Lecture: Anterior Vitrectomy and Posterior Loss of Lens Material During Cataract Surgery

Posterior capsular rupture is a relatively common complication of cataract surgery. The lecture will discuss management of the vitreous including the argument against cellulose sponges, use of triamcinolone, pars plana versus limbal vitrectomy, fluidics parameters, and why limbal infusion. In addition management of posterior dislocated lens, nucleus or cortex will be discussed: phaco probe should not be used in the vitreous, irrigation or lens lop should not be used in the vitreous and lens material will damage the retina. The general point is to avoid intraoperative vitreous traction.

Lecturer: Dr. Steve Charles, MD. Founder, Charles Retina Institute, USA.

Transcript

DR CHARLES: I’m Steve Charles in Memphis, Tennessee, currently at my satellite clinic in Mississippi, and I’m excited to talk to Orbis participants around the world to talk about intersegment complications, complications from cataract surgery. The thrust of this is that some years ago David McIntyre, one of the first to do minimally invasive cataract surgery — we need a better term, but to do outpatient cataract surgery with minimum equipment, asked me if I would consider working with cataract surgeons around the world to improve management when vitreous loss occurs, when lens material is dislocated posteriorly after capsular rupture, during cataract surgery. I’m director of education for cataract and refractive surgeons, and I’ve tried to get input from as many cataract surgeons around the world as I can to improve these ideas, even though I’m not personally a cataract surgeon. I have no economic interest here. So of course the problem starts when there’s a rupture in the capsule. Some of them are very small and don’t require vitrectomy, and the lens material, properly managed, doesn’t fall posteriorly. Obviously others are larger, and anteriorly vitrectomy must be performed. I’m gonna say this over and over and over again in this talk, but the crucial issue is not just: Is there vitreous left in the wound at the end of the case. The crucial issue is definitely not: Is there lens material left in the back of the eye. That can be managed later. The crucial issue is not creating acute vitreoretinal traction during surgery. Often people think as long as I get the lens out, as long as there’s no vitreous in the wound, it doesn’t matter how hard I pull on the vitreous. That’s the thesis behind, unfortunately, the cellulose sponge technique of anterior vitrectomy. So we’ll go into this now in some more detail. So one of the most important things to do is to try to prevent problems. Just as proper blood serum glucose management is better than vitrectomy in this diabetic retinopathy. If we can prevent diabetic retinopathy or treat it with anti-VEGF compounds, it’s better than having to do a vitrectomy. Well, protecting the capsular defect with Viscoat, which is the most widely recommended, obviously I consult for Alcon, but I have no interest in Viscoat, can protect this defect in the capsule, allowing you to remove the lens material. How to remove the lens material. First of all, if you use a high bottle technique, like David Gould does, lower the bottle. Because the bottle creates a pressure gradient through the wound, and will bring vitreous forward, potentially. If you’re gonna use phaco techniques to remove the lens material, instead of a lens loop as depicted here, you’ve got to be using low flow, or if it’s a Venturi system, a low vacuum technique. There are a variety of devices that can be used to remove the nucleus from the eye, if it’s still present. The cortex obviously has to be removed by some aspiration technique, I and A. But once again, low bottle, so there’s a low pressure gradient, low flow, low vacuum. These are crucial aspects of safety in this technique. What about what Charles Kelman, who brought us phacoemulsification, and everything I’m talking about applies to non-phaco techniques et cetera. But he recommended passing a needle through the pars plana to catch the lens material. Not only is that dangerous, because you have to force a needle into a soft eye with an open wound, potentially bringing vitreous forward — not only is that a bad idea, but it has another aspect. And that is the whole assumption is the problem is lens material falling in the back of the eye and damaging the retina. I’ve said this in a variety of different ways, but if you’re performing a penetrating keratoplasty, and you drop the world’s most jagged, rigid nuclear material from the moon through the pupil, it would not damage the retina, because water has such a high modulus of elasticity, vitreous is obviously 98% water, it’s more like if you dropped a rock in the swimming pool, it’s not gonna damage the bottom of the pool, because its descent is gonna be slowed by the material. Particularly with the viscoelastic properties of human vitreous. So in short, the problem was the assumption. That the problem is the lens material damaging the retina. And that’s simply not the case. There’s psychological or psychodynamic issues with dropped lens. First of all, if you’re talking phaco, roughly 98% success rate. There’s a problem in that you have automation, you’ve done this many, many times, and the problem is complacency. And pride is part of it. Oh, I never have problems. I never break the capsule. I never drop lens material. Well, when you do, don’t panic if you’ve got observers or people watching or video being done. You’ve got a very busy schedule, many cases to do that day. All these factors unfortunately can result in people doing dangerous things. The most dangerous of which is moving the phaco probe into the vitreous — anterior vitreous cavity to try to find lens material and remove it. This is simply bad practice always. And we’ll talk more about that as we go forward. If I had a lump of human vitreous on the table right now, and I put a phaco probe in it, it would liquefy the hyaluronic gel, and would be a blob on top of the paper, table, and you would get the perception that you did a vitrectomy, except it doesn’t cut collagen fibers. The collagen fibers are attached to the vitreous base, from the retina to the equator, extending anteriorly, and the retina is roughly 1/100 the tensile strength of the vitreous itself. Vitreous has a collagen fiber matrix. No one ever separated the vitreous base from the pre-equatorial retina. No one. When you hear a surgeon say they dissected the vitreous base, not really. They trimmed vitreous with a vitreous cutter to near the vitreous base. Nobody dissected or peeled the vitreous base. Never. The tensile strength of the peripheral retina is 1/100 of the tensile strength around the optic nerve. So you have a bad combination. When people say it’s only a simple anterior vitrectomy, there’s nothing simple about it, because the anterior vitreous is right by the vitreous base. The vitreous base is the strongest and totally permanent adherence between vitreous and retina, and it’s the weakest retina. So weak retina, incredibly strong adherence that can’t be separated, and proximity to exactly where the capsule rupture occurs and where the lens material typically resides, if it’s starting to move past the capsule into the anterior vitreous. So never, never, never put the phaco probe back there. The idea that if the lens is kind of resting on vitreous, and therefore you can remove it before it drops, again, what’s wrong with that is that you’re gonna encounter vitreous and tug on it. What else is wrong with that is it starts with the assumption that somehow the lens material is gonna damage the retina. Lens material has not damaged a single retina ever. Not the blackest, hardest, most jagged nuclear fragment can damage the retina. Only surgeons can damage the retina. Keep that in mind. Gerald Tenant in Dallas Texas for years advocated that if lens material was in the back of the eye you should irrigate to wash it to the front of the eye, to mobilize it anteriorly. This is a bad idea. How do we know it’s a bad idea? The late Robert Machemer and Wallace Folds from Scotland independently developed the retinal detachment model that is used to this day, and how did they make experimental retinal detachment? By squirting a jet of fluid on the retina. The jet of fluid penetrates the retina. Because retina has incredibly low tensile strength. So if you use a jet of fluid to make experimental retinal detachment, why in the world would you squirt saline in the back of the eye, or balanced salt, to try to irrigate lens fragments, to mobilize them anteriorly? Bad idea. What about lens loops? That seems a little bit safer than the phaco probe or irrigation, except it’s not safe. How do I know that? I’ve done many cases of dislocated IOLs in the back of the eye. And IOLs have a much greater surface polish, much greater lubricity of the surface. In other words, they’re slick. Whereas the most highly polished metal lens loop still has some surface roughness. Yet, when I take an IOL, I’ll think I have all the vitreous out, I’ll grasp the haptic with the forceps, try to mobilize it, and you’ll see the retina try to pull toward the device, indicating I’ve got to do a better job of removing all vitreous. So if I was talking primarily to vitreoretinal surgeons today about intraocular foreign bodies, I would say: Remove all vitreous first. If this lecture was primarily about dislocated IOLs, I would say remove all vitreous first. Well, the same argument applies here. Recall that you can’t see past the nodal point with a microscope. You have to have a contact lens on the cornea to eliminate the corneal optics, so to speak, or you have to have some non-contact viewing system, like the Biom or Resight or Ibis. Otherwise you can’t see posteriorly. It’s a dangerous maneuver and you can’t seen see what you’re doing. Doing this blindly might result in the patient being blind as well. So what’s your initial action? What should you do first, when lens material falls in the vitreous cavity? Stop. Pause. Relax. And plan what you do. Don’t act rapidly. There’s no hurry. Lens material doesn’t damage the retina. But you can. You only need to do a vitrectomy if vitreous prolapses in the anterior chamber. The presence of a capsular defect alone doesn’t mean there’s a need. Never pull back the phaco. There’s a natural tendency if something goes wrong to say I’ve got to get the phaco probe out of the eye. Don’t. Lower the bottle so there won’t be a pressure gradient, and then inject viscoelastic, preferably Viscoat, but some viscoelastic, over the defect, and fill the anterior chamber through a side port with the OVD, as you slowly, slowly, slowly remove the phaco probe. Otherwise, if you quickly pull the phaco probe out, it’s like pulling back on a syringe. You suck vitreous into the cataract wound. Never allow the anterior chamber to collapse. Keep it filled with a dispersive viscoelastic. The postcapsular rent or defect can be turned into a continuous curvilinear capsulorrhexis by careful maneuvers with the capsule forceps. If there are nuclear fragments that are still in the capsular bag, you can use viscoelastic to mobilize them above the iris plane, and then as I emphasized before, low flow, low bottle, if you’re doing phaco technique, otherwise you can use the lens loop to remove the lens material. If vitreous is in the anterior chamber, we can’t do that. If you’re going to do an anterior vitrectomy, we’ll come to that in a bit. But the most important thing to remember is to not chase lens material around the vitreous cavity with the phaco probe. If the capsular bag is sufficient to put a three-piece lens in the sulcus, you certainly can do that. If the capsular support is gone, if you’re qualified to do it, if you’ve done this before, and you have everything you need, you could do a Yamane procedure, which is becoming pretty much the standard. It’s in many ways replacing sutured IOLs or glued IOLs. If the patient has no glaucoma, and has no corneal problems, you could use an anterior chamber lens. Even if lens material has fallen posteriorly. Some vitreoretinal surgeons would say don’t put in an IOL. I would disagree with that. If after the capsular rupture, posterior lens material — if you’re comfortable with putting in an IOL, please do. If you have the proper visualization, et cetera. But again, never chase lens material around the back. Some surgeons consider this an emergency, so they’ll try to quickly mobilize, to do pars plana vitrectomy. I operate in a surgery center where our residents operate in adjoining rooms. So I am called upon from time to time to perform vitrectomy, because lens material fell in the back of the eye. But what are my criteria? I’m right there. The equipment is there. The staff is trained. Those are givens. You must be a pars plana vitrectomy surgeon. Don’t do this two times a year. You have to have the right equipment. You have to have a Biom or a contact lens visualization system. You have to have gas and laser in case a retinal tear forms. These are all essential steps, and you need Venturi base control for vitrectomy. Not peristaltic pump. So if all of that is available, which is the case with me, what are my criteria to go ahead? One, a pupil that dilates. Without having to go back in with hooks. Two, a cornea that’s reasonably clear. These are complicated cases. So if there’s extensive corneal edema or striate keratopathy, folds, extensive miosis, wait until another day. Let the wound become watertight, let the pupil because of inflammation subside, so the pupil can be dilated, and then you can do this selectively. This is an important notion. Let me go over these requirements again. You need a minimum of 2500 cuts per minute, if you’re going to do elective pars plana posterior vitrectomy to remove lens material. Again, this isn’t anterior vitrectomy I’m talking about now. This is lens material in the back of the eye. What do you need? Clear cornea, dilated pupil. You must suture the phaco wound. Hydrating the wound causes corneal edema and inhibits your view of the superior retina. And they leak whenever you put the trocar cannula — you insert the trocar cannula system. You must have an illuminator and wide angle fundus contact lens, because you have to see the periphery, not just the posterior pole. A flat contact lens, which allows you to see posterior retina, is not sufficient. You should do as much as you can with it. And never use coaxial infusions. It’s a bad idea. So you must remove all lens material, as I stated, before attempting to use the fragmenter. Then lift the lens material up with vacuum, away from the retinal surface, before you actuate linear ultrasound. I personally think the 20-gauge fragmenter is better than the phaco probe, but some experienced surgeons are using the phaco probe posteriorly, and having good results, so I must change my attitude a little bit about that. If lens material lollipops, because the ultrasonic fragmenter or phaco probe drills into the lens material, remember: You’ve got no capsular bag. So if it lollipops, use that technique to your advantage, and use the endoilluminator as a second instrument and chop that way. Chop the lens material. You can then push it off the tip. If it’s vibrating around the tip but not engaging, you can push it away with the endoilluminator so it can come back in. If it’s stuck on the port, you can use the endoilluminator as a second tool and do crush aspiration technique, smash it into the port of the fragmenter. It works very well. We’ve done this for 47 years. In this slide I have a 20-gauge fragment with a 25-gauge system. Hence the term 20/25. You must raise infusion as high as it will go for this technique, because the fragmenter has no cutter going back and forth, occluding the port in a pulsatile fashion. So unlike a vitreous cutter, it doesn’t have an inner needle, and unlike a vitreous cutter it doesn’t have a port that opens and closes. So it’s unrestricted flow. Secondly, fluidic resistance is proportional to the fourth power of the diameter and 20 gauge is 0.89 millimeters, whereas the 25 is 0.75 millimeters. So it’s very important to increase the infusion so you won’t get a collapsed eye when you get an occlusion break, when the lens material suddenly deforms into the lumen of the fragmenter. This is very important. That the second you stop using the fragmenter, put the vision back where it belongs, so you don’t occlude the central retinal artery. Some people have advocated using so-called heavy liquids. The liquid per fluorocarbons that Stanley Chang bought us for the break surgery, have advocated using that to float up a hard nucleus. It costs several hundred dollars per vial, it would take two vials, probably on the order of $700 US to do this, and I’ve heard people talk about it at meetings, and then I challenge them after they give the lecture. How many times have you actually done this? And the guy said once. So in short, I’m not an advocate. People say: Well, the nucleus is too hard for the fragmenter. The fragmenter has the same ultrasonic power as the phaco tip does. So if you were… If this was a phaco case, you shouldn’t have been doing it, if it’s too hard for the phaco, but in short, this is unnecessary to do. And I haven’t done it. Now let switch gears to talk about anterior vitrectomy. What are the goals? The goals are to minimize intraoperative vitreoretinal traction. Not just postoperative. That’s the biggest possible point. There are numerous anterior segment surgeons that believe that removing vitreous causes CME. Cystoid macular edema, which is an inflammatory process. Except it’s not true. We day in, day out do vitrectomy for floaters, epimacular membranes, and a variety of other disorders, and the patients don’t get CME, and we removed all the vitreous. So why do the anterior segment and cataract surgeons think this? It’s a misconception. And it’s actually because of iris trauma. So you put a cellulose sponge in, which you should never use in the first place, because vitreoretinal traction — it’s imbibing water, you remove it, rubs the iris surface, back of the iris, and creates traumatic iritis. So iris manipulation and iris damage is a major cause of cystoid macular edema, not the process of removing vitreous. If there’s some residual lens material, it’ll absorb it. That can create some inflammation as well. Remember that cataract surgery patients have, worldwide, high expectations, and they don’t expect a retinal detachment, so don’t make one. The cellulose sponge is a bad idea. It’s been a bad idea for 40 years. It was based — the late David Kasner, who was a wonderful man, who taught me at the VA, the Veteran’s Hospital at Bascom Palmer. Really worked hard to teach the residents. But the premise was: If there’s no vitreous in the wound, everything is gonna be fine. But in fact, there was a significant incidence of retinal detachment and CME from the use of cellulose sponges. For two reasons. One is, as they imbibe water, we call this wicking, the vitreous is pulled up onto the sponge, even if you don’t move the sponge. But obviously you stick this down into the anterior chamber, and you have to lift it up to get scissors behind it, to cut the vitreous, so now you’ve lifted it. So in short, cellulose sponge, anterior vitrectomy, cellulose sponge testing for vitreous is a bad idea, and it’s been a bad idea forever. This iris trauma thing… I’m convinced that iris trauma is the cause of much of the CME we see after anterior vitrectomy at the time of cataract surgery. But I’ve also seen many patients that have what’s obviously cellulose material on the residual vitreous when they send them to me for pars plana vitrectomy after this cataract surgery complication. Don’t sweep the wound. The idea with ciliary… I’m blocking on the name of it right now. Anyway, don’t sweep the wound with some device. Simply sever the fibers with the cutter or with microscissors like we use in vitreoretinal surgery. If you sweep the wound, it isn’t about what you’re doing at the level of the wound. So you’re trying to get vitreous out of the wound. That’s why you sweep. But the problem is that the other end of the vitreous, the collagen fibers are extending to the vitreous base and you can make a retinal break. Not a great idea. What about triamcinolone — some people call it staining. It’s not a stain, but it’s excellent. If you can afford it. Try Alcon’s Triesence. It’s preservative-free and it was developed for this kind of marking. It’s a great idea. It’s preferable not to reuse a multiuse vial. Sterile inflammation has been reported. Some people think it’s from the rubber stopper material. Some people think it’s from the alcohol swabs that are often used to wipe off the top of the vial in an attempt to sterilize it. So if you’re gonna use Kenalog instead of using Triesence, please don’t use a multidose vial. Use a fresh one, use it once, and throw it away. This is an important issue. We don’t want to create inflammation in these patients. What are the anterior vitrectomy requirements? The notion that an inexpensive vitrector is fine is wrong. I’m reminding you of what I said earlier. Peripheral retina is 100 times weaker than central retina, and an anterior vitrectomy is performed close to the vitreous base, where adherence is greatest. I said this before, but I’m repeating it intentionally. What cutting rate should you use? Always use the highest that you have. They don’t cut better. It’s just because the cut are — so it shouldn’t be called high speed cutting. It’s not high velocity. It’s just high cuts per minute. What does that accomplish? It minimizes the collagen fiber travel. The way I like to say it, and this is approved by the FDA, this language, is that it reduces pulsatile vitreoretinal traction. There’s two types of vitreoretinal traction. One is made each time the cutter opens and closes. Low flow, low vacuum, and high cutting rates is the way to minimize that. And the other one is because of a bad technique, which is engaging vitreous and pulling back. And here I must put the brakes on for a minute and make a crucial point. In cataract surgery, the goal properly is to mobilize lens material away from the capsule. So everything is brought centrally to the capsular bag. And so that creates the IA-like technique. Engage and pull centrally. Engage with vacuum. Pull centrally. That’s the opposite of what you want to do with vitrectomy. Vitreous needs to be sheared, and I say take the port to the vitreous. Don’t suck the vitreous to the port. So that means don’t engage the vitreous and then pull back. Always leave the cutter and let it cut free before it moves to a new location. Much like you would operate a lawnmower or an electric shaver. I call this technique continuous, engaged, and advanced. The idea that high cutting rates are more efficient — that’s not true. Efficiency is about: Are you engaged with vitreous or are you just removing infusion fluid? And of course, you must use infusion. We’ll go into that in a minute. So the highest cutting rates are always the best option. And never pull back the cutter while vacuum is engaged. Always cut free first. Let’s skip over that. Let’s skip over this too. I already covered it. So vitrectomy parameters. If phaco is being performed, you’re using a peristaltic pump instead of a Venturi pump, use the lowest flow rate. Always use cut IA, not IA cut. IA cut was developed for doing anterior vitrectomy after using IA on a pediatric cataract, and that’s the wrong setting. Always use the lowest bottle, the lowest infusion setting, because that reduces the pressure gradient across the port. We don’t need incredibly high flow rates, incredibly high vacuums, to perform anterior vitrectomy. We’re not trying to do this in one minute, instead of four minutes. We’re trying to do it safely. What about infusion? There was a time when I recommended infusing air, and although that’s safe, to infuse air, and it keeps the vitreous back, the problem with infusing air is that it makes it impossible to implant an IOL, because the anterior and posterior capsule are pushed together and pushed up against the back of the iris. So IOL insertion is impossible. So called dry, in other words, no-infusion vitrectomy, means obviously hypotony, which leads to suprachoroidal hemorrhage and miosis, as well as the cornea folding Descemet’s folds, so you can’t see. So it’s essential to use infusion. Never use the sleeve. Although I developed the sleeve many years ago, it was for pediatric cataract surgery, not for anterior vitrectomy at the time of cataract surgery. So it was for elective pediatric cataract surgery. So use the side port. Always infuse through the side port. Never with the sleeve. And always infuse infusion fluid, not air. And never do it dry. Those are the points. Two port versus one port. In the early days of vitrectomy, we had a so-called full function probe. The disc, the rota-extractor, et cetera. That had cutting and infusion and illuminating all on the one probe. That created turbulence around the port. We did three port vitrectomy for 45 years now, and it’s absolutely the best way. The same notion applies to anterior vitrectomy. You want to separate the vitreous cutter, bimanual technique, separate the vitreous cutter site from the infusion site. So always infuse through a side port. If you don’t have a side port incision, make one. Never infuse or do vitrectomy through the phaco. Never, never, never. Always infuse through a side port and do vitrectomy, either through the pars plana or through the other side port. So your options on the vitreous cutter are either a second side port or the pars plana. But not the phaco one. If there’s vitreous in the phaco wound, you can clean it out, but don’t do elective anterior vitrectomy through the phaco wound. It’s a bad idea. So never use this infusion sleeve. It causes turbulence and endothelial damage, and as I said, use side port infusion. I prefer the device at the top of this picture, the bimanual irrigation cannula, because you can manipulate the eye, and vitrectomy is not a two handed technique in the sense that you don’t need two active hands. If you’re doing something like Yamane procedures, or IOL suturing, repositioning, where you need two pairs of forceps in the eye, then anterior chamber maintainers, as depicted on the bottom — these are fine. But the instrument at the top is better for elective… Excuse me, non-selective anterior vitrectomy at the time of cataract surgery. Because you can switch hands to get vitreous, as well as residual lens material using the cutter. By switching sides. Again, two side ports or one side port plus an incision in the pars plana for pars plana vitrectomy. So this shows you the wrong way to do it. Because you’re in the phaco wound. If you just can’t get comfortable, or you haven’t been trained in a pars plana vitrectomy, still use all these advantages I’ve described to do safe bimanual vitrectomy, using the two-port technique. Don’t say… Well, I can’t do pars plana, therefore I’m gonna do it the old way. I’m gonna use cellulose sponges and I’m gonna go through the cataract wound. Use two side ports, as I said. Never pull back the cutter while engaging. Never use sweeps. Never use cellulose sponges. And the advantages of the translimbal approach is familiarity. That’s where anterior segment surgeons work, and there’s no conjunctival and scleral incision. There are advantages to the pars plana approach, which I depict here. The infusion is through the side port. The vitrectomy is through the pars plana. The advantage of this is vitreous flows from the anterior chamber into the anterior vitreous cavity naturally, with this technique. You don’t have to put an instrument in the anterior chamber, other than the infusion. So that means that there’s less turbulence, less endothelial damage, and a more complete anterior vitrectomy, and you’re much less likely to lead vitreous to the wounds. So you can perform a more complete and safe anterior vitrectomy this way. But you must be comfortable operating through the pars plana, and you must learn how. You must learn the technique. So there’s no need for cellulose sponges this way. What’s the disadvantage? When you make the incision in the pars plana, with an MVR blade, which I prefer, or using the trocar cannula system, the insertion force transiently raises the IOP to quite high levels, particularly if it’s a trocar cannula system, which can cause an iris prolapse. You must suture the wound. Hydration of the wound to keep it closed is simply inadequate. It is not the right thing to do. Many are now advocating the use of the trocar cannula. I’m not a big fan. But if you’re going to do pars plana vitrectomy, when you make the incision with the MVR blade, you’ve got to see it in the pupil. You’ve got to make sure there’s no non-pigmented ciliary epithelium or retina. You’ve got to go back through 0.5 millimeters. Always keep this cutter port in view. Never pull back on the cutter when aspiration is engaged, and as I said several times, always use the highest cutting rate, lowest flow, and relatively low infusion. Of course, you don’t want a soft eye. What about cutter diameter? Some are advocating 27 gauge. I’ve done hundreds and hundreds of 27 gauge vitrectomies, and there’s no problem with it, except we do a retrobulbar block. If you’re doing topical clear cornea cataract surgery, 27-gauge vitrectomy is a bad idea, because the rectus muscles are stronger than the bending force of these 27-gauge instruments and they whip around in the eye uncontrollably, and you can’t count on the patient in this emergency situation to hold their eye still. So it’s very bad to go 27-gauge. 25-gauge is rigid enough that the instrument won’t bend from extraocular muscle contraction. So I recommend 25 gauge. 23 is okay, but 25 is a better compromise, in terms of closure. Should you make a conjunctival incision? It’s better, because then you can close the sclerotomy with a single suture, and you can do it full thickness. So I don’t recommend going transconjunctival. If you use a trocar cannula system, obviously those are optimized for transconjunctival. I’m not recommending for the anterior segment surgeon to use a scleral tunnel technique. This isn’t about saying: Oh, I did sutureless pars plana vitrectomy. This is about safety. And you’ve got a soft eye, unlike what we deal with at the beginning of the surgery. And it’s easily possible, unfortunately, to get in the suprachoroidal space, or even in the subretinal space, but trying to insert an instrument at a 30-degree angle, like we use, to make a scleral tunnel. So go straight in, in other words. 25-gauge, straight in. If you insist on using the trocar cannula. Why do I not recommend the trocar cannula system? Although some surgeons do. In this instance. Because insertion force is higher, because as you move from the blade part to the sleeve that makes up the cannula, the diameter gets larger. And we measured it numerous times. Intraocular pressure goes up to near 100, and unless your cataract wound is really sutured tightly, if you for example put one 10-0 nylon suture in it, thinking it’s all about astigmatism, you can get an iris prolapse or worse, as the eye could completely collapse, and the trocar can literally penetrate the opposite side of the eye. So wound disruption and iris prolapse and worse yet, ocular collapse, penetration of the other side by the trocar, is a serious issue. These events have happened numerous times. People should be aware of it. I prefer a straight-in MVR blade. This isn’t gonna be done often. Capsular rupture rates are roughly 2%. So it should be something that you do in the most straightforward and safe manner. And the nicety of a so-called scleral tunnel is not the way to go. Straight in, sutured wound. I use one 8-0 vicryl, and it works just fine. This is all I wanted to cover today. Let see if there are some questions from the participants that I need to answer. Okay. What are the settings? The settings use linear vacuum, if you have a Venturi-based system. And if you’re using a peristaltic pump system, use low flow rates, and just increase them, the flow rate, until you see adequate vitrectomy. And you’ll be able to tell that by using this triamcinolone for particulate marking. Let’s see. They talk about elevating lens material, using a DK line. I’m not familiar with that term. But if you’re talking about irrigating to elevate lens material, it’s a bad idea. You should not do that. Let the lens material fall posteriorly. If you can’t remove it from the capsular bag safely. Oh, DK line is perfluorocarbon. Thank you. If you’re going to use perfluorocarbon, you have to do a pars plana vitrectomy first. Because the perfluorocarbon goes to the back of the eye and pushes the vitreous anteriorly. It’s not a good idea. So that’s all I wanted to cover today. I wanted to thank the participants for tuning in to this channel. My email is [email protected] Feel free to email me with questions. And again, thank you.

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October 18, 2019

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