30 The Cow-Hitch Suture Technique Late dislocation of the capsular bag–intraocular lens (IOL) complex can occur a few months to many years after surgery, usually without associated complications in the original surgery.1–3 A slow process of progressive weakening of the zonular support, even after years of evolution, can lead to this complication. Two fundamental mechanisms contribute to the late dislocation of the capsular bag–IOL complex: age-related zonular weakness4 and contraction of the capsular bag.5,6 These two factors, together or individually, result in a failure of the zonular support and the subsequent displacement of the intact capsular bag containing the IOL. The anterior circular continuous capsulorrhexis, described by Neuhann,7 could play an important role in the current incidence of this complication. Capsulorrhexis phimosis8 might be one of the causes of the late in-the-bag IOL dislocation. Likely, the major predisposing factor for in-the-bag IOL dislocation could be pseudoexfoliation.9–12 Furthermore, other causes might contribute to this process: retinitis pigmentosa,12 prior vitreoretinal surgery,13 a long axis,12 ocular trauma,13 and uveitis.14 Hanemoto et al15,16 described the use of the cow hitch for refloating and refixating the dislocated IOL, using a needle manufactured specifically for their technique. In this chapter we describe a new technique, performing the cow hitch inside the eye, but with common microsurgical tools. Using our new surgical technique, the cow-hitch suture technique (CHST), it is possible to recuperate the dislocated late in-the-bag IOL complex. For refloating the in-the-bag IOL complex, our technique of multiple globules of perfluoroctane (perfluorocarbon in the United States) is proposed,17 with minimized risk of entrapment of the IOL between the ocular wall and the perfluoroctane. For refixating the IOL, the intraocular implementation of a cow-hitch knot is recommended, using a disposable 23- or 25-gauge microforceps for peeling the inner limiting membrane (Revolution®, Alcon, Fort Worth, TX). It is necessary to fashion two holes in the capsular bag by the middle of each haptic, with the vitrectomy instrument. A forceps is introduced into the eye grasping a loop of 10-0 polypropylene suture using a sclerotomy in the bed of a scleral flap. Another microforceps, from the opposite 23- or 25-gauge microsclerotomy or using a corneal paracentesis, is passed through a hole made in the capsular bag by the middle of the haptic (Fig. 30.2). These forceps grasp the loop, and pass it to the first forceps that regrasps the loop and extracts it from the eye through the first sclerotomy under the scleral flap (Figs. 30.3, 30.4, 30.5a). (The handshake technique described in Chapter 29.) To complete the cow-hitch knot outside the eye, both ends of the suture must pass through the loop in the same direction (Fig. 30.5b). Finally, the surgeon pulls the ends of the suture, and the cow hitch goes into the eye, holding the haptic and IOL in the bag (Fig. 30.6). Another possible maneuver would be to pass the forceps with the loop, through the hole in the capsular bag, and then continue with the same procedure. To fix the suture on each scleral bed, both needles pass through the sclera and are tied beneath each scleral flap. One knot is made with each needle by using the corresponding suture end and a loop (Fig. 30.7). In that way, the capsular bag–IOL complex is sutured to the scleral wall by two cow hitches and four knots (Figs. 30.8 and 30.9). We have performed the CHST in 14 cases of late in-the bag IOL complex. Preoperative vision remained unchanged or was improved after the surgery in all of the cases. Mean visual acuity prior to surgery was 0.09 ± 0.29 standard deviation (SD) Snellen and mean postoperative was 0.27 ± 0.33 SD. The average postoperative follow-up was 9.99 ± 17.55 SD months (range, 1 to 48 months). All of the late in-the-bag dislocated IOLs remained well fixated and stable throughout the postoperative period. From these 14, 12 patients had associated predisposed ocular conditions. Six patients had a history or repaired retinal detachment by pars plana vitrectomy (42.86%). A pseudoexfoliation syndrome was present in four cases (28.6%). Other associated ocular entities were retinitis pigmentosa (one case) and ocular trauma (one case of Fuchs’s heterochromic cyclitis with posttraumatic aniridia). Fig. 30.1 The surgical steps of performing a cow-hitch knot are shown in this left eye of a posttraumatic aniridia with dislocated late in-the-bag intraocular lens (IOL) (one-piece AcrySof®, Alcon) complex. (a) The left hand introduces the loop through a hole in the capsular bag, and the right hand takes the loop. (b,c) The loop is pulled out by the left hand. (d) Once the suture is outside the eye, the polypropylene straight needle is passed through the loop. (e) The polypropylene curved needle is also passed through the loop in the same direction as the straight one. (f) Grasping the two ends of the suture, the knot passes into the eye, encompassing the haptic of the in-the-bag IOL complex. Fig. 30.2 The right hand introduces a loop into the eye with a 23- or 25-gauge inner limiting membrane (ILM) microforceps by a micro-sclerotomy in the bed of the scleral flap. The loop is passed through the hole of the capsular bag with the left hand using another ILM microforceps. Fig. 30.3 The loop is passed from the left hand to the right hand, incorporating the haptic of the IOL. Fig. 30.4 The loop is brought out of the eye using the same micro-sclerotomy. Fig. 30.5 (a,b) The cow-hitch knot is performed out of the eye, passing the two needles through the 10-0 polypropylene loop. Fig. 30.6 (a,b) Grasping the two ends of the suture, the knot passes into the eye, securing the haptic of the in-the-bag IOL complex. Fig. 30.7 Two ends and two needles of 10-0 polypropylene suture pass through each sclerotomy in the bed of both scleral flaps.
Surgical Technique
Cow-Hitch Suture Technique for Dislocated Late in-the-Bag IOL Complex (Fig. 30.1)
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