Lecture: Choosing the Right MIGS for your Patient

In recent years, Minimally Invasive Glaucoma Shunt Surgery has gained a lot of interest among glaucoma specialists and cataract surgeons. Saheb and Ahmed have pointed out 5 qualities as to why this approach should be favored.

  1. Ab interno approach through clear cornea incision
  2. Less traumatic procedures to the target tissue
  3. IOP lowering capacity
  4. High safety profile avoiding serious post-op complications
  5. Rapid recovery with good impact on the patient’s quality of life

This lecture will discuss the existing most popular MIGS in relation to how effective they are in relation to particular type and stage of glaucoma, based on published papers.


  • Manolito R. Reyes, M.D. D.P.B.O. | Far Eastern University Medical Center, Quirino Memorial Medical Center and Jose Reyes Memorial Medical Center, Manila, Philippines
  • Rommel Antonio D. Bautista, M.D
  • Raphael Anthony D. Guballa, M.D


DR REYES: Hi, everyone! I’m Dr. Manolito Reyes, a practicing glaucoma specialist here in Manila, the capital city of the Philippines. I’m here in connection with being a volunteer of the faculty of the Orbis International. I will be joined later by two more sought-after glaucoma specialists, on my right, Dr. Manuel Bautista, who finished his fellowship at Stanford University, and on my left is Dr. Ranier Covar, who finished his fellowship at the University of Sidney, Australia. So I was asked to lecture or say something about minimally invasive glaucoma surgery. These are my financial disclosures. So these are the prelecture questions. Number one: Schlemm’s canal MIGS is usually indicated for: Advanced glaucoma patients, closed-angle glaucoma, mild to moderate primary open-angle glaucoma, and/or refractory glaucoma. Please answer now. Okay. So everybody got that correct. More than everyone. Number two question: CyPass was taken out of the market primarily because: Letter A, IOP was not lowered as claimed, letter B, difficulty of the technique, letter C, endothelial cell loss, and letter D, too many early postoperative complications. You can answer now. The right answer for that question is endothelial cell loss. Question number three. The following MIGS challenges the Schlemm’s canal except: Letter A, InnFocus, letter B, iStent, letter C, Hydrus, and letter D, trabectome. You can answer now. And the right answer for that question is except InnFocus. Question number four: Moderate to severe glaucoma can benefit from: Letter A, iStent, letter B, Hydrus, letter C, Kahook dual blade, and letter D, Xen gel implant. And let me see your answer. Yes, majority got it. Xen gel implant. Okay. Since we will be discussing — wait for a while — okay. Since we will be discussing MIGS, we will focus on the primary open-angle glaucoma. As we all know, primary open-angle glaucoma comprises 74% of the total global glaucoma cases and by now it affects about 50 million patients. Topical antiglaucoma medications have been our first line. However, because of the rising problem with regards to adherence, compliance, persistence of putting the drops, and on top of that, here in the Third World, the expensive cost of the medication, progression of the disease is inevitable. Selective laser trabeculoplasty is another good first line in some patients, especially in mild to moderate cases. However, not all respond to it, and if they do, it loses its effectiveness over time. In recent years, new devices for microinvasive glaucoma surgery were developed, and have gained more interest among glaucoma specialists, as well as general ophthalmologists. According to Saheb and Ahmed, the term MIGS refers to a group of surgical procedures which share five preferable qualities. An ab interno approach through a clear corneal incision which is conjunctival sparing, a minimally traumatic procedure to the target tissue, an IOP lowering efficacy that justifies the approach, a high safety profile, which avoids serious complications as compared to other glaucoma surgeries. And rapid recovery with minimal impact to the patient’s quality of life. Over the course of our discussions, we will deal with these issues as well. With all these issues. So MIGS sort of fills the gap between the conservative and the surgical management — previously a candidate would be on one, two, three, or four medications, plus SLT. Sometimes we’d begin to think of trabeculectomy. But now MIGS can be done to avoid serious complications, that our beloved drops are very well known. So before we start our discussion proper, I would like to mention that most of the studies that will be presented are industry involved investigations. However, this does not negate the encouraging findings of the results that is worth mentioning. MIGS are classified according to their mechanisms. So mechanisms in which IOP is lowered by MIGS includes: The Schlemm’s canal MIGS. It increases trabecular outflow, bypassing the trabecular meshwork. The iStent and Hydrus are stent MIGS. The trabectome and Kahook dual blade are ablative unroofing MIGS. Suprachoroidal MIGS include CyPass and iStent supra, and lastly, the bleb forming MIGS creates a subconjunctival drainage pathway like the Xen 45 gel shunt and the InnFocus microshunt. This will be the scope of our topic for tonight’s webinar. The Schlemm’s canal surgeries and the bleb forming surgeries. MIGS devices are small and even very tiny. These are their actual sizes. There are numerous YouTube videos on how to put it. You can check it and learn from it. It will not be included in this webinar. So first we discuss about iStent MIGS. It is the first MIGS approved in 2012 in the US. It was approved as combination procedure with phacoemulsification, and in Europe, it can be used as a standalone, or combined with phaco. As was claimed, it is indicated only for mild to moderate glaucoma. And not used for severe stage of the disease. Currently, we could say that this is the gold standard amongst the MIGS devices, because of its well established efficacy and safety. This is also the most widely studied MIGS. Its mechanism is to create a permanent opening into the Schlemm’s canal. The recent meta-analysis involving 1767 eyes from 28 different studies, and among these subjects, they implanted only one stent in 999 patients, two stents in 685 patients, and three stents in 63 eyes. IOP reduction using the first generation stent — the mean IOP reduction of doing iStent implantation is around 4.67 millimeters of mercury if one device is implanted. 6.03 millimeters of mercury if two devices are implanted. And 9.33 millimeters if three devices are implanted. This only tells us that three stents is better than two. Two stents is better than one. Data revealed that the iStent alone group produces a significantly more pronounced reduction in IOP than the phaco-iStent cohort. The iStent alone group also had significantly greater preoperative IOP than the phaco-iStent cohort. Nonetheless, the iStent alone cohort had lower postoperative IOP relative to the phaco-iStent cohort. There was a significantly greater IOP reduction in the phaco plus iStent group when it was compared to phaco alone. Now we’ll talk about the iStent Inject. This was brought about by the previous study, that two stents are better than one. In every injector, there are two stents that are tucked in two different sites. This probably resulted in the previous study, that two stents are, like I said, better than just one. In this study, phaco iStent IOP reduction was 8.52, and postoperative was 14.94. iStent only group IOP reduction was 9.99, with a pre-op IOP of 24.18, and after 12 months of study, postop IOP was 14.13. There was also a greater number of medication decrease, with the iStent alone group. In the analysis, a second generation iStent Inject, iStent alone had a significantly greater IOP reduction as compared to the phaco-iStent. As to the safety profile, most common adverse effect is IOP elevation immediately postop, which was attributed to the viscoelastic use during the procedure, and eventually it resolves without any complications. Other complications include stent blockage, malposition, minimal hyphema. Most studies reported stable or improved visual acuity at the last follow-up. The use of iStent Inject is as effective as two medications, as seen in this study. Wherein they have two populations. The iStent group and the medical therapy. However, with the iStent group, they benefited from flat curve and lower side effects. This may be comparable to prostaglandin and timolol in newly diagnosed primary open-angle glaucoma. Let’s go to Hydrus. So this is a crescent-shaped device, inserted via preloaded handheld injector. And they dilate the Schlemm’s canal up to three clock hours, bypassing the trabecular meshwork. This is an efficacy study regarding iStent. After 24 months, Hydrus-phaco group achieved better IOP lowering as compared to the phaco alone group. It is also worth mentioning the Hydrus versus selective laser trabeculoplasty, and the Hydrus group significantly decreases IOP and medications, compared with the baseline values. Whereas the SLT group only decreases the IOP. And still the patient was given medications. So we go now to the trabectome and the Kahook dual blade. Like I said, the ablative or unroofing MIGS. This is now your trabectome system. And it was approved by US FDA since 2004. It ablates the trabecular meshwork, and inner walls of the Schlemm’s canal, to promote greater flow by utilizing high frequency electrocautery energy. It is less invasive as an ab interno approach and increases compliance, as fewer glaucoma medications are needed after the procedure. And as claimed by the company, it selectively removes the trabecular tissue, unroofing the Schlemm’s canal, which solves the trabecular blockage. The first study comparing trabectome plus cataract and cataract alone group, there was a significant reduction with a combined group, at 9.3 millimeters of mercury, versus just the cataract alone group, at 5.6 millimeters of mercury. In the second and third study, they used it in pseudoexfoliative patients, and the effect seems to be more significant in patients with PXG. After one month… No, after one year, at 9.7 plus or minus 9.3 millimeters of mercury, the authors postulated that the mechanical effect of trabecular meshwork removal facilitates the washout of exfoliative material, thus contributing to a greater decrease in the IOP. With that in mind, it can possibly be used for glaucomas such as steroid-induced uveitis and/or pigmentary glaucomas. Trabectome safety is that trabectome procedure did not influence — this is also another study, that after doing trabectome, and the patient was subjected to trabeculectomy, it did not influence the outcome of the trabeculectomy as was the second operation done. We now go to the Kahook dual blade. This blade is used for an alternative method for performing ab interno trabeculotomy. It elevates the trabecular meshwork prior to removal, enabling cleaner tissue removal and minimizing injury to nearby tissues. There are no randomized clinical trials that have been published. It experienced IOP reduction of around 16.8 millimeters of mercury at month six, while eyes with lower mean IOP experienced 23 millimeters of mercury. The meds were reduced by 1.6 medications in the high IOP eyes and 2.5 in the lower IOP eyes at month six. The adverse events were non-sight threatening and usually self-limited. So minimally invasive glaucoma surgeries — the Schlemm’s canal surgeries or the Schlemm’s canal group, the iStent, the trabectome, the Kahook dual blade, and the Hydrus, who is it for? We can therefore say that they are: For the mild to moderate primary open-angle glaucoma patients, when you need target IOPs in the mid-teens to high teens. When patients have poor compliance or tolerance to topical medication. In patients with persistent high IOPs after SLT. For pseudophakic or combined with cataract surgery. And for trabectome and Kahook blade, it also works well with pseudoexfoliative glaucoma and pigmentary glaucoma. So we now go to the bleb forming surgeries. The Xen gel stent and the InnFocus. The anterior end of the tube is in the anterior chamber. And the posterior end is nicely placed in the subconjunctival space about 3 millimeters from the limbus. In the study by Sheybani in 44 eyes, the IOP lowering was 20.8 millimeters of mercury, and after 12 months it went down to around 13.1 millimeters of mercury. The use of meds was also reduced, from 2.7 to just one medication postoperative. In the study where they compared standalone Xen to combined phaco-Xen, it showed baseline IOP of 20.7 millimeters of mercury, went down to 13.9 millimeters of mercury, after a year. However, 37% of patients required needling intervention. Xen implant has good safety profile. The most common adverse effect is intraoperative hemorrhage both intracameral and at the scleral exit point. We have to address postoperative encapsulation of the filtration bleb. Thus needling is an extreme necessity. And now here is the head to head comparison of Xen implant with trabeculectomy. This is the largest and the only comparative trial with Xen gel implant and trabeculectomy as standalone. It is a multicenter retrospective cohort study. Median follow-up of 15 to 17.8 months. And the population includes primary or secondary open-angle glaucoma, mixed mechanism glaucomas, or primary angle closure glaucoma. So the result of the study is that the median pre-op was 24 millimeters of mercury, with three medications. And the median postop was 13 millimeters of mercury with zero meds, in both Xen gel implant and the trabeculectomy group. However, the trab group has more postoperative intervention, with greater complications, as compared with the Xen gel stent implant group. There is one interesting case that I want to share. The patient had a blunt trauma to his right eye, causes lens rupture and iridodialysis from 12:00 to 3:00. The surgeon successfully removed the lens superiorly by extracapsular method and put in an IOL. He was referred to our service because of uncontrolled IOP in the 40s with three medications. I chose to put a Xen implant, short of putting a seton procedure. The one that is circled is your Xen implant in the anterior chamber. And this picture was taken six weeks postop, and his IOP was 8 millimeters of mercury, without any medication. With low-rise form bleb and less vascularized. And this is a beautiful bleb as what we see. Now, the InnFocus. The InnFocus microshunt is implanted in an ab externo fashion, and with the help of mitomycin C. So complications noted are: Transient numerical hypotony, anterior chamber shallowing, choroidal effusion, self-resolving hyphema, vitreous hemorrhage, and bleb leak, which resolving without any intervention. So in a study by Beckers et al., one year results of a three site study of the InnFocus microshunt in France, Dominican Republic, and Netherlands, 91 consecutive primary open-angle glaucoma eyes underwent standalone InnFocus, 38 phakic and 35 pseudophakic eyes. 18 combined InnFocus and cataract surgery. And the results are: The mean pre-op IOP was 24.3 millimeters of mercury with 2.4 meds. Decreased to around 13.3 millimeters of mercury, with 0.4 meds at 12 months. This time, prospective randomized FDA clinical trial comparing the safety and efficacy of the InnFocus microshunt to trabeculectomy in primary open-angle glaucoma is going on in the United States. So with bleb forming MIGS, the Xen gel stent and the InnFocus, who is it for? We can safely say that these bleb forming MIGS are for moderate to severe primary open-angle glaucoma, severe refractory glaucomas, closed-angle glaucomas, when your target IOP is in the low teens, patients with poor compliance or tolerance to topical medications, and patients who are poor candidates for glaucoma filtering surgeries. So best MIGS for your patient: The Schlemm’s canal-based surgery, this is what we can say this time. And for the bleb forming MIGS, these are the indications for such surgeries. In summary, MIGS has been generally proven to be a good treatment option, mostly for mild to moderate glaucoma patients with open angles, even for severe refractory glaucoma and closed-angle glaucomas. It fills the gap that existed in the treatment algorithm for glaucoma between the conservative, the spectrum, and the traditional filtering glaucoma surgeries. It can be combined with cataract surgeries for convenience of the patient. And it even works better as standalone procedures. It minimizes patient adherence problems to topical medications. And very importantly, MIGS increases the quality of life, less ocular techniques, and potentially reducing lifetime costs of expensive glaucoma medications. Now, I turn you over to my colleague, Dr. Rommel Bautista, to tell us about clinical experience with iStent G1, here in our country.

DR BAUTISTA: Thank you for inviting me, Dr. Reyes. And to Orbis, the organization, for allowing me to speak to you this evening, or today. To share with you our local experience with the iStent G1. Unfortunately, we do not have the iStent Inject yet here in the Philippines, so I will just be discussing with you our results with the first generation iStent. These are my financial disclosures. All right. The first slide shows basically the demographics of our patient cohort, which was followed up over the course of 12 months. Median age of 67. Almost an equal amount of male and female patients. Status preoperatively was that 62% had cataracts, 38% were pseudophakic, and about 5% had previous glaucoma surgery, particularly a failed trabeculectomy. In group A, which we call the iStent solo, wherein we essentially just inserted the iStent in pseudophakic patients, we had about 15 patients in this group, preoperative IOP was about 21.33 millimeters of mercury, and an average number of glaucoma medications was about 2.2. How can we scroll this down a bit? It’s supposed to be all the way to 12 months. Okay. In the second group, which we call the phaco-iStent, or phaco-plus procedures, the preoperative IOP was approximately 17.48, in 25 patients, with an average number of 2.36 glaucoma medications for this group. And for when we combined both groups, the average IOP preoperatively was about 18.93 millimeters of mercury, and again, glaucoma medications were roughly 2.3 meds per patient. Here’s a brief summary of our results. For the iStent solo, we had about a 28.4% IOP reduction, and about a 50.45% medication reduction in this patient group. And to mirror what the experience has been in the other papers mentioned earlier by Dr. Reyes, for some reason patients who had combined phaco and iStent did have an IOP reduction, but it was significantly less than if we were to put an iStent solo, alone. However, the medication reduction was roughly equal, about 55%. To combine the results, it’s about 17.7% IOP reduction for both groups combined, and again, roughly about a 50% or 54.7% medication reduction. Factors for variance in the results… Well, perhaps there is a slight learning curve, as to how to put the first generation iStent. First of all, proficiency in intraoperative gonioscopy is a must. There’s head tilting at approximately 30%, in which the microscope for the surgeon should also be pulled towards the surgeon’s eye by about 30%, which increases the working distance, as compared to performing, say, for example, a Xen gel stent implant. Other factors are, of course, the placement. This could be less than ideal. It could be shallow, or a partially occluded snorkel head. One of the things that I’ve personally encountered in placing these devices is that we normally have to target an area in the trabecular meshwork wherein we feel that the collector channels are most concentrated. And unfortunately, when you do that, and you start puncturing the Schlemm’s canal, using the sharp tip of the iStent, there’s excessive bleeding in some cases. In some cases, the bleeding is not as bad. And the iStent can actually be placed rather quickly. The bleeding in this case is relatively… Is an ironic event, because you actually would like to see a bit of bleeding, because that pretty much confirms that you’re actually in Schlemm’s canal. And to prevent too much bleeding while you’re performing the procedure, you need to pressurize the anterior chamber with a fair amount of viscoelastic. Unfortunately, if you put too much viscoelastic, you end up crushing the trabecular meshwork, which is essentially a sponge, making the implantation of the iStent a bit more difficult. Here’s a picture of a target area, wherein on the surface of the conj, you can see a significant amount of blood vessels, indicating that perhaps maybe this is a clock hour or a quadrant that contains the collector channel. As you perform intraoperative gonioscopy, when choosing a site, prior to the insertion of the iStent, you’ll see some patchy pigmentation on the trabecular meshwork line, and that pigmentation is actually a bit of blood reflux coming out of Schlemm’s canal. This is the ideal place to put the iStent. So things to note: Overall, some eyes ended up with no meds entirely, after stenting. And it’s also equally important to note that before we conducted this short study, meds weren’t actually discontinued. So in essence, there was no washout. So preoperative IOP should actually be higher. And more importantly, IOP reduction isn’t the only parameter that matters. And I’ll tell you why. Here’s some raw data that we just added last minute. The patient is a 67-year-old male. For the right eye, we put an iStent. Preoperative IOP was about 15 on a prostaglandin and Alphagan. Postoperatively, he had no medications, with an IOP of 10. For the left eye, pretty much the same. 15, 16 on a PG and brimonidine, and his postoperative result was 11 millimeters of mercury. Again, without medications. So that’s a big win. Not only was the pressure reduced significantly, but the number of medications also completely eliminated in this patient. Here is an 83-year-old female, who underwent phaco-iStent on the right eye. Preoperative IOP was about 16 on essentially 4 medications. PG, Cosopt, and Alphagan. Postoperatively, after the phaco-iStent, her pressures were 15. So it’s just 1 millimeter difference. However, I consider this a win, because she’s 15 without any medications whatsoever. Again, pretty much the same picture for the last patient here. 79-year-old female, wherein I performed an iStent solo, with a preoperative IOP of 15, on a PG and Alphagan. Postoperatively, pressures are the same, 15, but this time the patient had no meds. So I guess this underlies the idea that it’s not just a matter of reducing IOP for these patients, but essentially removing the burden of medication on these patients and the attendant complications that come along with it. Thank you. Thank you. Now I’m gonna turn you over to Dr. Covar, to speak about the Xen gel 45.

DR COVAR: Hello. Good evening, or good afternoon or good morning to those of in other parts of the world. Thank you to Orbis for inviting me over for this very short talk. So we’ve only had the Xen in the Philippines since January. So we’ve just begun. And most of the cases that we will present today are continuous cases that we’ve started with, especially with an initial learning curve that we all had to go through with this. As Dr. Reyes has mentioned earlier, there are three types of ab interno MIGS. The Xen is part of the subconjunctival. MIGS group of drainage devices. It bypasses trabecular scleral resistance. And advantages being that there’s no need for incisions in the conjunctiva or scleral flap, meaning you can do a trabeculectomy or other procedures, in the future. It creates a new outflow channel, and optimal pressure reduction, owing to low and diffuse outflow. So the mechanism and design of the Xen was based on calculations of aqueous flow. Because of a longer and thinner tube, it provides a larger pressure differential, or more distance to flow. Initially there were three types that were developed. The Xen 140, the Xen 63, and presently what was produced now is the Xen 45. It’s a 6 millimeter size and length, with a lumen of 45 microns. These are the actual patients, consecutive patients, that I’ve done so far. I’ve done 12, but my data presently that we have collated is only up to around 9. Two are females and everyone else were males. All except two were diagnosed with primary open-angle glaucoma. One had angle recession, and one had mixed mechanism glaucoma. These are the pre-op and postoperative IOPs. It is presented in this graph. You’ll see that preoperatively, we had mean IOP of 25.56, and it has gone down to 14.44. Eventually it goes up a bit in the first month and plateaus a bit after the third month. The first day postop seems to be a little high compared to literature values, but that is actually because, if you look at the individual IOPs of the patient, there’s actually one patient wherein the IOP day one postop actually surged higher than it was preoperatively. It was actually because there was an occlusion in the tip of the tube, inside the anterior chamber. Wherein we had to do an argon or a 532 laser in the eyes where the obstruction was, so that the tip would be free of any iris incarcerating into the lumen. If we look at the data without that patient, removing that particular patient, the day one postop — actually the IOP would go down to around 9, the mean IOP of all the other patients, and then still it would go up after the first week, and up to the first month, and then goes down by the third month. It actually… There’s actually an Allergan APEX study, which is ongoing prospective nonrandomized clinical trial in 23 sites in the countries, and they have two-year data already. Based on the results, it shows that their pre-op IOP of around 20 goes down to a day one postop IOP of around 9, and eventually creeps up, but plateaus to around 13 to 14.6 by the 9th month. If you look at the very small sample size that we have, my local data actually mirrors that of the much bigger sample size of 215. It’s a far stretch, but at least it’s very similar to what their graph looks like. So the efficacy of Xen in a very small population: Significant reduction in mean IOP, ranging from 20% to 60% at all time points. If you look at the number of antiglaucoma medications, you will see that patients preoperatively had drops of around 2, and then decreased to around 1.67 by the third month, but we have to note that it is suggested by Allergan that we decrease medications, or that inflammatory antiglaucoma medications, prior to surgery, and give some prednisolone topical drops to improve the postoperative results, hence the pre-op antiglaucoma medications have gone down to just around 2 or so. So there’s still a reduction in mean number of antiglauc meds from pre-op to postop. And lastly, if you look again at the graph, the results of this small group of patients, you will see that in the first month there seems to be an increase in IOP. A lot of the studies, and even in trabeculectomy, we do give some 5FU during the third to fourth week postoperatively, and I have done that in this small group of population as well. By the third or fourth week, we gave some 5FU injection, and the mean IOP before needling of around 17.6 millimeters of mercury has gone down to around 13.6 millimeters of mercury, after the needling. Hence there is a lowering of the IOP by the third month. So in this paper, wherein there’s a six month outcome of patients who have undergone Xen gel stent implantation and 5FU needling, we were able to show that needling revision following Xen gel stent implantation resulted in a good IOP lowering effect without any significant increase in antiglaucoma medications or significant complications. Adverse events. One is tube obstruction. It’s very common that you may get one during the first time that you inject the stent. But if you are able to control, especially with your dominant hand, you may get away without having a lot of hemorrhage during this procedure. So the aims of the MIGS, according to EGS guidelines, with the Xen in context, is that you spare the conjunctiva, prevent significant external scarring, there’s no symptomatic hypotony or major complications, and at one year, mean IOP may reach around 14 millimeters of mercury. So thank you for your time and thank you for your invitation.

>> Thank you, doctors. So we have about seven questions so far. If you want to open up the Q and A box.

>> Okay. So the first question is: What contraindication of MIGS? What features for patients who will pass MRI? So I don’t think the Xen and the InnFocus implants will have a problem with MRI.

>> The iStent… In particular, the iStent is a heparin coated titanium stent. It’s the smallest implant device in the world. For any specialty. And although it’s made of titanium, it is non-magnetic, and rated to about 3 Tesla. So it is actually safe for MRI.

>> Next question… Is the Ex-Press shunt considered a tube or a MIGS? In my own opinion, going into the history of Ex-Press shunt, where they thought that Ex-Press shunt will serve as a… What do you call it? You just put the Ex-Press shunt, and the pressure, aqueous humor, will pass through it, and then in the later part of the study, since they tried to put it as a — inside, it cannot be considered as a MIGS. The next question: Is there a need for antimetabolites with bleb forming MIGS? That’s very true. The iStent and the InnFocus and the Xen — I’m sorry. The Xen and the InnFocus is designed — will be more — the success rate will increase with antimetabolites. In fact, with Xen implant, most surgeons nowadays, although it is off-label, introduction of mitomycin, they inject the mitomycin this time. And with what Dr. Ranier Covar told us about increasing the efficacy of the Xen implants by needling with 5FU. So the need of antimetabolite is a necessity for bleb forming MIGS. If you have a deep sclerectomy surgeon, why go to MIGS? All right. Can you answer about that question? I’m not… I don’t perform this kind of surgery. I cannot comment on this.

>> Like any glaucoma procedure, I think we have also gone to a lot of other procedures in the past. But I think whatever works in your hands, in managing your patients, if you can do well with a trabeculectomy, then that’s fine. If in your area, it might not be… The other MIGS might not be available, or it might be very difficult to provide for your patients, then using nylon 10-0 sutures for your trabs might just be fine. But MIGS — I think MIGS is there just so that you have an option for some of our patients who might not want to have large incision, who might want to have a lot less hemorrhaging, or might want to have faster visual recovery, with less amount of surgery. So I think in the end, we work with what’s best in our hands, and with what’s good for our patients.

>> The next question: Is there benefit of injecting MIGS at a later date, after cataract surgery, due to inflammation settling down? And can MIGS efficacy decrease due to blockage, et cetera, by inflammatory cells? Well, a lot of the studies had shown that standalone MIGS works better than as combined with cataract surgery. So we can do that. Cataract surgery. And then if you still — and if people still want some IOP lowering effect, and you don’t want to put your patients on medication, then you can do MIGS at a later date. So can MIGS efficacy decrease? The next question. Is there a difference in preferred quadrant for implantation of various implants? To answer this question, yes. There are certainly preferred quadrants for implantation of various implants. If we talk about implanting an InnFocus, or perhaps maybe a Xen 45 gel implant, you’d want to put the implant away from an area, or away from an area that you might end up having to do a trabeculectomy later on, should the MIGS device fail. So that’s — you want to take up as little real estate as possible, as far as the conjunctiva is concerned. And again, if you are putting a Xen or, sorry, an iStent in the trabecular meshwork, then the preferred site is the site that shows the most patchy pigmentation, which typically is the site nearest the collector channels.

>> Okay. In addition of a drug like mannitol, — is addition of a drug like mannitol required pre-op if a patient has high IOP at the time of surgery? Well, I don’t think that you would like to put your patient on mannitol, prior to surgery. For one, before the surgery, and upon entering your anterior chamber, your pressure will definitely go down. And I will not like a patient who will be more toxic-looking, because of side effects of mannitol. So I will not require addition of mannitol for a patient who will have this type of surgery. And I don’t think that it will help. Next question is: If we compare glaucoma with cataract… Like Femto, is it like MSICS… Cheaper but effective?

>> It’s perhaps maybe… Sorry? You’re talking about IOP drop, secondary to…

>> Comparing MIGS with Femto, because you have to shell out more money? There’s a question here that says: How can you do MIGS in a closed-angle? Does MIGS require visualization of the angle? Yes, absolutely. Angle surgery requires visualization of the angle. But theoretically, perhaps maybe if you’re doing a combined phaco-Xen, or perhaps maybe a phaco-iStent, the minute you remove the cataract, you can easily perform goniosynechialysis, open up the meshwork, and visualize the angle in that area. I have heard of people in Singapore who have implanted a Xen 45 gel implant in patients with mild angle closure. However, that forces you to aim, and essentially insert the Xen implant closer to the endothelium, and that might be a bit risky. But yes, certainly, it can be done.

>> What is your experience with closed-angle glaucoma, Ranier, using Xen?

>> In the other patients that I had, I have a patient who I did phaco on, and put a Xen in afterwards. Of course, the removal of the lens made it easier for me to put in the Xen after. But regardless, it’s still a little bit tricky, because you don’t want the tip of the Xen to be rough on either the iris or on the endothelium of the cornea. So it’s not ideal, but it’s doable. Maybe not in the first few cases that you might have. But once you get the hang of it, and because when you do the Xen, they offer or provide you a gonio lens, so that you can visualize the angle, so when you’re a little bit more in tune with visualizing the angle from the reverse view, then it might become a little easier for you to perform these procedures.

>> Any special consideration in angle recession patients? Well, I don’t think that there is any special consideration for angle recession patients. When your angles to start with are very good, it’s deep already, so you can just aim a little above the trabecular meshwork area, and put — I’m talking about the Xen or the InnFocus, with regards to angle recession patients. Okay? So I don’t see any… Do you think, Rommel? If iStent will work on this kind of patient?

>> Yeah, if an iStent is placed well, it will certainly lower pressure, but typically in patients with angle recession, and the IOPs are high, and your target IOPs are fairly low, I would personally put a Xen — a bleb forming MIGS device, rather than gamble on the Schlemm’s canal type of MIGS, such as the iStent, since the pressure drop is not as impressive as that of a bleb forming MIGS.

>> Perhaps maybe amongst the available MIGS that you have in the country, Xen would be ideal for patients with angle recession, specifically because your angle is wide open? And because your drainage is already compromised, your Schlemm’s canal might not be working that well. If you put in other types of MIGS, it might not actually drain through your trabecular meshwork. So getting a Xen from the anterior chamber to the subconjunctival space might actually be the best, and the only problem I foresee would be… During the surgery, the patient will have very high eye pressure, so you might have to bring that down a bit, just so you have a better view, and the patient might not… Because of the decompression immediately after you put in the Xen, if your patient is cupped out or has severe glaucoma, your fear of wiping out whatever vision is remaining might just happen, so you just have to make sure that the pressure does not go down immediately too low in the 4 to 8 range, 4 to 6 range, because the Xen can actually do that. So if your pressure is in the 50s or 60s, and it drops to very low pressures, the fear of wipe-out might just happen. So just be careful with that.

>> An interesting question just popped up. Anyone using these this pediatric glaucoma? So I think with pediatric glaucoma, I would go for the goniotomy-assisted — no? So it’s an ab interno goniotomy tube that you put into the Schlemm’s canal, and then do a 360 degrees trabeculotomy. So I think that’s the most promising MIGS procedure for pediatric glaucoma. Any incidence of hypotony with MIGS? Yeah? There are, there are.

>> Hypotony with MIGS… Is a particular feature of bleb forming MIGS devices, such as the Xen. In fact, you sort of expect hypotony in the first day or two, you know. It’s not uncommon for you to have pressures of 2 or 3. But that quickly rises, as the gel stent, the Xen implant, actually expands. Because as it becomes wet with aqueous, it starts to expand. It’s also important to note that when you implant a Xen gel implant, you’re actually using a gauge 27 needle. Inside the lumen of which is actually the actual Xen implant itself. So as you implant the Xen, you’re actually creating a bigger tract than that of the actual device itself. So yes, you do experience hypotony in bleb forming MIGS. For the iStent, and the Hydrus, which essentially relies on — or works by connecting the anterior chamber to Schlemm’s canal, you do not expect hypotony with these devices, because the drainage is physiologic, and the lowest pressure you can actually get will depend on your episcleral venous pressure. So that in itself is a stopgap measure for hypotony.

>> All right, thank you, doctors. That looks like all of the questions, and it looks like we’re out of time as well, so this seems like a nice place to stop.

>> All right. That’s it.

>> Thank you.

>> Bye! All right, thank you so much.

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May 20, 2019

Last Updated: October 31, 2022

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