During this live webinar, we will discuss the diverse anatomic disorders characteristic of Angle Closure. Classification of angle closure based on the pathophysiology, and the implications for management will be reviewed.
Lecturer: Dr. Louis Cantor, Ophthalmologist from the University of Indiana, USA.
Dr. Cantor: Good morning. And welcome to everyone, it’s a pleasure to be presenting this morning and to share a little bit of time with all of you. We have a really large and wonderful, diverse group from all over the world. It’s nine o’clock in the morning here in Indianapolis, where I am. But I hope this finds you and your families all well. I want to thank Cybersight, first of all, and Orbis for making this possible. And a special thanks to Laurence, who is in the background, who’s really the individual who organizes all of us and allows all of this to happen smoothly for us this morning.
I’m Lou Cantor. I’m the Jay C. and Lucille L. Khan Professor Emeritus at the Eugene and Marilyn Glick Eye Institute at the Indiana University School of Medicine in Indianapolis. I’ve been director of the glaucoma service at our university since I started it 36 years ago. I’ve served in many roles, but probably most recently and one that’s relevant to education, is as the immediate past Senior Secretary for Education for the American Academy of Ophthalmology.
It’s a pleasure to spend, again, a few minutes together. We’ll cover some material regarding angle closure glaucoma today. Hopefully provide some insights and new information or reinforce some of what all of you may already know. At the end we’ll have some time for a few questions, depending on our timing, which we’ll try to get to. Without any further delay, let’s launch into our topic this morning of angle closure glaucoma.
We’ll start with primary angle closure and then later we’ll move to the secondary angle closure glaucomas. When we talk of primary angle closure glaucoma, most of our thoughts go immediately to acute angle closure glaucoma with pupillary block, which we’ll talk about. In some populations, certainly in the U.S., this accounts for about 90%, or the majority. But globally, that certainly varies by populations. We’ll talk about the pathophysiology about how this occurs with impedance or resistance to aqueous flow between the anterior lens service and the posterior iris surface. And we’ll talk about relative and absolute, especially when we get to the secondarily glaucomas, we’ll talk more about posterior synechiae and secondary causes.
To get us launched, I have a quick question. Which of the following regarding eyes predisposed to primary angle closure compared to normal eyes is false? You’ll have 20 second here to submit your answer. And looks like flatter corneal surface or smaller corneal diameter were primarily chosen. The answer is flatter corneal curvature.
The anatomic features, compared to normal eyes, eyes with angle closure tend to have smaller diameters, steeper corneal curvatures, shallow anterior chambers, thicker and steeper lens, a more anterior lens position, and shorter axial lengths. From these findings, we can usually predict eyes that may be predisposed to angle closure.
In terms of epidemiology, different races and populations have different risk of glaucoma. In the white/caucasion population, there’s about 2% risk of narrow angles in the population. But less than .1% actually develop acute angle closure glaucoma. In Asian populations, chronic angle closure glaucoma is common but acute attacks seem to be relatively rare. And in an African Americans and other African-derived populations, acute angle closure glaucoma is also relatively rare. Women, in most populations, have a higher risk of developing angle closure, three to four times more risk. They tend to have shallower anterior chambers. And in general, populations, especially in the white/caucasion populations, have hyperopia. Although myopia is not uncommon in Asian populations.
The prevalence of angle closure glaucoma increases with age, the anterior chamber depth decreases with age as the lens thickness increases. And the peak incident seems to be between 55 and 70 years of age in most epidemiologic studies. If we see a patient with primary angle closure who’s less than 50 years old, then you really have to have a high index of suspicion for plateau iris. And the risk for developing angle closure is certainly increased in first degree relatives of those who have angle closure.
As I’ve mentioned, the anterior chamber is really the key anatomic feature and the most important predisposing feature. That relatively forward position of the anterior lens surface in relation to the iris root and iris, the shallow depth of the anterior chamber due to that forward positioning, and increased lens thickness. And the anterior chamber depth can certainly vary throughout the day and some mild asymmetry is not uncommon. Normally the lens increases approximately a millimeter over a lifetime. And not only does it become thicker, but the anterior lens surface steepens with age, increasing that relative pupillary block or resistant to flow between the anterior lens surface and the iris. So the anterior iridocorneal angle width and depth are affected.
This is just a schematic of pupillary block where fluid behind the iris has a bit of resistance to getting between that space, between the iris and the anterior lens surface and into the anterior chamber, therefore pushing the iris forward. We call this relative pupillary block. Some degree of this normal. Most of us who don’t have glaucoma have some mild anterior bowing of the iris, just as a normal physiologic state. But when it gets to the point where there begins to be appositional closure or contact between the peripheral iris and the anterior chamber angle, then closure can start to occur and synechiae may gradually form.
This is a histologic section of an eye that had pupillary block with angle closure and you can see the very forward position of the iris, the shallow anterior chamber. And then on the left, the total obstruction of the iridocorneal angle.
The role of the lens and lens surface, as we’ve mentioned, is very common. But also, the relative tension or lack of it, of the zonules, can affect the lens position. And loose or relaxed zonules, either congenitally, or associated with pseudoexfoliation, or trauma, can allow the lens to migrate anteriorly and increase pupillary block and the risk of angle closure. Pupil dilation causes the peripheral iris to be thrown into folds. And may also, in the proper position, increase some of that relative pupillary block, as is shown in this schematic.
To assess the angle, and this is really critical in angle closure, you have to be skilled and have good knowledge of gonioscopy to really assess the iridocorneal angle in any patient who may be predisposed to angle closure. For that matter, any glaucoma patient. And gonioscopy is not only important for diagnosis, but for follow up as well.
For our second question, to challenge a bit of our basic understanding. From innermost going outwards, what are the layers of the trabecular meshwork? And again, this is going from the anterior chamber side outwards, peripherally. You will have 20 seconds. This was a hard question and it takes a lot of knowledge of that microarchitecture. The correct answer is uveal to corneoscleral to juxtacanalicular.
So here’s a schematic drawing of what the normal anterior chamber looks like. We see the layers, as I’ve just mentioned, of the trabecular meshwork going from uveal, toward the anterior chamber, corneoscleral next, and then juxtacanalicular, which is adjacent to the canal. Scleral spur, ciliary muscle, iris root and so forth.
I want to introduce, or cover briefly, our classification systems for assessing the angle and especially the Spaeth Gonioscopic System.
The goal of gonioscopy is to distinguish pathologic aspects off the anterior chamber angle from infrequent, but normal, variations. We know that the angle can vary quite a bit. There’s been a number of grading systems to do this, which we won’t cover all of them in detail, but I’ll mention a few of them briefly.
The penlight exam where the anterior bowed iris casts a shadow across the iris when you shine a light from temporally, is a quick, but obviously not very sensitive or informative test. But can certainly give you an idea as in this photograph, that maybe the anterior chamber is shallow so that the light is blocked from casting light on the entire iris. And the opposite side from the light is blocked. We often also use at the slit lamp, the Van Herick System, which looks at the peripheral anterior chamber depth and compares it to the corneal thickness as seen with a narrow slit beam on our slit lamp. And we compare the peripheral anterior chamber to that corneal thickness. So that with a deep, what we call grade four chamber, the peripheral anterior chamber depth is greater than the corneal thickness. For example, we’ll look at a couple pictures here.
So here’s a slit lamp photograph. We’re in the peripheral angle, which is where you want to be, just inside the limbus to do a proper Van Herick. We’ve got a very narrow slit beam, coming in about a 45 degree angle, and we see it cutting through the cornea optically. And then we see that gap of the anterior chamber before the light hits the iris. Here, we have an anterior chamber depth peripherally, which is probably a little less than the corneal thickness, which would make us a bit suspicious.
Here is another example where there is no gap present. The slit beam going through the cornea ends when the light hits the iris with no intervening anterior chamber, indicating a closed angle in this particular example.
The Shaffer System, while we don’t often refer to that name. But we talk about grade one, two, three, four angles, refers to really just the angular approach. Spaeth, however, in the late ‘70s, developed a system looking at what I believe are the three critical aspects of the angle that are important to understand in order to assess eyes with glaucoma, in general. And particularly, angle closure. And those three key components, which we’ll go through, are the iris insertion, where does the iris actually insert into the internal lining of the eye? What is that angular approach and also what does the peripheral iris contour look like? And there’s other things that you may note, but those were the three keys.
So let’s look at iris insertion. The iris can insert very anteriorly if there’s closure, into Schwalbe’s line or into the meshwork, even. And A and B iris insertions are always considered abnormal. It can be a scleral spur, which can be normal. It can be a deep angle recess where you see some ciliary body, or an extremely deep angle recess where you see lots of ciliary body.
And here’s just a schematic showing what an A, B, C, D, or E insertion looks like, relative to the trabecular meshwork that’s shown in this diagram. And if we look at some examples of this, of these various insertions, we can see that although the approach of the iris to the angle’s pretty similar in all these pictures, where the iris inserts is very different.
We then look at the angular approach. Now this isn’t the recess, this is an angular approach looking at the middle third of the iris to a line that forms a tangent there to another line which is tangent through the trabecular meshwork. Which, essentially, is what Shaffer did. So we draw this angle in our, we have to sort of visualize this in our mind. It’s not actually something that we see, but we estimate. And a normal eye would probably have a 35-40 degree angular approach. And again, that’s the middle third of the iris to the peripheral line that’s drawn through the trabecular meshwork.
But that’s not all there is to know about the angle. There’s still a very important part which is often overlooked. And that is, what does the peripheral iris contour look like? Is it flat, is it concave or posterior bowing as we might see in pigmentary dispersion? Is it bowed anteriorly or convex, or does it have a plateau or peripheral iris hump?
So putting it all together, we have the A, B, C, D, E insertion, followed by the angular approach, followed by the peripheral iris contour. And if we know these three things, we can describe the angle quite well and in exquisite detail, really. We use a system, the Spaeth System uses this classification. For example a D40f, would be a typical normal angle. But you can describe it in your own terms if you want to describe the anatomy more specifically, or if you want to use the code, if you will, for the system. It’s just something that makes it easier. And this is how we put that all together.
Here’s an example that I think illustrates some of this very well with UBM. So here we have a ultrasound biomicroscopic image, of an angle with angle closure, there seems to be bowing of the iris forward. We also see something behind the iris, which looks a little odd. But we know we have angle closure here. So our first step in treating this eye, once we understand the anatomy that there’s this anterior bowing of the iris, so we might describe this as an A, perhaps 20 or a 30 degree angle iris, that has a steep or concave, or even plateau iris configuration.
So the first thing you do is you do a peripheral iridectomy, in treating an eye like this. And with the peripheral iridectomy as is shown here on the UBM, the iris bowing seems to go away but the angle recess, if you look at their, is still very narrow and almost closed. Suggesting a plateau iris exists here. So you can have combinations of pupillary block with iris bowing with a plateau iris. So what do we do for the plateau iris? We do peripheral iridoplasty to thin that peripheral iris and get it away from the angle and open it up.
Let’s talk about some of our forms of angle closure. We have intermittent angle closure, which is where you have these repeated brief episodes, maybe there are some symptoms of dull ache, mild halos, blurring. But the eye seems fairly normal between episodes. Maybe it occurs in dim light or when someone’s reading, they’re self-limiting, usually lasting 30 minutes. And if we diagnose angle closure here and do a laser iridotomy, or we’ll talk about some alternatives in a minute here, that’s usually definitive and diagnoses it for us.
Sub-acute angle closure has somewhat more severe symptoms. Seems to be more common in Asians. Can produce a chronically dilated pupil from some iris ischemia that’s induced through the high pressure. With iris atrophy, angle closure with PAS can start to occur, and iris pigment starts to accumulate as it’s knocked off the iris.
Acute angle closure is the full blown attack where there’s more absolute pupillary block. Usually occurs when the pupil is mid-dilated. There can be a number of precipitating events that can predispose to acute angle closure. But often a precipitation event is not evident and does not have to be present. Again, the symptoms, sudden marked increase in pressure. You get corneal edema, leading to blurred vision, pain, and halos. Conjunctival hyperemia, patient may have nausea and vomiting. You’ve got a mid-dilated, fixed pupil and the iris looks bombay or bowed forward. And here’s a typical picture of an eye that’s very congested looking, very red. There’s corneal edema, shallow anterior chamber and so forth.
There may be an inflammatory reaction. If you look at the optic nerve, when there’s very high pressure you may see some disc hyperemia and even edema. But then you get pallor and cupping later and you can certainly be predisposed to having something like a central retinal vein occlusion during these high pressure episodes.
These attacks may spontaneously terminate because of iris ischemia, that finally allows aqueous fluid to get into the anterior chamber or through treatment. But can have visual field loss, cataract formation. And we can see this here, a very commonly talked about symptom. It’s not one you’ll always see very often, but these are little white flecks in the anterior cortical material of the lens. They’re called glaucomflecken. And as I’ve said, these are just infarcs of anterior cornea lens epithelial cells causing these opacifications. Some of which may fade once the pressure is normalized. But may also lead to progressive cataract.
Chronic angle closure develops from portions of the angle are permanently closed by PAS. There can be appositional closure and usually is first, with then creeping angle closure. And occasionally this may lead to an acute attack. But often chronic angle closure has minimal symptoms and may act like primary open angle glaucoma in many ways, and be overlooked unless proper gonioscopy and appreciation of the angle occurs.
Plateau iris, as we’ve mentioned earlier. There’s this plateau iris configuration where you see this hump, if you will, in the peripheral iris root that bows anteriorly. But then the central iris and the central anterior chamber is usually relatively well-formed and deep. When you have plateau iris syndrome, that means you’re starting to develop angle closure. The key to plateau iris, as was somewhat demonstrated in that case I shared just a few moments ago, is that you have to have a patent iridectomy or iridotomy, depending upon your terminology, first, to really confirm the diagnosis of plateau iris. You can suspect it, but there’s often a component of pupillary block as well. But if the angle remains narrow and capable of closure, after a patent iridectomy, then you have plateau iris.
Plateau iris is the result of large and anterior position ciliary processes and anterior positioning of the ciliary body, that pushes that peripheral iris forward. And on indentation gonioscopy, when you try to open the angle by applying pressure to the central cornea, you can see that hump. This is, it’s hard to photograph this, because just pressing on the eye can cause some stria and distortion of the cornea. But if you follow the light along the iris, we’ve pushed on an eye that has plateau iris. And while the more central iris goes back, in the periphery you see a hump. And that’s the plateau that’s causing the narrow angle and angle closure.
Here’s some examples again from ultrasound biomicroscopy, showing the anatomy with the anterior ciliary body processes that are contacting the posterior iris and closing the angle in this case. But with a deep central anterior chamber and fairly flat iris here.
This usually occurs in younger patients, often women. Family history is common and again, there may be some component of pupillary block. The treatment, first and foremost, is do a laser iridotomy to rule out the pupillary block or relieve it, and then treat with iridoplasty if the angle still appears capable of closure. So you want to eliminate the pupillary block, reopen the filtration angle with the iridoplasty, and control the pressure. Because there may still be some elevated pressure from prior damage to the trabecular meshwork.
The treatments can be quite varied and it really covers the spectrum. You can use hyperosmotic agents, carbonic anhydrase inhibitors I.V. or p.o., or any of our topical agents. We most often go with drugs that cause some degree of aqueous suppression. It seemed to be most effective, but any of our drugs can work. You do have to be a little careful about Pilocarpine in some of these eyes. As Pilocarpine can also, especially if used in higher concentrations of 3 or 4%, cause some anterior rotation of the ciliary body and narrowing of the angle more. So we try to use more 1 or 2% Pilocarpine as is mentioned here. Corticosteroids can be a useful adjunct because there’s often inflammation from the ischemia, and then treat other symptoms as needed.
In treating angle closure, sometimes to break an attack, you can just do corneal compression with a cotton tip applicator, a gonioscopic lens, even a muscle hook, or even your finger. Just to push the iris back and try to break the cycle of pupillary block, temporarily at least, so that you can relieve some of the corneal edema. Maybe make it easier to do your laser, give the patient some pain relief. So sometimes this is just a very quick intervention. Doesn’t always work and isn’t always effective, but can be.
The traditional treatment has been laser iridotomy to relieve pupillary block, that can be done with a YAG or Argon laser, whatever you have available. These are usually performed and should be performed, generally as peripherally as possible. If there are some preexisting iris crypts, I tend to look for those crypts because the iris is already thin there. There’s discussion about the position of where you should put these, because something can see a little stray light through their iridotomy. I still prefer to place these superiorly and under the lid rather than nasally or temporally, but it doesn’t really matter in terms of relieving the pupillary block, where the iridotomy is. And you can choose placement however you prefer. But I find that the issue of having that ghost image is relatively infrequent and I still perform these, typically, superiorly. While not at 12 o’clock, usually just to the side of 12 o’clock, perhaps at one o’clock or 11 o’clock or somewhere under the upper eyelid.
Here’s acute angle closure again with UBM, showing the anterior bowing that was relieved with a laser iridotomy and opened the angle.
When you have an eye that has angle closure, of course you have to pay close attention to the fellow eye, as there’s a high risk of angle closure in fellow eyes. And they generally should be treated with a laser iridotomy.
Again, repeat gonioscopy. Many eyes that have angle closure, even after the iridotomy has been performed, the angle may still remain narrow. Perhaps from plateau iris. They may have extensive PAS and the angle may not stay down, they may need medical therapy and follow up, and progreessive PAS can occur in some patients. Long-term, you want to continue medical therapy for the pressure, but be prepared to consider other procedures if necessary.
Now there are a couple studies, recently, that have begun to change how we want to look at angle closure. One is the ZAP Trial, which many of you may be familiar with. This was a study looking at angle closure prevention. And this was nearly 900 patients, where one eye received a laser and the other eye did not. The ages were between 50 and 70. These were primary angle closure suspects that had to have at least 180 degrees of appositional closure, even synechiae closure, but without elevated pressure. And they also couldn’t have a positive provocative test with dilation or dark room testing. They were followed for quite a long period of time.
Nearly 1200 individuals were screened for the 889 that were randomly assigned. Here’s the treated and untreated numbers. And the incidence of the primary outcome was that 19 of the treated and 36 of the untreated eyes developed elevated pressure and angle closure glaucoma, there were no significant adverse events. But the rates were relatively low for these large numbers of patients. So some of the conclusions the authors drew were that the incidents of angle closure disease was low, first of all, in that population. The laser peripheral iridotomy had a modest, but significant, prophylactic effect. But in view of the low incidence rate of outcomes they were advising at least in a broad sense, about prophylactic laser for primary angle closure suspects is not recommended based on their conclusions. I still think that this needs to be taken in the context of whatever your population is and the patients in your community and the ability for follow up. If follow up is more limited, I would still learn towards intervention more often than not.
There’s also the EAGLE Study. Which looked at clear lens extraction which has been discussed a great deal recently with regard to angle closure glaucoma. This was 419 eyes that were randomized to either clear lens extraction or laser iridotomy. Here’s the inclusion criteria. They had to have primary angle closure with elevated pressure. And here were the demographics of that population that were presented. Their refraction, they had early disease with a mean defect of minus three. But they had glaucoma with glaucoma damage.
At year three, without going through all the data, eyes that had clear lens extraction were on less medications and were less likely to have undergone glaucoma surgery than eyes that underwent laser. The complication rates between the two groups were very similar. The authors’ take home points were that cataract extraction can greatly improve intraocular pressure in patients with primary angle closure glaucoma, that medication burden was less compared to PI, and that maybe we need to start considering clear lens extraction as a treatment. This is still being debated, I think that these results need to be taken again in the context of local populations and practice. I’ve not advocated myself in many patients for clear lens extraction, but certainly if patients are at the early stages of developing a cataract, or have early symptoms and present with angle closure, and are starting to have some visual disability from cataract. Perhaps it’s worth considering early on, but I still, generally, in most of these patients, will opt for the peripheral iridotomy first.
So let’s move on to discuss a few of the secondary angle closures. I mean either one of these topics could easily have filled all of our time, because this is such a varied group of disorders. But let’s try to hit some of the highlights and some of the major secondary angle closure glaucomas.
First of all, when thinking of secondarily glaucoma, think of the mechanism. Is the iris being pulled forward or is it being pushed forward? So this pull-push understanding of the mechanism is very important because it will direct treatment to large extent.
Anterior pulling, so what could be pulling the iris up and closing off the angle? Angle neovascularization is perhaps the most common with neovascular glaucoma. Where you get conjunctival congestion, there’s iris neovascularization, ectropion uvea, anterior chamber inflammation, elevated pressure, synechial angle closure that are occurring. This can occur, obviously, associated with many causes, most common are probably diabetic retinopathy and central retinal vein occlusion from hypertensive disease. But uveitis, carotid occlusive disease with anterior segment ischemia, uveitis, tumors, and so forth can also cause neovascular glaucoma.
This is a gonioscopic image of a very early stage. While it’s difficult to see, there’s some fine little vessels in the angle that are just starting to develop. But the angle is still open. So this is an early stage of neovascular glaucoma. What you have to realize is that neovascular glaucoma is not just neovascular. It’s actually neofibrovascular. So there’s always a fibrous component and a membrane that grows with these vessels. The vessels are just the easiest to see and to visualize. But even with the angle open as it looks here, the pressure can be quite elevated because of that membrane that is occluding the trabecular meshwork. And it’s only over time that that membrane contracts and the angle closes. So neovascular angle closure is actually a late-stage of neovascular glaucoma, once there’s a neofibrovascular membrane and the angle that has already had time to contract.
So you see those vessels and there’s that associated fibrovascular membrane. You get PAS that are usually broad-based. And you can get other causes of elevated pressure in these eyes with debris, with blood, with inflammation. They may be on steroids, you may get synechiae around the pupil from the neovascular membrane that obstructs the pupil and leads to pupillary block as well. Which would be a posterior pushing mechanism on top of the anterior pulling mechanism, so therefore combined.
Here’s what some of the PAS will look like as they form these broad-based PAS that will gradually coalesce and close off the angle.
Another interesting condition that fortunately we don’t see very often is epithelial downgrowth. Where epithelial cells proliferate through a wound and they grow on the iris and they lead to membranes which then close the angle. There’s often a wound gape or incarcerated tissue and can be years after surgery for this to occur. You can see cysts, you can see adhesions, detachment of Descemet’s. This is kind of fun when you see it because if you aren’t sure what’s going on, you can use an Argon laser at relatively low power with a large spot, to irradiate the iris and outline where the membrane is. Such as is shown here in this image, those white spots in the center of the image are actually laser spots that were applied to the iris that define the extent of the ingrowth.
Other syndromes, the ICE syndromes: Iris atrophy, Chandlers, and Iris neves/Cogan-Reese syndrome. Can also lead to an anterior pulling mechanism where you have this abnormal change in the cornea that leads to growth and changes in the corneal endothelium, such as it grows over the angle and it acts more like a membrane with endothelialization of the anterior chamber angle and contraction, pulling it and PAS are common. And this is often what the cornea looks like in this syndrome with that ground glass, abnormal appearance. And you get these very abnormal appearing eyes and iris can be stretched and on UBM it closes the angle by pulling the iris forward.
The posterior pushing mechanism also can be the result of many different causes. One may be supraciliary effusions that cause anterior rotation of the lens-iris diaphragm. It can be somewhat localized or diffuse and annular effusion that’s very anterior. Hypotony, chronic inflammation, elevated episcleral venous pressure, scleral buckling procedures, extensive laser, sulfa medications can all lead to these effusions.
Here is an example where there’s an effusion shown to the left of that image where that star is. That’s a supraciliary effusion pushing the ciliary body forward and that subsequently pushes the iris forward. Here’s a picture of an eye that’s congested looking that has such an effusion.
Tumors may do so, most frequently uveal or ciliary body melanomas. This is an ultrasound showing a ciliary body melanoma, that in that region is closing the angle through a posterior pushing mechanism.
Lens-induced angle closure can cause pupillary block, which from an intumescent lens, a dislocated or subluxated lens, a microspherophakic lens, or complication related to anterior posterior chamber lenses, or phacomorphic glaucoma where you have a large, swollen lens pushing the iris forward. This is an example of an anterior chamber lens that was placed. And you can see in the slipping that the iris is starting to bow around the lens as there was no iridectomy performed in this procedure. And the lens is blocking the pupil here, causing the build up of pressure behind the iris and iris bombay. And after a laser was performed, you see the anterior chamber’s nice and deep, and all’s well.
Small, nanophthalmic eyes present unique challenges. These are unusually small but normally shaped eyes. But the lens is large for the volume of the eye. So remember we talked about the role of the lens previously. Well, here you have a small eye but with a normal sized lens that’s taking up extra volume, really crowding the anterior segment. Plus they have thick sclera, which seems to impede uveoscleral outflow. And they can get choroidal effusions and develop glaucoma, typically in the earlier decades of life.
And here’s an example of an eye with nanophthalmos with a very narrow anterior chamber. Also is developing a cataract here, also contributing to an increase in the lens size that finally tips things over into angle closure. And the thickened sclera, as is often seen in these eyes, can be a component as well.
Aqueous misdirection is a condition where the aqueous humor gets redirected posteriorly and accumulates posteriorly pushing everything in front of it. The lens-iris diaphragm forward and causing progressing anterior chamber shallowing, often called malignant glaucoma or ciliary block glaucoma. This can be a particularly challenging condition. Most often occurs after surgery and most often in eyes that were already predisposed to angle closure glaucoma. And those are the eyes that are at most risk for developing this condition. Even with just routine cataract surgery, but with glaucoma filtering surgery, can even be seen after laser. And I have seen cases where this condition seemed to occur spontaneously with no evident precipitating event or surgery.
Clinical features, you get a shallow central and peripheral chamber, so it’s not just pupillary block, it’s everything moving forward. And that’s what distinguishes aqueous misdirection from pupillary block where it’s primarily bowing of the iris peripherally, more than centrally. But in aqueous misdirection everything is moved forward, the central and peripheral anterior chamber,. The pressure goes up, can occur in phakic, pseudophakic, or sometimes even aphakic eyes if the anterior hyaloid is intact. You’ve got to differentiate it from a choroidal effusion, a pupillary block, or suprachoroidal hemorrhage. Ultrasound can be very helpful here if you can’t get a good look with your indirect into the back of the eye.
Here’s a case that had aqueous misdirection. There’s already been laser put in the eye and it’s still shallow. The management here is intensive cycloplegia, and pupillary dilation, aqueous suppressants to stop the posterior flow, or at least reduce it of aqueous. Maybe hyperosmotic agents to dehydrate the vitreous. You probably don’t want to use miotics. And then a laser can often be helpful, especially if there’s already a patent iridectomy, if not, you can perform an iridectomy. And just keep going until you go through the anterior hyaloid, which is relatively easy to do in pseudophakic eyes. And you convert the eye into a one chambered system. To have aqueous misdirection, you have to have an anterior and posterior chamber that are divided where they are competing against each other. If you open communication between the front and the back of the eye, and create it into essentially a unicameral, or one chambered system, then you can’t have aqueous misdirection because the aqueous can freely move forward. If laser isn’t sufficient, vitrectomy may be necessary to remove the vitreous and rupture the hyaloid face. If it’s a phakic eye, you may even need to remove the lens and get the anterior chamber reformed and get flow going in the right direction again.
And again, here’s that case I showed you before, above and then after treatment for the aqueous misdirection. The anterior chamber has deepened. This was done with just laser rupture of the anterior hyaloid.
So that’s a very quick overview of a very broad and complex topic of angle closure glaucoma. We’re going to open it up for questions here in just a minute. We’ll try to get to as many of the questions as we can. I’ve given you my email address if you have specific questions that we don’t get to, I’m happy to try to respond to as many of you as I possibly can. And to answer any questions. But I thank you for your attention and we’ll move to look at the questions.
We’ll start looking at some of the questions here. The first question I see is if a patient has cataract with advanced angle closure, do you do combined surgery or only try cataracts if you can open the angle with indentation? Very good question, I think it depends on the status of the eye. If they have cataract and angle closure but you can open the angle and there isn’t much optic nerve damage or the intraocular pressure hasn’t been very high, then you can certainly try cataract surgery alone. However, if there’s already significant glaucoma damage and poorly controlled pressure, then I might be inclined to go with some sort of combined surgery. And that combined surgery may be cataract surgery combined with a number of different glaucoma options, up to and including trabeculectomy. If there are some synechiae present, some may try a goniosynechialysis procedure at the time of cataract surgery to open up any PAS that may have been there and if the damage isn’t too bad. But if the damage is more advanced and this has been going for awhile, first of all, there would probably be a PAS and you may need to go all the way to performing a filtering procedure.
There was a question about what is iris synechiae? Synechiae is a scar tissue that develops anywhere in the eye. So it can be at the peripheral iris between the iris and the trabecular meshwork. That would be anterior synechiae. It could be between the iris and say the anterior lens surface, that would be posterior synechiae, that would occlude the pupil.
The next question has to do with how much aqueous fluid flows from the uveoscleral outflow? Estimates on aqueous flow and the relative contributions of uveo versus trabecular outflow vary. The majority of outflow in most eyes is trabecular. And that is probably anywhere from 60-80% and then the rest of it is through the uveoscleral outflow pathway.
There was a question about how many cases and percentage should be treated surgically? If I understand that question, in angle closure specifically, you have to really look at what form of angle closure we’re talking about. If we’re looking at a narrow angle with primary angle closure, I think the majority of these eyes can be managed with laser and medical management and not require surgery just for the glaucoma. Now they may develop a cataract later and become a candidate for cataract surgery. So I think that the majority of cases can be managed conservatively.
If we’re talking about some of the newer evidence around clear lens extraction and how many of those should we consider? I think that’s still evolving. For me, personally, anyway. Clear lens extraction is a very good procedure, but it’s not a completely benign procedure in a patient who doesn’t yet have a cataract and visual symptoms. So I think that’s still a very individualized question. I think most of these cases can still be treated conservatively.
The next question is excellent. Can the angle close again after treating? And the answer is absolutely yes. So that’s why repeat gonioscopy, as I mentioned, is so critical. You have to continue to follow these eyes. Number one, you may do a laser deep in the angle, but the PAS that are there may contribute to further zippering of the angular closure over time, even without significant pupillary block. In addition, there’s often some residual pupillary block. Your laser iridotomy can close or maybe it wasn’t big enough to start with to allow for enough flow, so that the angle remains narrow. So there’s a number of reasons why an angle can continue to close, so it’s very important to follow these eyes closely and to do repeat gonioscopy.
The next question had to do with can we see in gonioscopy the iris insertion and peripheral iris configuration? Yes. The peripheral iris configuration is something that we do see. That’s a direct visualization. We look at, through the gonio prism, or gonio lens that we’re using, and we can see what the contour is, what the peripheral iris looks like. Is it relatively flat, is it bowed forward? Is it concave like we might see in pigmentary? Or is it just a normal, relatively flat configuration? So that we can see. And the iris insertion, we can see at what level that iris is inserting into the angle. The part that we don’t see directly, that we have to sort of estimate in our mind, is the angular approach. What approach is that iris taking to the angle?
Among all methods used to grade the angle, which one is considered gold standard or much more recommended? Everybody gets comfortable with different ways of describing the angle. And what is important is to grade it. I think it is important to look at those three things that I mentioned, that the Spaeth Gonioscopic System addresses. The iris insertion, the angular approach, and the peripheral iris configuration. You can describe those in words, the system that Dr. Spaeth put forward is really just shorthand for describing all of those things. But if all you’re describing is just the angular approach, you’re not really understanding the angle anatomy very well and what’s there. I personally use the Spaeth System routinely and teach that to all of our residents and fellows. That’s the one that I use and a lot of people utilize. But as long as you’re describing those three important characteristics of the angle and understand them, that’s what’s most important.
The next question was when do we do trabeculectomy or iridectomy? In cases of angle closure, I think the most important thing to do initially is the iridectomy or iridotomy. I use the terms interchangeably throughout here. By whatever mechanism or technique is comfortable and available. Argon, the YAG, or even surgical iridectomy sometimes if you can’t do it otherwise. Trabeculectomy is more reserved for eyes that have had a laser done, for example, been treated medically, but the pressure’s still remaining poorly controlled and can’t be controlled medically, that you might have to go to a filtering procedure.
The next was a terminology question, is there any difference between acute angle closure glaucoma and acute primary angle closure? Yeah, I mean the terminology can be a bit confusing. Normally we refer to primary angle closure as the finding of angle closure on examination, but without evidence of glaucoma or elevated pressure. And then acute angle closure glaucoma when there’s actual glaucoma present, elevated pressure and/or evidence of optic nerve damage and visual field loss. And the acute part of it, if you’re having an acute episode that’s bringing someone in, then you probably have elevated pressure. But again, primary angle closure is generally asymptomatic, early, noted on examination that a patient has a narrow angle and seems to be predisposed to angle closure. Whereas angle closure glaucoma is where the glaucoma and elevated pressure has already occurred.
Next question is, is Humphrey Visual Field one of the must-have tests for primary angle closure glaucoma monitoring? Yeah, I think once you have glaucoma, whatever the mechanism, whether it’s open angle or angle closure, and you’ve done the initial steps to do the laser or to administer medications and control the pressure. That you then have to monitor those patients very closely. And visual field testing by whatever technique is available is certainly part of that follow up. So following visual function, following the optic nerve, following the intraocular pressure, which is standard for all glaucoma patients, but in angle closure patients, following repeat gonioscopy also is added to the mix and is an important part of follow up.
In a case of the next question, in a case of acute angle closure glaucoma, how much of the anterior chamber depth or shallowing is expected to differentiate it from malignant glaucoma? Again, in standard pupillary block, angle closure glaucoma, there will be some shallowing of the entire anterior chamber but it’ll be greater peripherally than centrally. So it’s the difference between peripheral and central where it’s normally a little bit deeper centrally. In malignant glaucoma, it’s all uniformly shallow. So I don’t know if there’s a percentage or direct way to differentiate it, but it’s comparing the peripheral to the central chamber depth. And if they’re the same, it’s probably malignant glaucoma. If the central anterior chamber’s a bit deeper than the peripheral, then it’s probably more from pupillary block.
The next question was, does a glaucoma patient suitable for contact lens wear or RGP lenses, any pros or cons? Yeah, I have many, many glaucoma patients who wear contact lenses. As long as they’re able to take care of them, the lenses don’t interfere with the medications, you can apply eye drops right on top of them. So many patients do wear lenses. Where we run into problems with patients with contact lenses is that number one, often our medications cause some ocular surface disease, or dry eye, so they may be less tolerant of lenses. And then of course if a patient’s had glaucoma filtering surgery or has a filtering bleb, they may have some issues there or are at greater risk for bleb-associated infections and things. Those patients, while I still have some of those patients who wear contact lenses, they have to be very vigilant about their care of the lenses. And very familiar and know what to do if they start to get a red eye or any signs of an infection.
The next question here in our last few minutes, is what’s the difference between chronic angle closure and secondary angle closure? When we talk about just chronic angle closure glaucoma, we’re generally talking about chronic pupillary block angle closure that occurs slowly and chronically over time. So it’s a primary angle closure mechanism, it just isn’t one that’s associated very often anyway, or at all, with an acute event. Where they have an acute angle closure. They just get slowly creeping angle closure because of a narrow angle from pupillary block. Secondary angle closure is usually one of those that we talked about at the end, where there’s an identifying cause for the angle closure. Be that posterior pushing or an anterior pulling mechanism.
The next question was does cataract extraction cause progressive worsening of nerve damage in glaucoma? No, it should not. The only way that cataract surgery can typically lead to progression of glaucoma damage is if there’s a pressure spike following cataract surgery. So you do want to be vigilant about cataract surgery. We often are a little bit more aggressive about if we’re just doing a cataract surgery alone in a glaucoma patient, whether they’re open angle or angle closure patients. I’m a little bit more vigilant about making sure all the viscoelastic is out of the eye, maybe I’ll give them some postoperative Diamox, or something just to minimize the risk of that early pressure spike that could cause progressive damage.
The next question was does anti-VEGF work for neovascular glaucoma? Great question. We didn’t talk about a lot of treatment for the secondary glaucomas, neovascular glaucoma of course being a very common one. I think it’s very helpful to have anti-VEGF, some sort of agent on board as soon as possible when neovascular glaucoma is diagnosed. It’s not going to always reverse the glaucoma, and frequently won’t have any effect on the glaucoma, but it will start to quiet down those blood vessels in the eyes. So that when you do the surgery, that’s almost inevitably necessary, such as a tube shut in these eyes, there’s less risk of bleeding. Not only into the anterior chamber but posteriorly. In addition, when we do something like a tube shunt, for neovascular glaucoma, there often is still some hyphema, or some bleeding in the eye, even if there’s been some VEGF on board because of the very fragile vessels. So that precludes a good view of the posterior pole and of the retina for a period of time until that clears. So you can’t really do appropriate follow up, say for their diabetic retinopathy or their vein occlusion.
So I like whenever possible to have some anti-VEGF treatment on board in the eye before we go to surgery for neovascular glaucoma. And the earlier you can get it in, the better.
The next question, does Argon laser trabeculoplasty/iridoplasty work in nanophthalmic eyes if a PI doesn’t widen the angle? Yeah, that’s a great question. And the answer is yes it can. These nanophthalmic eyes we’re often trying to avoid surgery and buy time because surgery does have unique risks in these patients. Surgery specifically to remove the lens and they may be just predisposed to problems from that and effusions and aqueous misdirection. So you can try iridoplasty/trabeculoplasty in those eyes peripherally, to try to maintain some open angle. So yes, I have done that and yes, it has been effective and has bought time. Although, eventually, many of those eyes will end up needing surgery anyway.
The next question is can a patient who underwent YAG iridotomy be dilated without any risk of acute angle closure? Certainly patients who have undergone a YAG laser can be dilated, but that doesn’t mean there’s no risk of angle closure. There’s a markedly reduced risk. The risk is probably highest if they had a YAG iridotomy and they had underlying plateau iris that then wasn’t diagnosed or appreciated. As I mentioned also, sometimes after a YAG laser iridotomy, the anterior chamber can still be somewhat narrow or shallow, which is why repeat gonioscopy is important. Because there may be a lens component contributing in an individual. And then with dilating the iris can bunch up and still cause some closure and the risk of acute angle closure. The risk is greatly reduced, but there may be specific cases where someone may still be at risk and you have to dilate with some care.
The next question was, can we give Pilocarpine in phacomorphic glaucoma? I probably wouldn’t recommend Pilocarpine in phacomorphic glaucoma as your first treatment. I would certainly go more with aqueous suppressants and maybe even in some of these eyes there’s advantages to dilating and cyclopleging the eye to try to pull the lens-iris diaphragm back. But it’s a tough, tough interplay at times. Because I have certainly seen cases where Pilocarpine, even given at a low concentration of 1 or 2%, has been effective. But also I’ve seen cases where we got a paradoxic response and anterior chamber shallowed more and it wasn’t helpful.
The next question’s kind of related in a way. Are miotics contraindicated in aqueous misdirection? Yeah, probably. They’re certainly not helpful in aqueous misdirection, again because they can allow the lens and iris diaphragm to move forward. But they’re not really offering any advantage. Your real treatments are aimed at cycloplegia and aqueous suppression and then trying to establish that unicameral eye where you don’t have, where the anterior and posterior chamber have a way to communicate so that aqueous can move forward.
There’s a couple of thank yous here, which I greatly appreciate. (laughs) And I thank everyone’s attention. We’ll do a couple more questions and then unfortunately our time will be over.
The next question is a patient who has been diagnosed with prostate carcinoma, is theoretically at risk for choroidal metastasis? If he has a shallow chamber, is a Yag iridotomy indicated to prevent angle closure? Yeah, assuming there’s no evidence of tumor in the eye as a complication. And if both eyes look similar, if you see a patient like this who has one eye that’s got a shallow chamber and the other eye looks deep, that would be a red flag that maybe there’s something going on. And maybe there’s a mass shallowing the chamber in the one eye and causing a problem. But if this is a patient who is being treated for prostate carcinoma who otherwise has a normal eye exam but has bilateral shallow chambers and looks to be at high risk for angle closure, I think a laser would not be unreasonable. You might want to coordinate that with their oncologist.
The next question is how long do we need to follow up a patient after a laser iridotomy? The answer really is forever. Even patients who just had narrow angles who we did a laser on, their chamber deepened, they never really had much, or any elevated pressures, we follow them every few months for a while or every six months. And then eventually maybe annually. But I think they need to know that even though they’ve had a laser, that things can change again. So I think an annual exam, at least, is indicated and more frequently if there’s anything of concern in that patient.
Another very gracious thank you in the question box, again, I appreciate that.
After how many days of cataract surgery for acute angle closure, oh, do you wait? I’m not sure I quite understand the question, but I think the question is, how many days do you go for cataract surgery for acute angle closure due to phacomorphic glaucoma? I think if you have a phacomorphic glaucoma that comes in with a full blown angle closure attack, I think it’s helpful to try to quiet the eye down and try to control the pressure before you go to cataract surgery, if possible. And that shouldn’t take very long. But if you can get treatment on board, some steroids, aqueous suppressants, bring the pressure down, allow the cornea to clear, so that you’re not doing cataract surgery through a hazy cornea. And then give it a few days or even a week, you’ll be fine. If you can’t break the acute attack that’s going on and the pressure remains elevated and out of control, then you may have to proceed with cataract surgery on a more urgent basis. But I think it’s always helpful to try to quiet these eyes down first if you can.
The next question has to do with UBM versus gonioscopy in terms of angle classification. I think they complement each other but nothing to me replaces gonioscopy, in terms of the clinical exam and really understanding what’s going on in an individual patient. And the UBM isn’t always universally available and it’s time-consuming and other things. Where a gonioscopy, in just a few seconds, you can have a great appreciation of the angle. But I think UBM can add some things that are hard to appreciate, sometimes, on gonioscopy. Especially if there’s a plateau iris, looking for that anterior ciliary body insertion or anterior ciliary processes. And UBM, and also I would mention the anterior segment OCT can be useful in terms of quantifying anterior chamber angles and approach and maybe helping us understand better how and why some patients are more predisposed to angle closure than others. And maybe who is at most risk if we don’t treat them.
The next question is this way you said that you recommend the treatment, which way do you recommend most? Again, I think it’s a stepwise approach with medications, laser, and then surgery, including cataract surgery if indicated. But as I said, with time. cataract surgery, and even clear lens extraction, may take on a more prominent role. But perhaps not yet.
And now for the last question, as our time is about over, is it possible to have primary angle closure from vitreous in the AC after a cataract surgery? And how can this be managed? Yes, it is possible to have, especially if the hyaloid face, if the anterior hyaloid face is intact. It can block the pupil or it can develop posterior synechiae between the pupillary margin and the anterior vitreous face that will cause anterior, a secondary angle closure glaucoma. it’s really not a primary glaucoma, it’s a secondary glaucoma in that case. Even if there’s an intraocular lens in place, you can get synechiae that can form and you get that posterior pushing mechanism and they develop pupillary block. And this is generally best managed, again, with a laser iridotomy. If there’s a lot of vitreous in the anterior chamber, you may want to consider an anterior vitrectomy to get the vitreous out of there and there may be other issues with that vitreous in the anterior chamber. But the pupillary block itself can often be relieved often with the laser.
Unfortunately we are at the end of our time. I want to greatly appreciate, I express my thanks again to Orbis for allowing us to have this time together. Appreciate everyone’s attention and the wonderful questions and I greatly appreciate the feedback and positive comments. Have a wonderful rest of your day and stay well.