Objectives of this presentation are:
- To look at the indications for each type of aphakia correction
- Understand the surgical techniques
- Understand the pros and cons of each
Lecturer: Dr. Emma Hollick, King’s College Hospital NHS Foundation Trust, London, United Kingdom
(To translate please select your language to the right of this page)
DR HOLLICK: So we’re gonna talk about aphakia management. So I’m gonna ask some pretest questions, and we’ll ask them again at the end, and see whether you’ve learned something in the lecture. Which of the following cannot be used to correct unilateral aphakia? So we’re talking about aphakia in one eye. Okay. Second one. Sulcus implantation. So putting the intraocular lens in the sulcus. So which of those would you use sulcus lens in? So in cases of more than six clock hours of zonular dehiscence, which lens implantation technique is advised? The objectives of this talk is to look at the indications for each type of aphakia correction, to have an understanding of the surgical techniques, and to understand the pros and cons of each technique. So there’s lots of options for correcting aphakia. And they range from the use of aphakic contact lenses to glasses to all the different lens implantation techniques, which we’ll run through in this talk. So aphakic glasses and contact lenses are a common way to correct aphakia. As you know, aphakic glasses, though, have downsides. One, they cannot be used in unilateral aphakia. The reason for that is that the image size would be very different in one eye to the other eye. So they would get a big image in one eye and a small image in the other, with anisometropia. Which would be very confusing for them. Also the glasses are often very heavy and can cause distortion around the edge of the lens. So the other technique is aphakic contact lenses. For daily wear, though, you need to be able to put them in and out, and extended wear has risks. So when would you use a lens in the bag? Well, for routine cases. Obviously we always try and put the lens in the bag. After complicated cataract surgery, you could use a lens in the bag in some situations. For example, if there’s an anterior capsule rim tear, it’s okay to use it in the bag. If there’s a small posterior capsule tear, a longstanding traumatic tear, which has got fibrosis, which you know is not gonna extend, posterior — if you do a posterior capsulorrhexis after a small tear. But you wouldn’t put a lens in the bag if it was very dehisced, if there had been a zonular dehiscence, or if there’s a large posterior capsule rupture. So when would you use sulcus fixation? Well, sulcus fixation is when there’s a posterior capsule rupture or a zonular dehiscence. If it’s a major zonular dehiscence, then you might not be able to use the bag. But with a mild or moderate zonular dehiscence, the sulcus can be sometimes appropriate. So you have to use a three-piece lens. You can’t use a single piece. So you can’t put, for example, the IQ Lens in the bag. You have to use an MA 60 or equivalent, with proper haptics, with a three-piece. So you need to — because the lens position is sitting slightly anterior to the bag, you need to reduce the lens power to the one you were planning to put in the bag. So you can see that, depending on the power of the lens you’re using, you reduce it — if it’s a very strong lens, you reduce it by 1.5. Medium power, reduced by 1. Low power, reduced by 0.5, and very low powered — you don’t need to change it. You can also consider doing optic capture, which I’ll show you on the video. So how do you put a lens in the sulcus? Well, if there’s vitreous in the anterior chamber, it’s very important to do an appropriate anterior vitrectomy. You can’t do — sometimes you can do an anterior vitrectomy with a sponge and scissors, but that puts a lot of traction on the vitreous base. It’s much, much, much better to do it with a proper anterior vitrector. So only small — if there’s just a couple of strands of vitreous, sponges and scissors is okay. But otherwise, you need to get the anterior vitrector out, and probably — if you want, you can use triamcinolone, because that allows you to see the vitreous a bit better. But you have to clear everything out of the anterior chamber after vitreous loss. All the vitreous out of the anterior chamber. The rest of the technique I’ll show you on the video. So here there’s been a posterior capsule rupture. The anterior capsule is intact. We’re using the anterior vitrector to clear the vitreous. But also to remove any residual soft lens matter. So we’ve got an AC maintainer in the eye, which is very useful to use if there’s vitreous loss, because an anterior chamber — an AC maintainer keeps the anterior chamber very stable. And one of the things that can bring more vitreous forward is if the AC keeps flattening. And for that same reason, you can see that we’ve put a suture into the main wound. Because you don’t want lots of fluid coming out of the main wound, if you’ve got vitreous loss. Because that just brings more and more vitreous forward. So here we’re putting viscoelastic between… So we’ll just watch that again. But the next step is we put viscoelastic between the iris and the anterior capsule. So that’s just checking that there’s no vitreous strands. Opening up their sulcus with viscoelastic. You have to enlarge the wound. And this is an MA 60 three-piece lens. Implant the leading haptic into the sulcus. Let it unfold. And then place the trailing haptic into the sulcus. And then, again, if you’ve had a case of — then position it with the dialer. And then usually then we put Miochol in, to bring the pupil down. So basically now we’re just putting a suture in. Always put a suture in, if you’ve had vitreous loss. And now we’re injecting Miochol, which is intracameral acetylcholine that brings the pupil down. So you want to check that the pupil is circular. There’s no vitreous remaining. However — yeah. Sometimes, if you have a zonular dehiscence, you’re still trying to use the capsular bag for the lens implant, but you might need to use a capsular tension ring to stabilize the capsule. So we use these capsular tension rings if there’s less than — well, 4 to 6 clock hours of zonular dehiscence. Some people use them in all cases of pseudoexfoliation and all cases of progressive zonular weakness, like Marfan’s syndrome. You can’t use them in children or if there’s a ruptured capsule, or if there’s a very significant dehiscence. So you can dial them into the capsular bag, and you use a second instrument to take some of the pressure off the area of dehiscence, so you don’t extend it. Often we use a capsular tension ring injector. So this is a case where the lens is unstable, and the cataract, very dense cataract, was wobbling around, and we’re trying to save the bag. So we’re putting iris hooks into the capsulorrhexis, to stabilize the lens during the phaco. So that hopefully prevents the zonular dehiscence from extending during the phaco. Basically, they’re weak zonules. It stops them weakening the zonules further. The cataract technique that I prefer is phaco chop, and that has less of an effect, I think, on weakening zonules further. So we’re injecting — now I’m injecting the tension ring into the capsular bag. And then you take the iris hooks out and put a lens implant in the bag. Okay. This is a preloaded capsular tension ring. They’re the same price in the UK as the other ones. And it has an injector. They’re very easy to implant. Again, just injecting it into the capsular bag. Sometimes you need to use a dialer to place the last bit of the ring into the bag. So sometimes you have too much zonular dehiscence to just use a ring, and you need to — again, you’re trying to salvage, keep the bag, to put a lens in the bag. But you need to stitch the bag to the sclera with one of these devices. So these are — you can use a ring, like this, which has got this little eyelet, and you stitch this eyelet to the sclera. Or you can use a segment. So you can see this case has got a zonular dehiscence, and the lens has been subluxated. I’m using iris hooks again to stabilize the area of zonular weakness into the capsulorrhexis. So then you do the phaco chop. So this is the Cionni ring. And ideally, we’d like to use 9-0 prolene, but it’s difficult to get, so often we have to use 10-0 prolene. We’ve made a scleral flap, or a Hoffman pocket, and we use a docking needle to bring the two sutures out. We’re dialing the ring into the capsular bag. Position it in the area of zonular weakness. Then tie the stitches so it’s attached to the sclera. Then put a lens in the capsular bag. And you can see that it’s quite nicely centralized. Here’s another case. This is a Hoffman pocket. So the benefit of a Hoffman pocket is you don’t have to dissect the conjunctiva, and it’s much quicker. Here’s the Cionni ring, with the prolene suture. And the suture is going through the bag. Out underneath the iris, out through the sclera. And so it’s pulling the bag, the dehisced bag, into the area of weakness, and holding it to the sclera. Then you retrieve the sutures from the Hoffman pocket and tie them. And then put a lens implant in the bag. So Ahmed segments are similar, but they’re just a segment rather than a ring. I don’t think they’re as good, because you have to use a capsular tension ring with them. So what about the situation when you have no capsular support? So these are cases where you’ve dropped the nucleus. If there’s been a very traumatic cataract, and the lens has come out. Previous intracapsular cataract surgery. A lensectomy from pediatric cataract surgery. Or very significant anterior and posterior capsular damage. So here the options are an anterior chamber lens implant, iris fixation, or scleral fixation. I’ve got a whole nother talk on this, so I’m just gonna run through this quickly, the options. And then I’ll show you videos in a second talk. So an anterior chamber lens implant is… All of them nowadays are these flexible, open-loop anterior chamber lenses. With these haptics out here, and it’s only a small part of the haptic that presses into the angle. So anterior chamber lens implants in the past had a very bad reputation. But they were completely different models. Current day ones have been designed to minimize most of the complications that the older ones had. But for an anterior chamber lens implant, you obviously need to have good iris support. Here’s an AC IOL in a person who’s had a traumatic dehiscence of their lens, and you can actually see their crystalline lens sitting at the bottom of their pupil here. What about iris fixated lenses? These need a good iris, but they also need a very deep anterior chamber. Usually the haptics are positioned… Usually the lenses are positioned in front of the iris, with haptic capture of the iris here and here. You can also position them behind the iris, and do posterior capture. And particularly in patients that have not got a deep enough anterior chamber to have them in the front of the eye. So these need to be preordered, and are quite expensive. Scleral fixation is when the lens haptics are fixated to the sclera either by sutures or by glue, or in a tunnel, a scleral tunnel. So the indications for scleral fixation is when you’ve got no iris support. Possibly after trauma or major loss of iris, for whatever reason. There used to be a debate — well, there is still a debate about whether they can be used in patients at risk of glaucoma, or patients with a poor endothelium, and there are relative contraindications, but we’ll go in the next talk and discuss that further. Surgery is relatively easier if you’re doing a penetrating keratoplasty at the same time, so that would be the preferred type of aphakia correction, if combined with a penetrating keratoplasty. Good. But the surgery is relatively difficult, and complications can be quite significant. And that’s why it’s slightly fallen out of favor, in favor of anterior chamber lens implantation. So to conclude this first talk, you always want to try and use a capsular — the capsule to support the lens, if possible. So you want to try and get the lens in the bag, or salvage the capsular bag. So you salvage the bag with a capsular tension ring, if you can. If you have to attach the bag to the sulcus, to the sclera, then you’ll use a Cionni ring. If there’s adequate capsular support, you’ll place a lens in the sulcus. If there’s no capsular support, you would probably use an anterior chamber lens implant if there’s good iris support, or a scleral fixation, if there’s poor iris. So if we asked these questions again, which of the following cannot be used to correct aphakia in one eye? Are you going to put your hands up? So who thinks it’s A? Anyone thinks A? B? C? Or D? D is the correct answer. And the reason for that is because you’d get too much anisometropia. Or difference in image disparity between the two eyes. Sulcus implantation can be used in which one? So A, B, C, or D? So the answer is B. So you would use the sulcus if there’s moderate PC rupture, with an intact anterior capsule. Which is what every one of our online people said. So in cases of more than 6 clock hours of zonular dehiscence, which IOL implantation technique is advised? So is it A, in the bag, B, in the bag with a sutured ring, C, AC IOL, or D, scleral fixated IOL? So it’s in the bag, with a sutured segment.
June 7, 2017