Scleral lenses are becoming more popular with patients as an alternative to smaller traditional gas permeable lenses as well as a method of successfully fitting irregular corneas. During this live webinar, we discuss how to insert and remove a scleral lens, the fitting characteristics of a scleral lens and how to assess a scleral lens on the eye using patient cases.
Lecturer: Anita Gulmiri, OD, FAAO, New England College of Optometry, Boston, USA
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DR GULMIRI: Good morning, everyone! And thank you for joining me today, as we discuss the basics of scleral lenses. My name is Anita Gulmiri, and I’m an assistant professor at the New England College of Optometry, as well as an attending optometrist at one of the College’s clinics. I work at their contact lens department, and I also spent some time in Boston Medical Center in the contact lens department as well. Without further ado, let’s get started on scleral lens assessment and fitting. As a general basic intro to scleral lenses, as many of you may already know, scleral lenses have made a comeback over the last decade, and before this time, only a handful of practitioners were fitting scleral lenses, and not many were being manufactured. Fast-forward today in the United States. We have countless scleral lenses at our disposal, each with their own unique design and features. So the first scleral lens was discovered in 1988, and it was made out of blown glass. Interestingly, it was still at that time being utilized for conditions such as keratoconus and even to correct high refractive errors, even back in 1988. After that period, scleral lenses sort of lost momentum, as glass was a poor oxygen-permeable material. Then they were reintroduced with the introduction of PMMA plastic material. Now, the PMMA plastic material was less fragile than glass, but it was more accurately able to allow for a more optimal fit. So that was the advantage of having PMMA on board. But once again, PMMA as well did not provide enough oxygen permeability to stick around. And then as corneal or rigid gas permeable lenses were introduced, followed by soft contact lenses making their way into the industry, scleral lens research and development sort of came to a halt for the time being. However, scleral lenses have made a full comeback, probably stronger more now than ever before, and we as scleral lens fitting practitioners have many different options at this time for even the most challenging fits, challenging eyes. And to me, one of the most rewarding aspects of scleral lenses is the ability to postpone or even prevent surgery, prevent corneal surgery, that is. All right, so just to get an idea of who I’m speaking with today, I would like to know how familiar you are with scleral lenses. This is our first poll question. So how familiar are you with scleral lenses? A, I fit scleral lenses in my practice all the time, B, I have fit a scleral lens in my practice before, but do so rarely, C, I have not yet fit a scleral lens in my practice but have fit them on colleagues or attended a scleral lens workshop, and D, what is a scleral lens? I’ll give you some time to answer that. Okay, great. So I see that we have some participants that have fit a scleral lens before. That’s great. And then we have some that kind of know a little bit about it, but maybe not much, and then some that want to know what a scleral lens is. So that brings me right to my next slide here. So what exactly is a scleral lens? So just as a review for those of you that do know what a scleral lens is, these are rigid, gas permeable lens materials of large diameter. And they’re designed to vault over the entire cornea and land peacefully on the sclera. In its most true definition, a scleral contact lens contacts the sclera, and there’s absolutely no contact with the cornea. This allows the lens to vault or clear over any irregularity or diseased ocular surface. This lens holds a liquid reservoir of non-preserved saline, so that the cornea bathes in this fluid when the lens is worn. With some but very limited tear exchange. So just to compare scleral lenses to corneal gas permeable lenses, many of you may be more familiar with corneal gas permeable lenses, and I still fit a lot of these in my practice today. Without going into too much detail about corneal GPs, they have a list of advantages of their own. But by definition, corneal GPs rest completely on the cornea. They’re typically smaller than 10 millimeters. They’re designed to move on the cornea, to allow for ample tear exchange, and since the cornea is an extremely sensitive tissue, with lots and lots of nerve plexi, there’s more lens awareness with a small diameter GP. In contrast, scleral lenses rest on the conjunctiva, which is far less sensitive. There’s also limited movement with scleral lenses, so there’s less lid interaction and thus less lens awareness. And it may seem counterintuitive, because of the large size of the scleral lens, but it’s surprisingly very comfortable, because there is no contact with the cornea. Another point to note: Compared to corneal GPs, a scleral lens tends to be a lot more stable on the eye. My patients that have trouble with retaining the lens on the eye, whether it be dislodging the lens or the lens decentering, I typically switch these patients into a scleral lens, and a lot of them report improved success with these types of lenses. So in summary, I would say scleral lenses provide similar if not improved visual potential, but more stability and more patient comfort as well. So the Scleral Lens Society introduced an internationally known nomenclature for describing scleral lenses, based on the resting zone of the lens and not lens diameter. So it was previously categorized — scleral lenses were previously categorized — by the lens diameter. The new nomenclature is basically characterized by where the lens lands. So if the lens lands on the cornea, it is deemed a corneal lens. If it lands entirely on the sclera, it’s called a scleral lens. And if it lands somewhere in between, it’s called a corneal scleral lens. So it sounds easy enough. Now, the reason behind the change in nomenclature is based on the relationship between different sized corneas and lens diameters. For example, in someone with a microcornea, that relationship with a 10 millimeter lens would be very different than that of a normal cornea that’s about a 12 millimeter cornea. So when there’s full scleral landing, the lens definition can be further broken down into a mini-scleral and large scleral design. If less than 6 millimeters larger than HVID, then it’s classified as a mini-scleral, versus a large scleral. If there’s more than 6 millimeters of HVID, sorry, if the lens is larger than 6 millimeters of the HVID of the patient. Now, these distinctions serve to emphasize an important point on corneal clearance. So larger lenses have a bigger sagittal depth, and therefore more corneal clearance. So greater tear reservoir under the lens, compared to a mini-scleral lens, which will allow some apical clearance. Now, other factors that may contribute to lens selection are anatomical barriers. A patient with a small palpebral aperture may do better with a smaller lens diameter, and if a patient has pingueculae, the decision to go smaller to avoid the pingueculae or larger to vault over the pingueculae. And then although scleral lens designs may differ — excuse me — from manufacturer to manufacturer, the basic scleral lens design is the same. And I just want to go over that with you guys real quick here. A basic symmetrical scleral lens can be broken down into three distinct zones: The first is the optic zone, which houses the base curve and power. Sophisticated optical designs can allow us to add front toric — front surface toricity to correct for any front surface astigmatism and to add multiple optics to the front surface of the lens as well. This can also aid in controlling the amount of central corneal clearance and overall sagittal depth. Steepening this zone can serve to increase sagittal depth, while flattening can serve to reduce sagittal depth. The transitional or intermediate zone is the point from the lens — and I’m just going to use my marker here — so this is our optic zone here, and then we have our transitional zone here. Demarcated in this little red. So the transitional intermediate zone is a point from the edge of the optical zone to the scleral lens landing zone or the haptic zone. This zone has a lot more impact on the sagittal depth, and what I mean by sagittal depth is this area here. So technically, our sagittal depth is all the way — the lens is all the way from here to here. But since the lens is landing on the sclera, and vaulting over the cornea here, I’m just gonna kind of tell you guys that the depths — including the corneal depths — can extend from here all the way to here. So that transitional zone has a lot more control over the sagittal depth. So manipulating that can manipulate the amount of liquid reservoir we have underneath the scleral lens. In most lens designs, these changes can also be performed independently of the optical zone or the haptic zone, so if you really only wanted to change the sagittal depth of the lens, that can be established with just manipulating the transitional zone, but maintaining the same optic zone and the same haptic zone. This zone can also be designed in a reverse geometry profile. And this is important for patients that are postrefractive surgery, post-LASIK, or post-penetrating keratoplasties. The haptic zone or the scleral landing zone is the area where the lens makes contact with the optic surface. So this zone right here, where it lands right on the sclera. The goal here is to distribute the weight of the lens evenly over the entire landing zone, so as to limit any pressure and to align with underlying conjunctiva as closely as possible, without bearing into the conjunctiva. In terms of scleral lenses, a back toric lens design — I’m just gonna quickly touch on this — refers to the peripheral edges being steeper or flatter, as compared to their opposite meridians. And we’re beginning to learn a lot more about the shape of the sclera, just because of the invention and I guess the resurgence of scleral lenses. We’re starting to study what the scleral topography is like more now than ever before. So besides corneal topography now, we’re delving into what the scleral topography is, to aid us in fitting scleral lenses a lot more accurately. So more often than not, the anterior ocular surface is actually asymmetrical in shape. And we know that the scleral shape in most eyes is steepest temporally and flattest nasally, and this is suspected to be related to the extraocular muscle insertion, in that the medial rectus is the most anterior, so it contributes to the lens sitting a certain way, in most design cases. So one of the other important discoveries over the last decade has been that the scleral toricity increases the further we move from the limbus. So beyond 16 millimeters, we’re likely to see a lot more toric peripheries than when we’re closer to the limbus. I also want to add that there’s also very little correlation between the corneal and scleral toricity, so just because a patient has an exorbitant amount of corneal toricity, it doesn’t mean that the scleral toricity is also going to be high, and vice versa. Moving on to talking a little bit more about the toric periphery. A toric curve landing design serves to better match the nature of the sclera, so that there are fewer areas of localized pressure and less lens edge lift. It also helps us in improving centration, and to decrease any air bubbles from getting underneath the lens, or any debris from entering underneath the lens. To assess the need for toric peripheral curves, a good method is to utilize sodium fluorescein, applying under the lens and watching as fluorescein enters the lens chamber. If the sodium fluorescein is entering in an asymmetric pattern or more in one meridian than another meridian, you might want to utilize a toric peripheral landing zone, to better align the sclera to the lens. So upon examination, if the tear reservoir also looks like a snow globe, where you see a lot of debris trapped underneath the lens, this is another sign that you may need to add some toric peripheral curves, as one of the meridians of the scleral landing zone may be flatter, allowing debris to enter the lens. Enter the lens chamber, I should say. And then you can also use OCT, and we will talk a little bit more about OCT in a little bit here. You can also use an anterior segment OCT, to visualize the edge of the scleral lens, and identify any areas of asymmetry across the edge profile of the scleral lens. So to review, and summarize, the benefits of a back surface toric design include providing even distribution along the lens landing zone, so that there’s a decreased localized pressure in one aspect of the sclera. And we have found that adding a peripheral toric curve also increases patient comfort, it reduces debris buildup, like we spoke about, it prevents bubble formation, it reduces flexure on the eye. It’s also beneficial in providing rotational stability, which is very important if you’re adding front surface toric optics onto the lens, because at that point you really want the lens to be stable and stationary. So overcoming these challenges can reduce a lot of valuable chair time as well and increase patient comfort. All right. Scleral lens indications. So there is an increasing number of applications in scleral lens indications, beyond just keratoconus, which seems to be one of the biggest reasons we’re utilizing scleral lenses today. The three main indications we’ll discuss are improvement in vision, protection of the ocular surface, and providing comfort. So these are examples of condition categories related to corneal irregularity in the setting of corneal ectasia or corneal scarring that can be neutralized by the fluid reservoir of the scleral lens, and more and more practitioners are beginning to fit scleral lenses on normal corneas for plain refractive errors such as high myopia, astigmatism, even irregular astigmatism, and presbyopia. So primary ectasias include keratoconus, pellucid marginal degeneration, keratoglobus, and postsurgical and secondary ectasias from status post corneal transplant, LASIK, radial keratotomy, RK, astigmatic keratotomy, and penetrating keratoplasties, like in this picture right here. And other corneal irregularities include primary corneal scarring, scarring from postinfection, herpes simplex, scarring from trauma, and then of course refractive error as well. Scleral lenses can also act as a shield to protect the eye from chronic desiccation, as seen in cases of surface exposure, neurotrophic disease, and mechanical insult, such as trichiasis. Now, there have been benefits described for patients with persistent epithelial defects. So in this top left picture here, we see this patient with lagophthalmos, from blepharoplasty. That results in exposure keratitis and keratopathy, as well as a lot inferiorly. This patient has an acoustic neuroma that resulted in corneal haze and this exposure neuroma. The bottom here with this persistent epithelial defect on a grafted cornea, and bottom right is a neurotrophic cornea from herpes zoster with persistent epithelial defect and subsequent thinning. So the use of a scleral lens as a therapeutic management of ocular surface disease was previously covered in one of the Cybersight lectures as well, so I encourage you to listen to that lecture, if you want to delve deeper into understanding this aspect of scleral lenses. And lastly, providing comfort. So scleral lenses can provide comfort by stabilizing the ocular surface in very extreme ocular surface diseases. They work to allow for epithelial healing and decrease symptoms of burning, stinging, light sensitivity, and foreign body sensation. These extreme conditions include surface conditions, such as Sjogren’s disease, graft versus host disease, Stevens-Johnson syndrome, and ocular cicatricial pemphigoid. So in this picture here, we have a patient with a graft versus host disease, with confluent bilateral staining and filaments, as you guys can see over here. And then after about three hours of wearing the PROSE device, which I can go over in a little bit more detail if there’s an interest in learning about Boston Sight and the PROSE device. So after three hours of wearing the PROSE device, we’re starting to see a lot less staining and reduced filaments here, and that’s only after three hours of wear. Now, let’s talk a little bit more about fitting scleral lenses. So we’re gonna kind of backtrack a little bit, and delve down deeper into just the basics of scleral lens fitting. So some of the challenges that practitioners might run into is a determination of the clearance values. So underneath the scleral lens, how much clearance do we really have? Is it adequate? Do we need to increase it, or do we need to decrease it? How much should we be expecting? All those kinds of questions. As many of you can understand, fitting can be time-consuming as well. There’s frequent remakes that require frequent visits from the patients to come in and try on the lenses. And then there’s complications that can arise with the debris under the reservoir. Surface issues, patient comfort issues, if there’s some lens edge awareness. Some studies have reported an estimate that a new fitting would require about 4 to 6 visits, and about 3.5 lens remakes per patient. Another aspect to the challenges is centration. So like I spoke about earlier, the toricity of the sclera sometimes can cause the lens to decenter. Typically the lens will decenter down and out. So that’s another challenge, is getting that scleral lens to fit peacefully and gracefully on the sclera, so it’s aligning well. One of the first issues is knowing where to start. Selecting a good initial lens can save you a lot of time from inserting, settling, and removing the lens three, four, five times per visit. So most manufacturers will include a fitting guide with their diagnostic fitting set and guidelines on which lens to start with, either based on keratometry values, starting with a standard lens vault, or even starting with a lens from the middle of the set. I cannot stress to you enough how important this initial step can be. Most of these manufacturers have put in countless resources in developing their individual scleral lens design, and so the fitting guide that they’ve prepared is a very good manual for your success. So I would highly recommend following the fitting guide to get started, and like I said, all lens designs typically come with a fitting guide, and most manufacturers also have consultants available at your disposal, that you can quickly call or chat online with, over email, and get any ideas on where to start, if that’s where you’re kind of stuck. So preparing the lens. First and foremost, preparing the lens for application is an important step. Make sure the lens is cleaned with appropriate gas permeable cleaning solution, wash your hands, and prepare the large plunger for application. So as a reminder, we typically use large DMV plungers for insertion, and then a small DMV plunger for removal. So in preparing the patient, it’s always helpful to have paper towels or something covering their lap, so that their clothes don’t get stained, because inevitably, you will have some fluid leakage, as you insert the lens into the eye. So it’s helpful to prepare the patient with giving them paper towels ahead of time, so that they’re ready to go, to capture any of the fluid loss. On the plunger, you want to center the lens onto the plunger. If the lens is decentered, that’s gonna cause some of the fluid to spill out, and also you won’t be able to insert the lens centered on the eye as well, and that’ll cause a bubble to form. You’ll have to remove the lens and reinsert. So it’s always a good idea to get that lens nice and centered on the plunger to begin with. The large DMV plunger has a suction on it, so that when you’re putting the lens on, the lens can be nice and centered on the plunger. And then nice and centered when you’re putting the lens in the eye. Now, an important thing to remember is you have to release the suction as you let go of the plunger as well when you’re inserting the lens. And I’ll go over that in a little bit more detail. Some practitioners and even patients don’t like the suctioning aspect, as it might be too difficult to press the suction, to release — sorry, press the plunger to release the suction. So an option is to cut off the end of the plunger here, so that there is no suction anymore. Now, this also serves to give the patient a little bit of a fixation target, as they look into the plunger, because they can see right through it. So it kind of helps in those two regards. Overflowing the lens to ensure that no air gets trapped under the lens. Now, this will serve to reduce any bubble formation underneath the lens. And then you’re filling the lens bowl up with non-preserved saline. So these are some of the saline that we use in clinic. Just as a side note, insurances may cover this for the patient. So I typically send a prescription to the patient’s pharmacy, and it’s written as a single unit dose of 0.9% saline, which is this AddiPak here. LacriPure in the United States has been FDA-approved to be used in the eye. I’m not too sure about ScleralFil, but I think it’s FDA-approved, and PuriLens is a bottle form of saline, as opposed to a single dose. Again, this comes with restrictions on when you should throw it away, within a certain period of time. So inserting the scleral lens. So the scleral lens should be placed on a large or medium DMV suction cup to aid stabilization of the lens during handling. Alternatively, the patient can use a tripod method, using their thumb, index finger, and middle finger to hold the lens. The lens should be filled with non-preserved saline solution. When I say filled, I mean overfilled. The patient is instructed to lower their head, so their face is parallel to the floor. This allows the lens to be inserted from below, so that the fluid in the lens doesn’t spill out. This is important to avoid bubbles. If a bubble is present, you’ll need to remove and reapply the lens. Otherwise it can lead to an area of corneal desiccation. It’s important to hold the upper and lower lids. Both lids wide open. And have the patient look downwards toward the floor. I typically have the patient hold their own lid, because it helps me kind of brace the lens a little bit better. But you have the option of holding both lids yourself as well. Another tip is to move quickly and smoothly. Move the lens up onto the eye so that it contacts the sclera. It’s important not to push too hard, as you insert the eye, insert the lens onto the eye. The great pressure can cause a lot of redness around the conjunctiva, if it’s squeezed up too hard. Once you come in contact with the eye, you want to squeeze the suction cup, so that the lens releases onto the eye. Have the patient close their eye, and make sure the patient has a paper towel or a tissue to just catch that overflow, like we spoke about earlier. You want to check the fit of the lens in the slit lamp, and also check to see if there are any bubbles present. Because remember, you’ll need to remove the lens and reinsert again. So patient positioning. Remember, the head needs to be parallel to the floor. What I like to do is actually raise the patient’s chair all the way up, so that they’re matching my height, and then I’ll have the patient lean their head all the way down. This helps me, so that I’m not crouched underneath, trying to get the lens on. If a patient has a very strong Bell’s reflex, you might want to give them a target to fixate on, so that they’re looking at that as you’re trying to apply the lens on their eye. Now, the eye should be centered between the lids for proper application, and then of course you can have the patient hold their lower lid in place as well, so that it’s a little bit easier for you to just grab the upper lid. So you want to retract both upper and lower lid. And move quickly. So with the other hand, you can hold your plunger. And you want to come around the patient to hold their upper lid. Kind of locking their head into place. You want to be careful. I mean, you don’t want to add too much force there. But you still want to kind of gently hold their head in place, so that you’re bracing their head, and they’re not kind of moving all around. You need them to stay stationary, as you apply that lens. It also helps to sometimes brace your hand with the plunger against the patient’s cheek, as you’re inserting the lens. This reduces the risk of losing fluid, and then once again, it improves the steadiness and aim, as you apply the lens. Move quickly. You want to squeeze the plunger as you apply the lens, pull the plunger away, and then release the eyelids, and let the patient kind of blink a little bit. And then you want to check for bubbles right away, to make sure that you don’t have any insertion bubbles. This is an example of a large insertion bubble. Something like this requires an action on your part to remove the lens and reapply. This is a great resource by Bausch and Lomb that I give to my patients. Typically I like to recommend the plunger method. If a patient is a little bit fearful of the plunger method, then I’ll recommend the three-finger method. But this resource I’ll give to them as they leave, after their insertion/removal training, because sometimes patients have a tendency to forget what we spoke about. So that they can quickly reference this. And I have linked the website below for you guys here, if you want to access this resource. And it also has the three-finger method as well, for any patients that, like I said, might be fearful of the plunger method. There are fixation targets and other devices available for patients that have issues with mobility or dexterity concerns, so just because a patient has limited movement, it doesn’t mean that they can’t be a good scleral lens candidate and wear scleral lenses. There are other options to help with this. All right, let’s talk about removing the lens. So lens removal. You want to use a small DMV suction device for this, without a hole. There’s two variations of the small suction device. One has a hole and the other one does not. I prefer the one without the hole in it. Have the patient look down with their head, in upright position, and then you can also have them lean it against the headrest. Hold the patient’s upper lid out of the way, place the suction cup on the superior portion of the lens, as close to the lens edge as possible, and gently rock to release the suction between the lens and the eye. Once the suction is released, gently rotate it upward and forward off the eye. It helps to have the patient look up after suction is released, to help rotate the lens off the eye for a smoother removal. Here you can see that the patient is sitting upright. Eyes are lowered. And you’re retracting the upper. I typically only retract the upper lid, but you can retract the lower lid too, if you feel that’s necessary. Apply the top edge of the plunger with the top edge of the lens. Tap the plunger onto the lens, and gently break suction, and then arc downwards, like you’re — if this is the cornea and this is the lens, you want to kind of move the plunger in this fashion. And then you can instruct the patient to look up, because that will help to kind of take away the suction as well. And I have a video here that my colleague and I made together. I’m just gonna play it here for you guys. (video audio inaudible) Sorry, one sec here.
>> Making sure to overfill it, so you see a large tear meniscus across the top. Slowly approaching the eye, squeezing the plunger and pushing the lens onto the eye, noting some of the extra fluid will drip down. Attach the small DMV plunger to the lower edge of the lens, breaking suction and pulling the lens off. The doctor can brace the upper lid, having the patient pull down the lower lid. To remove, the doctor has the patient look down, squeezes the plunger at the upper end of the lens, and removes the lens. Any large bubbles as seen here — the lens must be removed and reinserted without any bubbles.
DR GULMIRI: All right. So we’re on to our poll question number two. Which of the following is true regarding applying and removing scleral lenses? A, use a small plunger to apply, large plunger to remove. This is just to test your knowledge of what we just talked about. B, cutting off the large plunger helps with centration when inserting the lens, C, there are no fixation devices available for patients with limited dexterity, D, tripod or three-finger method is an alternative for patients fearful of the plunger method. Excellent! So most of us got that one correct. So the tripod or the three-finger method is an alternative for patients fearful of the plunger method. Now, remember, the large plunger is used to insert the lens, and the small plunger is used to remove the lens. Move on to our poll question number three. I think I made my point with this one fairly clear, so let’s see if we got that point across. If you see a bubble underneath the scleral lens, what should you do? A: Push-up method to dissipate the bubble, B: Do nothing. As the lens settles, the bubble will dissipate on its own. C: Remove the lens, fill the lens bowl with NP saline, and reapply the lens, or D: Rotate the lens until the bubble dissipates. Excellent! So yes, most of us got that correct. We should be removing the lens, filling the lens bowl with non-preserved saline, and reapplying the lens. Just know that if it’s a very tiny bubble, and it’s kind of moving in its place, not causing any disruption to the vision or comfort, that may be okay. When we refer to taking the lens off and reapplying, we’re referring to large bubbles that you want to avoid. All right, moving on to assessing a scleral lens. So steps for assessing a scleral lens. I typically like to take what I call the center-out approach, which means I assess the central clearance values first. So I assess the apex of the cornea first, and then I move to the midperipheral zones, so if a slit lamp image looks like so, I would look at this area first, and then move outwards, and then move my beam this way, and move it that way. It’s important to evaluate the limbal zone. And then evaluating the scleral landing zone, and where the lens comes into contact with the eye. Also important to evaluate the overall centration of the lens, because if the optic zone is decentered too much, then the patient’s vision will not be as optimal. And then assessing the movement of the lens is important as well. Making sure to document these findings is just as important as evaluating them. There are so many numbers that get thrown around with scleral lenses that it’s very important to keep that all clear and concise. So documenting the clearance values that you’re noting first, before the lens has settled. What I like to do is, when I’m evaluating, I always write down how long the lens has been on the eye for, because then it gives me an idea of how much settling the lens has to do, or if it’s kind of in the trial stages of settling. Determining the essential corneal values is very important. Sorry. Give me one sec here. So determining the clearance values using a slit lamp technique. Most practitioners use this, and this is the technique I would recommend for anyone that doesn’t have any OCT available. You want to make a very thin optic section, use white light, and make about a 45-degree angle, and you want to use — so it’s similar to the Von Herrick technique you would use to estimate the angles. White light, approximately 45-degree angle. Most practitioners use the lens thickness as a reference, which is what you should do. If you use a cornea — if it’s a normal cornea, that’s absolutely fine, because we know approximately it’s around 530 microns. However, irregular corneas, corneas with keratoconus, we know they’re unpredictable. So sometimes that’s not the most accurate way of measuring the clearance of the lens. Clearance underneath the scleral lens. So I would recommend using the known thickness of the scleral lens, because it’s a better reference point for you. It’s estimated that the human eye is capable of observing about 20 microns or more. So less than that to us appears as black. But this doesn’t necessarily mean that there’s frank touch. It just means that it’s something we cannot see. And that’s when the OCT becomes more valuable. Fluorescein — applying that to the lens bowl, where the saline is in, applying a dip of fluorescein, is also helpful when the lens goes on. And I’ll show you guys this in a second here. Even what was observed here — you can see that the fluorescein makes it a lot easier for us to see how much clearance there is underneath the lens. And then one interesting study conducted by the University of Waterloo showed that there is a consistent underestimation of about 50 microns between slit lamp technique and ultrasound technique. And this is regardless of experience of the practitioner with scleral lens fitting. So that’s something important to know as well. Lens assessment. I like this schematic to show you guys… This is the lens here. And this is the tear film, dipped in the fluorescein reservoir, and then your cornea here. So when you’re looking at a cross section of a scleral lens, and assessing it, this is similar to what you’re going to see. Now, the distance from the posterior lens to the anterior corneal surface — this here is what we’re measuring, when we’re talking about the clearance value of a scleral lens, or vault of a scleral lens. And once again, a good reference point is the lens thickness, as opposed to the corneal thickness, which can be very variable, and sometimes we don’t always have that information available. Whereas the lens thickness — most of the manufacturers will give us that lens thickness, as we’re fitting the lens. And then you want to move on to the midperiphery of the lens, and evaluate that from the center onwards, and then of course we want to make sure we’re not resting on the limbal zone there, because then we’re resting on the limbal stem cells, and that can cause trouble as well. When we’re measuring the corneal vault, we’re measuring it in microns, and as the lens settles, particularly in new wearers, the lens will settle more, so as it settles, we’re gonna see a decrease in the amount of clearance that we’re seeing, and typically it decreases about 100 microns or so and most of the settling takes place in the first two hours of wear, but the full amount of settling can take up to 8 hours. So I usually have the patient, when they’re coming back for a reevaluation, I make sure that they’ve at least worn the lens for two or three hours, so that I can see what the lens looks like, post-settling. Alignment of the lens with the scleral shape is important in preventing any air debris from getting trapped underneath the lens. Too tight of a scleral landing can lead to complications, such as blanching, compression, and impingement. Typically assessed by observing the lens bearing with a trial lens. So once you get your trial lens set, you put it on, and you want to take a good look at the periphery and see what changes you want to make. Other factors that we spoke about already: The toric peripheral zones, you want to assess the movement, you can add fluorescein on top of the lens as well, to help with identifying the outer edge of the lens as well, if you have trouble seeing that through slit lamp. And this is what they’ve done here, actually. So this is Ferris State University — developed a fit scale based on using fluorescein to estimate the vault values. In this case, the thickness of the lens is defined as 300 microns, so you can visualize this one to one relationship here. So 300 microns of the lens thickness, and then 300 microns of the tear reservoir underneath the lens, and then here’s our cornea here. So applying fluorescein to the front surface of the lens can help to identify what the top looks like, and it kind of gives you a good outline of where the lens is. Here you can see 50 microns, and how faint that line is there. 500 microns — kind of getting a little bit closer to the cornea here — 150 microns. This is kind of what we expect, when the lens has settled onto the eye. 600 microns — we want to reduce some of the clearance there. And then I’ll let you guys look at this on your own here, but it gives you a good idea of what the limbal vaulting should be too. You kind of want to have a little bit — so about 50 microns, 100 microns of limbal vault left over, after the lens has settled. Sometimes if there’s too much limbal vault, then you’re limiting oxygen getting into the eye as well. This is a good example of a picture of what it looks like underneath the slit lamp here, and we can see that the lens here — just judging by the way the fluorescein pattern is underneath the lens, we can see that the lens is slightly decentered inferiorly, because we’re seeing a lot more clearance inferiorly compared to superiorly here, and we might even have some touch here. It’s a little bit hard to tell with this little bubble, but you can tell that the fluorescein actually increases, as we evaluate inferiorly, indicating that the lens is dropping. These are some pictures — the ideal picture here, of what the edge alignment should look like. So this is what I would call scleral alignment, where the scleral lens is landing evenly onto the sclera. Here we’re starting to see blanching, which can lead to issues with discomfort and redness associated with longer wear times, and then this picture here, we’re seeing edge lift, which can result in lens edge awareness upon blink, and it indicates too flat of a peripheral edge. And this usually leads to problems with debris getting underneath the lens, and building underneath the lens, and getting that snow globe type appearance we talked about earlier. So in this case, look for a dark band or shadow to identify any lens lift. And then insufficient edge lift. If it’s too tight, it can limit tear exchange, and that can pose a problem with this zone as well. So coming to our poll question number four, this is a little bit of a challenging question here. Which of the following best describes this fit pattern? Is it A, excessive edge lift, B, adequate scleral alignment, C, impingement, or D, blanching? Yeah. That’s what I expected. We’re seeing some even answers here. So this was a trick question, and my apologies for making it a little bit tricky for you guys. So this is what we call elbow compression. So what’s happening here is that the lens is actually landing here, as opposed to landing all the way to the far edge of the periphery. Okay? So there is a little bit of blanching, so those of you that said blanching, that’s correct. And then there is consequently some edge lift here too, which you guys can see a little bit of, that shadow. So this is a scenario where we’re kind of getting both aspects. So we’re getting blanching as well as edge lift. And some ways to alleviate this is to pick a lens that’s a little bit smaller, so that the edge actually lands here, or you can steepen up the peripheral curves here, so that the lens actually lands in the far periphery, as opposed to the midhaptic zone here. And then I want to touch base on using anterior segment OCT with scleral lenses. A lot of us now do have access to an OCT, and this is certainly not necessary to fit a scleral lens, but it is very helpful in cases where you’re not 100% positive in assessing the way the lens appears, whether there’s too much corneal vault, too much scleral lens vault, or too little scleral lens vault, where you’re not necessarily sure if the lens is touching or not. Sometimes I like to take it behind the OCT, just to confirm my findings as well. So it also gives us an exact measurement of the central vault, midperipheral limbal vault, and it can give us an idea of the lens edge profile as well. So to give you an idea of what some images look like here… This is the cornea here. Our scleral lens is up top here, and then you see the fluid layer over here. Now, these images were taken using a Cirrus anterior segment biraster. You can measure the clearance under the scleral lens, which I like to do, to measure how much clearance there is under the scleral lens. 300 microns is preferable here, and you expect it to settle down between 100 and 200 microns. So 166 is excellent. It can also help you identify if there are things underneath the lens, trapped debris underneath the lens. Like, you can see these little flecks here, that represent some debris trapped underneath the lens. And then it can also help you identify areas of touch. So you can see here the lens itself is landing and touching the scleral lens here. This is a wide angle view. The ability to do that is with an attachment on our OCT. But the wide angle helps us to kind of see the total corneal sagittal depth with the lens as well. But again, we can see there’s some touch here. And I’m gonna skip this slide real quick, but there are additional benefits to using an OCT. In the interests of time, you guys can read this on your own, but a scleral lens OCT — sorry, an anterior segment OCT — can also help with identifying not only the lens thickness, but also the corneal thickness, if you’re worried about edema developing. So taking pre and postscleral lens wear images on the OCT is helpful. This is a full picture of what you end up getting, once you take an image on the Cirrus OCT. So here there’s a cross section, and it gives you about 5-line rasters, and once again, it can help you identify even the most minimal amounts of corneal vault. So this is a patient where I wasn’t sure if I had enough corneal thickness over the apex. So I did bring them here to check with the OCT and in fact we weren’t touching. We had about 16 microns clearing. And then in some cases, when there’s far too much clearance, it helps to also get an OCT, because at some point it just becomes too hard to estimate exactly how many lens thicknesses will fit in this range. So sometimes it’s just easier to put the patient behind the OCT, to get those numbers, those exact numbers. I really like to also look at the edge of the scleral lens, and how it lands and comes into contact with the conjunctiva. And the OCT can be helpful in this case as well. This patient here that we’re looking at the top two images — he kept complaining about lens awareness, and every time I would look at the lens, I thought to myself… You know, it’s well aligned. I really don’t want to tighten it anymore. So I was convinced that he was imagining this. But when I put him behind the OCT, I was able to appreciate a little bit of lift here, as you guys can see. So it does kind of help to confirm your findings behind the slit lamp. This is an example of severe impingement, where the lens is digging into the conjunctiva. What you want is this picture here, is an ideal definition. So what you want is about a 50/50 — 50% of the lens into the conjunctiva. So that’s kind of what we see here, where you’re seeing it kind of peacefully and gracefully land onto the sclera. Once again, this is good scleral lens alignment here, as you can see. And I do like to play around with the colors as well. Sometimes it helps me see things a little bit better in grey scale, as opposed to the color. Once again, a severe impingement, where the lens really is digging into the conjunctiva, and causing some conjunctiva to lift up. So this is what we call impingement, where the lens is digging so hard that some of the lens is lifting up. This brings us to our last poll question. When estimating the central corneal clearance of this lens based on the slit lamp photo, assume central thickness of the lens being 250 microns. What would you estimate to be the clearance? A, 300 microns, B, 500 microns, C, 100 microns, or D, 25 microns? All right. The 125% that got 300 microns, great job. I just want to go over that real quick again, because 50% of us thought it was 100 microns. Looking at the front surface of the lens, this refractive area here, is the outer surface of the lens, the outer edge of the lens, and then the little space here is the lens thickness itself, and then where the green area starts, it looks like it’s fluorescein there. So where that green area starts is the back surface of the lens. So from here on to here is what we’re measuring, and if we say this area here, if it’s 250 microns, this area here is very similar in size to that. So maybe slightly larger. So we could say it’s about 300 microns. Other considerations. We did talk about this in detail, but closely evaluate the need for an asymmetric lens design on the back surface. If we need toric peripheral curves, a lot of lens designs now offer toric peripheral curves and even quadrant-specific designs are getting more and more readily available. Make sure we have a proper and stable fit before you start to do an overrefraction, to determine the best corrected vision through the lens, and then evaluate for tear exchange, and then at each follow-up, make sure you’re removing the lens and staining the eye to check for ocular surface abnormalities. Any staining. If there’s any toxic reaction with punctate staining that you can pick up. Sometimes the patient won’t be exactly sure on what to fill their lens bowl up with, and they’ll fill it up with multipurpose soft lens solution, and then they end up getting a toxic reaction all over their cornea from the preservatives that are in that solution. And then any impingement staining. So you might notice a compression staining once you remove the scleral lens. And if it’s not too deep into the conjunctiva, sometimes that’s okay. Because the lens has been resting on the eye for 8-plus hours or so. But if it’s too deep and causing some staining around that area, then that fit needs to be flattened. The peripheral edge needs to be flattened. So scleral lens care — we’ll quickly go over this. So GP care solutions or peroxide systems are useful with scleral lenses as well. Care should be taken when cleaning and rinsing the lenses, due to the fragile nature. You still want to instruct the patient to rub each side of the lens, inside and outside, with cleaner, for about 15 seconds. There are larger cases available for patient purchase as well, so that their scleral lens can fit nicely into the case. If you guys have Clear Care in the countries… Essentially Clear Care sometimes can be too small to fit a scleral lens. So the larger chamber case definitely helps. GP solution should be rinsed from the scleral lens with sterile, non-preserved saline, prior to insertion, and then if the patient is not planning on wearing the lens for a while, then storing it dry is the recommended way to go. And then diagnostic lenses — so any lenses that are in your fitting set, that you’ve used to fit the patient, should be cleaned and disinfected properly either using a GP disinfectant solution or hydrogen peroxide, and then stored dry. Plungers. You can clean those with soap and water. Hydrogen peroxide, alcohol wipes. And then supplemental products such as artificial tears, to lubricate the surface on top, and then cleaners, such as alcohol-based cleaners, Progent is a good one, and Boston 1-Step is a stronger cleaner that I recommend your patients use every week or every two weeks, depending on how much buildup they get on their lens. Each visit, remember to review lens care and insertion and removal, especially if the patient is new to scleral lenses. I find this ACLE healthy habits sheet very helpful when I’m dispensing the lens. It has this little area here for writing down what they should be using to clean the lens, what they should be soaking the lens in, and then what they should be filling in the lens bowl. So typically I let the patient leave with a lot of resources after the fitting, their initial dispensing, so if they missed anything I said, because I’m giving them a lot of information in that visit. If they missed anything I said, it’s readily available for them to read. And then lastly, I just want to point out to use your resources. So there are multiple training videos that the manufacturers will put up on their websites for their lens designs. There’s certifications, kind of like quizzes that you guys can take as well, and then consultants are always available for us, for troubleshooting, ordering lenses, running anything by them. They’re available at our disposal. I use them all the time to help with my fits. And that’s it. I just want to thank Dr. Andrew MacLeod and our contact lens department for some support. And I’m happy to answer any questions we have at this point.
>> Thank you, Dr. Gulmiri. So we have I think seven questions. If you just want to stop your screen share and open it up.
DR GULMIRI: Sure. All right. So the first question I have is: What is the technique of the scleral lens? So I’m not exactly sure what you mean by that. If you want to elaborate on this question, I would be happy to answer it. Some more. Okay, is it possible to eliminate myopic of that patient using this? So I think this question… If you’re asking about refractive correction, and whether or not you can use scleral lenses for refractive errors, absolutely. If you have a patient with high myopia, and you want to put that prescription into the scleral lens, you can absolutely do that, and they will get far superior vision, compared to a soft lens. Now, if you’re asking about orthokeratology, which is a little bit different, where it’s a smaller diameter reverse geometry lens that compresses the tear film on the cornea, that’s a little bit of a different concept than scleral lenses. So in that case, we don’t do any overnight wear with scleral lenses. Or reshape the cornea in any way with scleral lenses. Next question is: Is corneal scleral lenses still being prescribed? Will there be no neovascularization in cornea on long time use? That’s a good question. So corneal scleral lenses are… I would say they’re not being as utilized as frequently as they previously were. With the advent of the scleral lenses being larger, and more commercially available, a lot of practitioners are using the full scleral lenses, so that there’s limited contact with the limbal area there. Now, if there is a lot of vault in that limbal area, or if the patient is wearing the lens for too long, or sleeping in the lens, or anything that is non-compliant, then we may see some neovascularization starting to form. However, with the advent of really good gas permeable lens materials, high DK materials, we’re seeing less and less neovascularization than we were seeing in the past. Can scleral lenses be fit in cases with scleral thinning? You have to be careful with scleral thinning, because you want to make sure that there is no impingement or no frank compression in those areas. So I would be very careful. I would probably work closely with a corneal specialist, if I’m fitting a patient with severe scleral thinning. You would like to know the axis stabilization in scleral lenses. So I’m not too sure about that question either. If you wouldn’t mind kind of elaborating on what you mean by axis stabilization in scleral lenses, I would be happy to answer that question as well. And then the next question I have here is: The solution which is put into the vault. How long does it stay for dry eye patients? For the most part, the solution stays throughout the time of the patient wearing the lens. So there’s very limited tear exchange that does go on. But if a patient — a lot of my patients — because the lens always feels much better when they first insert it, than after 5 or 6 hours of wear. So a lot of them, especially my dry eye patients, will like to take the lens out, rinse it, and then put the lens back in, so they have fresh saline and fresh solution bathing their cornea. But technically, it’s good to last up to 8 to 10 hours. Who is qualified to fit scleral lenses? So anybody that has had the training and kind of knows enough about scleral lenses to feel comfortable with fitting scleral lenses can do so. I would say get very familiar with one type of scleral lens, get to know it really, really well, so that you’re able to be almost an expert in that scleral lens. And again, you can use the consultants or the manufacturers to help you with fitting that lens, too. Have you checked or any problem with IOP with scleral lenses? Are you asking if there’s a concern for an increase in IOP with scleral lenses? If so, then no. There is no concern for increased IOP with scleral lenses. I think in one of the preregistration questions, someone had asked if there was a way to monitor IOP with scleral lenses. And as of now, I don’t think so. But I think that that idea is underway. I know for sure it’s underway with soft contact lenses, and it’s been tested multiple times, and I think it’s underway for scleral lenses as well. If the lens is centering inferiorly — that’s a great question. There are a few things you want to look for. If you have too high of a central corneal vault, you want to first start to reduce that central corneal vault, because what’s happening is that there’s a lot of fluid reservoir underneath the lens, so it’s causing the lens to decenter. The other thing you want to check for is the peripheral toricity, to make sure that the entire periphery of the lens is landing evenly. So what can happen is, if there is a lot of toricity in the sclera, and there’s a mismatch between the way the scleral lens is aligning with the sclera, there’s two edges of the scleral lens that are landing much harder than the other, so it’s not enough pressure to keep that lens in place, so it ends up decentering inferiorly. So you want to make sure that you add some toric peripheral curves, to better align the entire 360 of the scleral lens. And I’m not sure if we got more info on this axis stabilization one.
Oh, I have one more. What can be done… Oh, this is an excellent question. So if you find that the removal — small removal plunger — your lens is too tight, and you’re having trouble removing the lens, what you want to do is use the patient’s lid to push up and over, and create a bubble underneath the lens. In this case, you want to create a bubble, to break the suction between the lens and the conjunctiva. And that has been handy a lot for me. Once you get the bubble in there, it breaks the suction and you can easily remove the lens. All right. Thanks, everyone, for your time.
August 23, 2018
1 thought on “Lecture: Scleral Lens Assessment and Fitting”
Thanks for this lecture. Very helpful