Glaucoma and Canaloplasty Video Transcription
We’re going to discuss glaucoma, glaucoma treatments, and then toward the end of clock, I’m going to discuss a surgery, that although relatively new, has been the goal of surgeons for at least 50 years to achieve.
Anatomy of the Eye
So, first of all, before moving in to glaucoma and its treatments, let’s just talk for a moment about the anatomy of the eye. So, most of you have seen the front of the eye. You may not actually be familiar with all of the terms in the anatomy. The clear part that we put contact lenses on is the cornea. That focuses light through the iris, through the pupil (which is the center of the iris) – this muscle here. Through the lens – It’s the lens that eventually becomes a cataract. The lens, then, focuses light on to the retina. The retina collects that light, sends the signal back through the optic nerve.
Optic Nerve and Glaucoma
The optic nerve is the best thought of as the cable from the eye to the brain. Glaucoma is a disease essentially of this cable. So the best way to think about the eye is a bit like a video camera hooked up to your TV or your computer. And so light just enters the eye [at the] back to the retina and the video camera would enter through the lens through the aperture and then they would hit what’s called CCD Charge Coupling Device in the video camera. That link converts that light into an electrical signal and sends it through the cable to your TV or computer. Well, just like a video camera and a computer, if you got a node cable the CATV and all that, it doesn’t matter where you got the world’s best video camera and the best computer. That $5 cable is going to make all the difference in the quality of the image. And the same is true with the eye, you could have absolutely perfectly clear cornea and lens, beautiful retina with no macular degeneration or other condition, but if your optic nerve is damaged it doesn’t matter how good we are up. It doesn’t matter how healthy your brain is, you’re not going to get good vision. So this here, this little nerve about 1.5 millimeters in diameter is what takes the signal from the eye to the brain. This is what a healthy Optic Nerve looks. If you’re looking down on it from the front of the eye, down this cross section here, and what you see is that you got good healthy tissue here, the blood vessels are going back through the nerve. This is what a glaucomatous optic nerve looks like. Essentially this is what we called “Cupping”. What has happened is all these nerve fibers that go back through this tube had died up. And when they died up they have this empty space this cup. So this is what we’re talking about when we’re talking about Optic Nerve Cupping in glaucoma.
So actually let’s take a look at glaucoma. Alright, what happens is fluid is produced in what’s called a ciliary body and it goes around the iris and then exits out through what’s called the trabecular meshwork. If the fluid can’t get out, it causes pressure to go up in the eye, damaging the optic nerve. Now generally, glaucoma is something that does not impact your central vision right away but overtime it can actually decrease your peripheral vision and only in the end stages do you lose central vision.
So this is what so awful about glaucoma is since you’re not losing central vision right away you don’t necessarily notice it. Glaucoma is pretty common 2.7 million people in the United States have glaucoma but here is what’s scary: 50% of them don’t even know that they have it. This is why glaucoma is called the silent thief of sight. This slide was intentionally left blank to remind us that glaucoma blinds and unlike cataract surgery and other conditions of the eye, it’s permanent. It’s forever. You lose vision from glaucoma it’s gone. This is why it is so important to detect it and detect it early. So, in terms of detecting it – we’ve learned through many studies trying to detect not just glaucoma but other diseases such as prostate cancer and breast cancer that you don’t just want to test everybody because you’re going to actually end up catching people thinking that they have glaucoma when they don’t. So you need to test those who are high risk. We’ll who is at risk?
Who is at High Risk of Having Glaucoma
Well glaucoma is common in 2 points in our lives – when we’re infants and then pretty much we don’t see glaucoma through most of our young adulthood. But then as we start to get older – 40, 50, 60, the instance of glaucoma increases with every decade of age. So as we get older it is important to actually get tested for glaucoma.
Certain races are more common or more likely to have glaucoma. There is of African descent, there was a Latino descent, certain northern Europeans so I mean, it’s pretty common in many, many races. And then, actually quite common, the narrow angle type in many Asian culture.
Family history – If you have a family member with glaucoma, you are more likely to get glaucoma. Now, if you don’t have any family members that don’t get you up…but if you do you really should be tested. You should be screen.
And then medical history – glaucoma is more common in those who have health condition such as sleep apnea, diabetes, number of different condition including… common ones such as high blood pressure.
So how do we detect glaucoma? Well the intraocular pressure is a quick and easy way of screening. And generally, if the pressure is high about 22 we need to consider the possibility of glaucoma. But we now know that glaucoma can occur in those with normal pressures so just because your pressure is less 22 or less does not mean that you don’t have glaucoma. And indeed, we now know that in certain races – Asian races, especially the Japanese, low pressure or normal tension glaucoma is quite common.
Visual Field Test
So what do we do then if the pressure is not going to give us enough information? Well visual fields. I showed you earlier that glaucoma decreases the peripheral vision first. So what can be done about that? We can actually test your visual fields. This is not something that you can do on your own. Because, just as we don’t generally think about the fact we can’t see something behind our head you’re not going to notice if your visual fields slowly comes in until you start bumping into doorways. Well that’s a bit on the late side.
Optic Nerve exams
Optic Nerve exams – a clinical exam with an ophthalmologist looking at what is called a slit lamp or biomicroscope with special lenses can give a magnified view and allow the ophthalmologist to actually assess the health of the optic nerve. But we now have wonderful technology called SD-OCT which essentially gives a microscopic view of the layers in the eye including the optic nerve.
So once the glaucoma has been diagnosed, how is it treated?
Well traditionally it is treated with eye drops. We’re not going to spend a lot of time on the eye drops today because I really wanted to focus on a surgery, what’s newer on in glaucoma and there’s not much that truly the “new” about the eye drops for the last 10 or 15 years. The eye drops work well for most people. The older ones are quite inexpensive they can be as inexpensive as $5 to $10 a bottle. The newer ones, unfortunately, that are still branded can be anywhere to $80 to $150 a bottle. So cost can be prohibited with eye drops. Additionally, the eye drops, like all medications- even though you’re taking them on the eye, this eye drops can go back into the nose, get absorbed into the bloodstream through the sinuses and it is possible to actually have systemic symptoms …Eye drops around beta blockers, Timolol – generally safe in young and healthy people. I have a patient of mine, in his 40’s athletic, he took his first drop of Timolol, ended up in the emergency room because his heartbeat heart rate had dropped along with high blood pressure. So these drops are not without side effects but they can work very, very well. So what do you do if you can’t tolerate or cannot afford the eye drops or they are not working?
Well the next treatment is generally a Laser treatment and in Europe they actually go straight to the laser before the eye drops. If the lasers don’t work there are surgical treatments and we’ll talk about these in more detail. So laser surgeries…let’s go over these quickly. As I mentioned briefly, earlier in the talk, we believe that the restriction to flow – remember the fluid is produce in the eye here at the ciliary body. That fluid bathes all the structure in the eye. Keeps everything healthy takes out the garbage and goes out through this little drainage canal called the trabecular meshwork. Well that seems to get clogged up so just like your sink at home gets clogged up. So what do you do? Well there are a couple of lasers: Argon Laser Trabeculoplasty, Selective Laser Trabeculoplasty. They are low risk laser procedures that have been used for many years and there are some mechanisms that frankly we just don’t understand, it seems to open up the system and you get about as much effect as you would from eye drop. Very low-risk, occasionally as with any glaucoma surgery, you can actually end up, paradoxically, a spike in pressure after the surgery. But it’s rare and unusual with the selective laser Trabeculoplasty, which is available here in at San Gabriel. So any doctor, any ophthalmologist who is on staff in San Gabriel has access to that laser. Now that sounds great! What if you need more pressure lowering than the laser or a drop can provide? Or what if as it happens with selective laser Trabeculoplasty it wears off after some time? And this laser treatment does wear off in about 3 to 6 years. Then we need to consider surgical treatment.
The traditional surgical treatment is called Trabeculectomy. The interesting thing about Trabeculectomy is that trabeculectomy was first described in 1968 by Dr. Cairns. And what Dr. Cairns was trying to do back in 1968 was essentially open up window to the natural drainage canal called Schlemm’s canal. He did that by removing part of that trabecular meshwork that drainage gate. And the goal was essentially to get fluid to go through this grate around the canal and out through the natural drainage canals. The drainage system But what happened is it most everybody that had the surgery in 1968 whose pressure lowered actually ended up what’s called the bleb. So the fluid instead of going out the natural drainage system went through here and creates a blister underneath the clear part of the eye called the conjunctiva. Well that, to Dr. Cairns, was a complete failure. He was trying to avoid fluid leaving the eye through a un- or non- physiologic process. He wanted to re-establish the natural flow. But the crazy thing is that even though this was considered to be failures it work better than everything else that was available at that time and so trabeculectomy- a failed attempt to do what is called a non-penetrating surgery became the gold standard until this day. Trabeculectomy is considered be the gold standard of glaucoma surgery. Yet, it’s invasive- we have actually created a hole in the eye. You can have problem with severe bleeding. These blebs – these blisters, they tend not to last because, well, the body wants to get rid of the blister. It tries to scar it down. Now we can keep it from scarring down by using what is called anti metabolite, which is essentially a toxin that kills the tissue that tries to repair this bleb or the wound. Well what happens if you destroy tissue that’s there to repair, you end up with a lifetime risk of infection in the eye that’s had the bleb. And then because these blisters are so delicate, you have to limit your lifestyle. If you like to do things outdoors that involve dirt or water sports or things where you could accidently hit your eye – hit or minor trauma, this becomes an issue for you. So ironically, the most commonly performed glaucoma surgery in the world is actually something that was a failed attempt of doing something else but it just works better than anything else at lowering the pressure. Now, here’s the thing that concerns most patients, concerns me and most ophthalmologists. Glaucoma is a disease of slowly progressive loss of vision. We are trying to prevent further loss of vision. So taking a risk of creating your loss of vision is something that has to be considered very seriously. What is the risk of surgery versus the risk of not doing surgery? So, generally we do not recommend trabeculectomy until significant loss of vision has already occurred. And we see that it’s progressing fast enough that the person who has been offered trabeculectomy would most likely go blind during their lifetime. So around the same time as trabeculectomy was first described, another option was described; this is the glaucoma drainage devices.
Glaucoma Drainage Devices
Essentially what these are is instead of creating a hole, and the fluid is allowed to percolate back here over a plate. So this gets rid of the issue of having a bleb right here but there are always issues whenever you put an implant in the eye or anywhere in the body- that the implant can move! You put something in your body that’s not supposed to be there or not actually there, there’s a risk of infection. Scarring can cause double vision. See this the eye muscle here? Put the implant near or underneath the eye muscles and if this scarred the muscle you can get double vision. It’s kind of interesting actually (the original attempts ) these were called was Sextons. And the first Setons were actually horse hairs. So it implanted a horse hair here let it the fluid percolate around the horse hair underneath the surface of the eye. It didn’t work so well. They finally figured out they actually need a tube. Not just Seton.
Now, both trabeculectomy and tubes generally work very well at decreasing low pressure. But because of relatively high risk there’s been a lot of research. Lots of money going into technologies and procedures to lower pressure without much risk as glaucoma drainage devices and trabeculectomy. This procedure that was actually developed by some local ophthalmologist, Dr. Baerveldt, who actually developed one of the implants the Baerveldt implants. Despite having developed an implant, he knew there needed to be a better way. So what he look at doing was since this seems to be where the restriction is the drainage grate, the trabecular meshwork. He said, well what if we just find a way to cut through this and keep it from scarring down. So he developed this thing called Trabectome. Essentially an instrument. It creates a cut here and its cut in such a way that it is not to close back up. So you essentially keep that trabecular meshwork open for fluid to leave through the natural drainage canals through the canal of Schlemm’s that encircles the eye and then out to the natural collector channel into the venous blood system. So like many things in life it sound grand the results aren’t, though, as grand as we hope. Trabectome is something that generally can only be done at the time of cataract surgery because as you can see here you taking the instrument crossing over the lens. Well anytime you touch the natural lens or something the cataract develops. So this is not a procedure that you really want to do when there’s still a natural lens. But if you’re going take out the lens, well, its relatively easy and straight forward to go ahead after cataract surgery (or before) and remove some of that tissue. The pressure lowering effect is not as great as glaucoma drainage devices or trabeculectomy. But for somebody who’s having cataract surgery and needs pressures in mids- to upper teens, this is a good option. Here’s the thing though, not every surgeon has access to the Trabectome. It is a very expensive device. So in this area I believe the only access to Trabectome is essentially through Doheny USC. So you need to go through an academic center for that. My sense with Trabectome is it’s starting to fall out of favor for some of the other newer options.
Now here this is an EndoCycloPhotocoagulation. This is also one of those surgeries that you can only have at a time of cataracts surgery And the reason for that is you’re taking a probe and you place it underneath the iris and what you’re doing is you’re essentially frying this little, what are called, ciliary process. This is where fluids produced. So there’s a couple of ways that you can address glaucoma. You can either decrease the amount of fluid produce or you can help the fluid that is produced get out of the eye. So the case of drainage devices, trabeculectomy, Trabectome you’re helping the fluid get out of the eye. EndoCycloPhotocoagulation decreases the production of fluid. So it’s like turning down the tap. The problem is it’s really hard to*** How many of these little guys do you have to prod and nobody really knows. Because just sometimes you get wonderful effect. Sometimes you don’t get much effect at all and sometimes you get too much of an effect and just as having too much pressure can be bad for you, having too little pressure can be even worse. Because the lens sits right here you don’t want nudge the natural lens again. Again, you have to first take the natural lens out and put a man-made lens here.
So one of the newest procedures to come out which initially have a lot of excitement associated with it is called the iStent… What the iStent does is…it’s a little snorkel, it’s made of titanium and essentially takes this and plugged it into through trabecular meshwork into the collector channel. So now you created this tiny little hole to allow fluid in the collector channel to get out. So this is wonderful! Finally, we found a way to bypass the trabecular meshwork the point of restriction allowing the fluid into the natural drainage canal. Couple of problems with this… One is this really teenie, tiny hole right here and it doesn’t get a lot of fluid in there and it doesn’t get lot of effect. So, if you have the surgery at the time of cataract surgery and this is another one those surgery that is safest with cataract surgery. You’re going to get a pressure lowering for cataract surgery alone. It’s about 50% of people with cataract surgery alone a year after surgery had the satisfactory lowering. About 70% had a satisfactory lowering with the iStent. It’s about 20% more. Not a huge difference. Here’s the thing 2 years after this was placed the effect completely washed out. So you say well you’re here already. You’re having cataract surgery. This lowers procedure why not, I’ll tell you why not. This little device is a thousand dollars and the medical reimbursement for putting on this things in is a thousand dollars. That’s the same amount that Medicare reimburses for surgeries that work a whole a lot better. Pretty much every other glaucoma surgery out there… So it’s pretty easy to see that a $2,000 for this is not a very good ***. So i doubt that Medicare will continue to pay for this procedure much longer once all of the results starts coming out. And they are putting 3 of these things in a time, and that’s great if you got an extra couple thousand dollars to get an extra couple points of pressure lowering.
So now, I’m going to work on canaloplasty, which I believe brings us full circle. Dr. Cairns back in 1968 wanted to re-establish the natural flow of the eye. Canaloplasty essentially does that. It’s minimally invasive it uses the world’s smallest micro catheter. This catheter is 250 micron- that’s one quarter millimeter in diameter. It’s an amazing technology. And what it is essentially involves is passing us through the natural drainage canal called Schlemm’s canal. – Just like you would pass a catheter through the vessels in your heart. This is essentially angioplasty of the eye. Let’s go ahead and take a look at this video here… So once again, here’s the fluid being produce and it’s getting stuck right here. It can’t get out of this trabecular meshwork. So what canaloplasty does is, just as Dr. Cairns wanted to do way back in the day, a flap is created but a catheter is placed which goes all the way around the natural drainage canal, comes up the other end (there is canal up there) and hopefully reduce the air pressure. The neat thing is this, the catheter is pulled back and as it’s pulled back, a viscoelastic gel (it’s a special gel) is injected through the catheter. So just like the angioplasty, a balloon is used. Instead of using a balloon we used a gel to open up the canal. And then just like angioplasty with a step place with that catheter we can pull a suture back through that canal tie it up and tighten it. – Just like you would a ***.Pulls in on the canal opening it up. By opening up the canal you can now establish the natural drainage system. So what are the benefits of Canaloplasty? It’s non-penetrating, first of all. You’re not actually creating a hole in the eye. So it’s not an *** procedure. There’s no hole, so there’s no bleb. So the risks of the bleb are not there. It lowers the pressure as well as a glaucoma drainage device or trabeculectomy without Mitomycin C. So Mitomycin C is one of the common anti-metabolites that I spoke about earlier that keeps the body from scarring down. If you use Mitomycin C, your pressure will be a little bit lower with trabeculectomy but you’re also going… that lower pressure is going to be bought with higher risk. Just like everything, there’s a price, No risk.. No reward without risk. It is safer than the traditional glaucoma surgery, trabeculectomy and glaucoma drainage devices. Those are the features. But this is the real benefits. For people who have pro-active lifestyle this procedure is really beneficial to them. I had patients come to me who are ranchers, farmers, I have someone who raises lamas…I have a patient who is from down San Francisco. He is a big wave surfer. All of these people were told that they needed trabeculectomy. All of these people were told that would have to stop doing what they love. And all these people said I rather go blind. So this is really the first serious glaucoma surgery available for those who really want to continue pursuing their lifestyle and not have their disease take over what they enjoy doing such as water sports and outdoor activities. So I am saying that it works well. What does the study say, with the studies here 1 year on, we have 3 years results but looking on just a 1 year result here you can see that canaloplasty and trabeculectomy. The trabeculectomy with Mitomycin C does hit the pressure a little bit lower. Okay so we got a millimeter for a three difference. But what did you have to pay to get that a millimeter mercury difference? – Up to 20% hypotony maculopathy (with likely vision loss), less than 1% with canaloplasty, up to 20% trabeculectomy with Mitomycin-C. …Irritation from a bleb? No. Canaloplasty there shouldn’t be a bleb. You can’t have irritation from a bleb for life. Not everybody does but it is possible. You have bleb leak up to 4% per year with eye infection as a potential and that potential never goes away as long as you got a bleb you got the risk of infection. You need to be very careful to have good hygiene if you got a trabeculectomy. Cataract Formation: minimal risk about with canaloplasty. And if you do need cataracts after canaloplasty you got cataract surgery your pressure ups a couple of points in general. With trabeculectomy 78% of those who had trabeculectomy ended with cataracts in 5 years. One very famous common surgeon said, looking back at the literature people who have trabeculectomy is more likely in 5 years to have cataract than they are to have their pressures controlled. By the way you can if you had cataract surgery and you had a trabeculectomy the trabeculectomy is more likely to fail. So it’s really a no win situation with cataracts and trabeculectomy. And what about Lifestyles Issues people able to enjoy water sports, able to wear soft contact lenses, able to walk on ranch, yes with canaloplasty, No, no, no with trabeculectomy. This are the 3 year results that should you along, does the *** pressure lowering stay? And in general it does. Look how in the case of canaloplasty only here in this study everything is very stable 16, 16, 16, 15, If we combine it with cataract surgery works even better 12, 13 13, 13. So, Dr. Robert Stegmann- he’s the one who figured out how to do this. He had a population in South Africa, where he said he’s just a bush Dr. – that’s how he described himself, and his patients were really not ideal patients for trabeculectomy because 1) they were African descent -they will likely to fail trabeculectomy, 2) He see them a couple of times and he might not see them for another 5 years because they were sometimes 100 miles away. It wasn’t easy to see him. He develops the surgery specifically to be a surgery that you could basically do it and forget about it. And he continues to work on this he’s got some really exciting additional things (that are not available yet in the US) that can be added to canaloplasty. But I think that this quote is really gets to the core of issue, “It is vital to find a safer more predictable operation with preferably no complication at all. This is the closest I have ever come to that”. And that’s Dr. Robert Stegmann.