in depth review of the surgical aspects of keratoconus will be provided. Focus will be on non transplant options, including corneal collagen cross linking, intracorneal ring segments, photo therapeutic keratectomy in combination with cross linking and the use of phakic lenses in the visual rehabilitation and stabilization of keratoconic eyes.

Lecturer: Dr. Guillermo Rocha, MD FRCSC FACS, Professor, Department of Ophthalmology, University of Manitoba, Canada



DR ROCHA: So my name is Guillermo Rocha. I’m a doctor, a cornea specialist and an ophthalmologist, in central Canada. And I’d like to welcome you to this webinar, put together by Orbis and Cybersight. So it’s a real privilege to be able to present to you some of our experiences, in terms of managing keratoconus, and just pushing the limits in what we can offer to our patients. So I’d like to start by presenting a typical case. This is a 42-year-old female, a Canadian submarine strategist. And she came — she was referred with a stable refraction, and that’s the key. Stable refraction. And uncorrected vision of count fingers, but a significant myopic astigmatism. And so you can see that there’s still a reasonable corrected visual acuity of 20/30. And the question is: What do we offer this patient? And so the question is: Do we offer observation? Do we do some medical treatment or surgery? As this patient basically has keratoconus. And you can see here in the axial map a significant steepening of the cornea. Central thinning. And then on the elevation map, posterior elevation map, a significant area of elevation on this Scheimpflug imaging. This is the left eye, which shows very similar findings as well. And so the question is: Well, again, what do we offer someone like that? She’s unable to perform her job anymore. These are very high prescription glasses. And she’s just not able to tolerate them. And so the first message I would like to get across is: When we’re dealing with keratoconus patients, and interesting options, the main thing is: What is the chief complaint? And then finally, what is the goal? So in her case, she wanted to get rid of some of the prescription that she had. The goal was to be able to function better without glasses or contact lenses. But she was willing to compromise with some of that. So define the chief complaint and define what is the goal as well. If we look at the players in keratoconus, we can see clinical findings, we can see topographic and tomographic findings, and pachymetric or central corneal findings as well. In terms of the management, we have both non-surgical and surgical options. And here I would like to mention that I did receive a lot of questions from the group when they were registering. And so I will try to incorporate some of the aspects of those questions into my presentation. So keratoconus is a fairly prevalent disease, with 1 in 2,000 presentation in the population. And the main thing is obviously the thinning and steepening of the cornea. That results in irregular astigmatism, increased coma, and decreased quality of vision. And although there’s several systemic associations, the main ones are atopic disease, as well as rubbing. So this is an example of the coma, and how it distorts the vision. Early keratoconus, histopathologically, presents with several findings. This is Bowman’s layer. So we can see fragmentation of Bowman’s layer, thin epithelium and stroma, folds and breaks in Descemet’s membrane, as well as diffuse scarring. Somebody brought up the issue of talking about the biomechanical effects or biochemical effects as well in keratoconus. There’s actually a number of factors that can contribute to keratoconus, as you can see here. Some environmental. Some inflammatory. Genetic. Biochemical. Or biomechanical. And in fact, analyzing these can get pretty complex. You can see that there may be a role for matrix metalloproteinases, some of the immune factors and inflammatory cytokines, as well as a decrease in the antiinflammatory cytokines. So all of these are potential associated factors in keratoconus that lead to oxidative stress, keratocyte apoptosis, as well as increased matrix metalloproteinases. Now, all of that in theory leads to damage. There’s also cytokines. Inflammation that can cause issues. And there are reports that report that inflammatory cytokines like IL-1, 6, and 8, TNF alpha, TGF beta, as well as platelet derived growth factors, can increase the risk — or are found in increased numbers in the tear films of keratoconus eyes. Such as these other factors as well. Like tumor necrosis factor alpha, MMPs, the matrix metalloproteinases, ICAM, VCAM as well, and a decrease in the antiinflammatory proteins as well. And so the idea is that collagen crosslinking also has been found to represent less collagenases, as well as decreased IL-6 and IL-8, and perhaps this is one of the things that leads corneal collagen crosslinking to a stabilization of the disease. So there are significant factors. But one of the most significant ones is the eye rubbing, which may actually be the initial trigger of all of these changes. If you can hear the sound of the rubbing… I hope you never hear that. I sort of cringe when I’m hearing that sound, when people are really rubbing their eyes. And one of the easiest ways of ensuring that the eye or the keratoconus will not progress is to tell our patients not to rub their eyes. Okay? And so if you look at the etiology of keratoconus, you have sort of molecular hypotheses, but there’s also a significant contribution of this mechanical hypothesis, where the eye rubbing itself is at the center of it all, and leads to all the inflammatory responses that we have described. Other associated factors include many, as we have mentioned, including mechanical stress, perhaps genetic factors, and also things like mitral valve prolapse, atopy, eye rubbing, and a positive family history. But again, another message to give you, when you’re looking at your patients, is ask for these four questions: Is there a history of allergic disease? And mainly eye rubbing. That should be stopped. And if so, and if they have keratoconus, also go further. We are physicians, after all. So ask about sleep apnea, and if necessary, refer to the sleep clinic. Floppy eyelid syndrome, as well as mitral valve prolapse. So there seems to be a kind of association with these four factors, and I would encourage you to find out more about that. Now, there has been a world panel consensus looking at the definition, diagnosis, non-surgical management, and surgical management of keratoconus. This was put together a few years ago, and reported. And I’ll review some of the findings from it. Initially, we’ll look at the eye, and how the vision can be distorted when the wavefront that goes through the eye is separated from the actual light image that we wanted to obtain. So this separation, this deviation from what we were hoping to obtain, is called an aberration, and that’s where we get the wavefront aberrations. We can assign numbers to these wavefront aberrations and start calling them names like defocus, astigmatism, trefoil. With which many of us are familiar. We can assign charts to them as well. And then classify them a second, third, fourth, and fifth order, in Zernike terms. And we can give them diagrams. And I’m showing here the wavefront aberration of coma, which is the most typical one in keratoconus, and will have bearing later on in today’s talk. So we see how these fit in, and we have vertical coma and horizontal coma, and again, this is the most significant one in keratoconus. Now, this is important, because it is coma that gives us the blur and double vision associated with keratoconus. Other aberrations can give other types of symptoms. For example, trefoil can give starbursts. And in addition, with the current equipment that we have, we’re able to measure these aberrations objectively right here. And the question is: Well, what level of aberration will actually give us symptoms in a particular patient? So the numbers I use are simply these. So if someone has higher order aberrations in the whole eye of less than 0.2, the symptoms are really none. 0.2 to 0.3, mild. 0.3 to 0.4, moderate. And greater than 0.4 are severe or marked symptoms. Blur, double vision in the case of coma, starbursts in the case of trefoil. Now, in terms of presentation, one can have keratoconus in its typical form, but also as a form of post-LASIK ectasia, which really is probably undiagnosed keratoconus. And then also pellucid marginal degeneration with a more typical pattern of those sort of crab claw or kissing doves as well. Clinically, without a topographer, one can diagnose keratoconus in a number of ways. So one way is Munson sign. The other one is Vogt’s striae, Fleischer’s ring, the protrusion, the conical protrusion of the eye, and Rizzuti sign as well, simply with a pen light. So these are clinical ways of assessing keratoconus. Now, classification of keratoconus is a bit of an interesting thing. So if you look at this, from the old, old Amsler-Krumeich classification, you can see that if one has myopia of astigmatism less than 5 diopters, and mean keratometry readings of less than 48 diopters, with maybe a little bit of eccentric steepening, well, one could be classified as stage I keratoconus. And I wonder how many people here on the seminar right now, on the webinar, have these characteristics. I know I do. So am I stage I keratoconus? Most likely not, because I’ve done topography. So this classification really needs to be updated. And that’s what doctors Belin and Ambrosio have tried to do. When you look at keratoconus and you try to fit any shape to a best fit sphere or best fit curve, you can really appreciate that things may balance out the actual cone. Whereas if you eliminate the protruding area, like here, and you analyze that separately, you analyze this separately, you can get a lot more information. So you see here in this pattern, instead of normalizing with a line somewhere around here, they’re actually selecting the area that is abnormal, and in the ectasia software printout of this Scheimpflug image, they’re able to — and we’re able to — appreciate the elevation maps on the left and the progression of pachymetry on the right. And this gives us a lot more information, and of all of this, one of the most important numbers is the D index right here, on the right hand corner. An index of up to 1.6 is normal, compared to the normal population database. So with this, one could potentially have a more complex classification. And a new way of tomographic classification of keratoconus. And this is personally what I’m using now, and it’s similar to the surgical classification of tumors, like tumor, zero, nodes, zero, metastases, zero. TNM. Well, this is similar in the sense that we have an A for anterior, B for back or posterior, C for corneal thickness, and D for distance vision. And if all the numbers are close to zero, well, then, one can suppose that there’s really no presence, or it’s a low risk of keratoconus. And we can assess that, because this looks at the front and at the back layers of the cornea. Thus translating that into a proper report. So this is one of the additional classifications that I’m using now in a more practical way. Now, some conclusions of that Delphi panel that I mentioned to you is the fact that there’s actually no adequate classification system. Keratoconus can present with normal corneal thickness as well. The diagnosis is an abnormal posterior elevation. Thickness distribution is abnormal. And it’s in general thought of as non-inflammatory. Although the evidence of that is sort of changing now. And we really cannot generalize treatment. And so if we cannot general use treatment, and we’re talking about pushing the limits in the surgical correction of keratoconus, as it is in this session, well, really, I just would like to show you a couple of algorithms, but then I’ll tell you a practical way of approaching these cases. So this is a more complex algorithm that came out of the Delphi panel, which is good. But sometimes can be a bit confusing. This is another one that I used to use, considering eyes that had forme fruste keratoconus, stable keratoconus, and progressive or advanced keratoconus. And I’ll tell you a simplified, more practical, functional classification of keratoconus that I use when I see my patients, and a treatment approach based on the goal. Remember, we always have to define: What is the goal for the patient? Why are we doing anything for them in terms of surgery? And so I simply decide if a patient has mild, moderate, or severe keratoconus. And mild and moderate/severe is cut off basically by where is it that I’m gonna be able to offer surgical options that are not a corneal transplant option? So corneal transplant option is for severe forms. It’s when the cornea is really thin, less than 400 microns. And the K readings, the keratometry readings, are greater than 55 diopters. These are corneas that really — other options may not work as well. In terms of the options where we really can offer a lot to our patients without resorting to a transplant, either a DALK or a full thickness transplant, these are patients or eyes that have pachymetry readings greater than or equal to 440 microns and keratometry readings less than 55 diopters. More or less. And so also we include a functional classification here. Why is it that they want something done? Is it because of employment? Is it because maybe they have very good vision, but they cannot tolerate or wear contact lenses, and then that’s an indication. Whereas in the more severe, I would really go more towards a transplant, if they have apical scarring, marked thinning, or really poor vision, regardless of what we try to offer them. And so ultimately, we always have the option of a transplant, but we should strive towards keeping our patients in the mild or moderate form, so that we can manage them or help them a lot more than what we do with the different options that we have. And one of the questions was about contact lenses. I think the mini-scleral contact lenses work really well in any of these options, once we’ve stabilized or determined that the eye is stable, in terms of keratoconus. So if we look at the cornea, which measures roughly 545 microns, we see that there’s a number of options that we as corneal surgeons utilize, including laser, segments, and endothelial keratoplasty or full thickness or partial thickness grafts as well. So in the past, and these are two studies from colleagues of mine in Toronto, but in the past our lists were almost half and half for endothelial disease, versus stromal disease like keratoconus. But what we have seen, at least in Canada, over the past several years, is the fact that the ectasias and the thinning conditions really have started to come down. And they form now in any general practice less than 5% of the indications for corneal transplant. So we are doing something else. We’re removing those eyes from the need for corneal surgery, for corneal transplant surgery. And allowing those tissues to be utilized for other conditions, such as DSAEK or DMEK. And so in terms of the treatment approach based on the goal, what is it that we want to achieve with these patients? There are several aspects, and I’ve outlined here the main one is rubbing. Prevent rubbing. And stress that to the patients. Then we need to consider stopping progression, strengthening the cornea, changing the shape, improving vision, and so all of these of course are a lot of aspects, but if we plot them in this way, you can see that we have indications to stop progression, strengthen the cornea, change the shape, improve vision, and improve astigmatism. And when we plot that against the techniques that we have, so we’ll talk about crosslinking, intracorneal ring segments, laser approaches, and combined approaches using intraocular lenses, be it phakic lenses or cataract lenses — and so we can appreciate, then, that there’s no one single procedure that will address all of this. So another message I’d like to convey is that every eye in every patient is different. And so we need to really sit down, determine the goals, determine what we’re gonna be doing, and then decide which combination of options it is that we’re gonna use. Do we need to stop progression? Do we need to change the shape? Or do we need to improve the vision and quality of vision? Or do we need to do all of them? Okay? So these are the three questions that I sort of frame for my discussion with any patient I see with keratoconus. Do we need to stop progression? Sometimes we’re seeing the patients for the first time, but they can tell us, you know, for the past 5 years, it’s been really bad, getting worse. Do we need to change the shape of the cornea? And I’ll address that in the sense of whether or not we can get a patient to see past 20/30 vision, more or less. That’s sort of my cutoff. And do we need to improve quality of vision? And that’s when somebody has a lot of aberrations. Okay? Keeping in mind always: What is the chief complaint? And what is the goal? Because if somebody comes in… I was just curious to see if I have keratoconus. I function well with glasses. My job is still good. Well, then, we don’t really need to do anything to that person. But if somebody comes… Look, I’ve been getting worse. I can’t wear the contact lenses. This is affecting my job and my lifestyle… Then we have a different decision. Even if the eyes look exactly the same. So let’s start with crosslinking. So crosslinking — the bottom line is that it strengthens the cornea. And so with this, we’re able to achieve stopping progression, strengthening the cornea, and changing the shape, and sometimes the vision a little bit. That’s not the goal of crosslinking. So I always tell patients with crosslinking the goal is to stop your disease. So we saw a little bit of improvement in the quality of vision. The refractive changes were not significant. Remember, this is not magic surgery. What we’re trying to do is to… What we’re trying to do is to reduce the progression of the keratoconus. That’s the goal of surgery. With crosslinking. And so if we look at the parameters: Vision, refraction, keratometry, pachymetry, we see that with crosslinking, there’s no major change in vision, no major change in the refractive status. A little bit of flattening, maybe, with the keratometry readings. Changes in pachymetry that are minimal. And a significant decrease in higher order aberrations. And all of this has been assessed and determined by different people. Different publications right here. Okay? Now, there can be failures with crosslinking. And so one needs to be conservative. And so this is a study by Seiler and Michael Mrochen, where they showed that if you really push the limits, if you go over 58 diopters, and if you’re treating patients that are older than 35 or 40, which I’ve treated, but always respecting that 55-diopter range, if you treat patients that have higher corneal steepening than 58 diopters, you probably will have a lot more issues with failure. Now, what happens when we want to go beyond the moderate treatment of keratoconus and crosslinking? So we need to consider other options, like intracorneal rings, laser corrections, and intraocular lenses. So there are different intracorneal ring segments, like the Intacs, Ferrara, Keraring, and MyoRing. Now, if we look at this, this is the shape of the cornea with a handheld keratoscope. This is how the corneal rings change. And what we’re trying to do with the ring is regularize those mires. Regularize those rings. So since I started doing Intacs in 1999, purely for myopia, so I had reservations about using them for keratoconus. Until I started seeing the results, and in 2005, I started doing surgery for keratoconus using rings. No crosslinking. There was no crosslinking at the time. I used the IntraLase to insert them. And what you can see here is the change of shape — so you’ll see before surgery and after surgery — so you see the change in the shape after the surgery. And so what we obtained with Intacs is a strengthening of the cornea, but not necessarily stopping the progression. We also get a changing of the shape, and improvement in vision. Okay? So this is the effect pre and post-Intacs, as you can see there. We can use them symmetrically or asymmetrically. We can put them paired or simply one, in one position. And this was one of my first cases, where I had to do Intacs. So you can see the Sim-K readings are around 52 and 46. This was the correction in this particular patient. Vision obtained was around 20/30. And then the question: Do we need to stop progression? Do we need to change the shape? Yes. We needed to change the shape of the cornea. And we needed to improve the quality of vision. And so the goal was to reduce their dependence on certain glasses or contact lenses. We observed a flattening effect of the cornea, a change in the shape, and also an improvement in the refraction, as you can see here. So this was one case that actually motivated to continue doing Intacs. From that time on, there’s tons and tons of publications regarding the use of Intacs and intracorneal ring segments in keratoconus. And what one can expect is: Basically a change in manifest refractive spherical equivalent of around 3 diopters, a change in cylinder of around 3 diopters, with good stability of the refraction, and reasonable predictability. The majority — I would say over 90% — do better. Very few get worse. With improved uncorrected, best corrected vision, reduction in refractive parameters, and better ability to wear glasses or contact lenses with stability and delay in full thickness grafts. We have developed a kind of nomogram for Intacs planning, and we always identify the cone on the elevation map, whether it’s central or inferior. We target the axis position of the ring based on the manifest refraction axis. And the nomogram is really this. And we tend to use more of the thicker rings, 0.4 and 0.45, and we tend to use more of the regular rings, as opposed to the SK rings, when we talk about Intacs. There are nomograms for Keraring and for Ferrara, and all of them work well. The concept is that we can change the shape with the use of intracorneal ring segments. Now, in this particular case, we see that this patient has keratoconus. Contact lens difficulty. He had been stable for years. So all we did was an inferior Intacs of 0.3, got a vision of 20/30 uncorrected. A pharmacist that now can continue working without fiddling with the contact lenses. So you see the combination therapy of crosslinking and Intacs or intracorneal ring segments as providing the additional ability to stop progression. And so here we have someone with ectasia. With inferior thinning. We put a ring inferiorly with crosslinking, and the result ended up from this refraction that you see up above to a refraction of uncorrected and corrected vision, basically plano, with 20/20 vision. And here’s the change of the shape that we obtained before, and that was the change that we obtained. This is another combined treatment using Intacs and crosslinking, with an inferior ring of 350, plus crosslinking. And so a significant reduction, a significant improvement in the elevation, as you can see here. Actually in the steepening. And here is the effect, and that was the change. You can see that there was a significant flattening effect in the central cornea, with a good result. So this is the combination. It is always important when we’re doing these treatments to look at the preoperative, postoperative, and the actual difference of what we were able to do. Now, a further planning issue is targeting coma. We mentioned that coma is very significant in keratoconus, as an aberration. And that it has this shape. And that we can measure it as well with our clinical testing. And so one of the things that we’ve started doing following the advice and publications of the group in Oviedo in Spain with Dr. Alfonso is to start targeting the position of the Intacs based on the axis of the coma. And this is fairly easy to use, because with most of the topographer aberrometers, we can detect the symptoms. We can also detect the coma. And where the axis of the coma is. So this is 275, and we would do a perpendicular axis of alignment in this way. And so what we do — and this is their study — is that we can take this information, do a perpendicular of this axis, 283 would be right here, so that’s the perpendicular, and that’s where we would put the orientation of the ring segment. And with this, we have seen very exciting results. Because now we’re combining the use of intracorneal ring segments with a very small amount of phototherapeutic keratectomy and crosslinking to stabilize. And this is the type of refraction that we’re obtaining, or the type of result. With 20/40 vision improved in this particular eye, with a very high cylinder. As you can see there. So we have looked at this in detail. And we have a number of eyes, up to 55 eyes, at this point, that we have looked at. You can see the uncorrected and corrected visual acuity is significantly improved. The amount of eyes that we have with good vision — 20/30 or better — improves in the postoperative period, and we have improved corrected visual acuity as well, comparing pre-op to the post-op period. Plus a significant reduction in sphere and cylinder. Look at the reduction in cylinder of around 2 to 2.5 diopters. We also showed a significant change in the keratometry readings. And also the high order aberrations. So when we look at high order aberrations, mainly coma, spherical and secondary astigmatism, all of them improved significantly with the use of this approach. Not so much for the trefoil. So there could be concerns with safety, scarring, delayed healing, or a hyperopic shift that always come up when we’re using combined procedures. But we really have not seen any of these issues, and we have noticed that essentially only two eyes had worsening of one line of vision, but these ones significantly improved their uncorrected vision. And remember, these are eyes that are coming — or these are patients that are coming just to stabilize their keratoconus, and are leaving with functional vision. And no issues with scarring, delayed healing, or hyperopic shift. So what we see in this combination is that we can improve vision, reduce the refraction, and also improve on the quality of vision. In terms of coma, spherical aberration, and secondary astigmatism. As you can see here. So this is an improvement from crosslinking alone. Now, why would we talk about laser surgery? We know about laser and ectasia and the possibility of thinning and weakening the cornea. But really, we’re not using it to stop progression or strengthen the cornea, but rather to change the shape and improve quality of vision. And the big, big question with any of these treatments is: Well, is a cornea strong? Or is a cornea not strong? If we look at the topography, the problem is that if we look at the topography, we don’t know if it’s strong or not. If we look at the Golden Gate Bridge or we look at the Eiffel Tower, we know these are strong structures. They’ve been there forever. For years. And they stand the test of time. However, by looking at a topography, we don’t know if those lamellae, the corneal lamellae, are strong or not. Even if we use tests like ocular response analyzer, we really don’t know if we’re using a laser on a healthy cornea or we’re really using it on a cornea that could lead to keratoconus or ectasia because the cornea is intrinsically weak to begin with. So despite a number of tests that are available, we really don’t have the ability to guarantee that a particular laser treatment is not gonna hurt the cornea. So if we’re gonna use the laser to reshape a cornea with keratoconus, I always use it in combination with crosslinking, to add that effect of stopping progression and strengthening the cornea. But we have found a significant, significant role for improving vision. So I’ll show you a couple of examples using the laser. And this is an example where we simply took a patient with keratoconus — you see it here — and we were able to do the crosslinking, in combination with the laser treatment. And the goal obviously is: Are we able to improve from previous studies, where we just did crosslinking? And there are several studies where they’re combining the use of laser in combination with crosslinking to improve the visual result and the visual recovery. And so what we did in this particular case, as we started with this area of laser and crosslinking, was to simply split the cylinder in a bitoric way, and then add crosslinking. And so with this we’re able to obtain a significant improvement in the vision and refraction of this eye. We included a number of cases with keratoconus, always respecting those numbers. These are the two numbers you have to remember. A cornea thicker than 440, with K readings less than 55. It and there are different options to use the laser, such as topography-guided, treating the refraction, and wavefront-guided. And so we basically use these ones, and mainly more recently we’re only using the wavefront-guided ablations. And that’s what I’ll show you. But there are a number of reports in combining laser and crosslinking with keratoconus patients. This is another example where we simply did a PTK. That was just a circle. To try to regularize the cornea a little bit. And look at the improvement in uncorrected vision, and also in corrected visual acuity right here. We were able to regularize the cornea. And what happens is that even just removing the epithelium with the laser helps in eliminating part of the cone. Because you see — if we look at the pachymetry of the cornea and we look at the epithelial map, just looking at the epithelial map, we see that the epithelium is thinner. The epithelium is thinner over the area of the elevation. So if we take that elevation and we simply use a laser, we will be hitting the cone first, leaving the rest of the epithelium as our masking agent to protect the more regular, more normal corneal stroma. And so this allows for a significant reshaping of the cornea that’s very subtle. And I’ll show you here: By turning the light down in your laser, you can see the DNA breakup and the fluorescence in the epithelium, and then you see that black area. That dark area is the initial hit on the cone itself. And you can see that, and you can see how that correlates with the area of thinning over the cornea. And so we now use the laser regularly to prepare the cornea for any kind of crosslinking. And in this particular study, we did a bitoric stromal ablation. Never exceeding 40 microns. We have to be very conservative. And what we found in this case was also a significant improvement in uncorrected, best corrected vision, with a good safety index. We also saw this at one year. So at six months and one year. We saw a significant reduction in sphere and in cylinder. So by about half. Because we’re very conservative, right? The goal is not to eliminate glasses. This is not a refractive surgery. But it’s more — the goal is to stabilize the corneas and improve the visual acuity for these patients. So we saw an improvement in the keratometry readings as well. No real change in pachymetry, once corrected for the level of ablation. And in the indices of Pentacam, the Scheimpflug imaging, all of them improved with the exception of the central keratoconus index. Higher order aberrations — this is not what we were expecting, but in this initial study, we found no change in higher order aberrations. So we said: Well, combining a laser treatment with crosslinking can improve a number of things, but not higher order aberrations. And the question is: Can we do better? And so there is technology available in a number of ways. We have been using a particular laser, the Schwind, that allows us to plan these procedures in a very customized way. Once again, asking the questions of: Whether we need to stop progression, change the shape of the cornea, or improve quality of vision. And what is the goal and the chief complaint? I’ll show you this 30-year-old male with significant keratoconus, mostly in the right eye. And that is the result we got after wavefront-guided laser treatment with crosslinking. This is the prehigher order aberrations and the post. You see, we begin to see how we can really change the shape of the cornea and target those aberrations by customizing the treatments and customizing it ourselves. Another example here of a wavefront-guided treatment as well — you can see the improvement in uncorrected and best corrected vision as well, that you can see here. With the differential maps, with the more central steepening, compared to the inferior cone present. So you see the change here once again. And so we got really excited with this approach. And so we’ve looked at our numbers as well. And look at the improvement. From around 20/60, 20/70, to 20/40, 20/30. Remember, these are again people who are coming just to stabilize their keratoconus, and we’re offering them an option to become more functional as we go through the treatments. Improvement in vision, in corrected vision, from pre to post-op, and also the improvement in the sphere and cylinder. We’re also very conservative with these treatments. And here’s the kicker. Here’s where we got really excited. If you see coma, spherical aberration, secondary astigmatism, and the total higher order aberrations, all of them were significantly improved, compared to pre-op, with the exception of trefoil. So we know that we can now improve vision, we can now improve the refraction, but also improve total higher order aberrations and coma, which is one of the most important ones in keratoconus. So we’ve looked at crosslinking alone, crosslinking with Intacs, crosslinking with laser. So what is next? Before we move on to that, I’ll just express the safety issues with the combination of crosslinking with laser. As you can see here, there was basically a gain in more than two lines or better in uncorrected and corrected vision, and again, some of the eyes that lost one line actually improved their uncorrected vision. So it was not really a big, big loss. Now, there can be some extreme reports and results, and we have not really seen any of these ones, I’m happy to say. There can be some haze formation. It usually goes away after about three months. We do use mitomycin C in all of these cases. And so we really have not seen major cases of haze. And typically the haze goes away after a few months, if there is. So keep in mind this. This is the basic slide. What is the chief complaint? What is the goal? Do we need to stop progression? Change the shape? Or improve quality of vision? And this leads you to this. To the use of intraocular lenses, which was another one of the questions in the preseminar questions. So I have used both the toric intraocular lens implants, the phakic ones, as well as the toric posterior chamber lenses, in cataract surgery. This is a patient, 48-year-old, with a significant correction, but with stable keratoconus. I simply placed a toric ICL, and the result was excellent. We have looked at that. We have a series of patients where we have done implants of phakic IOLs, and in all of them, we see a significant improvement in the uncorrected and corrected vision. Improvement in the corrected vision as well. And a significant improvement, if you look down below here, in the sphere and cylinder of these patients. And they become really functional. So that brings us back. You remember, we started with this Canadian submarine strategist. And so she had been stable all her life. But she had a high correction, and she had keratoconus. She was not rubbing her eyes. So we simply put a toric ICL, and this is the vision that thee had about a week later. And then a few months later, I got a report from her ophthalmologist. She was still functioning well and working well inside her office. And not wearing glasses or contacts, but happy with the vision. So we were able to significantly reduce that amount of correction that she had. And there are numerous reports of the use of phakic IOLs in keratoconus, as you can see here. And along those lines, well, what do we do with cataract surgery patients that have cataract surgery, but that have keratoconus? And so this is a very good article, if you want to jot it down. But I’ll summarize it in basically saying that when you’re doing your calculations, if the K readings are less than 48, go ahead and use the actual K readings from your machine. And target around -1. If the K readings are 48 to 55, use the actual Ks from your machine, and target around maybe 1.25, 1.5. Now, here is where it gets tricky. If the K readings are higher than 55, you should ignore the actual Ks. You’re gonna leave that eye very myopic. And simply use a standard K of 43.25. And I’ll put it right here again. And so if the Ks are less than 48, use the actual Ks. Target -1. If the Ks are 48 to 55, use the actual Ks. Target a little bit more myopia. But if the Ks are more than 55, ignore those Ks. And simply use 43.25, and target -1.50 around that. Okay? So there are not many reports, but it works. And here’s an example of a patient, and this was her pre-op. This is her keratoconus. And this was the result with a toric IOL after cataract surgery as well. One can use that as well. Toric intraocular lenses in keratoconus. There are several reports. And what I’ve done as well is: Sometimes you start with crosslinking or crosslinking with Intacs. Or with laser. And then you may find that you still need to improve vision or reduce astigmatism. And once the cornea is stable, then one can proceed with a toric ICL, for example, a phakic IOL. And so that has been done. And this is a group from — colleagues of mine from Mexico. Where they actually implanted Collamer lenses, the phakic IOL, after intracorneal ring segments for keratoconus. This is another combined Intacs and posterior chamber toric lenses, after patients with extreme myopia. And I have a few patients like that. And this particular gentleman had Intacs, then crosslinking, and then a toric ICL, and we left him with about this correction. Still significant distortion, but he simply did not wish to wear contact lenses, because he’s a carpenter. Lots of dusty environments. And he’s happy functioning in this way. And you can actually see in this eye the Intacs, the crosslinking effect, and the ICL all in one. All in one. But remember, I will not put an intraocular lens unless I’m certain that the cornea has been stable for at least six months. There is also — this is another study, sort of confirming and reporting on the use of phakic lenses to improve visual outcomes in keratoconus patients — those are the Collamer lenses, and the Artisan lens can also be used for that. So there’s a number of options. And so we go back to our table, where we have the different techniques. So we know if we want to stop progression, the only thing that does that is crosslinking. If we want to strengthen the cornea, well, intracorneal ring segments and crosslinking does that. But then we have a number of options to improve distortion, such as laser, which is becoming my favorite at this point, in good cases. And then also other options to minimize the need for glasses or contact lenses, if the patient wishes. And of course, each of these options is sort of adding one thing or another, and so we have to use them judiciously, with good conversations with the patients, and with good discussion of the different options. Always going back to the goal. What is the goal for this patient? What is the indication? And then those three questions that I mentioned. Do we needed to stop progression? Change the shape? And improve vision? So once again, just to summarize, this is — the best results we see in any of these combination options are pachymetry readings greater than 440 microns, keratometry readings less than 55 diopters. This is where we really can shine as ophthalmologists, in terms of offering something that will be short of a corneal transplant. Of course, corneal transplants work well. But in young, active individuals, the problem is that those can result in trauma, wound dehiscence, infections, and of course a long-term risk of rejection. And so if we can avoid a corneal transplant and stick with the other surgical options to stabilize the disease, then I think we’ve done a good service to our patients. And this is just a place of summer in Canada, where I am not sure if you’ve ever visited, but I hope that you can visit at some point. Canada is beautiful in the summer, as well as in the winter. Even though it’s a bit cold right now. But I hope you have enjoyed this session. And once again, I would like to thank Orbis and Cybersight for coordinating this session. I would like to leave you with a concept of stressing to the patient the no-rubbing issue. Working with them, with their allergy specialist, controlling allergies, if present. The second point is always defining the goal for your patient. Why do we want to do something? Are they fine with glasses or contacts? Or do they need something else? And the third thing is answering those questions. The three questions. Do we need to stop progression? Do we need to change the shape? In which case we would use either laser or corneal ring segments. And do we need to improve the quality of vision? In which case we have several options, such as mini-scleral contact lenses, after we stabilize the cornea. We have the option of reshaping the cornea with laser. With intraocular or intracorneal ring segments, or other options such as glasses, even, or contact lenses, to try to minimize those distortions that these patients may have. What is your opinion about the treatment of keratoconus in young children? This is a very important issue. A lot of the patients that we see are children that are coming. I think the youngest one I’ve treated with crosslinking — and it’s been usually just crosslinking, not combined with any other options — but the youngest one was about 11 or 12. And so you sort of have to gauge how good the patient will be, how good the parents are, and the first thing in children is: Addressing the issue of rubbing the eye. And often they might not say it. The parents might not have noticed it. But that is the first issue I would do. So in children, look for atopic disease, allergic conditions. Now, if that’s controlled, and the keratoconus is progressing, then you really need to do something. And I would suggest just doing the crosslinking. Surprisingly, even young kids like 11 or 12 may be able to do it. If they can’t, then that becomes an issue. And practically speaking, it is hard to find a place that can keep a patient just stated or in an operating room with an anaesthetist to do a procedure that’s really an in-office procedure for 40 minutes, 45 minutes, to try to lock the cornea. But in terms of concept, yes. It is important to treat keratoconus in children. I always address the issue with parents in a similar way as vaccination. I mean, do we know if this is gonna progress or not? We don’t. We don’t know if somebody is gonna get a disease. But we vaccinate. So do we know it’s gonna progress or not? But we have a treatment that will stop it. Might as well stop it, if there is significant evidence of keratoconus. When is a transplant needed? Okay. Thank you, Maria. So I mentioned a couple of sort of separate things. If you have a patient or a cornea that has corneal thickness of around 440, let’s say, it’s ideal. And keratometry readings that are less than 55. And they can tolerate glasses. They correct well with glasses. But there’s a fear of progression. Maybe they can’t tolerate their contact lenses, and the quality of vision is not as good. So those eyes that have corneas of around 440 or more, and their K readings are not as steep, as curved, then you can do all of these options that we discussed. Now, if the corneas are thinner, if you can’t really refract them, if they have scarring in the surface, if they have a bit of apical or focal scarring, if they cannot fit contact lenses, even if you can refract them in the office, but they can’t tolerate contact lenses or glasses, and they’re not able to function, well, that would be an indication for a corneal transplant. Interestingly, at least here in Canada, we get coverage for corneal transplant, but we don’t get coverage for any of the other options. So as far as the government is concerned, I could see 10 patients with keratoconus would who be a candidate for crosslinking or something else, and I could transplant them, and they wouldn’t say anything. Which is not really a good approach for patients. And so what I would say is: When to transplant them? I really leave it as a last option, at this point. I really leave it as a last option. And it is a good option. And if I’m gonna do a transplant, I would prefer to try a DALK, deep anterior lamellar keratoplasty, to try to leave an extra layer of tissue for strength in these younger patients. Another question, from Jagrup. What is the criteria of selecting a patient for toric ICL in stable adult patients of keratoconus? And that’s a very good question as well. All of them have been very good questions. But this is also a very good question. Because you mentioned a very important thing. A stable adult patient with keratoconus. So the criteria for selecting would be that first of all it’s stable. And if they’re not stable, you could always crosslink, wait, and not do any of the other fancy things. Just crosslink. If they have a high prescription. Second criteria is of course that they have enough space. So usually I do 3 millimeters, 3.0 millimeters, of space in the anterior chamber as the criteria. And second is that you can actually refract them. If you can refract them, and you go by the refraction, right? As with any ICL planning, you go by the refraction. You don’t necessarily go by the topography. So if they refract well, consistently, I would check it at least twice. I would explain that this is completely off-label, because this is not an indication for ICLs. And then once you have one or two refractions that are stable, and they refract to at least 20/30, I would not put an ICL in someone who — the best corrected vision is 20/60, for example. If they’re 20/30, 20/25, 20/20, then by all means go ahead. Otherwise I think the distortion on the cornea is just too much for the eye to really enjoy the possibility of the ICL. I hope that answers your question. Now, the other question is from Albert. Do we need to treat higher order aberration? Or use Intacs? If there is good vision with scleral lenses? Actually, this is excellent. So I like scleral lenses. I don’t fit them myself, but we have that at our clinic, and we have a specific optometrist that fits them. Once again, Albert, we’re going to the goal. What is the goal? So let’s say you have a patient that comes and says: Look, for years I’ve been managing okay with my scleral contact lenses. But I feel that there has been progression. And you see that there is actual progression on the elevation map, from time to time. What you can do is, for example, crosslink. And don’t treat anything else. You just crosslink, let them stabilize, but with crosslinking alone after three or four weeks, they can go back to their own scleral lenses, and they will enjoy better vision, because now the corneas will be stable, they will have lost some of the irregularity, and with the scleral lenses, they will work well. So it’s going back to the indication of surgery, the goal of surgery, and in the particular example that you’re saying, no, if they get good vision with scleral lenses, all we need to do is ensure they’re stable, and that their contact lenses fit well and they tolerate them, and they will get just as good or probably even better. Because the scleral lenses are really providing a nice new round service on top. Now, in patients with antecedent PTKs, or laser vision correction and crosslinking, which formula do you use to calculate the IOL? Again, this is a very, very good question, Daniel. I’m not sure if you’re familiar with the program Panacea. It’s from Costa Rica, and this has been promoted by David Flikier. I see your name is Daniel Fuentes. Maybe you’re from Latin America or not. I’m not sure. But there is that formula. Otherwise what I actually use, in terms of formula, is just the IOLMaster 700, with the Barrett. The Barrett calculation. Now, a couple of important things, and this is why I mentioned the Panacea. The Panacea is the only formula that includes the Gullstrand ratio and includes the Q asphericity factor, the Q factor, as well. And you can include those in that formula. Keratoconus eyes are hyperprolate. So they behave in a bit of a different way than a normal postlaser ablation would. So in a normal postmyopic ablation, you would get an oblate cornea. You would get a lower Gullstrand ratio, and an increased Q and an increased spherical aberration. A posthyperopic ablation causes negative Q, decreased spherical aberration, and an increased Gullstrand ratio. Well, guess what? A keratoconic cornea has a lower than normal Gullstrand ratio, and also has a lower Q and a lower spherical aberration. So it’s almost a combination of things. So it’s more complex. So in these cases, after those treatments, I would do several formulas. I would do the Barrett, I would try to do the K readings as well, I would look at the Gullstrand ratio, I would look at the Q, and try to use the Panacea, which is downloadable, and hopefully I can get some concordance amongst all of that data. But the Barrett seems to work really well with just any situation. So I would base a lot on the Barrett, and then you can also run it through the ASCRS, but the problem is, as I said, that it does not behave — the cornea does not behave in the same way as a purely postmyopic or purely posthyperopic — because with the laser treatments that we do, that can be topo-guided or wavefront-guided, we are actually really just reshaping the cornea. So that’s a very important point, and I don’t know if I have a clear answer for you. But I would start with the Barrett, and I would use the Panacea. Hopefully that helps you. Corneal thickness is important in intracorneal ring selection. What about level of astigmatism? Should it be considered in the plan? And that’s from Nala. Definitely. Definitely. You know, I’ll tell you… When I started doing all of these approaches, obviously you start with the different treatments, you start with the corneal rings, with crosslinking, and this. And obviously you see that it works, and you start pushing the limits, pushing the limits, until you realize that there is a limit. And then you sort of backtrack and become more conservative. So in the intracorneal ring segments, definitely the corneal thickness. You want to have at least 440 centrally. Maybe in some cases 400. It depends on the type of rings you use. So, for example, I only use Intacs, but I use regular or SK. You want to look at the periphery, the thickness of the periphery. And you also definitely want to look at the astigmatism. If the astigmatism is up to about — more or less 5 diopters, then I would consider the use of Intacs. However, there’s something important here. You should be able to refract. And you should be able to refract these patients to a decent level. So, for example, if I’m considering Intacs in a patient that has 20/80 vision, best corrected, despite moving the axis, despite my best efforts, despite their cooperation, I wouldn’t consider Intacs. I might just do crosslinking and then we’ll see what other options we can do. If they can refract to 20/40, 20/30, even if they don’t go beyond that, but if they can refract that, and more so if the axis of the cylinder matches the axis of the topography, then I would feel more comfortable, even if the cylinder is very high. Okay? And so I think the highest I’ve corrected in some of the examples I’ve showed is probably around 5. Maybe 5, 5.50. But not more than that. And always in the setting of being able to refract these patients. Otherwise, it’s a waste of their time, their money. If you’re combining that with other procedures, it might be painful as well. And so I’ve become a bit more conservative, but I know they work, and every eye is sort of different. I hope this answered your questions. If not, let me know. Type it again and see if this answered your question. So what is the crosslinking protocol that you usually do? Do you like accelerated crosslinking? No. We’ve looked at that. And I’ve used two in the past, and there’s only one really that I use right now. So I use riboflavin, 0.1%. I always have the dextran, 20%, and the hypotonic. So I have the two. And I use every 2 minutes for 30 minutes. Epithelium off. And then every 2 minutes, every 2 minutes, I will do one of dextran, another one of dextran, and then the hypotonic. So every 2 minutes, they’re getting something like that. For 30 minutes. We soak the cornea. And then I do the 10 minute. And I haven’t gone below that. I think 9 minutes, depending on the machines that you have, 9 minutes is probably okay. But going below that, there’s some evidence that simply says that it just doesn’t respond the same way. I have tried epithelium on in some cases, but I know there’s a specific protocol with a specific formulation. We’ve used it a couple of times, and it did not work, but not with that formulation that’s being studied in the United States, so that might be a different thing. I have seen some reports with iontophoresis, and I don’t think the results are as robust as with the Dresden protocol with 9 or 10 minutes. And finally, in some patients that have very thin corneas, I’ve done a couple of things. One is use the Daya Disruptor. So it actually just pokes holes on the corneal epithelium, and it allows to soak. I’ve done a couple of cases like that, which seem to work okay, but not necessarily as well as the Dresden. And the one thing that I’ve started doing now is taking a contact lens, and it’s made by Bausch and Lomb, and it has to have no filter. No UV filter. And that actually adds about 100 microns of thickness. So you soak that lens in the riboflavin. You do your soaking of the cornea while you’re soaking that lens. And then when you’re ready to do the ultralight, you put that lens on the cornea, continue with your drops, but in very thin corneas, it would allow you to get that extra bit of thickening that you need. For crosslinking and also for Intacs, any time you see a lot of Vogt striae… I would say Vogt striae… It’s really… You can almost predict that these eyes are not going to respond as well as when you don’t see as many Vogt striae. It almost means the cornea is not going to strengthen as much, because it’s become very, very flimsy. Okay. Max Rojas. Besides corneal opacities, when would you indicate a penetrating keratoplasty? Okay. Well, let’s start with some practical aspects. Besides corneal opacity… So, for example, I have patients — many of these — in fact, I would say all of these procedures are not really covered by our government here in Canada. Except corneal transplant. So I have had patients who say: Look, I cannot afford any of this. But I cannot function. And I need a corneal transplant. It’s still a good procedure, of course. It has its pros and cons. And so that would be the case. Let’s say we try crosslinking, Intacs, something, and still there is distortion. Right? What I tell patients is that you have a keratoconus that is not going away. It’s simply not going away. And so if you want better vision, there’s always gonna be a limit. And that limit is going to be determined by the curvature of the cornea, the irregularity of the cornea, and so if you’re not able to tolerate contact lens, and if we’ve done Intacs, crosslinking, all that, your cornea is still irregular. It is still diseased. So if they’re still not happy with that, and we’ve sort of determined that they’re at that limit, maybe the cornea was a bit thinner, maybe the prescription was a bit bigger, or a bit higher, and they’re still not happy with that, then I could consider a corneal transplant. It’s very rare now, I have to tell you. And it’s very rare for patients to convince me about that. Because, to be honest with you, I’ve had two patients who were young, around 40 to 45, both with bilateral transplants, both with excellent vision, both who had freak accidents, and ended up with wound dehiscence, bilaterally blind. So it’s very hard to convince me that you would do… That I would do a corneal transplant, when they are candidates for something else. But it’s still doable. Especially if they cannot afford multiple treatments or other treatments or crosslinking or laser or Intacs. Then I would certainly consider it. How is laser ablative procedure justified in a weak ectatic cornea? Okay. So another question here from Jangrup. How is laser ablative procedure justified in a weak ectatic cornea? Yeah, so this is what I had mentioned. If I’m going to do a laser procedure, it’s not simply to do the laser procedure. It’s to reduce the irregularities. I always do it — so first of all, I always would do it in combination with crosslinking. That would be the one thing. Second, I’m very, very conservative in the amount of tissue that I remove. And with the laser that we use, we can actually target specific areas, and the most I will remove in the central region is probably around 15 microns. So we’re really not targeting any major levels of correction, but we’re trying to reshape, and as we showed, we actually can reduce higher order aberrations, coma, secondary astigmatism, and spherical aberration, by doing that. And so what I would say is: We justify it on the basis of improving quality of vision, quantity of vision, and because we’re going to remove the epithelium, I mentioned that I do epithelium-off anyway. So I’m going to remove the epithelium anyway. I’m going to do crosslinking anyway. Well, maybe I can reshape the cornea a little bit, and we’ve shown good results with that. So that’s how I would justify that procedure. Well, thank you very much for all your questions. Your participation. And I hope this is useful.

January 24, 2019

Last Updated: October 31, 2022

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