7.3.4 Pupil Repair

Blunt trauma often causes injury to the iris sphincter. An isolated rupture of the sphincter muscle is repaired with single interrupted sutures, similar to the technique illustrated in Figs. 7.1 and 7.2. When there is more generalized damage to the iris sphincter, caused by either multiple ruptures or ischemia, a different technique is needed. The surgeon can generally determine by careful preoperative inspection whether generalized iris sphincter injury has occurred. At the preoperative slit lamp examination, while varying the illumination through the pupil, the surgeon can inspect whether there is reactivity of the iris sphincter. In addition, the iris sphincter architecture is carefully inspected. When the iris sphincter architecture is not preserved and there is little to no reactivity, then a larger-scale repair of the pupil is needed.

The surgeon has two choices. The simpler choice is to place multiple interrupted sutures. This will typically result in a squareor diamond-shaped pupil (Fig. 7.4). Although cosmetically suboptimal, the optical benefit to the patient is substantial.

Alternatively, the surgeon can perform a 360° pursestring suture. This procedure was originally demonstrated by Dr. Pius Bucher of Austria and is illustrated in Fig. 7.5. The placement of the suture occurs after the completion of any cataract removal and IOL placement, of course. In the iris cerclage purse-string suture technique, a 10-0 Prolene suture on a CTC-6 needle (Ethicon) is recommended. In addition to the larger principal incision used for simultaneous cataract and IOL surgery, the surgeon should place two or three paracentesis openings at approximately equally spaced intervals. The needle is introduced through the principal incision and is passed in and out of the midperipheral iris stroma, typically for three or four passes.

The needle is then passed out of the paracentesis by “docking” the needle tip into the end of a blunt 27-gauge irrigating cannula that has been passed through the paracentesis into the anterior chamber. In this manner, the pointed needle can be externalized without engaging the corneal tissue around the paracentesis. The needle is then regrasped with the needle holder and reintroduced into the eye, repeating the process for another quadrant or third of the iris. In reintroducing the needle through the paracentesis, great care must be taken not to inadvertently engage the lip of Descemet’s

a

b

Fig. 7.4 (a) Diamond-shaped appearance of the pupil after four interrupted sutures reduced a large atonic pupil at the time of penetrating keratoplasty. (b) High magnification shows the four polypropylene suture knots

membrane or any of the stroma. It is of great help during needle reintroduction to wiggle and side-sweep the needle tip while advancing the needle within the paracentesis to ensure that no corneal stromal fibers are engaged. If the surgeon encounters difficulty passing the tip of the needle through the paracentesis cleanly, placement of some viscoelastic in the paracentesis can be a great aid in opening the passageway.

In one approach, the bites of the cerclage suture are placed in the midperipheral iris, not close to the pupillary margin. The reason is that, once the suture is tightened, the suture between each of the bites will tighten and constrict. If the suture bites are near the pupillary edge, the suture material will be pulled into the pupillary opening, resulting in scalloping and a petalloid appearance to the pupil border. In contrast, if the suture material is kept in the midperiphery, the suture material itself will not be able to cross over the pupillary zone itself. In an alternate approach, the sutures bite

Fig. 7.5 (a) Four side-port incisions are required, spaced at 90º intervals. (b) A long needle such as the Ethicon CTC6L is employed. As the needle passes through the incision, care must be taken to avoid piercing any corneal tissue. The needle pierces the iris about 2 mm peripheral to the pupil border. An instrument such as the Kuglen hook is usually needed to support the highly flexible iris so that the needle will penetrate. (c) The needle is passed up and down through the iris in small bites until one quarter of the iris is sutured.(d) The sharp needle point is docked into the end of a blunt-tip cannula so that the needle can be guided out of the side-port without engaging any corneal tissue.

(e) The needle is then regrasped by the needle holder and reintroduced into the side-port incision, continuing the process of suturing the next quadrant of iris. (f) After completing a full 360º of suturing, both ends of the suture are ready to be tied. (g) The knot is created outside the eye and then advanced into the eye and tightened with the aid of an instrument such as a Kuglen hook. The pupil will then contract as the purse-string is tightened. At least 4 throws of the know are made for a secure knot and the suture ends are cut short with an intraocular scissors or blade. Illustration by Christiane Solodkoff, Neckargemünd/ Heidelberg, Germany