This live webinar will discuss different approaches to vision rehabilitation shortly after crosslinking for keratoconus. The main focus will be given to specialty lens modalities such as rigid gas-permeable, hybrid, specialty soft and scleral lenses and to the challenges associated with special lens fitting post-surgically.
Lecturer: Dr. Boris Severinsky OD, FAAO, FSLS, Chief, Contact Lens Service, Emory Eye Center, USA
DR SEVERINSKY: Hello, everyone. My name is Boris Severinsky. I’m a contact lens specialist. Working at Emory University. And today we’ll be discussing our approaches to specialty lens fitting after corneal collagen crosslinking. Most of you definitely know the long history of crosslinking being around for the last 20 years, the procedure was approved in 2016, and you can use it right now. You can use the crosslinking technique delivered by Avedro Systems. So why crosslinking? It’s definitely a first line treatment for progressive keratoconus, any other type of corneal problem such as pellucid macular degeneration, or post-refractive surgery. It may improve corneal measurements, decrease in steepness and aberrations, and prevent the loss of best corrected vision. We’ll talk about it later. Trying to avoid by any means the need for penetrative keratoplasty, and, again, functional vision with contact lenses. This is basically the up to date treatment protocol for cases of progressive keratoconus. Again, anything that could be done to prevent corneal transplant, especially in young patients, definitely is more than welcomed. So I just wanted to give some definitions for the progression analysis in cases of progressive keratoconus. So as most of you know, we define progression as changing of more than 1 diopter. Even 0.5 diopter of change will be considered as a progression. Or again, change in maximal K readings, more than 1 diopter. So to do our scans properly, of course, patient history is important. Habitual contact lens correction. Stop it 2 to 3 days for soft contact lenses, 7 for RGP. I just want to go over corneal changes, over a period of almost 4 years, and just wanted to emphasize that basically when crosslinking is not done in time, patients are losing their best corrected vision. So as you can see here, this progresses from 2.75 diopter to almost 6, best corrected vision with spectacles, still gaining good vision with RGP contact lens. And the patient was offered crosslinking for a number of times, but for some reason they denied it, and finally they got it 4 years ago. Decreased vision even with RGP contact lenses. And as you may see, definitely some evidence of apical scarring, which actually precludes good corrected vision. So what is crosslinking? It basically increases stiffness of keratoconic cornea. And there’s some evidence that keratoconic cornea is actually softer than a normal cornea, and that’s actually why everything associated with eye rubbing — it may be related to keratoconus starting to progress. So crosslinking will definitely compensate for this weakness. And some say that the stiffness increases by a factor of 1.5, which is definitely significant. Again, just a reminder — we cannot crosslink corneas below 400 microns. Worrying about the possibility of endothelial damage. But we can do contact lens-assisted crosslinking, especially in young patients with keratoconus, corneal steepness… Corneal abrasion about 8 millimeters — use of riboflavin, 20% dextran solution, and radiation for 30 minutes. Many devices, as you know, only the cornea is irradiated, accelerating the crosslinking procedure, but basically the new technique may shorten the time needed for treating to be done. Now, why it’s so important? Because our topic is not really crosslinking, but how to fit contact lenses after the crosslinking. The cornea definitely won’t stay in the same shape after crosslinking. It takes about a week for the cornea to revitalize itself. And then — and we actually were very surprised at the beginning, when we started to do crosslinking 10 or 12 years ago, that corneas actually get steeper in the few months after crosslinking, and it is definitely explained by the apical changes, going through epithelialization, remodeling, so in the first month, you’ll see kind of a bare cornea, and as the epithelium covers the steepest and flattest points, in some cases you’ll see significant flattening of the cornea. Again, it emphasizes very, very nicely as the steep K is changing over the time, seeing some flattening effect of almost 2 diopters, and best corrected vision also improves, as the cornea gets flatter. But again, actually, as in this case, we’re seeing steeper Ks of almost 2 diopters. About two months after the procedure. And if we look at this cornea with hypertrophic epithelium, the process of the remodeling — just covers the gaps between the corneal apex, and then after 4 months, basically, cornea just came to the same presurgical measurements. You may see also improvement in best corrected visual acuity. There are also changes in corneal regularization. The steeper point of the cornea — the apex gets a little bit flatter. It’s still an elastic tissue. As the steep K gets flatter, probably the flat gets a little bit steeper, as you can see over here. But it actually all helps and this is an extreme case. The patient came with astigmatism slightly above 1. It increased in the spherical component — if you look at that spherical equivalent, it’s pretty much the same, but his spectacle corrected vision improved significantly. Again, why should we be careful with contact lenses after crosslinking? It’s all about changes to the corneal epithelium, and trying not to interrupt this normal process of changes. After initial crosslinking. In many cases, we may actually disrupt this epithelial remodeling, and again, we need the most appropriate time to start with contact lenses. Most of the complications probably will be in more steeper corneas. Which definitely makes sense. The steeper the apex, the more regular is the surface. Probably will take longer for the epithelium to get to its normal thickness, and it goes through the remodeling process. So again, here comes a question about contact lenses. Should we eventually start it? And can we do more damage rather than benefit to the cornea? Just recovering after the procedure? So basically even so — keratoconus is considered not an inflammatory disease, but there is definitely some degree of chronic inflammation in keratoconic cornea, both from contact lens use, microtrauma, and microerosions to patient-related eye rubbing, which also takes place very often, and to the toxic effect by contact lens solutions. So all this may even without going through the crosslinking process make dry eyes and compromised corneal epithelium. There is also some damage that actually may have been from the procedure itself. Because it will be toxic to the corneal epithelium. So everything basically to some degree of irregular healing — which is, again, crucial for normal reepithelialization and remodeling process to basically take this cornea to the normal healing, after the procedure. And again, how the contact lens is fit over the cornea may disrupt this natural remodeling effect. Again, going through basic types of contacts, speaking of rigid gas permeable contacts, which have been around for the last 70 years, a little less, probably 60 or 65, to more newer designs, as corneo-scleral contact lenses, hybrid lenses, hydrogel, and definitely scleral contact lenses. Going back a little bit of history… Spherical corneal lenses were the gold standard for many, many years. They consist of base curve, which takes place at the central part of the lens, followed by peripheral curves, which help with alignment, helping to align the lens, over the corneal periphery, and the edge lift that helps with tear exchange. But is it still the gold standard? We’ll see a little bit later. So a few approaches to fitting rigid contacts in keratoconus — probably the most common, the most known one is the 3 point touch approach. And the second one is apical clearance, which was developed slightly later, after the CLEK study results were published. So we’re trying to spread contact lens weight over the healthy peripheral cornea, where the corneal thickness is normal, and trying to avoid any contact with the corneal center, due to, again, center stromal component and definitely more irregular, and also center epithelium. And again, why CLEK study results are so important: They definitely show that corneal touch of flat fitted lenses are very highly associated with degree in appearance of corneal scarring. So again, this is not something that you would like to see when you fit your postcorneal crosslink patients. So this has advantages and disadvantages to any of these designs. Three point touch may have a slightly better visual acuity for scarred cornea, but on the other hand, we’ll definitely see a higher rate of contact lens induced erosions, which may lead later to fibrosis in corneal scar formation. Again, speaking about crosslinking, most of these factors will lead to some degree of epithelial damage, and interrupt epithelial remodeling, after the procedure. So minimum apical clearance is definitely the better approach, when we fit crosslinked corneas, again, trying to avoid any epithelial compactions, disruptions, or erosions, and in most of these approaches, we can define it as apical clearance, feather apical touch, but still no heavy corneal contact, to the full apical clearance. Large diameter rigid contacts actually were better in both patient comfort and lens stabilization, decreasing basically lens movement, and again, it’s definitely logical. As we go and increase the lens diameter, we decrease the detachment effects. The lens stays more stable, disrupts the epithelium less, and in these contacts we can also decrease or increase corneal vaulting, making this lens to look almost like a scleral lens, with its limbal support. So again, this lens can be designed better, to avoid any possible corneal touch. Piggyback, sometimes it’s a well promoted technique, but it still may be working pretty well in cases of keratoconus. In both promoting lens centration, because the soft lens is like a bandage, and due to its thickness, it will shelter the surface, decreasing the degree of corneal irregularity, and due to the bandage effect, it prevents any possible rubbing to the surface, association with edge left of rigid contact lenses. Some patients are not really ready to work with using two lenses a day. And in cases of rigid lens still not centering very well over the cornea, like this picture down below, it will actually be inducing more of a coma-type higher order aberrations, which will create some reduction in visual acuity, due to ghosting or double imaging. One of the solutions to overcome the centration problem is a pocket lens carrier, or what’s called a pillow lens. So it’s basically a self-carrier, with a little pocket created into it, and then rigid lens can fit exactly in between. So again, everything should be designed — you definitely know the size, the diameter, of your pocket to design the rigid lens, and in terms of vision, it definitely works better, because it’s definitely way more centered. On the other hand, the soft carrier is mostly done in HEMA style of materials, which decreases oxygen permeability to the cornea, because the rigid lens will be losing its pumping mechanism, because it won’t really have good edge lift, sitting inside of the pocket. It won’t create any tear pumping. Fenestration helps a little bit, but again, this type of carrier is very often associated with neovascularization and decreased healing times. Going again to our topic of contact lens fitting after corneal crosslink, we talked about epithelial remodeling and changes to the epithelial cells. There was an interesting study in Ophthalmology in 2014. It studied basal plexus epithelial nerve density in crosslinking eyes, in rigid contacts, and actually found a decrease in basal epithelial cells and neural plexus density, and they claimed it probably comes, again, from rigid lens rubbing effect. And the cornea may remain hypoesthetic for up to 3 months after corneal crosslinking, so it may lead to disrupted reepithelialization mechanism, and having this hypoesthetic cornea may possibly increase the risk of contact lens-related microbial keratitis. Speaking about rigid lens fitting after corneal surgery, there was a study back in 1999 by Zadnik et al. that said in case of PRK, they usually waited about 3 to 4 months for rigid contacts to be fitted, trying to avoid any possible complications. So in terms of corneal recovery, there’s basically no difference between PRK and post-crosslink, because the reepithelialization process is basically the same, but in the case of keratoconus, it also makes the reepithelialization maybe take longer or be more difficult, because of the nature and shape of the cornea. So this is one of our patients. That underwent a very successful crosslinking. And was advised to cease any contact lens wear. And of course, he started doing his old rigid contacts, about two weeks after crosslinking. And he developed a central corneal ulcer. It’s thought to be related to contact lens rubbing effect. Causing some abrasions, and then also happened — so this nice-looking cornea after crosslink turned out to be a corneal scar in the center, which definitely diminished patient’s visual acuity. And speaking very briefly about CLEK study results, rigid lens use by CLEK study almost doubled the risk of corneal scarring. So what can we do on our end? Trying to decrease contact lens mechanical impact? We’ll talk now a little bit more on newer types, newer designs, like special lenses, soft lenses, keratoconus hybrids, and definitely scleral lenses, which evolved very dramatically, during the last 10 or 15 years. We’ll go to our first patient now. We were thinking about the first few months after crosslinking — what would you recommend? Would you recommend rigid contact lenses, start immediately with rigid contacts? Should you take greater precautions to avoid epithelial damage fitting contacts? And if you do document apical touch fitting, to help this corneal remodeling? So absolutely yes. The correct answer will be B. We’ll definitely need to take more precautions fitting rigid contacts or any type of contacts after crosslink. Just to avoid any possible epithelial damage. So as we said, we’re trying maybe to avoid rigid contacts. May be fitting it more on a piggyback type. But we still can use what’s called the conventional contacts after crosslink. And it might be toric lens, it might even be spherical lens, in keratoconus it’s mostly keeping the visual axis almost undistorted, in the case of mild cases, but the key point: If you can refract this patient to 20/40, 20/30 visual acuity, just with your correction, you should try the conventional lens first. Very often you will be surprised how good the vision can be. And again, if you can keep especially your young patients from using more specialty type of contacts, you will just improve the quality of life. Because these people, they really want to be like anybody else. Using maybe not glasses, but regular contacts to get better vision, and not going into scleral hybrid whatsoever, when it makes all the processes more complex and bulky. So in my opinion, stiffer silicone hydrogel will work better, because again of the corneal regularization effect from the stiffness of the material itself. So contacts like AirOptix Night and Day, toric — may really work very well. Like in this case, so astigmatism — just corrected with the appropriate contact lens. The other type, and we’re going more into the specialty lens field. It’s what’s called soft mini-sclerals. And you’ll see why they’re called mini-sclerals. Or just very thick soft contacts for keratoconus. So this lens is basically fitted almost like a normal scleral lens. You’re trying to minimize your apical touch. And again, the picture on the right — it’s fluorescein pool. Underneath, beneath the soft lens. It’s not a scleral lens. This material is completely soft. You see here the fenestrations. So this big soft lens rests over the perilimbal sclera, and partially over the limbus, but basically still over the limbus, similar to big scleral lens. It may go up to 0.5, 0.6 millimeters, and the rigidity of the material — because the thicker we go, the more rigid surface we’ll create — will help to create a tear lens and more regularized cornea underneath. As far as I know, three companies are doing that. Soflex, Cooper Vision, NovaKone, and Flexlens by X-CEL here in Georgia. So talking about the soft silicone hydrogel scleral lenses — they go up to 17 millimeters in diameter, it’s a very thick lens, staying over the perilimbal cornea, and sclera, and vaulted in the center part, and this lens may create a small pool of tears, and just to see… It’s still not a rigid scleral lens, but it’s almost like a scleral lens, it has fenestration to improve oxygen delivery, because it’s quite a thick lens overall. And this we are taking after crosslink, without the lens and over the lens. The center is almost spherical. It goes from 47 diopters. In the inferior part, it goes to 40. And basically creates very little amount of astigmatism. Causing marked improvement in patient visual acuity. The second lens will probably be a hybrid lens, which is basically a combination, as you see from its name, of rigid and soft materials. So the hybrid lens has a rigid button in the center, made out of highly permeable materials, surrounded by a soft skirt. There are many different types, and this type of lens is still evolving. The newest one, the most recent one, is probably UltraHealth, a company in France, doing very similar type of hybrid, but not available in the US. It works very well for mild and central cones, very similar to rigid contact lenses, but unfortunately it’s not complication-free. So again, very similar to the picture. With scleral lens, pooling of tears at the center, and the lens actually rests with the RGP over the rest of the cornea, but skipping any contact with the treated zone. And the biggest thing is the scleral lenses, which work for basically any type of surface. But they work especially well over a compromised ocular surface, because again, having this protection, protecting the vaulting effect, not having any contact with the central cornea and also not having any limbal contact, they actually help to improve this remodeling process. Because again, when you rest your lenses over the limbus, you’re actually still disrupting the normal epithelial migration from the limbus to the center, so not covering the cornea completely, and not interacting with epithelial cell migration probably will be the best thing to do. Many different types, and most of the mini-sclerals, 14 to 17 millimeters in diameter, work well for central type and not very steep cones. There are some limitations in terms of adhesion and conjunctival vessel disruption and blanching, and again, everything could be fixed. Sometimes we use limbal fenestrations to provide better oxygen flow, break down adhesion, or just make coverings throughout a larger area. So the fitting definitely should have sufficient vault over the cornea, trying to avoid any contact with the treated zone, and as you may see on this video, it also may move a little bit. But you see very, very nice pool of fluorescein underneath the lens, and if you do have scleral lens with some movement, it may facilitate — underneath the contact lens, it helps to make the fit more physiological. Full sized scleral lenses — every type of cornea may be fitted. If you see corneas with more than 60 diopter in central thickness over the maximal K point, I would definitely recommend to start with these lenses. Non-corneal touch are definitely the way to go after the crosslink. I’ll just show you the results of one of the studies we did of different types of specialty lenses after crosslinking, the soft mini-sclerals, hybrids, and sclerals. And most of the patients were able to tolerate these sclerals very well. In the group of soft sclerals, Kmax of 65, which already puts them in the advanced group, some were able to achieve 20/40 vision, so even as a temporary retainer lens, the soft lenses may work very well until the cornea goes to its more stable shape. Definitely in scleral lenses. The best in their optical properties, and also something we will touch on a little bit later. Most of the eyes go — and it’s almost 50% in our group, undergo some degree of corneal flattening. Which has to be addressed with the proper lens fitting. So in terms of safety, some of them stop using the lenses in soft lens and hybrid lens group, due to complications like corneal erosions, and not good lens wetting, which may happen with the soft type of silicone hydrogel materials. Sclerals didn’t show any type of fit-related complications. Hybrid lenses, we should be fitting them with more precautions, because of the settling effect. Very often you’ll see this type of ring erosion over the cornea, or skirt erosion. It happens when the lens starts bracing over the cornea, and when there’s collapse, you can also see some degree — the mark here — of central type of erosions. So just be more careful, when you fit hybrid contacts. And having this type of impression ring or circular erosions, it’s actually bad for proper epithelial remodeling. And not just that. It also opens a place for possible microbial keratitis, so try to wait at least 2 hours before you evaluate hybrid contacts because of the skirt flattening and compaction effect. And because of this skirt pressure effect, these lenses also may have some influence over the corneal geometry, causing molding and significant corneal flattening, like in this case, and it’s not crosslink-related. It’s basically corneal — rigid part of the lens related. So again, extra caution should be taken, fitting hybrids. So what’s our proposed paradigm in fitting specialty lenses after crosslink? Usually wait for at least a month. Again, it’s definitely healing dependent, but at least a month before starting contact lens fitting. Some patients who cannot tolerate the vision we may start a little bit earlier, but our go-to lens will be the soft scleral lens, due to its very gentle properties. Not disrupting epithelial remodeling. And then we allow 3 to 4 months, and if the cornea shows signs of stabilization, we’ll advise scleral lens fitting. It may be any available design you feel comfortable with. And surprisingly, many of the patients will prefer to stay with the soft mini-scleral, because again, due to convenience, they’re not limiting to any special tools, special lens treatment, scleral lens may require, because the soft mini-sclerals basically work as a soft normal lens. So we have the stages of the cornea, as it goes through many changes. The surface may be compromised by both the procedure and previous contact lens use, and may show signs of delayed healing. Steeper corneas may take longer to recover. In terms of both proper reepithelialization, proper epithelial remodeling, and it seems that scleral lenses — both soft and rigid — will be a more viable option for postcrosslink cornea. And our aim, again, is to minimally interfere with normal corneal recovery, after the procedure. Now, for question number two. So what do you think seems to be the best fitting scenario in the first one to two months after corneal crosslinking? Is it waiting for — not doing any contacts for 2 to 3 months, until K readings come to pretreatment levels, starting rigid contact lenses as soon as possible, to improve VA because the patient cannot see well, or a step fitting approach, when you start with specialty soft lenses first, and then slowly move to hybrid and scleral lenses? That’s correct. Correct answer is C. I’m sorry. The correct one is C. So I believe we still have a few more minutes left. So I just wanted to speak briefly about sclerals after crosslink, and maybe touching a little bit what we do when we’re fitting kids after crosslink, that we definitely do more and more. So when you fit a patient with a scleral lens, do you think it will change the corneal shape? Because basically the scleral lens stays over the cornea. Does not touch it. So why we should expect — should we expect any changes to the corneal shape, after wearing the regular lens? And again, we should ask: How should we monitor the progression of keratoconus? How do we monitor success of crosslinking, if the patient is wearing a scleral lens? And if it doesn’t have any influence on the cornea, or it does? So I will just go very briefly — all of you know that scleral lenses are a big thing now. And almost 30% of practitioners even three years ago have been using sclerals to address keratoconus. Again, how do we monitor progression? This type of change, going from 48 at the center to 44, we see contact lens and not contact lens-related. In this case, it’s actually scleral lens-related. And again, very similar. This cornea ranging from 50 to 55. So with this imaging — it’s a very well fitted lens. There’s no corneal touch, but it still gets flatter. Another example — at baseline, it’s 43, and after starting sclerals, it actually got steeper, and as you see on the right, it’s a difference map, shows some steepening, and we discontinue for two weeks, and then back to refitting measurements. So it’s still a scleral lens effect. In this case, it’s actually different. It’s a crosslinking-related flattening, which mostly will happen, so sometimes it’s very hard to differentiate. But it probably mostly will happen in the center, with this type of flattening, a flattening scleral lens-related — it will be more superior or peripheral. So again, how do we differentiate, and how do we follow up on progression, in scleral wearers? And just in terms of the slide: We evaluate keratoconus with crosslinking and keratoconus without crosslinking. All received similar contact lenses in terms of contact lens size, and none of the contacts showed any type of corneal touch. So the fit was assessed by anterior OCT, to verify there’s no corneal contact. And in both groups, the cornea got flatter after two hours, and more significantly after five hours, underneath the scleral lens. Talking about good fitted lenses with no corneal contact, but it still gets flatter. And there was some difference between crosslinked eyes and non-crosslinked eyes, but all of them show this type of corneal flattening. Definitely scleral lens has a flattening effect over the cornea. And these few approaches that we thought to influence this flattening… It might be epithelial thinning-related, because of the fluid forces underneath. Again, scleral lens — most of the mini-sclerals are thin lenses, so basically no liquid exchange underneath. Basically negative pressure of the liquid may cause this type of flattening. Others thought it was corneal swelling. Even so, it’s physiologically acceptable, and you won’t find any corneal edema in these eyes, but it still swells by 1.5 to 4%. In our study, it was 1.7% of corneal swelling, and swelling is definitely associated with corneal flattening. So this is probably the most reliable mechanism in what we think that causes this corneal flattening. Blink forces through the contact lens also may cause it. It’s like a pumping effect of the liquid under the lens. Again, just to emphasize: Scleral lenses are a good thing. It’s probably the best fitting scenario, after crosslinking, but still it has its side effects. Making the follow-up a bit more difficult, and we still need to remove these lenses. To allow for proper corneal imaging. When we have to decide about the procedure, or when we just do our normal follow-up after the procedure. So the lenses definitely should be discontinued. We do recommend 7 days of — best case scenario — but it may be impractical, because the patient cannot function properly, not having a good vision even in one eye. So we often just recommend maybe doing one eye at a time. Stopping with one eye, doing scans, and then resuming the lens going back. And our question number three: May scleral contact lens cause corneal molding and flattening similar to rigid contacts? Which is false, true, or depends on the amount of corneal clearance. Underneath the scleral lens. And of course, yes, I will say: It’s mostly B, because if you remember the study results, all the lenses were fitted with very similar corneal clearance. Up to 300 microns, and there was no strong association between amount of clearance and corneal flattening. So most of the eye still will get flatter, underneath the scleral lens. And we’ll show a few complication pictures. Which also may happen under bandage contact lens. This is poorly fitted bandage lens-related. You see the margins here, it barely covers the cornea, the cornea is so steep that it won’t cover it sufficiently. Soft lenses, also not complication free. A lot of variable compressions and SPKs. Also improperly wetted surface, causing significant vision disruption, fluctuations, again, because of the high percentage of silicone in this material. So you should address first the ocular surface and treat dry eye. A large diameter RGP do not move because of dimple veil, which is very benign, but still changes the shape of the cornea, and putting fenestration will help with oxygen delivery. In hybrid, even so, scleral lens type contact lens, in terms of corneal clearance, but having good clearance over the center you still will find some significant lens impact very often. Be careful and always remove hybrid lenses when you do your posterior lens fit evaluation. And sclerals also involved complications. Again, depends on the fit. And it’s more common with this type of compression rings and erosions, more common with the mini-sclerals, when you don’t have sufficient distance between the lens and the cornea over time. And just a nice picture to conclude with. It’s a keratoconic cornea with very bad vision, and unfortunately not possible due to very thin cornea — you’re probably seeing it here, this cornea is vastly neovascularized, almost 160 degrees over this point. So this is for transepithelial crosslinking without scraping, and then was fitted with a scleral lens. Drastic improvement in visual acuity. And also use this in pediatric. We definitely fit scleral lenses in cases of pediatric keratoconus. And it might be a bit challenging, due to age. Most of these kids show up to the clinic with a very severe degree of cones. Opposite to adult keratoconus, pediatric you see it’s very severe, it may develop in some cases — it got steeper in two months. Most of them allergy, most of them eye rubbers. So everything we can do to stop eye rubbing, it’s definitely very much appreciated. In this case, very thin corneas. This kid underwent contact lens assisted crosslink. And was able to get good vision with sclerals. And we also did a short study on our pediatric patients. Mean age of 12 years. Some of them used contacts for surface disease indications, but scleral contacts for keratoconus visual rehabilitation, and in this group, 6 eyes after crosslink, and all of them showed very good acceptance rate, and also decrease in steepness of K readings. So crosslinking — scleral lenses is the next kind of thing, and this is the best treatment we can offer our patients. But again, if patients cannot afford the scleral lenses, because the cost is still high, I guess it’s high worldwide, and some of them just don’t have enough insurance to cover these expenses. Okay. So again, we talked about it. And my final slide. It’s always a challenge to fit keratoconic patients. It’s definitely time-consuming procedure, with multiple visits. It requires many design changes, and even with best fitted lens, the vision can be variable, and there are definitely expenses behind specialty lenses in these cases, but still we have the procedure now that can break this lifelong circle of bad vision. And especially in pediatric patients, if we can stabilize the cornea when they’re still young, can put them in scleral contacts, they might not require PK never. And they keep using these lenses for good, and who knows what technology will be available in the next years. So thank you for your attention. I will try to go if time allows over some questions. The question about the age limit? Basically not. If the patient is cooperative. So basically, if the patient is cooperative for crosslink, under topical anesthesia, we’ve done kids as young as 8 years old. Some of them just need short sedation. And they do fine. We also have experience with kids with Down syndrome, who can do crosslink even under topical. To the next question… So the question is about if the procedure should be repeated or not. Some studies are saying 3 to 5% of crosslinking should be repeated, because corneas keep changing. It all depends on how fast the collagen-fibrin turnout rate… The younger the patient, probably the collagen will replace itself sooner, but most of the studies show in terms of 10 to 15 years, the need for repeated crosslink was less than 5%. Question about color and contrast sensitivity acuity. If it will be impaired. Yes, it mostly happens due to postcrosslink corneal haze. And most of the cases it improves throughout the period of 3 to 6 months. It depends on the intensity of the haze. Some patients really need prolonged use of steroids for three to four months after the procedure. Just to decrease the inflammatory response. Some of them will definitely respond badly. Again, it’s patient-related. But it’s very uncommon, having haze for longer than 6 months. Rose K2 lenses? It’s all about the approach of clearance. If you can fit such a lens without any corneal impact, SPKs, erosions under the lens, it will work. We very often recommend if I see patients that basically didn’t — doesn’t have any change to their K readings after the procedure, and still cannot afford, let’s say, changing the lenses, but the fit is still good, just go with a piggyback lens for a few months. The daily silicone hydrogels are available. If you just make the fit safer, some patient will just like the comfort, in terms of protection as well. Question about three point touch. Basically you’re trying to put lens weight over the peripheral cornea and central cornea you’re trying to avoid impact. But you will eventually cause some disruption to the epithelium, so we think that the apical clearance will still be better in such cases. Question about vernal conjunctivitis, vernal catarrh. Often with my pediatric patients, they go through first fitting on any type of cromolyn, available eye drops, to do it for two weeks before they start using contacts, and continue doing it routinely. Crosslinking is contraindicated when we don’t have sufficient corneal thickness. If it is below 400 microns, it’s contraindicated, if the patient has severe or significant stromal or central scarring, it will be contraindicated. Hydrops is also one of the contraindications. Which technique of contact lens manufacturing works better? It’s not better in terms of what’s better to the cornea, to the patient. It’s case to case-related, but again, the less impact to the cornea, the better it is. The earliest indicators that an optometry student can diagnose keratoconus? If you don’t have corneal topography in your clinic, you should still have a retinoscope and keratometer. Most of them will show distorted mires that won’t change with the blink, and retinoscopy will show. I still use my retinoscope. Every time a patient is diagnosed with keratoconus, keratoconus suspicion, I always do retinoscopy. How long to wait for rigid lens fitting? If you don’t have dryness over the treated area, if the K readings are back to the pretreatment level, you can definitely start with RGP. Again, we usually wait with RGP at least six weeks, if possible. And so a question about the role of scleral lenses after refractive surgery. We do it a lot in cases of corneal ectasia after refractive surgery. It’s an evolving, new technique. Sometimes we use negative aberration of the front surface of the scleral lens to counteract positive spherical aberrations, in case of large pupils, but it’s mostly corneal topography related. So you assess that individually. A question about corneo-scleral lenses. It’s a good option. It definitely may be… A go-to option three months after crosslinking, when the cornea is already healed, before trying sclerals. Some patients may have less tolerance to corneo-sclerals because of the edge lift effect, but if the cornea is not too steep, not too vaulted, it will stay good, so some of the corneo-sclerals, when you go to a very steep basis, to fit over this very steep cornea, it will make the lens to adhere to the cornea, and it will make it stop moving so good, and you have to move to scleral lens. In terms of visual acuity, it might be better than soft sclerals, but we often see the soft sclerals as an interim, an in between option for the first three months, to have minimal impact over the eye, allow it to reepithelialize, and then going and fitting sclerals. Let’s take one more. A question about no rub, no cone. I think it’s true. Sometimes we just see unilateral keratoconus. In a patient who has been sleeping on a particular side of their face. For a long time, yeah. I think it’s… This doctor definitely nailed it. A question about scleral soft contacts. I think I mentioned before, you can get it from CooperVision or Soflex, or Bausch and Lomb, AirOptix Toric, most of the cases, will work. AirOptix Toric is 14.5. Not very severe cases. It will work for very mild cases, when refraction is still possible. It may work just fine. If a patient has more than 3 diopters of corneal cylinder, it won’t be the best option, because I think it goes up to 2.25. Bausch and Lomb lenses may go… Yes, as an option, it will be Biofinity XR, which may go up to 4.75 diopters, but it has to be specialty made. Advanced keratoconus and crosslink — as long as corneal thickness allows, it will definitely work. You should have no scarring, no surface disease, and sufficient thickness. Mini-scleral lenses and scleral lenses are basically size related. And I think… Very good question about keratoconus with limbal stem cell deficiency from vernal conjunctivitis, requires keratoplasty. It’s very hard to answer. I think it’s more to refer to cornea people. But if you still have clear central cornea in patients willing to wear scleral contacts, scleral contact lenses will basically address both. The surface, surface disease, and most definitely improve the limbal stem cell deficiency, just having the protective effect and improve vision. Very often in cases of radiation-related limbal stem cell deficiency, or toxins, corneal burns — we fit them in sclerals to improve the surface, absolutely. And I think we’re good with everything. So thank you so much. And thank you for having me here. And you have my email. So if you have any other questions, please let me know. Thank you.
July 31, 2020
4 thoughts on “Lecture: Contact Lens Fitting After Corneal Crosslinking for Keratoconus”
When to Adapt Scleral Contact Lens After Cross Linking, thanks
Corneal cross linking is generally advised in cases of progressive keratoconus. This can possibly be achieved when you are dealing with a patient who is regularly coming to the clinic for years. In a case where the patient is new and he/she may or may not become a regular one, is cross linking a must whether or not keratoconus is progressing? – Editor, Optometry Today
Thanks for your comments, the corneal cross linking is as you say an indication to halt the progression of keratoconus, if there is no progression it is not necessary, one difficulty nowadays is the lack of one standard criteria for “progression”. We have complementary methods such as the anterior segment UBM that allows us to see early changes at the epithelial layer but not everyone has access to this technology. So in the case of the patient who lives in another city and we are not sure if there is a progression, I recommend taking two things into account, one is undoubtedly the family history, age, the presence of eye rubbing…and on the other hand it is always you can do topographic tracking in the distance with the use of telemedicine.
CXL is a safe and minimally invasive surgery, but the procedure should be performed only if there is the appropriate indication, not always.
Thank you for sharing