During this live webinar we will show different techniques of Glaucoma Drainage Device (GDD) Implants both valved and non-valved. We will also show the preferred surgical procedure. Surgical pearls will be discussed including common perioperative complications and how they can be avoided. In addition GDD implants in some challenging situations will be discussed.
Lecturer: Dr. M. Nazrul Islam, Phaco & Glaucoma Surgeon, Bangladesh Eye Hospital & Institute, Bangladesh
[Nazrul] Good morning, good afternoon, and good evening wherever you are. I am Dr. Nazrul Islam working at Bangladesh Eye Hospital and Institute in Dhaka, Bangladesh. I welcome you all in this presentation on “Glaucoma Drainage Devices Made Easy.” I do not have any financial disclosures.
In this presentation, I’ll try to discuss the different technique of glaucoma drainage devices implant, both valved and non-valved. Preferred surgical procedure, surgical pearls step-by-step, common per operative complications and how we can avoid it, and of course in some GDD implants in challenging situations.
We know that recently glaucoma drainage devices are being used in many indications so understanding their action, implantation technique, managing the complications are important and to learn it’s very important for us.
Let me have a poll, please give your answer within two seconds. Okay, I can see that 77% already don’t do it. But only 1% did more than 100 and 3% more than 50. Many of you already didn’t start it and so I hope after the presentation you’ll be inspired to start the glaucoma drainage implant.
All of you know that there are many indications for the glaucoma drainage implantation. But some of the cases like neovascular glaucoma, post surgical PKP, retinal detachment surgery, ICE syndrome, traumatic glaucoma, inflammatory glaucoma, and of course the failed trabeculectomy cases, refractory infantile glaucoma, these are good cases for the glaucoma drainage implant. Because the trabeculectomy do not work better in these cases.
Especially if we say only four or five cases, the neovascular glaucoma, inflammatory glaucoma, or surgical like not only trabeculectomy, after PKP, after vitreoretinal surgery, after damaging the conjunctiva from chemical burn, actually we need to do implant the glaucoma drainage implant.
Now there is another poll question, please answer within two seconds. False is this one, Ahmed glaucoma valve and Ahmed Clear Path. Many of you already answered correctly, very good. Very good you answered correctly because we know that Ahmed glaucoma valve is a valved one. But from the same company, New World Medical, Ahmed Clear Path is not a valved one. The other statements are correct here.
Next coming to the common glaucoma drainage devices. I think all of you know that we have different type of glaucoma drainage devices. Some are valved, some are non-valved or open tube. Valved one most commonly used throughout the world is the Ahmed glaucoma valve. It is a flow-restricted valve and also Krupin implants is also valved one. On the other hand, there are many non-valved devices. Most common is the Baerveldt implant both 250 and 350. Then open aqueous drainage implant from Aurolab India. The PAUL glaucoma implant from Singapore, then Molteno implant, Schocket Tube, these are all non tube, open tube or non-valved implants.
This is a very important slide for all of you. How the glaucoma drainage device works. We know that after the implantation, or after the insertion, around the tube, around the plate, there is a collagenous capsule that forms around the bleb of the valved or the non-valved devices. And it’s around that bleb granulomatous reaction occurs. But this reaction resolves within four months and capsule becomes stable, matures over time, usually becomes thinner after six months, and becomes a very good filtering bleb formation. And how that IOP will decrease. This is the way that it works both valved one and non-valved one.
A very important study done for the tube versus trabeculectomy. And this study showed many results. One of the important result is that it would do in the refractory glaucoma tube versus trabeculectomy. Trabeculectomy has better results and complications also less in the tube. And again the requirement of surgery, surgery is more in the trabeculectomy group. It indicated that in every way, tube is better in the refractory glaucoma than trabeculectomy according to this TVT study.
Now the question comes in your mind, whose device is better? The valved one or the non-valved one? There are many studies on this and especially the Ahmed glaucoma valve versus the Baerveldt glaucoma implant in this study. And this showed that if you considered long term success, the non-valved devices are better because the IOP decreases better after 3-5 years in the non-valved one. On the other hand, if you see the complications, the complication is less in the valved one, than it is the AGV, Ahmed glaucoma valve. But the devices has its pros and cons, advantages and disadvantages.
Now I have another poll for you. Which statement is false? The valved devices need to be irrigated to open up is called priming of the valve? Is it false or true? External plate is usually sutured with 8/0 or 9/0 nylon? The anterior border is placed 9-10 millimeter away from the limbus? Tube placed in the anterior chamber parallel to the iris plane? And device implant at the superonasal quadrant is preferred as it causes less diplopia? Which statement would be false? All are correct except one. 71% given the correct answer that supero nasal is not the right place, supero temporal is the right place. It would make a supero nasal, then it will cause diplopia, rather than all the statements are correct. Thank you very much for giving the correct answer.
Now let us talk about the Ahmed glaucoma valve. This is a silicone implant, mostly we use the FP7 and FP8 for adult and pediatric. And also we have the polypropylene implant, the Model S2 and S3 for adult and the children. Both work so good but polypropylene model sometimes with it and has more chances of hypertensive phase and more chance of failure. So mostly commonly we use the silicone implant, the silicone plate. And mostly the FP7 for the adult and for the pediatric FP8. But some surgeon also use the FP7 for the pediatric use, including myself.
Now let us see how easily we can implant the AGV, Ahmed glaucoma implant. For this implant we need a very good anesthesia for the patient. And I prefer to give the peri bulbar anesthesia with two CC lidocaine and bupivacaine. But my anesthetist always help me by giving the Midazolam and fentanyl intravenously so the patient will become calm and quiet and usually is a painless surgery, takes 45 minutes to one hour. But in case of one eyed patient, end stage glaucoma, I prefer not to give PB and instead I used sub tenon’s anesthesia.
The glaucoma GDD implant technique is different with different surgeon. Every surgeon has a choice of doing the procedure. My personal, I’ll try to describe my way of doing it. Like many people will use fornix based peritomy, limbal based peritomy, some people use patch graft, some people use the full thickness, half thickness scleral flap, and people suture the plate anchoring. So many ways of doing. I’ll try to show you my technique.
The next poll question for you. GDD tube should be covered either by donor graft, or by patient’s own? Which one is correct? Thank you very much, answered correctly. Most of you, there were 40% answered correctly the processed amniotic membrane. Actually there are many surgeons they use the membrane but in many studies it has shown that is not useful because it does not stay for a long time and the possibility of a tube exposure are very high. It is not used much. Mostly we use the pericardium or corneal scleral patches and still then you have answered correctly. Thank you very much for the answer.
Let us see the video clip how I do it and I’ll try to show you how easy we can actually implant this Ahmed glaucoma valve. And I call it the short tunnel short flap or STSF technique. I try to mark my conjunctival peritomy here. And I’m doing the fornix-based peritomy here. What happens if we do not mark? Sometimes you can cut here and there. But I’m going to 12 o’clock to around the right eye, the lateral rectus muscle. You will mark it, it becomes easy for you to do it.
This is another procedure I’m showing that you can separately dissect the conjunctiva and the Tenon’s capsule to separate. It becomes a very good dissection. After dissection you just open the supero temporal quadrant here. The very important step priming of the valve. Just with BSS you give some fluid through the tube so that the valve is open. You know that there’s two elastic membrane in the valve. This may be across each other, so it should be primed. This is a case I’m doing the pre placed suture of the plate. Sometimes the plate can be lost posteriorly so it is pre placed. It does matter, it’s not possible to show you that you can do it. Now anchoring the plate by 9/0 monofilament nylon here. I give one, or sometimes two bite so that the whole plate becomes secure with the sclera and does not move with the movement of the eye.
Now I am doing the STSF technique that is making a short flap here about four millimeter, just like trabeculectomy, you all do trabeculectomy. And this if four millimeter I am doing the tunnel, short tunnel. I named it short tunnel short flap. It is very easy to do and you can easily get your tube through the tunnel. And in the flap, under the flap you put your tube in the anterior chamber. Let me show you. This is a very important part to cut the tube in the bevel though the up direction. Have a 40 degree angulation as you can see is very important so it has more surface area. Aqueous outflow will be better if you cut like this.
Now regarding the entry we use 23 Z needle mostly but of course you can use 22 also, 22 is not good, but 24 also. Especially in children and myopia cases where the eye is not very flexible. In that case you can use the 24 also, but mostly we use the 23 Z needle. The tube goes nicely through this needle track. And very important part is this during the needle track, you should go in the parallel to the iris and with practice you will understand how it goes parallel to the eyes, why it is not touching the cornea, why you’re not touching through the iris, that should practice and definitely will learn. This process you can go either deep or superficial, but after doing it, you can do it.
Then fixing of the tube is very important. Otherwise the tube may move here and there and the tube may expose sometimes, so fixing in different sites is very important by 9/0 nylon again. And bury up the nylon is very important because if you do not bury it can produce a hardness over sometime, it can just irritate the patient’s conjunctiva later on. This is very important to bury it.
Now you can see I’m using, in this particular case, I’m using the patient’s own sclera graft here that I do sometimes. But most of my patients I do the STSF technique but whenever in children or in the highly myopic patient, or esclerbinatia, in that case I definitely ought to put the donor scleral or corneal graft for the pericardium graft. Here I suture it, at least to do four suture, just to fix it over the tube. And then over it you can cover it by Tenon’s capsule and conjunctiva.
I’m showing another way that it is called the long tunnel. You can see here, I’m making a tunnel of four millimeter and then from this tunnel I’ll go to the anterior chamber. That is the long seven millimeter sclerocorneal tunnel. Actually this is not a very easy technique, I’ll not recommend for the beginners. Of course if experienced you can do it. Even myself, I don’t do much of this consider it’s on the video. This is the long sclerocorneal tunnel. It’s another way you can do and you can do. But I feel from the beginning you should not do it, you should start with the STSF technique. Or with the donor scleral or corneal or pericardium graft.
After that, you close the conjunctiva, plus it is better to close the Tenon’s capsule, then the conjunctiva or that you can close it. Mostly we use the 8/0 vicryl. And apposition in the two corner, here and here, but after that I do a horizontal mattress suture from one corner, the whole side of the peritomy. So they should be a water track suture. Sometimes tissue glue can be used here but I did the 8/0 vicryl suture to close the conjunctival layer. It takes some time but I think if you do the suture totally from one corner to the other corner, it gives a better result, better secured conjunctiva suturing is very important. Though it is more important for trabeculectomy but also in valve implants.
After that we can give a subconjunctival antibiotic and we can finish the surgery.
Now, we’ll discuss about the non-valve devices. Already I mentioned that Baerveldt implant and the Ahmed Clear Path, these are a few of the commonly used non-valved glaucoma implant. In our country, Baerveldt is not easily available. Sometimes we get it, but easily we get the AADI, the Aurolab aqueous drainage implant. And we’re fortunate, the AADI is really cost-effective for our patient so we can use it very cheaper rate comparative to Baerveldt implant. And we also have a few got some PAUL glaucoma implant from Singapore, Ahmed Clear Path is not available in our country. Mostly we do the AADI in our country.
The non-valve, especially the Baerveldt, it is the unique feature that large surface area 250 and 350 square millimeter, which can still be inserted via one quadrant incision, most is superotemporal if it’s level. Uses a silicone tube and silicone plate which is barium impregnated for easy radiographic visualization. And commonly we use 350 square millimeter for design because larger surface area of the plate gives better result. The plate had fenestrations into which the fibrous growth occurs. This serves to reduce the bleb height and prevent complications including the diplopia.
Regarding the AADI is the same. Actually it is a copy of the Baerveldt made from Aurolab. Almost the same kind and we get a lot of study already published that AADI is giving us almost the same kind of result like the other non-valved devices.
Let me show you the AADI procedure in a few minutes. Similarly I mark the whole conjunctival area so that I know how much to, here to dissect a little bit more because AADI all the non vertibles are placed and cover up the two muscle. It is superotemporal I am covering the two end of the plate should be undercover of the superior rectus and lateral rectus. You may use the ripcord suture or may not use the ripcord suture, just 4/0 Prolene can be used as a ripcord suture. I use many cases without any ripcord which is no problem, but ripcord suture gives better result. Because I’ll close the tube better and postoperative hypotony is very rare. I’ll close the tube with the ripcord.
So I’m implanting the whole device, the plate and that superior rectus passed and the rectus then I’m changing my hand to under the lateral rectus. Once it goes through the lateral rectus, the plate nicely makes it position. And you can see here the plate is nicely fitted here. Now there is an anchoring hole here so anchor with this plate by 9/0 or 8/0 nylon. 9/0 here I’m doing it with 9/0 nylon. Securing is very important because it should not move so that it can cause some diplopia, cause some muscle mobility related problem. It’s very important that it’s under the muscle, it should be fixed at this point. It is very important. And bury the suture.
Now you can see I’m ligating the tube of the AADI by this 6/0 vicryl. By 6/0 vicryl, or 7/0 vicryl also, you can use. And after that you test it, the air bubble is going or not over the ligature. Whenever you’re sure that no air is going, occlude is going, then of course you’re sure that ligation is 100% complete, then you can put your tube in the anterior chamber. Similar to the Ahmed glaucoma valve, you’re making the short tunnel and short flap here. But probably in this case I am doing the short tunnel and not doing the flap, rather directly with the middle track I’m going to the anterior chamber here. It is also possible most of the time you would not use the flap, use the donor graft then no need to do a flap. So definitely you can use like this. Go directly with the needle with the 23 Z needle to the anterior chamber. And through the same track, I just hold it with the two forceps here so that the opening becomes easy for me to enter into the… Sometimes it’s very difficult to enter in the track, but it will hold it by the two forcep, it becomes easy to do it.
I found my tube a little bit larger, so I made it bend here and I sometimes I do it, I sutured it so that it should not be larger size of the tube in the anterior chamber. In the anterior chamber it should be two to three millimeter not more. It is a very important part is the venting of the tube or fenestration of the tube. You see with the same needle, 26 needle used actually, this small needle here. Thus fenestrations in the tube so that given the ligation the fluid, if possible, cannot come through this. Through this fenestration some aqueous will be passing through this and I’m testing it to see if the aqueous is coming. So that after surgery, some fluid will come with this and IOP will be decreased a little bit.
Now as I use the ripcord suture here, I’m putting another end of the ripcord in the lateral part of the lateral canthus of the patient. After that, suturing of the conjunctiva just as I did it in the Ahmed glaucoma valve cases. Now the Ahmed Clear Path, this is not available in our country. But to show you it’s a really good device. It’s a very small, flexible plate. And you can see you do not need to undercover under the muscle. This put in between the two muscle that will remain. And this device comes built in ripcord suture. It comes with a ripcord suture. Definitely you can use the ripcord just like the AADI/Baerveldt, you can ligate the tube here. And just here anchoring the plate first, then ligation of the tube, and similar like the AADI and other Baerveldt and other non-tube devices, you can ligate the tub. I’m going to the anterior chamber with the 23 Z needle and putting it. It’s a simple situ.
Now I’m talking about the PAUL glaucoma implant. Is a very good device, a very large surface area that’s 342 square millimeter. Is made by Advanced Ophthalmic Innovations in Singapore. The advantages of this tube is its small, very narrow tube. It’s a so very narrow tube. You have to make a needle track with 27 or 28 Z needle is quite enough. And as it’s very narrow, you can go to the anterior chamber and takes very little space and even the closed angle glaucoma it can put the tube in the anterior chamber. I have little experience with this some of valve and I find my patients do very good. But still, unfortunately, not available in our country, we cannot do more. But hopefully it is one of the good devices.
Now I’ll show a few cases of challenging situations. Like after the surgery. Say it is a post PKP patient and I need to do the valve implant, patient is very, very high, there is a cataract also. So here a few things are very important, you should not touch the cornea and the surgery should be as minimum handling as possible. I did the cataract surgery nicely and I thought I’d hold the tube just under the sulcus. But I found this is quite deep here. If so I could put the tube in the anterior chamber as usual. Thus the cornea there is no way you can touch the cornea so that cornea will be decompensated later on. A little precaution is there, otherwise it is also possible to do the surgery post PKP or other surgery.
Here again I’m doing the flap, it’s short tunnel short flap technique I’m doing in this case. Here I have just needle track, I have not done with the crescent blade, just a needle track. The needle track you can also make a tunnel and 23 Z needle, the same size of the tube. It goes to the other side and onto the flap you can go to the anterior chamber. This is also a careful surgery you can do the successful surgery with the tube in this case also.
This is another case that post AADI surgery, our retina colleague many times send patient with very high IOP after vitreous surgery. And most of the patients with trabeculectomy doesn’t help, doesn’t become successful so we have to do the valve surgery here. STSF also I’m doing the STSF technique to work the tube here. Same kind as I showed in the Ahmed glaucoma valve video clip here, the same way. There are some difficult cases but it is possible to do.
Now regarding some complications. We all know that every surgery has its complications. Mostly we find motility disturbance, infection, choroidal effusions, anterior or posterior tube migration, hypertensive phase. Very important. Hypertensive phase is usually after three month.
Let me show different stages like intraoperative, then early postoperative, and late postoperative complications.
First of all, if you do not mark it, suppose I am just marking here in the 12 o’clock position here so that I know why the position. If you do not mark it you can make the conjunctival incision a little bit error from here. Means more dissection and under dissection can happen. I always try to mark it to avoid the unwanted dissection and complications.
Corneal traction suture is sometimes very rare but it can happen. That you can have a perforation through and through. In this case the eye become very soft so you have to put some high density viscoelastic in the anterior chamber and come back from the surgery. And sometimes if one bite becomes difficult and you can make two bite here. You can make two bite so that the traction becomes very easy. You can make traction with the 6.0 vicryl silk and also you can make traction with ripcord suture. But mostly I use the corneal traction suture.
Very important this part, is do not hold the valve area of the AGV. Because if you hold the valve area, the valve action will be damaged. Never, never, we should hold it in the valve area.
This is one of my video I got only one case in my life that a lost and found. Whenever I just putting it see, it is going posteriorly. I really puzzled what to do. I tried at least for a few minutes. I struggled to get it down, it was not coming. So I thought I’ll call my oculoplastic colleague but finally, fortunately, I found it again and I could. Many surgeons now give the pre plus suture only to prevent it. Others should be precautioned that it should not go, it should have popped out, it should not go down. I’ll just hold it in one corner with forceps so that it should not go down or up.
As I do the STSF technique, I found in one of my cases just doing the tunnel I got scleral perforation. This is very uncommon but it can happen just to tell you. Of course you can suture it, nothing else.
It is very important that putting the tube in the anterior chamber is not always easy. Sometimes you are to take not one attempt or even three attempt you can do. But important is that if you cannot put the tube in one attempt, you take two or even three attempts. You must suture the needle track. Because if you do not suture it, that will leak the aqueous from that track and it’s one of the most common cause of postoperative hypotony. It’s very important that you could even take one or two track, sometimes you need it, but it would make like this you should suture with the 10/0 monofilament nylon, the needle track, so that there’ll be no leaking postoperatively.
Now covering the postoperative complications. As I mentioned, hypotony is one of the complication that we sometimes get early, sometimes get in the later stage. This is one of my cases referred to me. You can see here there is the ciliary staphyloma and you can see the tube is always extruded out, sorry. And we had to dissect the whole area and definitely you can needle track the other way, another place, and of course you can cover it by donor patch graft, scleral or corneal patch graft, whatever you have. Otherwise this can again make a staphyloma, the tube will be again extruded. In this case, definitely, we had to use the donor graft and suture it. Sometimes you can, the conjunctiva is not enough. In that case you are to take the conjunctiva from the other side to make a pedicle graft here. I make a pedicle graft taking the conjunctiva on the superior side. You can see that sublux seclusion will be better and pedicle graft has better success rate.
Hypotony sometimes may cause the suprachoroidal effusion, suprachoroidal hemorrhage, and retinal detachment. If this case definitely refer this patient to your retina colleagues.
These are the important complication I tell because after surgery of the non-valved devices, as we ligate the tube, post operatively most of the cases we have higher intraocular pressure. And we’re to give anti-glaucoma medication as usually we use for the patient. Many patient do not accept it, but you are to convince the patient, you’re to counsel the patient that higher IOP is a common thing after the ligature of the non-valved devices and after six weeks probably it will be alright.
This is another important part is the hypertensive phase. Actually glaucoma drainage device has three phases. First of all, especially in the valved devices, hypotensive phase that can occur immediately postoperatively within a week. Then hypertensive phase mostly occur within three months. Because the bleb becomes intense, bleb congestion, it can have hypertensive phase. And lastly, after four months is a steady phase or stable phase, that becomes very nicely bleb and the IOP will become decreased. And that is ultimately the wanted phase, the steady or stable phase.
Whenever there is a hypertensive phase, define the hypertensive phase that IOP more than 21 millimeter of mercury during the first three months after surgery with or without medications. And of course you must exclude the percent tube obstruction, retraction, or valve malfunction. Then we call it the hypertensive phase. And of course, if we use the antimetabolites, now many surgeons use the antimetabolites, MMC, during the valve implant just to decrease the hypertensive phase. People use the collagen matrix and a variety of approaches is done. But definitely whenever we get hypertensive phase, we try to give the anti-glaucoma medication first, we give topical steroids, we massage the bleb, we can give the subconjunctival mitomycin C or 5FU, and many times we can do the bleb needling with the mitomycin C. Finally if it doesn’t work then we can do the revision of the surgery with the same glaucoma drainage device and many cases we need to change the device as a new implant.
Question comes to which device has more common hypertensive phase? Yes, it has been proved in Mr. Ayyala and his colleagues found that many of the patient in Ahmed valve has more hypertensive phase, 40-80%, than the Baerveldt 20-30% or Molteno. Definitely Ahmed glaucoma has more tendency to have the hyptertensive phase.
There is many studies that showed the collagen matrix if we use augmented AGV implant it decreases the hypertensive phase.
Even in child, and because the child lives longer, so definitely their chance of failure is high. If we use the collagen matrix, studies have found it lives a long time above success.
Corneal decompensation is one of the complication. You can see here the tube is long enough and touching the cornea so in this case definitely we are to cut short the tube if possible. If it doesn’t work definitely you have to change the tube as it’s a pseudophakic case send the tube in the sulcus. Here I am using the needle, micro forcep, just to hold the end of the tube, and from the above I cut it in my appropriate size. And with the micro forcep I just get it out. Very easily it can be done.
Tube exposure is very important because it is not uncommon to find tube exposure sometimes in the life of a patient of the glaucoma drainage devices. Here again you can see I covered the scleral patch graft but there is no conjunctiva so we had to take the donor conjunctiva from the same other side of the patient and just cover the whole thing. And after that it will cover with the amniotic membrane.
Tube migration is one of my case, children with Sturge-Weber syndrome. And you can see after about 7-8 years I found there is tube migration anteriorly. Pressure was also high, it was FP8 model actually. I dissected the whole fibrous tissue, the capsule, then I put the Ologen over the plate and then I sutured it, the whole thing. Then patient was doing very good, pressure came down. And after many years I found the patient was doing very good.
There’s a resistance complications in endophthalmitis like the trabeculectomy, it has the same possibility it can have endophthalmitis. And most of the time it is early endophthalmitis where you have to remove the whole plate and tube. But if it is late, definitely you can do some treatment and possible medication treatment or surgical treatment you can keep the valve for a longer time.
Friends, in conclusion I would say glaucoma drainage device implantation has excellent property to decrease IOP especially in cases where trabeculectomy cannot help. I believe every glaucoma surgeon should learn it. And every step of the surgery should be meticulous to prevent per op, post op complications. I thank you so much for your kind listening. Thank you very much.
How long do you leave the tube? Actually I think he wants to know how long? Between 2-3 millimeters, that is the right way. But definitely in case of children, we keep a little bit longer, at least three millimeter, because there is a chance of retraction of the tube in children. In that case, of course, we leave a little bit. But otherwise two millimeters is ideal. Thank you very much for your question.
What is another question? Do you use mitomycin C in AGV implantation? Well, I do not use in my common, routine practice. But in case of failure, especially in the hypertensive phase, I do needling of the bleb by MMC. Otherwise routinely, I do not. Because many studies show that it doesn’t have any positive result. But in many studies it’s also found it decreases the hypertensive phase. There is different opinion but I routinely do not use, I use only in some refractory stays of course.
Then the question, how do you decide regarding the length of the tube inside the AC? Already I mentioned in case of children only, I do a little bit longer, otherwise it should be 1.5-2 millimeter is enough for the adult cases.
Another question. Do you recommend the tube in Fuch cases? Yes. In some cases. Whenever I do not want any hypotony. In that case you can like it but mostly routinely I do not. But if I find in Fuch cases I had to do, if I find there is no leak, I do not find any leak then I have to ligate the tube, even in the AGV tube, but post operatively. We do not do this in surgery.
Okay, next question. I used to do Ahmed valves implant at my center. Recently, I encountered flat chamber at 10th postoperative day in two of my patients. Very unusual for me and what is your approach for this case? Actually when there’s a flat chamber, a shallow anterior chamber, definitely there is leaking. There is hypotony. Otherwise it should not be like this. When there’s hypotony, you should search why there is hypotony? The valve is working or not? Whenever you implant the valve, did you prime the valve or not? How was the result of the priming? And it will have two or three needle prick, needle track. Did you close it or not? There is many ways you can search for that cause of hypotony. And I found in some cases if you put the high density viscoelastic like VisCoat for a few days, but sometimes it forms the anterior chamber. You can try with that. If not, definitely you have to reopen it and in the previous case remember, I reopened it, I closed all the tracks, all the places as possible. And of course I ligated the tube so that the hypotony decreased and the flat anterior chamber became formed.
Another question from anonymous. How would you approach AGV implantation in a treated retina just treated with a scleral buckle? Very good question, very good question. I think I showed you a video, I didn’t mention it, that was a patient with RD surgery with a scleral belt buckle. What happened? I did the AGV implant, you just your plate should go just below the buckle, just below the buckle. And only problem is that it can make the height of the bleb higher and may cause some diplopia or ocular strabismus, otherwise shouldn’t be a problem. You can just posterior to this and suture it and enter to the belt buckle, it is possible. Otherwise you can take the help of the retina colleague and they can cut some part of the belt buckle and you put your AGV or other implant in there.
It is a must to put in the prolene through the non valve tube and ligate it? No, it’s not. Many surgeons do not put the ripcord 3/0 or 4/0 prolene. But they tie or they ligate the tube in such a way that it should not have any kind of hypotony or any kind of fluid shouldn’t go through this. It’s possible. But of course I have seen in my practice if I put the ripcord suture that has become more tight and like I said, make it more tight and easily the tube becomes more nicely ligated. I use in some cases I have had good result.
What are the contraindications of AGV? Yes, there are some cases when all four quadrant, you’ll find some ciliary staphyloma or some scarring, that small eyeball, they cannot put the plate around it. I think that’s not a good cases. Microphthalmus is very difficult to put the plate in that cases. Small eye, anterior chamber is very shallow. Of course in some case I should say it, in some cases, in that cases you can make the posterior vitrectomy by your colleagues and of course you can put it posteriorly to the pars plana, that is possible in some cases.
Where do you put the GDD if there is prior superotemporal failed trabeculectomy? Yes, the next choice is inferonasal or inferotemporal. And that is possible and in many cases we did it and especially in the silicone filled eye, filled with silicone oil, and easily it goes superiorly it can block your tube. In that case it is better to remove the silicone oil completely if you want to put in superotemporal or you can put in the inferotemporal or inferonasal quadrant. Thank you for the question.
You mentioned that in early endop, you remove the GDD, but in late you do not do other using the endophthalmitis. No, actually, that is true that if the endop can be cured, if the endophthalmitis is totally removed make better by your retina colleague and your team, then it is possible to keep the valve in the same place. But unless this, if the cause of endophthalmitis is from the plate or from the tube, definitely we should not keep this tube here, we must remove it. Thank you.
Can AADI be placed in patient with a scleral buckle? Actually I don’t have any experience with this, it is very difficult because AADI plate is 350 degrees, very big and not like the Ahmed, the Ahmed is a little bit longer. I don’t have any experience. But of course if the retina colleague removed part of the buckle, it’s possible. Then you can put it.
We use corneal graft to cover the tube, what is the ideal method? Of course we have the donor cornea you can cover it, if you have the donor sclera you can cover it, if you have Tutoplast donor graft, definitely you can use it. But most of my cases I use the patient’s own scleral flap because the donor graft sometimes you have to have the issue of inflammation or infection. Although our graft is in glycerol and we clean it very thoroughly with BSS, but still, there is an issue sometimes. I feel comfortable with the patient’s own scleral graft rather than the… But if we have definitely a donor processed graft, definitely we can use it.
What needle size do you use to enter the anterior chamber? Mostly I use the 23 gauge needle but for the children and for the myopic patient I can use the 24 Z needle. That is ideal for that cases. Thank you very much.
In case of short or retractable tube in anterior chamber, how to correct it? Oh, my God. Definitely if it’s retracted then you can just have the extension of the tube by already Ahmed’s glaucoma has the extension tube so you can just suture the extension tube along with this and you can put this extended tube into the anterior chamber. It’s possible. Though there is some locally made tube is possible, I don’t think it is useful. Only New World Medical they have the tube for the extension that you can use.
What should I do if the GDD gets out of direction with the conjunctiva with good IOP? Hm. What should I do if GDD gets out of direction with the conjunctiva with good IOP? No, if out of conjunctiva, definitely you should restructure it, recover it. Because it can cause inflammation in patient. You cannot leave like this.
If the trabeculectomy patients, how will you manage refractory with glaucoma? Definitely I told if it’s not possible then you can do the trabeculectomy again in some other side like the nasal side or other side or you can do the vitrectomy and try to do the pars plana. If anterior to plana is difficult you can try the pars plana tube implant in that case. But I think most of the cases we can, any of the quadrant is possible to put. And I’ve seen one patient that three quadrant used three valves, three Baerveldt. It is possible that with difficulties it is possible to use all four quadrant of the patient. Some quadrant will hopefully will be present.
Which is your preferred GDD? Mostly I do the Ahmed glaucoma valve implant because most of my cases I want the IOP should come down, even in the postoperative period. In some cases behind the patient the vision is very poor. One eyed patient, if I do the AADI valve implant, next day patient can be higher and patient’s vision can come down, visual field can come down. And definitely that is a risk of going down the visual field. I try to convince them to use the Ahmed glaucoma valve and in most of the cases I do the Ahmed valve implant.
What AGV do you prefer with child with congenital glaucoma and exophthalmos and why? Again for the child I prefer the Ahmed glaucoma valve implant. But of course if the patient’s, the children’s eye is exophthalmos, that is size of the eyeball is larger, then I try to use the FP7 model, not the FP8 model, not the children model. Because I find the larger surface area of the plate will help better success.
What is the where manage a case of visual obstruction by vitreous in anterior chamber. Very good question, Mezavin, thank you very much. Yes, sometimes we find there is iris strand in the tube, or the vitreous is still in the tube, especially in these pseudophakic cases. Very easily we can extract the vitreous by the air. It’s very easy. By air we can do it most of the time. But in one case I remember it was not possible so I had to use the vitrectomy in the anterior chamber. It’s not very difficult.
From Singapore, Dr. Wilson asked which is the feature of the implant that you like the most compared to the other GDD? I think he’s from the Advanced Ophthalmic Innovation. Yes, I already mentioned that all glaucoma implant I liked it because of its very narrow tube. Because very narrow tube gives them less hypotony. And of course, though it is a non-valve device, it has very possibility of less chance of hypotony. And of course if you ligate the tube, of course you can use the report also. And another important thing is very small, narrow tube you can put in the anterior chamber, even the angle closure glaucoma. I liked it. Thank you very much for that question.
From Philippines, Dr. Angela asked what are the parts of the implants in children? Nothing different, the only thing is if the eyeball is smaller you should take precaution. And it is microphthalmus it is very difficult to put the tube into the anterior chamber. In that case also, you can have the possibility and put the tube in the pars plana area.
From Sri Lanka, Kushalini asked that two months after AADI valve the IOP goes to 20 millimeter of mercury? Yes, it can go. The AADI valve also might have the hyptertensive phase, you know that after six weeks it usually comes down. But if it goes up, then already I mentioned representation. Both the valve and the non-valved one can have hyptertensive phase. In that case you are to start anti-glaucoma medication if it goes over 20.
Asi Muden from Brunei. Dr. Asi Muden from Brunei, thank you for the question. Tips for transition from trabeculectomy to valve implants. Thank you for the question. Actually those who are doing trabeculectomy they can easily go to the valve implant as I showed you the STSF technique. Because there are two things to do, only the posterior dissection and put the implant. Otherwise, you’re doing almost like the trabeculectomy, you’re making the flap like the trabeculectomy. Definitely you can do as you like.
From Nigeria, Ifyoma, Ifyoma, thank you for the question. You asked management of hypertensive phase in the valve surgery? Prevention of post op strabismus? I think I answered in the presentation how to manage the hypertensive phase with different anti-glaucoma medication, steroids, needling, massage, all these things.
From India, Dr. Vercuty asked, how to avoid shallow anterior chamber post operative and post management. Just postoperative the shallow anterior chamber, sometimes you can give high density viscoelastics for some time. And usually many of the time it works. But if you give it one or two time and it doesn’t work, definitely you are to search for any leak. Otherwise it should not be like this. Then you have to search, you can still comorbidity management I also do is that you can use the doxycycline, it cause some inflammation and there is some possibility of less hypotony. You can use it. And if not possible then of course you are to go to the insertion site and find out if any leakage or not.
Solomon Ahmed from Bangladesh, does the device aid the patient life long or is there is some failure chance too? Of course. All devices can fail. Very rare cases that it will go life long. Many of the cases it remains for 10-20 years. But I’ve seen even 15-20 years valves are working. But many valves are not working at 10 years. It is not, the patient needs to follow up, patient needs to come every six months to the doctor, to the surgeon, and if there is any problem definitely you can change it.
Phetus Oshaba from Nigeria, she asked best technique if we already had GDD and wants to change GDD? Only if you want to change GDD for some reason, say for infection or some failure, fibrosis, the patient is very high. And you have already done needling, already dissected the capsule, dissected the fibrous capsule, you have put some Ologen, you have given some MMC, still it is not working. Definitely, you have to change that GDD. In that case, just open it and all that quadrant you can clean, all these things. If it is very healthy in that quadrant you can put the valve in that quadrant. But if it is not, it is better to put the valve in another quadrant. If it is superotemporal, you go for the inferonasal or inferotemporal, that should be ideal.
I think if there is no other question, Lawrence, any other question?
[Lawrence] We have three more live questions if you want to answer those and then we can.
[Nazrul] How do you manage the average place of which is so common AGV. Already I mentioned in the presentation that in many ways, first of all we give the anti-glaucoma medication and it doesn’t work, we give a steroid, topical steroid, we give the bleb massage, we can do bleb needling by MMC or 5FU, can division of the bleb. There is many ways we can do. In 80% of the patient I tell you, it is usually become better with the anti-glaucomas only. Thank you for the question.
Next question from Victoria. Do you start beta blockers only post operatively to prevent encapsulation in Ahmed? Yes, it is better to give that kind of drug that decreases the production. Beta blockers or carbonic anhydrase inhibitors. They are the two drugs that are preferable. Thank you very much.
I think the last question to this session is your opinion about the anti-VEGF. Very good question. I love this question because I have used, in many of my patients, the anti-VEGF. Even after doing at the end I give the anti-VEGF I used even in trabeculectomy. I have a study of 200 trabeculectomy in that case I used the anti-VEGF Avastin. And I found better results in my study. Even in the Ahmed glaucoma implant I put the AGV and the Avastin at the end. Routinely not, but in case of bleb needling and I used the anti-VEGF especially Avastin in some cases. In my clinical experience, I think it works. It does not harm on it like the MMC there is a possibility of complication. But in the anti-VEGF Avastin there is no complication I found so definitely we can use it.
I thank all of you, I thank again Cybersight. I thank all the participants, I view many participants from across the world here. I welcome and thank you all for being here and listening to my presentation. Thank you all.