I use three techniques to manage small pupils: stretching, iris hooks, and the Malyugin ring.
Pupil stretching used to be one of the main ways that I would force mydriasis. This is really a good technique if you have posterior synechiae or if the patient has been on Pilocarpine chronically. However, more and more I am avoiding using pupil stretching techniques because it is contraindicated in patients that are on Flomax (or other alpha blockers) as it can lead to even more problems with iris prolapse. Compounding this problem is the reality that so often patients cannot remember having been on Flomax (or their other medications). Because my practice is concentrated at our VA Hospital here in Iowa City, I have a lot of patients who have been on either Flomax or junior varsity versions of this alpha blocker in the past (Hytrin, Cardura, saw palmetto…) and so if they have a small pupil I just assume that have had Flomax. I also think pupil stretching should be avoided in patients with shallow chambers, as there is a tendency for iris prolapse in those patients as well.
The technique that I use for pupil stretching is to use two Kuglen hooks -- one through the paracentesis and the other through the main wound. The hook through the paracentesis grabs the pupil and pulls it towards the paracentesis and then the other hook pushes 180 degrees across from the paracentesis to stretch the pupil. The stretch is held for a few seconds and it is not uncommon that you will notice some hemorrhage along the pupil. This is a good thing as it shows that there has been some change in the pupillary sphincter. Following stretching of the pupil, you need to use a dispersive viscoelastic which is highly viscous to help push the pupil open. There is really only one highly cohesive dispersing viscoelastic for me -- Viscoat; although others, such as Healon D and Vitrax, may be available in your area. I like to place the Viscoat in a circular pattern, around and around, to gently push the pupil out. You often find that at first you didn’t think there was much effect from the pupil stretch, and then after adding the Viscoat in this fashion, you gain enough mydriasis to safely proceed with surgery.
I will also caution you that during hydrodissection, the fluid wave can catch the dispersive viscoelastic, pulling the iris with it out of the eye, producing prolapse of the iris. As such, I recommend that you remove the viscoelastic over the lens, before hydrodissection, either using the automated irrigation/aspiration unit or use a syringe with BSS to wash out some Viscoat. This will reduce the likelihood of iris prolapse during hydrodissection. However, you just need to be careful during hydrodissection to avoid iris prolapse.
Iris hooks are a great technique for the small pupil and I use them often, although I don’t use them as often as I used to as I am transitioning some to the Malyugin ring, which I will discuss below. Iris hooks are great for shallow chambers, they are great for complex cases where you might have to convert to a large incision extracapsular procedure or if you have to use complicated suturing of IOLs or Cionni rings during the case which would make an internal device such as a Malyugin ring more difficult. I usually avoid iris hooks if there is a bleb present, because it is sometimes hard to work around the bleb and you have to be very careful not to damage the bleb. They are also harder when there are narrow lid fissures because the hooks get in the way of the lids, and so I tend to avoid them in that situation.
The way I like to use iris hooks, I described in a paper with Louis Omphroy.1 In this technique, we use a diamond configuration of the hooks such that there is one hook under the main incision, one across, and then one hook 90 degrees to either side of the wound. This creates, relative to the incision, a diamond configuration of the iris. I like to use a 27 gauge needle, a Grieshaber knife, or a 75 blade to make the four paracenteses for the iris hooks. You want to make these as posterior as possible and you want to make them short and angled slightly down, such that the hook, when it is placed in the eye, is aimed towards the iris. I like to place the hooks before I add viscoelastic so that the chamber is not so deep that it makes it very difficult to grab a hold of the iris. After placing the hooks, then I add viscoelastic and make the incision just anterior to one of the hooks. I tend to use a Kelman McPherson and a straight tie to place the hooks as shown in the video below.
I like the Malyugin ring and use it most of the time now for small pupils. The Malyugin ring comes in two sizes; one with an internal diameter of 6.2 mm and the other with an internal diameter of about 7 mm. The Malyugin ring is great in patients that are on alpha blockers such as Flomax2. It is great in patients that have narrow lid fissures because it does not involve any external manipulation to the eye and so you don’t have to have proptosis or great exposure. I would recommend avoiding the Malyugin ring if you think you are going to convert to an extracap as this is very difficult with the ring as opposed to being relatively easy when using iris hooks. I would avoid the Malyugin ring when using other intraocular hardware such as Cionni rings or suturing inside the eye, as the Malyugin ring can get in the way (relative to iris hooks) when doing these complex procedures.
The Malyugin ring is placed with a special inserter into the eye and the leading eyelet is engaged onto the iris and then one toes down a bit as the ring is pushed further in, trying to engage the lateral eyelets as well. Very often, only one of the two lateral eyelets is also engaged in the initial insertion process. The trailing eyelet often is very difficult to disengage from the inserter without introducing a hook through the paracentesis to push the ring slightly to the side to allow the inserter to exit the eye. I tend to use a Kuglen hook to subsequently place the eyelets that were not initially engaged with the inserter; a Lester hook can also be used or Sinskey hook.
Retraction of the Malyugin ring is probably the trickiest thing. You want to first disengage the leading eyelet which is across from the wound and then you want to disengage the leading eyelet and T it up slightly to the side and anterior. Use plenty of viscoelastic so that you don’t engage the IOL during this process and that so that the cornea is safe. The inserter is then placed in the eye slightly to the side of the eyelet, but over the ring, and then is turned such that the hook is over the entire eyelet and then pulled back and engaged onto the eyelet and pulled back into the inserter. It is most important that you not completely retract the ring into the inserter, as funny things happen when you do this. As shown in the video below, odd things will happen if you try to totally retract the ring, so just pull it back so that it is just thin enough to come back through the wound and pull it out of the eye.
There are two choices for the Malyugin ring; one which is 6.2 mm in internal diameter which is useful for most cases, but if the pupil starts off big or if you are going to use a particularly large IOL, then I would recommend using the 7.0 mm Malyugin ring. We tend to stock both in the operating room here, and use the smallest ring that you can to get the job done. The advantage of the smaller ring is that it is easier to insert and easier to retract, and the advantage of the larger ring is that you can use it when the pupil starts off bigger.
References:
1. Oetting TA, Omphroy LC. Modified technique using flexible iris retractors in clear corneal cataract surgery, Cataract Refract Surg 2002;28(4):596-8.
2. Chang DF. Use of Malyugin pupil expansion device for intraoperative floppy-iris syndrome: results in 30 consecutive cases, Cataract Refract Surg 2008;34(5)835-41.
