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Skilled pupilloplasty improves patients’ visual function and appearance
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Surgical repair of the iris is a frequent procedure for the consultative ophthalmic surgeon. My first introduction to suture repair of the iris came from one of my early mentors, Malcolm McCannel, MD. He developed the so-called McCannel suture technique primarily to help stabilize subluxated iris-supported IOLs following intracapsular cataract extraction in the 1970s. Malcolm also applied his suture technique to repair irises damaged by trauma. He traveled the world teaching his McCannel suture technique with surgical movies, not videos, and often quipped while lecturing that his “reputation hung on a thread.”
In addition, in the ICCE era, many small pupil cases were treated by creating a sector iridectomy. I was taught in my residency how to close these after surgery with two interrupted 10-0 nylon sutures. Today this is never required, but occasionally we need to close a peripheral iridectomy that is too large. We now have many pupilloplasty or iridoplasty techniques that can be used to close an iris defect, make a fixed dilated pupil smaller, center a pupil on a diffractive multifocal IOL, close a congenital iris coloboma, close a large symptomatic peripheral iridectomy or iridotomy, or round up an irregular pupil.
The tools required include suture, for me usually 10-0 polypropylene on a long needle, available from Ethicon and Alcon. In addition, in select cases, microscissors or a vitrector are helpful in trimming and “rounding a pupil” to the right shape and size. I find the MST microforceps and scissors very useful in many reconstructions. Synechiolysis is often required, and viscodissection along with blunt and occasionally sharp dissection in cases with a history of trauma and long-standing peripheral anterior synechiae often release a remarkable amount of useful iris for repair.
A few thoughts on the iris anatomy and specific cases. The vasculature includes a major circle of the iris that is just outside the iris insertion in the ciliary body and about 36 radial arterioles that extend to the minor circle of the iris near the sphincter. In the Urrets-Zavalia syndrome, familiar to all corneal surgeons, an acute elevation in IOP after keratoplasty results in a dilated pupil unresponsive to miotics secondary to ischemic necrosis of the iris sphincter muscle. These pupils respond well to iris cerclage, and the techniques discussed in the accompanying cover story can be viewed on YouTube.
It is important to learn the methods of tying a knot taught by Steve Siepser, MD, Robert Osher, MD, or Steve Safran, MD, and the iris cerclage techniques. I have found it is possible and sometimes tempting to make the pupil too small with iris cerclage, and a target of about 3.5 mm diameter is my preference for both cosmesis and function. The iris stroma is fibrovascular tissue and when sutured together side-to-side will heal. Thus, a permanent suture is less necessary when approximating iris-to-iris in pupilloplasty repairs than it is in iris cerclage. Still, I primarily use 10-0 polypropylene and 10-0 polyester sutures in these cases.
It is useful to remember when closing a congenital iris coloboma that unless iris relaxing incisions are placed, the pupil will usually pull back down inferior with healing. In addition, the pupil location can be influenced after healing and in the normal iris with the argon laser, as mentioned by Eric Donnenfeld, MD.
Finally, we also have clinical trials ongoing in the U.S. on synthetic artificial irises. These are available in Europe from Morcher, Ophtec and HumanOptics. They are amazing in the quality of cosmetic and functional improvement that can be offered in patients with aniridia. There are about 15 to 20 centers in the U.S. where these are available, including from David Hardten, MD, and Sherman Reeves, MD, at Minnesota Eye Consultants.
A well-centered round pupil generates the highest quality of vision, and we as surgeons can often significantly impact our patients’ visual function and cosmesis by perfecting the surgical skills of pupilloplasty.