lowing surgery (26 of 32 cases in one series38). Less commonly it occurs during surgery or several months after surgery. The presenting visual acuity with aphakic correction may be very good, but is commonly decreased to a moderate degree despite the best spectacle correction. Patients with luxated or subluxated PC IOLs are usually symptomatic because of the variable position of the optic in the visual axis. In addition, a mobile PC IOL may also generate unique floater-like symptoms, or even lead to pupillary block glaucoma.

The presenting symptoms of patients with dislocated IOLs range from minimally symptomatic lens decentration to complete luxation into the vitreous cavity.36 Decentration usually refers to mild malposition with the optic still covering more than half of the pupillary space. In many cases of decentration one haptic is in the ciliary sulcus and the other is in the capsular bag. Progressive decentration may become apparent with progressive capsular fibrosis. Patients at this, the milder end of the spectrum, usually present several weeks after cataract extraction with good visual acuity, normal IOP, and without inflammation. Visual symptoms usually are mild and may be related to glare from the edge of the optic.

MANAGEMENT OPTIONS

There are four general classes of management options for dislocated IOLs: observation, removal, exchange, or repositioning.38–45 The management plan and timing are formulated based on clinical factors such as the type of IOL and any observed secondary complications.

Patients presenting with substantial intraocular inflammation, retinal detachment, or with cystoid macular edema (CME), especially when associated with vitreous to the cataract incision, constitute definite candidates for surgery. Although a completely dislocated IOL may be well tolerated in many patients, the difficulty in visual rehabilitation necessitates surgical intervention in most. For symptomatically subluxated IOLs, surgery may be performed via a limbal or a pars plana approach. Patients with less extensive subluxation can be managed through a limbal incision with minimal or no anterior vitrectomy if the posterior capsule is largely intact. However, if there is a large posterior capsular rent, vitrectomy using a pars plana approach may offer optimal control to achieve the goals of surgery and address unforeseeable intraoperative complications.

Observation

IOLs with simple decentration are usually satisfactorily managed by observation. Observation also may

be recommended even for luxation if other superseding medical or ocular problems prohibit further surgery, or if the patient simply elects not to pursue further surgery. Occasionally, management with topical miotics can be visually beneficial, especially for minor subluxations. In a series of 15 patients with dislocated anterior chamber or iris plane IOLs that were observed, a visual acuity of 20/40 was reported in 60%, but retinal detachment occurred in two patients.39

Removal or Exchange

The IOL is usually exchanged when there is damage to the IOL during surgical management (e.g., broken haptic), if available instrumentation to effect repositioning is lacking, or if highly flexible haptics, or polypropylene haptics that are appreciably misshapen, make the IOL unsuitable for sulcus fixation.

One encountered circumstance in which IOL exchange may be considered occurs in certain cases with silicone IOLs.46 Silicone IOLs are slippery and more difficult to grasp than polymethylmethacrylate (PMMA) IOLs, but can usually be engaged and elevated from the retinal surface with a vitreoretinal pick or a lighted pick. A serrated or diamond-dusted forcep may be necessary. Caution should be exercised to avoid scratching the center of the optic during attempted repostioning. Silicone plate haptic IOLs are extremely floppy and difficult to manipulate. They are designed specifically for capsular bag fixation. Damage to the silicone optic or presence of a plate haptic lens that cannot be repositioned within the capsular bag will require IOL exchange.45,47

In patients for whom repositioning PC IOLs proves problematic, an intraoperative decision can be made to remove and exchange it with an AC IOL or scleral suture fixated PC IOL. Exchange for a suture-fixated PC IOL has been simplified by the availability of IOL designs that include holes (eyelets) in the haptics. However, explanting and reimplanting an IOL may risk more corneal endothelial cell trauma as compared to repositioning techniques. Exchange for an AC IOL may be less traumatic to the corneal endothelium and may be easier and faster to accomplish. Newer AC IOL designs reportedly avoid complications caused by the mechanical side effects of earlier AC IOL designs compared to PC IOLs, and the results can presumably be extrapolated to dislocated IOL management.48 In general, scleral suture fixation with a PC IOL is preferred by the authors over AC IOL implantation.45 In any case, it is important that the possibility of either PC IOL or AC IOL implantation should be anticipated with proper IOL power calculations, and IOL availability, before surgery.

An ancillary option is observation of the dislocated IOL, in which case visual rehabilitation is achieved with implantation of a second (usually AC) IOL.49–51 This should be considered an option of last resort, however, as most patients are concerned with the presence of a dislocated lens implant.

Intraocular Lens Repositioning

IOL repositioning completes the initial surgical objectives of the cataract surgery and is the most commonly elected surgical approach. There are three basic approaches to IOL repositioning: (1) IOL repositioning without sutures using residual peripheral anterior or posterior capsule, (2) iris sutured fixation, and (3) scleral suture fixation.

Subluxated IOLs associated with an intact, or mostly intact, posterior capsule may be repositioned from an anterior approach if there is only moderate subluxation. Usually at least one haptic is posteriorly malpositioned—either protruding through an unseen zonular dehiscence in an area without posterior capsular support or posterior to the residual capsule. A pars plana approach is optimal for patients with large posterior capsule defects, for patients with IOL luxation into the vitreous cavity, and for patients with coexisting ocular complications such as retinal detachment.

Recognition and use of adequate capsular support are as important for repositioning the PC IOL as they are for primary placement. Generally, the IOL remains well supported if at least 180 degrees of peripheral capsular material is intact. More extensive support is necessary, however, when the inferior capsule is absent or if the margin of the residual capsule where IOL haptics are to be placed is of questionable integrity. Repositioning by capsular fixation is the most common management technique in reported series38–45 and is the authors’ first choice when technically possible. Surgical success depends on accurate placement of the haptics into the ciliary sulcus, which requires visualization of the residual capsule.52,53 Placement of iris hooks is useful in selected cases, but usually strategic local iris retraction with a hooked instrument allows confident visualization. A useful maneuver in a pars plana approach is to bring the IOL anteriorly and capture at least one haptic anterior to the iris (Fig. 26–3). After the IOL is stabilized in the anterior chamber, the second haptic can be guided between the residual capsule and posterior iris surface either by rotating the lens or by grasping the haptic with an intraocular forceps via the pars plana. Because of the widespread use of capsulorrhexis, the peripheral anterior capsule is usually intact and serves as an effective interface for sulcus fixation (Fig. 26–3). Repositioning a PC

FIGURE 26–3 When repositioning a posterior chamber (PC) intraocular lens (IOL) onto residual capsular remnants, it may be useful to bring one haptic anterior to the iris to facilitate accurate visualization of haptic placement over residual capsule. (From Regillo CD, Brown GC, Flynn HW Jr. Vitreoretinal Disease: The Essentials. New York: Thieme; 1999:572, Fig. 35–7.)

IOL permanently into the anterior chamber also has been reported, but is not recommended because of chronic chafing of the iris by the IOL and lens power considerations.54

Iris fixation sutures were initially described for the use of dislocated AC IOLs.55 However, their use has been modified for fixation of dislocated posterior chamber implants using a limbal or a pars plana approach.52,56 This technique requires that a suture pass through the cornea, iris, around the IOL haptic, and back out through the iris and cornea. Because accurate placement of the needle is difficult, it is challenging to optimize IOL centration. Also, concern regarding iris-mediated chronic inflammation and the technical difficulty encountered during suture placement have led to the development of other techniques.

Scleral fixation sutures were first introduced for implantation of secondary IOLs and for primary IOL placement in the absence of satisfactory peripheral capsular support in a limbal or pars plana approach.21–32 Early reports described pulling the haptic to or externally through57–59 a sclerotomy to position a suture on the haptic before suturing to the deep part of the sclerotomy wound. Subsequently, IOL repositioning using transscleral fixation sutures via a pars plana approach mimicking the techniques of secondary IOL fixation was described. Numerous innovative modifications have made the technique easier and safer and will be reviewed below. Components common to all scleral suture fixation techniques include (1) retrieving the IOL, (2) introducing a suture loop through the ciliary sulcus region into the vitreous cavity, (3) passing the suture loop around the IOL haptic, (4) securing the suture to the sclera, and (5) covering or burying the scleral suture

knot. A wide variety of techniques have been described to achieve these goals.

Most proposed techniques modify how the suture loop is introduced and attached to the IOL haptic. Such techniques have included imbricating the IOL haptic into the sutures used to close the sclerotomy,60 externalizing the haptics to attach a suture,61 using a needle guide to thread the suture around the haptic,62 introducing a small needle intraocularly to capture the haptic,63 suturing through IOL optic positioning holes,64,65 backing a large needle into the eye to introduce a suture loop,66 grasping a loop by intraocular forceps,67,68 and introducing the suture from a third sclerotomy.69 Other proposed variation techniques include achieving threeor four-point fixation to lessen lens torsion,70 using specially designed small-gauge forceps to aid in maneuvering the loop around the haptic,71 and using perfluorocarbon liquids to place the implant in a convenient position for suturing.40,72,73 Most posterior segment surgeons find the use of perfluorocarbon liquids unnecessary.

The current technique preferred by the authors will be described and illustrated.74 A standard threeport pars plana vitrectomy is performed to remove the formed vitreous and to mobilize the IOL. Partialthickness, limbal-based scleral flaps are dissected, most conveniently in the 1 and 7 o’clock meridians to avoid the previous cataract wound and yet be accessible. A disposable 27-gauge needle75 (EscalonTrek Medical, Milwaukee, WI) with a hole located in the bevel is threaded with 9–0 polypropylene suture and introduced into the eye 1 mm posterior to the limbus in the bed of the partial-thickness scleral flap (Fig. 26–4). Slack is created in the suture along the shaft of the needle by withdrawing it slightly. The IOL haptic is guided through this loop using the intraocular forceps to grasp the optic. The haptic is captured in the loop as the needle is withdrawn (Fig. 26–5). A partial-thickness scleral needle pass in the bed of the scleral flap allows fixation of the scleral suture. A similar procedure is repeated for the other haptic, unless capsular fixation is possible for the opposite haptic. Occasionally it is necessary to guide the haptic through the loop by using intraocular forceps (Figs. 26–6 and 26–7). The scleral flap is then closed with an absorbable suture and, if necessary, the vitrectomy is completed through the standard sclerotomies.

Scleral Suture Fixation Techniques

Histopathologic and ultrasound biomicroscopic studies have shown that little or no fibrosis occurs around sutured PC IOL haptics,76 but one study has shown cicatrization around the haptics.77 Either way, it is vital

FIGURE 26–4 Suture connected to one needle is threaded through 27-gauge straight needle with hole within bevel of needle. Needle and suture are introduced into the vitreous cavity 1.0 mm posterior to the limbus through the bed of a partial-thickness scleral flap. Under direct visualization the haptic is threaded through the loop along the shaft of the needle. A scleral plug is placed in the unused open sclerotomy. (From Regillo CD, Brown GC, Flynn HW Jr. Vitreoretinal Disease: The Essentials. New York: Thieme; 1999:573, Fig. 35–8.)

FIGURE 26–5 The needle is withdrawn, and the suture is tied under the scleral flap in the usual fashion. (From Regillo CD, Brown GC, Flynn HW Jr. Vitreoretinal Disease: The Essentials. New York: Thieme; 1999:573, Fig. 35–9.)

FIGURE 26–6 A similar procedure is performed for the other haptic, unless the second haptic can be secured by capsular fixation. (From Regillo CD, Brown GC, Flynn HW Jr. Vitreoretinal Disease: The Essentials. New York: Thieme; 1999:574, Fig. 35–10.)

to use a nondissolving suture material because it may provide the sole means of support at the ciliary sulcus.

IOL torsion and decentration can be avoided by accurate ciliary sulcus placement and by adequate excision of bulky capsular and cortical remnants. It may be necessary to exchange some IOLs that are too short from haptic to haptic for sulcus fixation. Anatomic studies have located the sulcus approximately 1 mm posterior to the limbus.78 Consequently, suture placement more posteriorly may cause IOL optic torsion by forcing the circumferentially oriented haptic

over radially oriented ciliary processes. The sutures must be placed 180 degrees apart for proper centration. Also, the IOL must be rotated minimally and cautiously to the center at the end of the case.

OUTCOMES OF SURGERY FOR

DISLOCATED POSTERIOR CHAMBER

INTRAOCULAR LENSES

The final visual acuity probably depends on not only preoperative macular function, but also complications from the original cataract surgery, such as CME and retinal detachment. Still, recent series report a final visual acuity 20/40 in more than 90% of eyes (Table 26–4). However, surgical series are difficult to compare accurately due to nonhomogeneity and the variety of management techniques.

POSTOPERATIVE COMPLICATIONS OF

THE SUTURED IOL

An intraoperative or postoperative vitreous hemorrhage commonly occurs given that sutures are placed through the vascular ciliary body, but are almost always self-limited, and of little clinical significance. Bacterial migration along the transscleral suture tract has been described as being the possible route for infection in cases of delayed-onset endophthalmitis.39 Rotating the suture knot or the use of a partial-thickness scleral flap to cover the scleral suture knot should reduce the risk of this complication. However, the suture knot can erode through the flap.

Other postoperative complications are difficult to separate from those that would be expected with complicated cataract surgery. Both CME and retinal detachment have been described after IOL repositioning surgery. Retinal detachment occurs in about 2% of cases, and may be less frequent than with retained lens fragments.33 Approximately 17% of

FIGURE 26–7 Side view of Fig. 26–6 shows scleral fixation of first haptic and relationships in retrieving second haptic. (From Regillo CD, Brown GC, Flynn HW Jr. Vitreoretinal Disease: The Essentials. New York: Thieme; 1999: 574, Fig. 35–11.)

TABLE 26–4 VISUAL ACUITY OUTCOMES

OF PARS PLANA VITRECTOMY (PPV) FOR

DISLOCATED IOL