Lecture: Ocular Surface Reconstruction for Severe Ocular Surface Disease

DR. FARID: Hello, everyone. And welcome to today’s webinar. And my name is Marjan Farid. I am a professor of ophthalmology at the University of California-Irvine. And thank you so much for everyone joining from around the world. It’s really a pleasure and honor to be with you today discussing ocular surface disease, ocular surface reconstruction for severe ocular surface disease. These are my financial disclosures. And I am going to jump right in. So, first of all, let’s sort of define what is severe ocular surface disease. These are, you know, ocular surfaces that I define with limbal stem cell deficiency. The most severe forms are those that have resulted from perhaps chemical or thermal injuries to the surface of the eye. Certainly severe autoimmune, Steven-Johnson syndrome, for example. These are the most severe forms that are significant conjunctival disease. And patients with aniridia have complete loss of their cornual stem cell function. Then there’s other, more overlooked causes of limbal stem cell deficiency. I will talk about those, those include things like contact lens over-wear, severe atopic disease. Chronic use of topical toxic preserved eye drops, for example, patients who have long-term glaucoma and may have been on glaucoma drops for years and been exposed to preservatives. So, usually with loss of stem cells, what we first see is that the architecture of the limbus is not clear. It becomes obscurated. And those Palisades of Vogt are gone. And that distinction between where the sclera ends and the cornea begins, that area of the limbus develops some neovascularization and irregularity. And the next stage, we see irregular fluorescein staining of the corneal surface. You get this column like and then whorled epitheliopathy that can extend into the axis and be visually disruptive for the patient. What we see is the inferior or superior limbus is affected earlier than the nasal or temporal limbus are. Then you can get conjunctivalization of the cornea. And then finally, non-healing epithelial defects of the cornea. And then severe disease, perhaps some blepharon from the lids to the surface. Some of the earlier causes, overlooked causes of stem cell deficiency. Again, contact lens related wear. Usually soft, chronic years of hypoxic damage to the limbus. The conjunctiva is often injected, they are irritated and inflammation is common. They are highly myopic. That’s why they wear their contact lenses for so many hours. They hate to come out of their contact lenses. Usually the main treatment is to get these patients off of that chronic insult to their limbus. A scleral lens option for some of these patients is often better because it removes that hypoxia from the limbus. But it also improves their vision as it smooths out that irregular astigmatism that has occurred from the irregular epithelium. The next overlooked cause of limbal stem cell deficiency is cron you can use of toxic topical drops such as preserved glaucoma drops or patients who may have had longer than necessary exposure to, for example, trifluridine, an antiviral used for herpetic keratitis. They can develop limbal stem cell deficiency. Their limbus looks irregular, they get punctate keratitis. And they look abnormal. Severe atopic or vernal disease. For example, vernal keratoconjunctivitis. Is often allergic-related. With the lymph tissue is inflamed. Often that burns out the WIMP ball and causes stem cell deficiency. These patients have goblet cell loss as well and can have sequelae from that. There are systemic medications that result in disease and long-term stem cell loss. One is this drug, dupilumab for atopic dermatitis. And in long-term uses has been shown to have problems with limbal stem cell loss. And discontinuation of the medication is often necessary to stop the progression of the disease. So, a lot of these earlier stem cell problems can often be misdiagnosed as herpetic keratitis, they cause breakdown and lacerations on the cornea. If the topical anti-virals are reintroduced, that exacerbates and worsens the problem. My rule of thumb, if the epithelium doesn’t heal after one to two weeks of drops, perhaps the diagnosis is incorrect and we need to think about something else. So, you know, the medical management of these cases is often just — will improve the situation. We moving that offending agent, whether it’s contact lens or whether it’s preserved topical drops. Taking these patients off of any drops that have preservatives. The BAK drops. Switching patients on glaucoma drops to preservative-free versions. Or perhaps even earlier laser or surgery to get these patients off the ocular surface toxicity. These patients are often inflamed. When we test their tear-filled inflammation, their MMP-9 is often positive for inflammatory cytokines. A short course of anti-inflammatory, steroids, or modulators on the surface may help in terms of improving the tear film quality. Other things, autologous serum drops or PRP drops have been shown in a lot of ocular surface diseases, including neurotrophic keratitis to help improve the epithelial healing time to sort of supply some of the growth factors to the ocular surface and allow that epithelium to normalize. And so, I use this in all of these early stages of limbal stem cell deficiency. There is a process of getting that autologous serum. So, you have to have a phlebotomist working with perhaps a compounding pharmacy. Some people can do it out of their office. You have to have the centrifuge and be able to produce a good, sterile product. Amniotic membrane, specifically fresh frozen amniotic membrane can also be helpful. Those I’ll usually place on the ocular surface, maybe for about a week. The self-retaining ones that come with a ring and can be placed in the office are usually very helpful for this purpose. Again, scleral contact lenses are also great. They create a microenvironment for that ocular surface to heal over time and they help certainly with visual acuity. Vitamin A ointment can also be helpful in patients who have, you know, severe drying of that ocular surface. So, then we move on to the surgical management. In patients where we can’t get that ocular surface and the limbal stem cells to heal with just medical management, we move to surgical options. And I look at the status of the other eye of the patient. If the other eye is good and has a healthy limbus and the disease is unilateral, then we are often able to take stem cells from the other eye and transplant them over. We call that a conjunctival — excuse — a conjunctival living autograph. It’s nice to use the patient’s own patient, then the patient doesn’t have to be immunosuppressed. If both eyes are affected and diseases, then we are looking at allograft, from a cadaver, a keratolimbal. Or from a living person, that’s a conjunctival living allograft. If the patient has family or siblings, they can be tissue-matched and their tissue, as long as that is healthy, can be used as well. Certainly allograft tissue, however, because it is vascularized tissue will require systemic immunosuppression. And very similar to solid organ transplantation. We use their systemic immunosuppression protocol. I’ll go over that in a few slides as well. And the patient’s age and the severity of their disease really determines the length of the systemic immunosuppression that’s required. So, patients who have less inflammation on the eye may not need as long of an immunosuppression protocol. Patients who are older than the age of 70 also don’t have as much of a robust immune system and often their immunosuppression can also be shortened. They tend to do — they tend to not need as much systemic immunosuppression long-term. Mitomycin-related disease and there’s another cause of overlooked limbal stem cell deficiency. We use mitomycin C for things on the eye, glaucoma surgeries and other surgeries. This is a patient who had a PRK done in one eye only. And mitomycin was used during the procedure. I think some escaped and there was longer exposure than there should have been. Within three months, the patient describes this conjunctival on the cornea. He thought this was pterygium. It’s not, it’s no elastic conjunctivalization. And there’s just the limbal loss of architecture in those areas. This patient had a normal eye on the other side. His other eye had LASIK with no mitomycin. We were able to take a segment of conjunctival limbal autograft from the other eye. You can see, we take conjunctiva, but we extend 1 to 2 millimeters to get those limbal tissues. We brought that over to the diseased eye. You can see, initially, we’re taking off the diseased conjunctiva that has encroached on to the cornea. And basically, we used tissue glue and took that autograft that we took from the other eye and placed it — we actually cut it in half. We took a piece, cut it in half, and used it for both the temporal and the nasal side. And you can see here the two segments taken on both sides. We were able to use a little bit of amniotic membrane as well to fill in some of the gaps. But heated very, very well. No need for systemic immunosuppression as we used his own tissue. This is after one month. You can see the cornea stayed very nice and clear and stayed that way long-term. He’s now out a few years. So, there’s — this is another case of a 61-year-old woman who came in. She had been wearing a contact lens for most of her life. Or most of her adult life in her left eye only because she was a monovision patient. No history of contact lens wear in the right eye. And her vision had been worsening. She thought she was developing a cataract. She came in for cataract evaluation. When we looked at the ocular surface and stained with fluorescein, we saw this staining across the superior cornea that extended into the visual axis. This is classic limbal stem cell deficiency related to the contact lens overwear. Her other eye was healthy. Had not had any contact lens wear exposure. That was another case where we were able to take tissue from her other eye. A small piece, transplant is over, and you can see that her cornea on this eye remained beautiful. Nice and smooth with, you know, no further evidence of irregular epitheliopathy. The other eye is, as long as it is healthy and has not had exposure to contact lens wear or long-term exposure, we can certainly use that tissue with no long-term sequelae or issues to the donor eye. In this case, I took one segment, about 3 clock hours from the superior limbus of her other eye and she did fine in both eyes. So with I’m gonna jump ahead a little bit more now to the more severe forms of severe ocular surface disease. And I know that questions are coming up into the question and answer box. I will definitely address those at the end of the PowerPoint slides. So, just hang on to those questions and we will certainly get to those. So, now we’re gonna jump into, again, the more severe forms of this disease. These are, you know, we usually stage these according to the degree — how much of the limbus is involved. If there’s less than 50% of the limbus that’s diseased or more. And we grade it also by how much inflammation is on the ocular surface. So, for example, an aniridia patient will have 360 degrees of limbal stem cell loss and involvement, but they have no inflammation. Their eyes are nice and quiet. This is a congenital disease and so they’re graded as a stage IIA. For the most severe forms, these are the ones that are very, very hot, inflamed. And a lot of the limbus is involved. These can be patients with severe alkali burns to the ocular surface. Patients with severe Steven-Johnson syndrome, ocular — are in this as well. Depending on the disagree of information and the amount of limbus involved, we stage these because it really affects their prognosis and also the amount of stem cell tissue that needs to be transplanted. So, again, sources of donor stem cells, we talked about this. We can get it from the fellow eye. We can do to a cadaver. The cadaver will give us limbal tissue, corneal tissue, scleral tissue. We need the conjunctiva attached. So, when I order these from our eye banks, I ask for cornea tissue with large scleral limb and the conjunctiva needs to be attached. That’s important because often time when is these donor corneas are harvested, the conjunctiva are cut off at the limbus. These are not appropriate for the tissue we need here. We want the conjunctiva to be attached. We can use living related donor tissue. In those cases we get limbus and conjunctiva. And certainly the future of this will hopefully we will be able to go into ex vivo expansion of limbal stem cells where we can get tissue either from the patient’s own tissue or a cadaver and expand these ex vivo and, you know, transplant those on to the eye. That is all in research phase at this point. So, we talked about this again. Systemic immunosuppression. So, this is how I prepare my cadaver, keratolimbal allograft tissue. We order the corneas with the large rim, conjunctiva attached. We take a trephination of the central part, take the limbus and cut it to whatever size we need. So, usually if I’m transplanting 360 degrees of the limbus, I need two donor corneas from the same donor because it usually requires 2.5 segments to transplant the entire limbus as we move out a little bit. That tissue — that limbal tissue — then is lamellar dissected about one-third/two third. We need about that one-third of the anterior surface of the keratolimbal tissue. We bring it to the eye. There’s a certain way to process the tissue and I have a video to show that. We trim the corneal edge so that the transition from the donor cornea to that host keratolimbal allograft tissue is smooth. There’s no step offs. We don’t to want create dellens. And even when we go 360 degrees, make sure there’s no gap areas. And then if there are gap areas, that’s where we see neovascularization occurring or irregular epithelium coming in again. This is how we take conjunctiva limbal allograft tissue, from the patient’s other eye or a living donor. We take two to three clock hours from the inferior and superior limbus of the donor eye. Again, we want to make sure that donor high has a healthy limbus. The nice thing about using fresh tissue like this is that we get a lot more conjunctiva, healthy conjunctiva as well. Very good for cicatrizing diseases that have lost their goblet cells. Able to restore some of that through that allograft tissue. Less rejection especially if you can tissue match your donor, again similar to kidney transplant patients. You do get less stem cells with this type of tissue, but again, you get more conjunctiva. If there are multiple donors. Usually siblings have the closest donor profile. And if there’s multiple siblings, you can tissue match and find the best match. Dr. Ed Holland and his team, Dr. Albert Cheung, they have done a lot of research in this area with a large cohort of patients that Dr. Holland has done. Looking at limbal allograft patients compared to living allograft donor for these patients. And the conjunctiva limbal allograft recipients have actually done much better than just pure keratolimbal allograft recipients. It really helps to tissue-match and to get that additional conjunctiva for those patients. What about the most severe forms of these eyes? These are eyes, again, that have the highest inflammation, 360 degrees of involvement. Cicatrizing disease. They often need both conjunctiva limbal allograft fresh from a donor as well as what we call the Cincinnati Procedure, coined by Dr. Ed Holland, he’s pioneered this type of surgery. Where he fills in the gaps with then cadaver tissue at the 3 and 9:00. You can see the pink areas where tissue is brought over from a living related donor. And then the 3 and 9:00 is filled in with cadaver tissue. And again, 360 degrees of transplantation so that there’s no gap areas. This type of procedure in general really requires a ocular surface team. It’s a team approach. There’s the cornea surgeon, but often these patient’s lids have involvement. There’s ectropion and lid irregularities from the disease. Those need to be addressed. Certainly they have glaucoma and that needs to be managed. And because we put these patients on systemic immunosuppression, we also use an internal medicine transplant immunologist or a kidney transplant doctor who can help us manage the immunosuppression. You can see here, the glaucoma is usually aggressively treated first. Then the lid abnormalities are corrected as a second procedure. Sometimes mucous membrane grafts are required to restore the inner lamella of the lids. And then suppressed using topical and systemic immunosuppression. And finally, this ocular surface transplantation, limbal stem cell transmissivity. And for the visual rehabilitation is when we use the corneal transplant tissue or artificial cornea. If we need artificial, it’s better to restore the ocular surface with limbal stem cell, and ocular surface transplantation. They tend to do better and have more long-term retention. So, here is a patient of mine. 26-year-old woman with severe Steven-Johnson syndrome. Her acute disease had resolved. This is about one to two years out and you can see she has total conjunctivalization, severe disease. We were able to take her into surgery. We were able to — her brother to be her donor. And first, you know, removing this severe fibrovascular tissue. And we were very nicely surprised to find that the cornea underneath was clear. This is tissue from her brother. Again, a large segment including limbal stem cell as well as conjunctiva to restore her conjunctiva as most of her conjunctiva had cicatrized and was diseased. We transplanted that to the 6 and 12:00 limbus. And then we filled in the 3 and 9:00 areas with keratolimbal allograft tissue. We do a dissection of the tissue. This is probably the most surgically challenging part of the case is to get a nice dissection of this keratolimbal allograft segment. We want it to be as thin as possible. And we also then trimmed the inside of the corneal edge so that there’s a smooth transition when we lay it down between that donor and the host cornea. And then you see we’re putting in reinforcing sutures between all of these four donor segments. So, that there’s no gap areas. So, 360 degrees of the limbus will be fully covered here. And you can see again, that’s the before, that’s the after picture immediately. Long-term these actual segments really cosmetically thin out. And they look very, very good on the patient. Here is what she looks like at month four. I’m sorry, this is not the best picture. But you can appreciate her cornea is staying nice and clear. She is on systemic immunosuppression. Another patient of ours that had AGA cicatricial pemphigoid, they are challenging. I try to avoid surgery in these cases. But in her case, both of her eyes were being lost in terms of visual acuity. She was losing her ability to take care of herself and so, her systemic immunosuppression, she was getting IVIG with her dermatologist. Her systemic disease was controlled well. We were able to take tissue from her sister and cadaver, again, do a 360 degree what we call Cincinnati Procedure. This was what she looked like a week after the transplant, 20/40, no more transplantation after removing the scar tissue from the surface. The other eye — and because she’s immunosuppressed and undergoing treatment, she has maintained a stable ocular surface. Her other eye looks like this. We’re wait on this. Again, I try to avoid touching these until I absolutely have to with the pemphigoid patients. She’s doing very well and now about 2 years out from surgery. So, how successful are we? It depends on the severity of the disease and the underlying inflammation. Lower inflammation eyes tend to do better, have a higher rate of success. Severe Steven-Johnson, pemphigoid have a longer term rejection possibility. And the stability on the ocular surface, the need for lamellar keratoplasty. There’s greater success with longer duration immunosuppression. They have shown that these patients do require long-term immunosuppression, very similar to kidney transplant patients. Often if they’re taken off of their immunosuppression early, within a year, these patients will reject. So, it takes years of immunosuppression in most of these cases to maintain that stability. And our immunosuppression protocol is very similar to kidney transplant immunosuppression. So, we start them on Prograf or tacrolimus, mycophenolate or Cellcept. The prednisone, we try to get the patients off of the prednisone in three months and maintain them on the others long-term. These patients require monitoring of their level, we monitor for systemic toxicity, their kidney function tests, and so on. So, they’re under close monitoring throughout as long as they’re on these medications. How safe are these medications? So, this is very interesting because our population of patients that require these systemic immunosuppression are often healthy young patients. These are patients who may have had Steven-Johnson and so on. Dr. Holland looked at his large cohort of patients and looked for systemic comorbidities. And because these patients are a healthier group compared to, for example, kidney transplant patient who is often have diabetes and many other comorbidities, our patient population is healthier to begin with. And they do better. Their adverse events from the systemic toxicity is much, much less compared to other solid organ transplant patients. And again, we follow these patients in collaboration with renal transplant immunologists. And older patients don’t need as long of immunosuppression as younger patients. So, in summary, visual rehabilitation in severe ocular surface disease requires a multidisciplinary approach. We do tissue matching for living related donors when we can. And success is really directly related to appropriate systemic immunosuppression. Which requires management with a transplant coordinator. Toxicity is uncommon in this group of patients. So, you know, I urge my corneal colleagues who see these type of patients to not be afraid of the systemic immunosuppression. It’s an area where ophthalmologists often don’t want to go into that area. But really if you have a collaborative institute or you’re part of a group with somebody to help you manage the systemic immunosuppression, it’s certainly a doable. And then these patients have long-term success. I’m gonna jump into one final topic. And that’s patients with severe symblepharon or recounter symblepharon. That can be partial or complete adhesion of the palpebral conjunctiva to the bulbar conjunctiva. These can be from trauma, iatrogenic, post pterygium tissues, we can see them on the ocular surface. They’re difficult to manage. Reoccurrence is very, very high. And so, traditionally just removing these and leaving that area bare or placing amniotic membrane or conjunctiva autograft, even oral, nasal tissue has been described to reconstruct these areas. But reoccurrences still remain very, very high. So, what we have been doing is using keratolimbal allograft tissue like for stem cell transplant. We find this tissue helps to provide a robust tissue alternative as a spacer. It also provides healthy limbal and conjunctival stem cells. We published the results of our initial cohort in the Cornea Journal back in 2015. Again, the tissue is prepared as we had described before. Punch out the central 7.5 millimeters, take that corneoscleral rim. Section that to whatever size is required. Do a posterior lamellar dissection and we thin out that corneal edge. And take that segment and place it on the ocular surface. So, we took a group of patients who had restrictive symblepharon due to trauma and some of them had failed previous surgeries with spacers, amniotic membranes, mitomycin. And some were post pterygium excision, it occurred and diplopia and primary gaze with restrictive ability to move the eye in various gazes of motion. So, what we do is we take down the symblepharon. Sometimes we have to isolate the muscle. And we basically trim that corneal scleral limb, the allograft, to the size that we need. And we use tissue glue to place those segments in the area that we removed the symblepharon. And these patients don’t need to be immunosuppressed for really sometimes they don’t need any systemic immunosuppression, just topical. We’re not looking for stem cells, they have good stem cells. We’re looking for a robust tissue to act as a spacer. So, this patient had severe symblepharon that kept occurring after she had an orbital floor fracture. Multiple attempts at repair and this symblepharon kept recurring. Severe restriction to nasal duction. We put in three segments initially of allograft tissue, that was on day one. That remained clear. Had a little reoccurrence deep in the fornix to the edge of the last allograft, and we put in a fourth segment deeper in that fornix and she was then completely happy. She had beautiful movement of her eyes and all gazes of motion. You can see cosmetically over a few months it looks very, very natural and clear. And so, this has remained now completely, you know, intact post-op year three or four that she is. Here is another patient. She had a motor vehicle accident with severe symblepharon superiorly. We were able to replace with a segment there. She’s now able to look down with no restriction. Another patient, similar situation. You can see, she had lid surgery here and it developed restrictive symblepharon. We were able to restore, again, that surface so that she’s able to gaze down. This is one of those patients who had several pterygium surgeries. This is not a reoccurrence, but a thick band that’s come over. He had restriction to lateral gaze. We were able to put two segments in and he’s reoccurrence free after that. This is a patient with severe symblepharon in multiple areas. We were able to take all of this down and place keratolimbal allografts across the surface and he has full motion now as well. Here’s another patient, again, severe inferior symblepharon. We were able to replace with one large segment of keratolimbal. And it looks natural. And that occurrence is the lymph tissue in the allograft tissue. That can swell up and develop a purplish hue. That’s not so much a sign of rejection. But that goes away. But we do put them on topical immunosuppression. So, these patients are on topical steroids for long-term. And our results with this is that the diplopia in primary gaze resolved in all cases with full range of motion. And no recurrences on to the keratolimbal tissue itself. There were mild reoccurrences to the edge of the tissue, and subsequent placement of additional k keratolimbal resulted in full range of motion. This keratolimbal tissue is a healthy robust replacement for these severe symblepharon patients. It’s a mechanical deterrent to the symblepharon reformation and reoccurrence. And it does provide the healthy limbal and conjunctival stem cells which I think contributes to the long-term health of the ocular surface. And we were able to achieve anatomical and functional success. With that, I’m going to thank you for your attention and for sitting through that entire lecture. I’m going to go ahead and go to our question and answer box. And start answering the questions. There was a question on what does BAK means. That’s benzalkonium chloride, used in many of the earlier topical drops. So, it’s a preservative. MMP-9 testing. In the United States, we have this — it’s matrix metallics 9 — an inflammatory cytokine. We use a aliquot of the patient’s tears and look for tear inflammation. If the MMP-9 is positive in the office, we know that patients have inflammatory tears. The next question is how long do you continue the immunosuppression after repeat in a 37-year-old man with chemical burn. Do you recommend the Cincinnati Protocol? It depend on the amount of limbus involved in the disease. It demands how much cicatrization of the disease. If you have done an allograft 360 degrees, you need immunosuppression. In a 37-year-old, looking at 3 to 5 years of immunosuppression. But I monitor them. You have to monitor the systemic immunosuppression. They come in every few months. We check their blood levels of tacrolimus, checking the ocular surface to make sure it’s stable. That there isn’t signs of rejection. If there’s science of rejection, we may need to increase the levels. The tacrolimus really for the first six months, looking at levels between 8 to 10. On blood levels, over time if their ocular surface looks stable, we’re happy with blood levels of 5 to 8. And so, this is monitored constantly. Sometimes early on these patients need blood draws every few weeks to make sure they’re in that therapeutic dose. The next question is why do you prefer superior and inferior limbal stem cell donor tissue and not temporal or nasal when conducting living related — so, the superior and inferior limbus have more limbal stem cells in those areas. That’s a good question. Also anatomically, we tend to heal better. From a cosmetic standpoint, it’s better to not take from areas that are exposed to the environment. The next question is how do I split the donor tissue one-third/two-third. I say one-third/two-third, ideally, it’s just splitting it by half. Often times it comes out 50/50 in terms of dissecting that tissue, we do our absolute best. Usually you require a nice assistant to help you hold the donor tissue and with a crescent blade create a 50% dissection which is often sufficient to get that nice, thin tissue. So, you need the side that has the limbal stem cells, right? So, we use the top one-third. Okay. The next question is: What do you do to living donors area when the graft has been taken? That’s a great question. If a large area of conjunctiva is taken, I will use tissue glue to bring down the rest of their conjunctiva so they don’t have a large area of opening. But honestly, you can leave it open and they heal by secondary intention as well. You don’t need to do too much after you remove the tissue from the living related donor. You don’t need to do a lot of work on that eye. You can sort of leave it open and it heals. The next question is: What is the suture material used? I often use Tensilon. It’s less inflammatory, I think, than Vicryl suture. It’s a little bit more inflammatory. I want to minimize inflammation to the surface so I use 10-0 nylon. The next is what is the indication for stem cell transplant in aniridia patients. They are interesting because they often have decreased vision to begin with from macular hypoplasia. And so, I look at what their baseline vision was. Often they don’t have great vision. Maybe their baseline vision is 21/50. So, these patients are okay for years. It’s not until, you know, later in life that they start having secondary worsening of their vision from irregular epitheliopathy. So, you can stain their ocular surface. They have 360 degrees of limbal stem cell deficiency. That’s the nature of their congenital disease. And so, when the ocular surface develops a significant epitheliopathy and their baseline vision drops, the patient will often tell you, this is worse than my normal vision is. That’s the time really to go in and transplant those patients. Those patients often if you take healthy living related donor, sibling or a parent that has healthy limbus and doesn’t have it, obviously, you take just two segments and transplant them over and do some immunosuppression, they do fine. They don’t need 360 degrees. They don’t have conjunctival disease. They don’t need a lot of conjunctiva. They just need some healthy stem cells. Okay. So, the drugs of choice — the question is what is the drug of choice for immunosuppression. We talked about that. We use tacrolimus and Cellcept and prednisone, and taupe their off, and then the others. And the next question, what is the treatment for dermoid cysts. That is beyond the topic today. But dermoid cysts, usually you can leave those alone unless they’re amblyogenic, very large, causing astigmatism. You can remove those. There’s enough stem cells, doesn’t need to be reconstructed. Sometimes I’ll just use amniotic membrane in the area that I have removed that and that is often sufficient. So, let’s see. The next question is: Do patients require prophylactic antibiotics post-operatively since they are on steroids and immunosuppressives? I do use topical antibiotics certainly for the ocular surface post operatively. Systemically, they are on Bactrim for a short-term to prevent secondary infections. They are also on an antiviral for about the first 6 months to prevent secondary CMV infections as well. This is factually the protocol that kidney transplant facilities use. The next question is do you cover the graft with conjunctiva in case of symblepharon surgery. Remember in the cases that I talked about with symblepharon surgery, those keratolimbal allograft have the tissue attached. We order from the eye bank specifically with the conjunctiva is attached. You don’t need additional conjunctiva. They have conjunctiva and corneal epithelium. You put those down. I just connect the patient’s own conjunctiva to the edge of that keratolimbal allograft to make sure there’s no edges and that’s it. Is it possible to use keratolimbal allografts for lens patients? I have not done that. But that’s a good idea and probably will help with filling some of that thinning in the area for Mooren’s ulcers. That’s a good idea and can definitely be attempted. I look forward to hearing your experience if you do use that. Let’s see. What is your experience with insulin eye drops in non-healing corneal defects? Do you have experience with subconjunctival platelet rich plasma in treatment of severe dry eye, little bit off topic. They can have their own lecture. I have not used insulin eye drops. I have use autologous serum and plasma eye drops which definitely help in those cases. We also have access to recombinant human growth factor here in the United States. So, we have been using those in those cases where there’s neurotrophic corneas involved. I have not used subconjunctival PRP. I just use it in an eye drop form on the ocular surface and that helps with severe dry eyes, certainly. Let me see… the next question is are there specific genetic markers or mutations that are associated with increased susceptibility to ocular surface disease? I think there are. There are really none right now that are readily — that can be readily used. For example, we have seen patients who have worn contact lenses for a very short time where you would not expect a patient to develop limbal stem cell deficiency after only a few years of contact lens wear, but they have. And so, is there some kind of genetic mutation in those patients where their limbus started out abnormal? I think there is. Have we isolated that yet? No, we haven’t. The only ones we really know have a congenital abnormalities are the aniridia patients who have that genetic mutation. That’s a great question. There aren’t any at this point markers that I know of. The next question is what is the measurement of the segments that you usually use for keratolimbal allografts. It depends on how much we need. So, if I’m doing — if I’m filling the 3 and 9:00 regions only, then I basically take one donor tissue, cut that keratolimbal allograft ring into two segments and trim those segments so that it fills in my area of defect. So, you sort of trim your segments to fill in the areas that you need. Let’s see… any role in conjunctival fornix massage after thermal chemical eye burn. I’m not sure what a conjunctival fornix massage is,lysis, in the acute phase of chemical or thermal eye burn, you know, there’s a whole acute protocol certainly with washing out of the chemical injury. Sometimes symblepharon can be used, I like to use amniotic self-retaining. It comes on a symblepharon ring and has a dual purpose of keeping it formed for us as well as providing that tissue to the ocular surface in the acute phase to try to prevent some of that cicatrization that occurs. Next question. If the living donor site is left to heal by secondary intention, is there a role for steroids for healing and comfort? Yes, I put them on a short course of topical steroids and antibiotics, absolutely. The next is how long of conjunctival tissue can we stake before risk to the donor? We take easily six clock hours, three from the superior, three from the inferior. As long as it’s a healthy limbus. I make sure the donor is not a long-term contact lens user. And as long as they have a very healthy-looking ocular surface, they do just fine. we have not had a patient that we have pushed into a stem cell failure. If you ask Ed Holland, he says they do very, very well. We can take up to at least six clock hours with no secondary issues to the donor. Question is which concentration of cephalosporin drops do I use for suppresser and how much? That’s a great adjunct to the post operative drops and safe enough if the patient is tolerant to them, I’ll keep them on long-term as well. In addition to topical steroids. I think the topical steroids are more effective however. The next question is can you briefly throw more light on how to rightly make diagnosis of an HSV keratitis? Again, that’s its own lecture. So, I won’t go into that in too much detail. But, you know, certainly if you felt that there is a dendritic HSV keratitis and you have put patients on topical antiviral drops, if they’re not healing after two weeks, then we need something else. I find oral antivirals very helpful in those cases. But I’m very, very cautious about continuing topical antiviral drops for any longer than two weeks. After that, they become more toxic than helpful. Okay. I think… we are sort of close to the end of our questions here. And with that I would like to thank you again for your attention, for being here today, and on behalf of Cybersight, we appreciate you being here. I believe this lecture is recorded and will be placed on their website as well for future reference. Thank you for your attention.