11.1 Introduction

Permanent mydriasis creates significant disability both during the day with photophobia and at night with glare from lights. When the mydriasis is due to focal areas of iris sphincter dysfunction, the condition may be treated with localized suturing. When the sphincter dysfunction is diffuse with no areas of meaningful contraction, then a 360° suturing solution becomes more beneficial. The most commonly used iris cerclage technique today utilizes a curved needle and a finishing knot tied inside the eye. It was first presented and then published in the peer review literature in the late 1990s. ^{1 , 2 , 3 , 4 , 5 , 6 , 7 , 8}

11.2 Preoperative Assessment

The preoperative evaluation in the office usually provides all the information needed to determine if the symptomatic mydriasis is due to nonfunctional iris sphincter. In the nonpharmacologically dilated state, if the pupil is large when examining it through the slit lamp with very little light, and there are no areas of the sphincter that appreciably constrict when widely opening the light diaphragm on the slit lamp, then the sphincter dysfunction is very likely diffuse and rather complete. One can further confirm the lack of iris sphincter activity if instillation of an iris sphincter relaxing drop, such as tropicamide, does not make the pupil larger, or instillation of a sphincter constricting drop, such as pilocarpine, does not make it smaller.

In contrast, if there is something like a 180° of pupillary sphincter that constricts well, then the mydriasis might be reparable with interrupted (two-bite, or multibite) sutures in the dysfunctional area. The pupil activity assessment may be confirmed intraoperatively by injecting acetylcholine (Miochol) into the anterior chamber and observing the pupil response. When making an intraoperative assessment, one should avoid using epinephrine or phenylephrine in the infusion bottle for any concomitant procedures as this tends to significantly blunt the constricting effect of acetylcholine. In fact, if the pupil is large enough, then no preoperative dilation drops are even needed for a concomitant procedure, which further decreases the chance of confounding the assessment. If one is not efficient at performing an iris cerclage suture, then strong consideration should be given to using a corneal light shield to protect the macula. Although we standardly perform iris cerclage at the same time as cataract surgery in eyes that have need for both procedures, one may wish to consider staging the cerclage 1.5 months or more after a primary cataract/intraocular lens (IOL) surgery to allow time for the capsule to seal around the IOL or to decrease the amount of surgical time per session that the patient experiences.

11.3 Surgical Technique

For the procedure, the globe needs to be kept pressurized using either a limbal infusion cannula with relatively normotensive infusion pressure (if the lens capsule diaphragm is disrupted) or ophthalmic viscosurgical device (OVD) in the anterior chamber (if the lens capsule diaphragm is intact). Rectus bridle sutures can be helpful for stabilizing and elevating the globe during surgery, which may make performing the procedure easier for some surgeons.

The surgeon creates three to five paracentesis openings at the limbus with the inside of the paracentesis wider than the outside to facilitate exiting the eye at the paracenteses as well as passing the needle in through the paracentesis on its way to the iris. If a concomitant procedure was performed with an incision, then that incision can be utilized as one of the paracenteses. Generally, a cerclage for very large pupils needs more paracenteses than for moderately large pupils because of the geometry involved in accessing the pupil margin when it is far in the periphery.

It is important to realize that the central most part of the mydriatic pupil is not always the actual pupillary margin. As the iris dilator muscles are in the back of the iris, they can cause the pupil margin to roll posteriorly when the pupillary sphincter activity is lost. Hence, using an IOL manipulator with a knob to hook the underside of the pupil to unfurl the iris may be needed in some cases to retrieve and expose the pupil margin. In other situations, intraocular forceps may be able to grasp the pupil margin and pull it centrally to prestretch the iris before suturing (▶Fig. 11.1).

The typical needle/suture for performing an iris cerclage is a long, curved transchamber needle double armed on 10–0 polypropylene (e.g., CTC-6L spatula needle, double armed on 10–0 polypropylene, 9091G, Ethicon). Keeping both needles on this 4-inch suture gives the surgeon a second avenue of attack in the opposite direction if the first needle should become too dull, or breaks off, or the ergonomics of the first direction become excessively difficult. One of the needles is passed in through a paracentesis making sure not to catch any corneal tissue with the needle. Using an instrument, such as a cyclodialysis spatula, to hold the paracentesis open while sliding the needle along the side of the instrument dramatically decreases the chance of catching corneal tissue. Once the needle tip is through the paracentesis, it should be moved side to side in the paracentesis to verify that it moves the width of the paracentesis, which confirms it has not caught corneal tissue. Usually, the pupil margin needs to be pulled centrally with an intraocular forceps or an instrument like an Ogawa iris reconstruction hook (6–109, Duckworth & Kent) to begin needle passes through the iris. These passes should start near the paracentesis—usually going down through the iris (▶Fig. 11.2), and then back up through the iris (▶Fig. 11.3) in a basting stitch fashion before continuing with a whip stitch with each bite going through the iris from its underside until reaching the next paracentesis (▶Fig. 11.4). This whip stitch variant, as has been presented at multiple major meetings by Michael Snyder, MD, may produce a smother pupil margin than with continual basting stitch, perhaps because it is easier to get the suture bites closer together—the more, and closer the bites, the smoother the pupil margin. The needle must exit the eye at the next paracentesis again, without catching corneal tissue. The cyclodialysis maneuver can be utilized; however, a 24-G IV plastic angiocatheter (with the IV needle removed) functions well to dock the needle for externalizing through the paracentesis without dulling the needle tip. A 27-G steel cannula provides a more stable docking receptacle for needle exit but does have a greater tendency to dull the needle (▶Fig. 11.5, ▶Fig. 11.6, and ▶Fig. 11.7).

The suture needle goes back into the paracentesis through which it was just externalized using the same maneuvers as the first needle pass into the eye. At each paracentesis, the surgeon should pay close attention to the location of the last needle pass through the iris before the needle exited, and the first needle pass after re-entering because this is the easiest place to create a gap between needle passes resulting in a “notch” in the pupil margin when the case is complete (▶Fig. 11.8, ▶Fig. 11.9, ▶Fig. 11.10, and ▶Fig. 11.11). After continuing this process for 360° (▶Fig. 11.12, ▶Fig. 11.13, and ▶Fig. 11.14), the final needle pass can exit the limbus through the original paracentesis (▶Fig. 11.15 and ▶Fig. 11.16) or any convenient limbal location as the needle will soon be cut off and the suture arm can be externalized through a paracentesis of the surgeon’s choice.

Some surgeons prefer a thicker, taper-cut needle for this procedure as it is more stout (e.g., CIF-4, taper-cut needle, 788G, Ethicon), but with this type of needle, one needs to enter and exit just through the paracentesis openings because it does not pass well through corneal or scleral tissue without a precreated path (like a paracentesis). Additionally, this needle gets thicker further back from the tip; therefore, there can be a progressive drag on the iris as the needle is passed through the iris, which can place excessive stress on the iris tissue.

To complete the cerclage, the suture arms should be tied together with the surgeon’s choice of intraocular knot (▶Fig. 11.17 and ▶Fig. 11.18). Unlike many iris suture knots, which gain friction from compression of iris tissue, the knot for a cerclage is a free-hanging knot, analogous to a knot in the middle of a clothesline. Experience has demonstrated that the knot should have the internal friction strength of at least a 2–1–1 (two-wrap first-throw, single-wrap second-throw, and single-wrap third-throw). A 2–1 or four-wrap single-throw knot, for example, while generally adequate for interrupted iris sutures, does not provide adequate internal friction for this use. ⁹ As the first throw of the knot is tightened, the new size of the pupil is determined. Approximately, a 4-mm pupil (as measured externally) is generally large enough for retinal examination yet small enough to control photophobia (▶Fig. 11.19). The pupil can be made larger or smaller than that depending on the individual patient needs. If with the first throw of the knot, the pupil becomes smaller than desired, a pair of IOL manipulators with rounded knobs may be used opposite each other inside the pupil to pull outward, causing the first throw to slide and the pupil size to become larger. This same maneuver may be performed if, as the second throw is tightened, the knot does not cinch and both throws start sliding, making a smaller pupil. Once the knot is finalized, then coaxial intraocular scissor works well for trimming the suture tails, leaving them about 1.5-mm long (▶Fig. 11.20). The procedure is completed with gentle removal of any OVD and sealing of incisions as well as any other surgeon-preferred case completion steps, such as verification of IOL position and/or pupil centration by inspecting Purkinje image alignment (▶Fig. 11.21) (▶Video 11.1). ¹⁰