Lecture: Lens & Angle Closure: The Obvious, The Known, The Future and The Unexplored!

Primary angle closure disease has a multi-factorial etiology with varied and unpredictable interplay of race, gender, genetics, biometry, lens parameters, static and dynamic iris measurements, choroid and, yet, many unknown factors. A prevalent thought at the moment is that Cataract surgery may provide a simple and universal solution to this complex entity. However, the evidence has shown extensive success, provided some caveats are met. We will go on an journey to look at the evidence, in a manner, as complete and unbiased as possible, to look at the utility and limitations of Cataract extraction in Angle closure disease across the spectrum.

Lecturer: Siddharth Dikshit, DNB, FICO, Consultant, VST Center for Glaucoma Care, L V Prasad Eye Institute (LVPEI), India


DR DIKSHIT:Welcome, everyone. Or good morning or afternoon. I know it’s various times at various places. So welcome, everyone. Today I’ll be talking about what I really like to talk about. Being a glaucoma and a cataract surgeon. Something that joins and combines glaucoma and cataract surgery, about lens and angle closure. Like it has never done before. So I am from Hyderabad, and believe it or not, that photograph that we just saw is me a few — not a long time back. So the objective of the presentation that I’ll be doing today is to understand the role of lens in angle closure disease. Now, you’ll realize that I’m talking about angle closure disease, and not angle closure glaucoma, because the angle closure disease includes a spectrum which includes primary angle closure suspect, primary angle closure, primary angle closure glaucoma, as well as acute primary angle closure. With a subvariant, which may or may not be considered a complete part of it. To understand the measurable parameters of the lens, to understand the impact of lens removal in angle closure disease, and the special consideration that one needs to give to plateau iris syndrome. And the consideration when you’re doing a cataract surgery in one such patient. And how to decide between cataract and combined surgery. Well, there’s no conflict of interest or financial implications of the presentation that we’ll make today. So the lens. Now, I’ll have a question for you about relative pupillary block. What is true about relative pupillary block? The options are right in front of you. You can poll in and choose an option. The Mapstone’s hypothesis explains the importance, it’s maximal in mid-dilated position of pupil, the intraocular lens is a factor, IOP rise may occur in PACG by mechanisms other than relative pupillary block. I will wait for you to finish these questions. Right, so most of you have actually got it right. You had to choose what is not correct here. So the intraocular lens in sulcus is a factor for secondary angle closure glaucoma by pupillary block and pigment dispersion, but not by causing a relative pupillary block. We’ll go into what a relative pupillary block is. Now, what Mapstone told us almost 100 years ago and still holds true — about 150 years ago — the iris has two muscles, the sphincter pupillae and the dilator pupillae. The dilator muscle is in the mid-stroma, so that’s in a direction that stretches from the pupillary margin to the root of the iris. And this keeps on changing. So you’ll see that at this point of time, the force of the sphincter is horizontal. And the dilator pupillae can be resolved into two vectors, one of which is pulling it down towards the lens, and one of which is pulling it outwards. So when you put a dilating drop, a mydriatic, it pulls the pupil rapidly outwards. However, at the point where the pupil is at the mid-dilated position, the configuration of the iris is such that in susceptible eyes, the sphincter pupillae force and the dilator pupillae force, they cancel out each other. The only force that’s acting on the lens at the same time is the force that is pulling toward the mid-circumference of the lens. And this is what precipitates a relative pupillary block and acute angle closure. Now, this was proven by Ritch, when he got the high definition UBM. And what you can see here is a mid-dilated pupil where the pupillary margin is adhered to the lens surface, and what is called an iris bombe, causing acute angle closure. So this proved that without the lens and the relative pupillary block happening, this iris bombe configuration and acute angle closure cannot happen. So this is pretty obvious, and does not need any proof that pseudophakes cannot have primary angle closure. Can be secondary angle closure, but not primary one. And you won’t find evidence for it, because it is very obvious, and it’s been noted throughout, and all the studies which have been done for cataract surgery in angle closure glaucoma mention that acute angle closure does not occur ever after a PA or maybe in some cases after a PA, but not after cataract surgery. So what are the parameters of the lens that we tend to measure with the anterior segment OCT? So there are a lot of things that the anterior segment can measure. But the primary thing of importance that the OCT measures, which cannot be measured by UBM or biometry, is the height of the lens that lies above the line joining these two scleral spheres. If you think logically, this is the amount of lens that is pushing the iris forward. So more is the lens vault, more is the shallowing of the anterior chamber. And of course, there are a lot of angle parameters also, which tell us how shallow the angle is. Like the angle opening distance, the angle recession area, measured at angle recess area — measured at 570 microns from the scleral spur. This area, again, measured at 750. A lot of other parameters, but these are the main ones. So when eyes across the spectrum of angle closure were studied, people realized that the anterior chamber depth and other measures of anterior chamber depth rapidly decreased when one moves from the spectrum of primary angle closure suspect towards acute primary angle closure. And on the other hand, with the iris parameters remaining the same across the spectrum, what is causing it is the rapidly increasing lens vault from PACS towards acute primary angle closure. Now, this was the population that was different from this study, and this study also shows the same results, rapidly declining angle depth parameters, increasing lens thickness, and lens vault. The lens vault is much more responsible for decreasing anterior chamber depth than the lens thickness. So even if the lens thickness is not increasing that much, the lens vault is increasing, because of possibly an anteriorly positioned lens. So that is what causes an increase in lens vault. So you see here that the fellow eye of the acute angle closure — primary acute angle closure eyes — they have much higher lens vault than the other lower ranks of angle closure disease, including chronic angle closure glaucoma. Which means that these are more susceptible to having an attack of acute angle closure. And quite logically, what happens is when you do a surgery in these eyes, these parameters change drastically. So these parameters change drastically because the lens vault is removed and this will change most drastically in acute angle closure and least drastically in primary angle closure suspects. So it’s quite well known now that the lens parameters, the thickness and especially the vault, go on increasing from normal to PACS to PAC to PACG to acute primary angle closure eyes. Now, as we discussed, cataract surgery will deepen the anterior chamber, but what more will it do? This is another question. For the audience. Phacoemulsification will reduce the intraocular pressure maximally in what condition? Acute primary angle closure, primary open-angle glaucoma, pseudoexfoliation, or pigmentary glaucoma? Various studies have shown reduction in intraocular pressure. Right. So around 30% of you are not absolutely correct, because you have chosen options other than acute primary open-angle closure. Now, what you see here is a forest plot. The forest plot on the top shows you the amount of intraocular pressure reduction from baseline, which is the central line, in various studies. The larger is the box, the larger is the sample size, and the farther away it is from the center, the more is the reduction. So you see when I place two similar red colored boxes on both these lines, you see there is much more number of studies showing greater decrease in eyes with primary angle closure glaucoma. So it’s very clear that though there is a reduction in open-angle glaucoma, which also includes pigmentary and pseudoexfoliation glaucoma, it is much more severe in primary angle closure disease. And all these studies just pull the data in favor of angle closure glaucoma. I’ll come to more of it. Before that, there’s another question for you. A patient with acute angle closure has been on maximal therapy for three days. The intraocular pressure is still 58. There is dense corneal edema. The evidence-based recommendation says that the best next step is? Choose one of these options. Right. It’s very interesting. It’s interesting because in different conditions, all of these hold true. So pilocarpine is not an option, because maximal medical therapy means that the patient is already on pilocarpine, and going intracameral in an eye with a pressure of 58 would be very dangerous. Argon laser won’t penetrate this cornea, or at least won’t be able to do an iridotomy that well. What is recommended in this situation is either the laser iridoplasty or a surgical PA. This was the recommendation until cataract extraction came in. Now let’s look at the evidence to find the answer. There are various prospective non-comparative trials with small sample size, which show that in acute angle closure, the success of intraocular pressure reduction is 100%. With very few complications. So this should mean that if there is a patient with acute primary angle closure, instead of doing a PI or a peripheral iridotomy, you should go and do a cataract surgery. But it doesn’t completely hold true. Because the second half of the table will show you that these are patients who in most of these situations had mild to moderate severity of angle closure disease. And none of these definitely had an intraocular pressure of 58. The visual acuity in these patients also don’t seem to be very great. After doing a cataract surgery, you don’t expect 40% of your patients to have the best corrected visual acuity to be less than 20/40, and even worse in some of the series. Now, isolated case series are not the best examples. So you should look at randomized controlled trials. So let’s see if the randomized controlled trials are good enough for this. These are the two biggest randomized controlled trials which have compared a laser PI to phacoemulsification. And they show good results. What they do show is that the intraocular pressure outcome is much better with phacoemulsification with greater absolute success lower intraocular pressure, and lesser number of failures. The complications are also not much, but one of the things that is very common is some fibrin. But what you should look at here is that the visual acuity, again, is not very great. And in one situation, the laser PA group actually has better visual acuity. So the most important thing is not this, but what is the most important thing? Is in these patients, in the randomized controlled trials, these were very well controlled acute primary angle closure situations, where the intraocular pressure was either less than 30 or less than 21, after medications. So though there is evidence to suggest that in mild to moderate acute primary angle closure, cataract surgery works very well, there is no evidence to suggest that it will do equally well in a patient who has an intraocular pressure of 58. Despite maximal medical therapy, for three days. And doing a cataract surgery there might be very risky, and the definite answer to the question of what the evidence-based recommendation is is clearly that you cannot — don’t have evidence for doing a cataract surgery. Or a lens extraction in such a situation. Now, this table just goes on to show that not only phacoemulsification but even ECCE had a very good result across decades. In all these series. And there is significant variation here. So the success percentage is not uniform. It’s as low as 5% in certain situations. 65% to 76%. So what one has to realize is that the success is not uniform throughout the spectrum. And there is quite a bit of variation here. So when we look at the more successful studies, we tend to get carried away. But one has to remember that not all studies in even acute angle closure show an excellent result. Sometimes there may be as many as 30% of patients who didn’t have good reduction of intraocular pressure, despite maximal medications. Now, what you have here is that apart from intraocular pressure reduction, the cataract surgery in patients with primary angle closure glaucoma, not the acute situation, also reduces the amount of fluctuation. Now, this is quite surprising, but probably the cataract surgery is doing more than just reducing the anterior chamber depth, and this then happens to be a result of that action. So to summarize, we know that cataract extraction will reduce the intraocular pressure and its fluctuation, and that it increases in proportion to the increase in depth after surgery. The reduction is hence maximum in acute primary angle closure. But you cannot extrapolate the results to severe uncontrolled acute primary angle closure. There is one special situation, the plateau iris, which is quite common in the Asian and the Southeast Asian population. One must also remember that the angle closure glaucoma in the Caucasian population is not very common. And a lot of people believe that most of the angle closure in the Caucasian population happens as a result of plateau iris. So this is not a situation which is isolated to the Asian or Southeast Asian population, but is universal. And more and more studies are showing African subcontinent — population from African continent, and Caucasian groups who have plateau iris. So what happens when you do a cataract surgery in plateau iris? What Ritch and his team showed: That the angle here failed to open, despite an increase in the anterior chamber depth. So the anterior chamber depth in those days, which was measured centrally, and probably was not as developed, has decreased, but the angle remains closed in all these patients. On the other hand, you have evidence that the filtration has become better, after the cataract surgery, by the virtue of reduction of intraocular pressure and the prone position test being negative. So the same authors have also shown images where they have shown that the anterior chamber — peripheral anterior chamber depth or the angle has opened up after cataract surgery, compared to the preoperative images. What they have also noted is the ciliary processes, which are aligned a little forwardly oriented. The direction of the ciliary processes has also changed. So there is contrary evidence, although these studies are from two different populations. So are we looking at two different kinds of plateau iris? Or are these two different spectrums of plateau iris? You don’t know, but this study, which showed the angle to have opened, has been done in the Southeast Asian population and Japanese population, to be more exact, and the study showed that the angle that did not open up was in a Caucasian population. So what is unknown is the impact that cataract surgery is going to have on eyes with plateau iris. Now, once we know that the cataract surgery is beneficial, at least in a lot of situations, why is it a challenge to do a cataract surgery in angle closure glaucoma? First of all, it’s a shallow anterior chamber. Quite clearly. And you not only struggle because you have very little space to emulsify the nucleus, but also because the fluidics of most modern day phaco machines would get altered when the amount of vertical space for the fluid to move becomes limited. The lens is quite large, which means that you need to emulsify a lot more of the volume, and need to use a lot more energy. The pupil tends to be small in these cases, either because of iris atrophy, or use of pilocarpine. The patients are very frequently on proinflammatory prostaglandin analogs and pilocarpine, which happens to be the drug of choice for plateau iris syndrome. And there is a problem with the intraocular lens calculation also. We’ll look at that. And you cannot predict for sure — or you at least need to monitor the intraocular pressure control prior to and after the surgery. Now, why the cataract surgery option is enticing is because it has got fewer long-term complications. But short-term complications are not completely — don’t completely get rid of the short-term complications, and sometimes have complications like shallowing, cornea edema, decompensation, et cetera. So what kind of preoperative preparation is required for these patients? Let’s just go through one more question here. So what is true about… Okay. The cataract surgery being performed in a patient during phacoemulsification, whether you should always do a surgical PI, you should give acetazolamide, corneal decompensation is more common, or you should discontinue pilocarpine and PG analogs right on the day of surgery. I hope I get some wrong answers, because that means I have the opportunity to share some new information. I can see the answers right now here, and the second least chosen option is postoperative acetazolamide reduces the chances of intraocular pressure spike. Now, that happens to be the true answer here. Because a percentage of patients who get spike after cataract surgery, without acetazolamide, ranges from 30% to 70%. And with acetazolamide, maybe as low as 5%. So especially if the patient was on antiglaucoma drugs, do give oral acetazolamide to patients if there is no contraindication, during the immediate postop period. Also the pilocarpine, which not only increases the pupil constriction, but also increases the chances of inflammation, when you handle the iris during surgery, should be stopped one to two weeks in advance, and should be replaced with the acetazolamide, if there is no contraindication, again. Prostaglandin analogs can continue ’til the day of surgery and stopped for about 8 to 12 weeks. Now, there is a lot of evidence and voices rising in favor of resuming PG analogs early. Not enough evidence now. And please do remember to control and monitor the intraocular pressure preoperatively, and reduce it to as much as possible, through medications. And in certain situations, intravenous mannitol injection may be required. Now, as I said, intraocular lens calculation is a challenge. So which of the formulae here is accurate enough to have a prediction capacity of 95%? For a residual refractive error of less than 0.25 diopters? Not an uncommon demand in today’s world. Especially if you want to do a clear lens extraction. Okay. SRK/T. Now, what I’ll share now is information from various studies, which show that in this study, around 40 eyes, 40 to 45 eyes, from two groups were compared. And obviously the anterior chamber being shallower, the lens thickness being smaller, but what is important to note here is that the axial length is still quite normal. So 22.62 plus or minus 0.86 is not small eyes. It’s very much within the normal range. But what surprise you get here… Is that 21 eyes or 50% of eyes end up with spherical equivalent greater than 0.5. So the formulae are not even 50% accurate. And none of these parameters, the lens thickness or the anterior chamber depth or the axial length actually can predict the problems here. Now, another study which looks at various formulae, found that the Haigis formula was the most accurate. The Hoffer Q and SRK/T actually not doing too well, with quite a high number — amount of variation in the ultimate refractive error. Myopic in Hoffer Q and hyperopic in SRK/T. In this study, the percentage of subjects which were off by more than 0.5 was 50% for Haigis, and more for the other two. None of these are actually acceptable. One can say these are studies that are 7 or 8 years old. So I’ll come to a trial, the EAGLE trial, which is one of the most talked about trials, as far as clear lens extraction and angle closure goes. This shows that almost 40% of patients were off by more than 0.5 diopters, and 15% by more than 1 diopter in angle closure glaucoma. So this is something that I’ve discovered not very early in my understanding of angle closure. But because of factors which are unknown, or not yet revealed by studies, the formulae don’t work well. And you’re likely that — it is likely that you may end up slightly hyperopic in these patients. If you are using any of these formulae, please aim for a slightly myopic refraction. What is a much better bet is to use modern formulae like the Barett’s, which is available freely online, and ask for parameters which all the machines measure. And you can actually do it. So though there are no studies looking at angle closure, Barett’s looking at a large series, in more than 10,000 eyes, was proven to be the most accurate formula. So let’s hope Barett does the trick. You should also avoid multifocals in these patients, especially in presence of a PI, or in a patient who has a significant glaucoma. Because the contrast sensitivity is already hit, and you don’t want to reduce the contrast further than what it has already become. Also, if you want to do a toric IOL, you must inform the patient that in case a trabeculectomy is needed in the future, the toric intraocular lens may not work as well as it is working right now. Preoperative intravenous mannitol is something that we use for all advanced glaucoma. And patients with plateau iris syndrome. What is important to remember is you should use it at least an hour in advance, because though the medication, the mannitol, starts acting by 30 minutes, the peak of action is not reached by one to one and a half hours. So you should wait for some time after the mannitol injection to start the surgery. You cannot just expect the mannitol to work after you have given it five minutes back. What is a surprise benefit of giving mannitol is that you’ll see here that it also deepens the anterior chamber. So it has deepened it from 2.84 mean millimeter value to 3.30. So you will not only get an eye with pressure that is not high. You will also get a deeper anterior chamber, which reduces your challenges during the surgery. And this brings us to the next question. So you have to find the wrong statement. Which one of these is wrong? I’m not reading the options, because I want to take a break. Okay. So the maximum number of people feel that you should not use a rapidly acting mydriatic. And 40% have chosen the right option, that intraoperative pilocarpine will reduce the chances of floppy iris disease. This is a wrong statement. Now, the logic behind using a rapidly mydriatic combination, along with a long acting one, is because you don’t want the pupil to get stuck in the mid-dilated position. So you want it to move rapidly, and with strength. So that it can overcome the power of the sphincter pupillae, and not let the pupil get stuck in a mid-dilated position, and if that happens, that is when the intraocular pressure starts rising. The chances of a positive pressure and vitreous loss and aqueous misdirection go up. The other things I will discuss… So dilatation should be started 15 to 20 minutes — because the rise of intraocular pressure starts happening about 40 to 50 minutes after instillation of a mydriatic, when the action of the mydriatics become a little slower. So if you use a mydriatic, the action starts declining 45 minutes onwards, and it’s been noted that pupillary block happens about an hour and a half later. The painful pupillary block — so it’s probably set up around 40, 45 minutes. So you should not be doing the surgery at that point of time. And as I said, you should use a rapidly acting and a combination of strong mydriatic. Why do you want to use cycloplegia along with mydriatic is because it will help in deepening the anterior chamber, by shifting the iris lens diaphragm backward, and this is important especially in plateau iris, which is a risk factor for aqueous misdirection. And it is also protective against floppy iris. So it is not constriction which reduces floppy iris, but dilatation. And the iris in patients with angle closure, especially those who have had a PI, tend to be very floppy. And once you have the iris coming through the wound, or the phaco incision, it just begins a chain of unfortunate events. You should not allow this to happen. The other thing is: It is best to do these surgeries under topical anesthesia, but if you want to use anesthesia because of the challenging surgery, you should use the minimum amount of block. Minimum volume of block for a peribulbar anesthesia. Because the parameters here clearly show that the blood flow to the optic nerve head decreases after a retrobulbar anesthesia. And in an eye which is compromised because of primary angle closure glaucoma, it may react very badly and have a wipeout, if you reduce the blood flow further. At least, it increases the chances of wipeout, if you really push the huge volume into the orbit. Also, avoid compression or ocular massage with pinky ball. And it is shown in patients who have had peribulbar with compression, these are the patients where the optic nerve head blood flow becomes the minimum. Though the others are not spared. So the best way to go ahead is a topical or subconjunctival anesthesia. But if you want to give anesthesia, you should use either a posterior sub-Tenon’s or subconjunctival. If you have to give a peribulbar, avoid retrobulbar, which has greater chances of compressing the optic nerve and reducing the ocular blood flow. Give small amounts of injection inferotemporally. And wait for the eye to become soft, and then repeat if required. But don’t use any compression on the eye, to make it either soft or to spread the anesthetic. It is also important to avoid a large volume of local anesthetic, because it’s a risk factor for positive pressure. In our practice, we use a lightweight titanium self-retaining speculum, and make sure that it is not really stretching the eyelid, because once you start stretching it, the pressure goes and gets transmitted to the globe, and in a suspected — in a susceptible case, this may start a chain of increased positive pressure, and then go further onwards. Now, what is very often neglected: That straining also causes similar problems. So please ask your patient if they want to go to the restroom prior to the surgery, especially if you have given mannitol. Because that’s a very strong diuretic, and you don’t want your patient to desanitize your operation theater, and you definitely don’t want to be in a situation where the bag is touching the endothelium. Clear corneal phaco is the best option. But if one does a manual small incision cataract surgery, please leave one quadrant of conjunctiva untouched, if you need to do a trabeculectomy later on. You cannot use all the conj yourself as a cataract surgeon. Please, as a glaucoma surgeon, leave some conj for me. Clear corneal ECCE may work better than manual, because that is conjunctival sparing, but if the case is challenging, use the technique that you are most comfortable with. I will share a small video, which encapsulates the challenges and the principles of surgery. And this is a patient who had an acute angle closure. The lens has a very early cataract. And I’m doing a cataract surgery here. So what may be clear is that this is a topical anesthesia. And while going in with the paracentesis, I’m trying to be as parallel to the iris as possible. And also, making it slightly longer. Than other patients. If you see here, you can see the site of the peripheral iridotomy, and though this is my natural side to do a paracentesis, I’m going a little away, because the iris around this place is likely to be very floppy. Now, after you have done the paracentesis, you can dilate the pupil using either a viscoelastic… So what you see here is that I’ve gone and hid the iris. There is no space in the anterior chamber. And that is why what I did is started injecting viscoelastic down here, so the iris goes down, and then the anterior chamber can get filled up. Sorry again. So then the anterior chamber gets filled up from the top of the cornea, and not from the bottom, because that is likely to push the iris outwards, and be careful not to overfill the anterior chamber here. Because that again can push the iris back into the paracentesis. The rhexis tends to be slightly tricky, because these are large lenses, and the rhexis repeatedly needs to be pulled… (cell phone ringing) I don’t know if you were disturbed or not, but I definitely got disturbed by a call. So you need to be careful that the rhexis does not run out, and try to manage the rhexis with not a huge volume of viscoelastic. The phaco incision again should be slightly longer here. I am struggling with the keratome. Not a pleasant sight. When you do the hydro, don’t overfill the eye. Because if the lens starts coming out, coming up, it can become nasty. Now, typically, you are told to keep the irrigation on, while going in, but because here a sudden increase in intraocular pressure can again prolapse the iris, I went in with irrigation switched off, and then switched on the irrigation gradually. You can change the settings on your phaco machine to do that. And if you see the irrigation port is again not directed towards the pupil, because I don’t want to disturb the pupil. I don’t usually do a stop and chop, but here the advantage of doing a stop and chop is you will get a lot of volume, centrally. To do the phacoemulsification. And the fluidics will improve. And you have the vertical space to move — for the fluid to move. Now, because the fluidics here won’t work well, because of a crowded chamber, you may actually use the second instrument to pull the quadrants close to your phaco tip, before you actually do the phacoemulsification. Be careful to do the phacoemulsification away from the endothelium, because the natural tendency for you to be — for one is to come closer to the endothelium, because then you will get more space. But chop into multiple small pieces and do the phaco behind the pupillary plane. When you have taken a few pieces out, not a full quadrant, you will start getting more space, and you can later on do more phaco with a larger piece of the nucleus again. Now, I don’t know why I have so much of phaco shown here in the video. The IA is typical. Be sure not to shallow the chamber too much. The intraocular lens you place — this one is a hydrophilic intraocular lens. The haptics should be placed in 3 to 9 o’clock direction. You can move it with a bimanual or a Sinskey. Here I am using a bimanual to do that. And the superior and inferior — the 12 o’clock position is spared, because you might have to do a trabeculectomy later, and you don’t want the haptic of the eye to prolapse. Now, I’m getting iris into the wound, into the paracentesis here. So you start inflating from one end, but don’t inflate it too much. Go in very small steps, and once the iris falls back, make sure there is no leak, and then close the eye. At the end of the surgery, you always check the pressure over the cornea, with the metallic instrument, and don’t leave the eye overfilled. So this is what a typical surgery with angle closure glaucoma is. A lot of cases are much more difficult. We have many patients of plateau iris, who have a very small pupil. Principles of management of small pupil come into force. But largely the principles remain the same. So what about the postoperative management? Typically you give a steroid and antibiotic, but don’t forget to give oral acetazolamide, if it’s not contraindicated. And drugs which are contraindicated, like pilocarpine and PG analogs, should be replaced with alternate agents, and if required with oral agents, and it is beneficial to use NSAID drops for 4 to 6 weeks, especially if a prostaglandin analog has been used perioperatively. If you get a spike, before making a decision to go ahead with the surgery, control the inflammation as well as you can, because it is largely the inflammatory cells and pigments which are dispersed during surgery that cause the trabecular meshwork to function suboptimally. Use syrup glycerol to do this surgery. It’s best to do it 4 to 6 months later. But don’t run from it if you have to do it. You can resume PG analogs after 3 months. A very silly thing to write here, but I have seen cataract surgeons doing it. Do not forget to give a prescription of the antiglaucoma medication, rather than just telling the patient to continue the drugs. Because not everyone is as intelligent as the surgeon. And do not forget for the management of glaucoma you need to repeat the fields after two to three months, for a fresh baseline with clear media. One of the biggest questions that comes to us is: When do you decide to do a combined, rather than a cataract. Now, a cataract is preferable, because the combined surgery is associated with a lot of long-term complications and requiring a lifelong follow-up. But what is very clear is that in patients who have had combined surgery, the intraocular pressure tends to be lower than that with phacoemulsification. Provided both are done well. So you might want to do combined for the benefit of 2 to 3 millimeters of mercury in certain situations. Now, if a patient has advanced glaucoma and is on one or two medications, remember that the only medications he will be able to use in the immediate postop period, the only topical medications, are a beta blocker, an alpha agonist, and a carbonic anhydrase inhibitor. So if you have a patient on two or more medications with advanced glaucoma, who cannot tolerate spikes, the incidence of spikes with combined are much less likely than cataract. A patient with glaucoma on three or more medications, a patient whose glaucoma has been progressing despite good control, a patient who cannot afford the economic burdens of using multiple medications or whatever the current medication the patient is on. A patient who has difficulty in following up. Combined, after the initial follow-up, if the patient does well for the initial few months, is likely to do well for a very long time, and if the lens factor is insignificant, as measured by the lens vault. A lens vault that is less than 700 microns or so, though there is no definite cutoff — for me, that is the cutoff — is not very significant. So a lot of this stuff here was eminence-based rather than evidence-based, but this is what we practice at LV Prasad and largely across India would agree upon. So to summarize what I spoke ’til now: Very clearly the lens is an essential component of relative pupillary block, and a patient who does not have angle closure glaucoma will not go on to develop angle closure glaucoma if the lens is removed. A patient will not develop acute angle closure, and cataract extraction will cause a benefit in patients across the spectrum of primary angle closure disease. Though most in acute primary angle closure. Not all patients are benefited equally, and unfortunately we don’t know what factors will absolutely for sure predict the outcome as far as the intraocular pressure is concerned. In patients with acute angle closure, who are under good control or borderline control phacoemulsification is a good option. I would like to do a PI and then go ahead with the cataract surgery, because in our opinion here, the chances of developing an aqueous misdirection is lesser with a patent PA. And don’t treat this as a completely normal phacoemulsification. Take care preoperatively, intraoperatively, and in the postoperative management. So a lot of things that we know, but there are a lot of things which are still unknown. Which are the dynamic properties of the lens. Just like the iris, the lens also moves. So does that have a role to play? What are the causes of persistent occludability? And how are you certain whether it’s just a pupillary — plateau iris or the lens thickness that is causing it? And what kind of factors can predict the intraocular pressure outcomes and chances of complications in a patient with angle closure glaucoma? And surprisingly, even in today’s age, we are not sure of the IOL calculation. That are available. But there is promise in the form of new formulae. One has to remember that lens is not the only factor, and there are factors beyond pupillary block. So a patient with gross trabecular meshwork damage and goniosynechiae is likely to benefit a little lesser. A patient in whom plateau iris is a prominent factor — they may not benefit as much as other patients without these factors. So keeping in mind these factors, if one is careful and looks carefully at the data in front of their eyes, you can actually benefit the patient a lot if your cataract surgery is done carefully. So that’s all from me. And I’ll be happy to take questions from the audience across the spectrum.

>> Thank you, Doctor. We have two questions so far, if you want to open up the Q and A.

DR DIKSHIT: Right, so I’m trying to open it, yeah. I’m also trying to stop the share. Okay, I think I’m there. Okay, so I think a lot of these are questions about the certificate and proof of attendance. I don’t think these are directed at me. Oh, I was looking at the different outcome… Okay. So the first question is: Which is better? Combined or a single surgery? So as I said, if the patient has advanced glaucoma, you need to be very sure that there should be no spike. You need to be very sure that the patient does not need more than two medications, like an advanced glaucoma patient who is on three medications. There you would prefer a phaco-trab. But in most situations, in good hands, you would prefer to do a cataract alone, rather than a combined surgery. Iridectomy during surgery is not necessary, because you are eliminating a pupillary block, relative pupillary block, by taking out the lens. However, if you see an increased risk of aqueous misdirection, like in cases of severe plateau iris, a prior PI, laser PI, or a surgical PI, is not going to cause you any harm. What is your opinion about the use of anterior chamber maintainer in these types of cases? Excellent question. So anterior chamber maintainer — even in the presence — even when you’re doing a phacoemulsification — you would prefer to do if and only if you foresee a significant risk on shallowing of the anterior chamber suddenly. So this kind of risk is greatest in patients who have had an aqueous misdirection earlier in the same eye or in the other eye, and in patients with severe plateau iris, where you can see a sign clearly on gonioscopy, or you see a forward directed anterior ciliary process. Other than that, we don’t use anterior chamber maintainer. So Olly is asking: I once performed an argon laser iridoplasty of an NLP eye with phacomorphic glaucoma. What do you want to do in such a case? You have to really be sure that the eye has no visual potential. Now, by the virtue of having a pressure of 50 millimeters of mercury, an eye with otherwise 20/200 vision may become no perception of light for a temporary time. But the more common cause that falsely gives you no perception of light is not using a bright enough source of light. So if you are not 100% sure that you’ve taken care of this, please take care of this. But if you’re sure that the eye has no perception of light, surgery would be indicated if the patient is in severe pain, because of the raised intraocular pressure. And you cannot control the pressure otherwise. But transscleral cyclophotocoagulation is also an option to reduce the pain, because in a patient who has long-term and severe glaucoma is also a risk factor for aqueous misdirection. So tread carefully, but there may still be situations where you want to do a cataract surgery and take out the lens which is causing the problem there. Any role of topical glycerin to decrease corneal edema? I have not personally used it, but I have seen videos. I know of people who use it. If it’s available as a sterile solution, you can definitely use it. Otherwise, in situations where you desperately need a view, scraping off the epithelium is an option. Because the edema — because of raised pressure — lies within the epithelium, the microcystic edema. Okay. The next question is: In angle closure patients, should you use adrenaline? Yeah, I like to use adrenaline. If there is no cardiac disease, be careful not to excessively use adrenaline in patients with cardiac diseases, because it can cause tachycardia and challenges the heart to pump more. So not only intracameral adrenaline dilates the pupil, but it will also act as a prevention factor against floppy iris. Along with intracameral adrenaline, you can also use an intracameral preparation of lignocaine, because the mechanism of action for dilatation through lignocaine is different from adrenaline. It acts as an adjuvant to adrenaline. I have found that adrenaline mixed in the irrigating solution of about 500 milliliter in a volume as low as 1 milliliter in 10,000 works well. So you don’t really need to inject adrenaline separately. Just the irrigating fluid that you have in a syringe for hydro procedures will serve equally well. No harm in using intracameral adrenaline. So I think I have answered this question already, the iridectomy. Oh yeah, pupil expanders are a must. This is a very interesting question, because the view that we share here is that in eyes with angle closure glaucoma most of the intraocular pressure rise happens because of pigment dispersion. So manipulating the pupil, touching the pupil, is something that you don’t really want to do. If you can do it without the pupil expanders, which will cause pigment dispersion, do it. But if you think the safety of the surgery is compromised, please don’t hesitate in using a pupil expander. Also, an iris hook rather than a circular pupil expander or eye pupillary ring like a Malyugin ring, or a B-HEX ring that is available in India, would be preferable, because that is additional protection against floppy iris. So an iris hook over a ring, if you have to use it. Okay. Now… You are doing peripheral iridotomy in patients with PACS? Okay. Now, usually we don’t do anything for patients with PACS, apart from observation. There is lack of good quality data, but the present understanding is that over a period of five years, maybe only 10% to 15% of patients will progress to PAC, and none of them to PACG. So if over a five-year period none of these patients are going to have any visual field loss or optic nerve damage, why do you want to treat these patients by doing anything? I would guard against doing a clear lens extraction for any of these patients, because as you saw, the visual acuity outcome in many of these studies is not optimal. So if a patient who is 20/20 with maybe even hyperopic glasses like me — you can not be 100% sure that you will get the patient a 20/20 vision after doing a clear lens extraction. So the risk in my opinion is high. I wouldn’t recommend that. Site of PI? The recent studies of a large number of patients from India has shown that the site of PI does not differ. Does not make any difference, as far as visual symptoms are concerned. However, again, there is another caveat here. It’s that the angles tend to open maximally near the site of the PI, though there is not much difference. So you can choose to do it slightly superiorly, because in most of the primary angle closure disease, the superior angle is shallower than the inferior angles. But in a patient who has thick iris and a crypt that’s 6 o’clock, please don’t hesitate in doing it anywhere. There is hardly anything — any way that you can harm the patient, and I do it anywhere. None of my patients actually complain of any symptoms. I have had patients who have a well-covered peripheral iridotomy done superiorly and have symptoms, and even the randomized controlled trial did not show any difference in visual symptoms. So visual symptoms point of view… Nothing to care about the site. The superior angle closure is first in primary angle closure disease, across all the spectrum. However, there is a variety of angle closure that is called creeping angle closure. Where the angle closure closes gradually in all sites. So if you see an angle that is partially closed all around, then you can diagnose creeping angle closure, and it is a progressive disease. There you need to do PI. Otherwise it will progress further.

>> All right. Thank you, Dr. Dikshit. I think this is a good place to stop.

DR DIKSHIT: Yeah, I’ll stop — because one question has come, Lawrence. I’ll just answer this. The role of vitreous tap is controversial, but can have a role in patients with proven risk of malignant glaucoma and anophthalmia. But be very careful while doing it. You can not do it with syringe and a needle. You need to do it with a very well controlled automated vitrector. I have come across many cases and witnessed one case which had a suprachoroidal while doing it. So this is not risk-free. If you can do without it, please do without it. If you want to really do it, please make sure that an expert is handling a very good quality anterior vitrector, which is not a probe that is meant for anterior vitrectomy, but one that is meant for pars plana vitrectomy. Right, right, Lawrence. I’ll take your cue and leave, and thank you so much, everyone, for attending. Thank you, Cybersight. Thank you, Lawrence.

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December 13, 2018

Last Updated: October 31, 2022

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