Robert H. Osher, MD,
Robert J. Cionni, MD,
Michael E. Snyder, MD,
Christopher D. Riemann, MD,
Andrea P. Da Mata, MD
Contents
|
• |
General Methods |
|
|
• |
Surgical Techniques |
|
|
• |
Conclusions |
|
CHAPTER HIGHLIGHTS |
|||||||||
|
Although most eyes that undergo cataract extraction and intraocular lens (IOL) implantation are rapidly rehabilitated from an anatomic and visual standpoint, a small percentage of them develop complications that require repositioning, removal, or exchange of the pseudophakos. In the past lens dislocation and chronic intraocular inflammation were the most frequent indications for lens exchange.[1] Occasionally, the cause is faulty lens design, which results in chronic inflammation or opacification of the optic with a reduction of vision justifying an IOL exchange. In other cases, a material interaction creates a problem such as the hydrophillic optic absorbing trypan blue stain and the symptom of blue dyschromatopsia leads to IOL exchange.[2] A lens of an inappropriate size leads to unacceptable lens mobility and an uveitis glaucoma hyphema (UGH) syndrome. Incorrect dioptric power may result in anisometropia, asthenopia, or other refractive symptoms. Improper intraoperative positioning of an anterior chamber lens may cause iris tuck, uveal irritation and a UGH syndrome. A posterior chamber lens may decenter because of any number of reasons, including asymmetric haptic placement, inadequate capsular or zonular support, disproportionate IOL/bag size, progressive posterior synechiogenesis with pupillary capture, endocapsular fibrosis, late zonular dehiscence, enlargement of the neodymium:yttrium-aluminum-garnet laser posterior capsulotomy, or postoperative trauma to the eye.[3,][4]
Complications of malpositioned and dislocated anterior chamber lenses include uveitis, glaucoma, hyphema, cystoid macular edema (CME), and corneal decompensation. While a full-blown UGH syndrome is also possible,[5] complications of dislocated posterior-chamber IOLs (PC IOLs) tend to be less severe and are primarily optical in character. For example, PC IOLs can induce diplopia from several causes including binocular symptoms of anisokonia or, by prismatic image displacement. Monocular symptoms are numerous, including blurred vision and monocular diplopia from a refracted image through the edge of the IOL competing with an image through the aphakic portion of the pupil. Decentration and glare may occur as a result of refractive or diffractive effects on the lens edge or, in older IOLs, positioning holes. Rarely, a well-centered IOL with the correct power may mysteriously cause a permanent positive or negative dysphotopsia severe enough to warrant IOL exchange. Similarly, undesired halos or glare may result from multifocal or accommodating IOLs. Patient whim can also lead to a lens explantation, for example, when a request is made to exchange a monofocal IOL for a presbyopic/correcting IOL.
Although surgical intervention is definitive, it is not the only approach available in the management of difficult IOL cases. Conservative observation and pharmacologic therapy should always be considered.[3,][4] Many eyes with IOLs that dislocated into the vitreous cavity during the earlier days of implant surgery have maintained excellent aphakic-corrected vision with no surgical intervention. The course of action must reflect the type and location of the lens, the age and health of the patient, the symptoms, the visual acuity, the corneal endothelial health, the presence and severity of intraocular inflammation, and the status of the fellow eye. Conservative therapy such as observation may be appropriate for an eye with an anterior chamber lens that is associated with a peaked or oval pupil, as long as signs and symptoms of intraocular inflammation are absent. Pharmacologic management consisting of topical steroids may be indicated in the case of mild cell and flare that is unassociated with symptoms or with reduced vision. A trial with a nonsteroidal anti-inflammatory agent in combination with a steroid is justified as a first step in symptomatic pseudophakic CME. Edge-related reflections, diplopia, or glare may, in some cases, be managed successfully by topical apraclonidine or pilocarpine. Topical sodium chloride might be preferable to surgery in treating peripheral corneal edema associated with incipient corneal decompensation in an elderly, frail patient who has a low endothelial cell count.[6] The malpositioned iris-supported lens associated with refractive or inflammatory symptoms is less successfully managed by conservative measures because of our recognition that this design is inferior when compared with both open-loop anterior chamber and most other styles of posterior chamber lenses. However, the posterior dislocation of a single haptic of the Copeland lens or the loop of a Binkhorst or Medallion lens may be associated with posterior synechiae or a fixed pupil that acts to prevent dislocation of the optic. Sequential pharmacologic manipulation of the pupil can result in successful repositioning of these older lenses in selected instances.[6–8]
Decentered and dislocated PC IOLs have become more prevalent because these designs account for more than 98% of all lenses implanted in the United States today. The most common presenting complaint with decentration is unwanted optical images caused by the edge of the optic within the pupil. If the symptoms are infrequent and limited to the evening when the pupil is more dilated, the surgeon may elect to manage these patients conservatively by using a topical miotic. More severe or disabling symptoms can be managed by repositioning, explanting, or exchanging the IOL. When complete dislocation of a posterior chamber lens has occurred, historical options include:
|
1. |
observation and correction of monocular aphakia by external means |
|
|
2. |
IOL repositioning |
|
|
3. |
IOL exchange.[8–10] |
Effective suturing techniques both for secondary placement of posterior chamber lenses and for repositioning of dislocated lenses have further increased the available options.[11,][12]
In this chapter the authors discuss a technical approach to the management of IOL problems that requires surgical intervention.
General methods
Preoperative evaluation
All patients being considered for surgical correction of IOL problems require thorough preoperative evaluation, which includes the determination of a bilateral best-corrected visual acuity, slit-lamp biomicroscopy, gonioscopy, and dilated fundus ophthalmoscopy. Keratometry, topography, A-scan ultrasonography, specular microscopy with endothelial cell count, and, in some instances, potential acuity meter testing should be performed. Ultrasound biomicroscopy can offer valuable insights into the anatomic pathophysiology.[13,][14] A review of the original operative report and knowledge of the lens power, style, A-constant, and location which it was originally placed, as well as the postoperative refraction may be useful in achieving a more emmetropic pseudophakic refractive error. IOL master axial length measurements have markedly improved our ability to choose an IOL power for an exchange in the already pseudophakic eye, especially when access to old records no longer exists.
On reviewing all information available, a surgical strategy with a preliminary plan can be made to reposition, remove, and/or exchange the IOL. When surgical intervention is under consideration, a decision must be made with regard to the timing of surgery, the approach (anterior versus posterior), the composition of the surgical team (cataract surgeon, vitreoretinal surgeon, or both) and how to achieve the disposition of the pseudophakos (repositioning, replacement, or removal). If the pupil fails to dilate in the office, the procedure chosen to correct a malpositioned posterior chamber lens cannot always be finalized at the time of the preoperative examination and should be reassessed during surgery when the pupil is maximally dilated to allow direct visualization of the anatomic relationships. Poor visualization can be managed by either a Fry stretch technique,[17] the use of iris retractors, or a Malyugin ring.[17a] Occasionally, ocular endoscopy can be very helpful in gathering useful anatomic information. Adequate visualization is essential for understanding the pathophysiology of the malpositioned posterior chamber lens and for correcting the underlying problem.
In addition to correcting the IOL problem, the surgeon should take advantage of the opportunity and also correct residual refractive error. Moderate or high astigmatism can be reduced by incision placement, astigmatic keratotomy, limbal relaxing incisions, or even an exchange for a toric IOL. In addition to improving the refractive error, surgical intervention may accomplish other objectives. Synechiae can be separated, the capsular bag can be reopened, Soemmerring's material can be removed, and the posterior capsule can be vacuumed or polished. An iris defect may be repaired by an imbricating suture or even a prosthetic iris device. A pupil can be enlarged, made smaller, or translocated. Zonular weakness can be addressed with a capsular tension ring (CTR).
Copyright © 2010 Elsevier Inc. All rights reserved. Read our Terms and Conditions of Use and our Privacy Policy.
For problems or suggestions concerning this service, please contact: online.help@elsevier.com
Surgical techniques
Anterior chamber intraocular lens
Repositioning of an anterior chamber lens should be performed when a haptic incarcerates iris tissue, when iris has acutely prolapsed into the incision, when the anterior-chamber intraocular lens (AC IOL) haptic migrates through the iridectomy causing decentration, or when the haptic migrates anteriorly contacting the corneal endothelial surface. If diagnosed early, iris incarceration and haptic malposition can be corrected by flexing, lifting, and repositioning the offending haptic. Intolerable optical images might occasionally be corrected by the repositioning of the iris and AC IOL; however, explantation may be required to eliminate unacceptable symptoms.
Although repositioning might suffice in selected cases, IOL explantation is necessary when the lens size is wrong. Lens movement or “propellering” indicates that the lens is too small, while severe tenderness, pupil ovalization, and indentation of the ciliary body suggest that the lens is too large and rigid. Explantation of an AC IOL is also necessary when the lens is associated with chronic UGH syndrome that is resistant to medical therapy.[8,][11]
Exchange of an AC IOL depends on the style of the implant and whether any of the haptics are encased in synechiae. The closed-loop anterior chamber lenses, most notably the Azar (91Z), the Leiske, and the Stableflex, have loop haptics that may become enveloped by peripheral anterior synechiae. When synechiae are present, the explantation technique involves severing the haptics from the optic to remove the lens in pieces, thereby avoiding bleeding, iridodialysis, and severe damage to the angle. This can be achieved with an intraocular scissors or by using the YAG laser preoperatively.[16] The optic should be manipulated carefully because the severed haptics are sharp and potentially hazardous. With viscoelastic material filling the anterior chamber, a spatula placed under the optic serves as a ramp to prevent snagging of the posterior lip of the incision during removal. Since almost all AC IOLs are made of polymethylmethacrylate (PMMA), the incision will need to accommodate the size of the rigid optic, which must be removed in one piece. Once the optic has been explanted, the remaining haptics are threaded back through the synechial tunnels until they are free in the anterior chamber where they can be easily and safely removed (Figures 46-1 and 46-2).
|
Figure 46-1 Anterior chamber lens with filamentous haptics encased by peripheral anterior synechiae. Scissors are used to sever the haptic from the optic. |
|
Figure 46-2 After removal of the optic, the severed haptics are backthreaded into the anterior chamber and removed. |
If a posterior capsular remnant is present and offers adequate peripheral support, the AC IOL may be exchanged for a PC IOL. Suture fixation of a posterior chamber lens to either the iris or ciliary sulcus is an excellent option, especially in a patient with glaucoma or with an abnormal anterior segment (e.g., extensive synechiae, angle recession).[17–22] If the posterior capsule is intact and the capsular membranes are fused, sulcus fixation may suffice. Posterior optic capture also provides an elegant alternative. If they are co-existing, a zonular dialysis is present, and sulcus fixation will require augmentation to prevent later decentration. This additional support can come in the form of an iris or transscleral safety suture or by creating a primary posterior capsulorrhexis with capture of the PC IOL optic through the opening.[23]
Iris-supported lenses
These IOLs are rarely seen today. As a general rule, a dislocated or malpositioned iris-supported lens should be either explanted or exchanged for an anterior or posterior chamber lens. Surgical repositioning of these lenses can be considered in situations where a more extensive explantation-exchange procedure may be risky, such as in an elderly patient with a dangerously low endothelial cell count. In such an instance, the main surgical principle in these eyes (which have invariably undergone previous intracapsular surgery) is to perform minimal manipulation. Before repositioning the IOL an air bubble may be injected through a paracentesis incision to avoid having to deal with the exposed vitreous face. Alternatively, a dispersive ophthalmic viscosurgical device (OVD) can be used since the chance of IOP rise postoperatively will be less than with other agents. If vitreous gel is present and entangled around the IOL, a vitrectomy should be performed first to prevent traction on the vitreous base and possible retinal detachment. Two microhooks introduced through strategically placed limbal stab incisions are effective for haptic manipulation. These incisions are made just anterior to the corneoscleral junction to avoid bleeding into the eye. One hook is used to retract and depress the iris, while the other elevates and decenters the optic in the opposite direction. The haptics are repositioned, and the pupil is pharmacologically constricted to ensure IOL fixation.
When an iris-fixated IOL is associated with chronic irritation or progressive endothelial cell loss, explantation is the procedure of choice. Separation of posterior synechiae, often in conjunction with an anterior vitrectomy, aids in achieving atraumatic explantation. Retrieval of the lens dislocated into the anterior vitreous can be accomplished using a two-stab anterior approach by ensnaring the visible haptic with a C-shaped hook and ushering the lens back through the pupil and into the anterior chamber. A second hook is then placed under the lens, which reduces the possibility of “losing” the lens. Once the lens is forward, the pupil is constricted with an intracameral miotic trapping the lens in the anterior chamber. At this point, it is safe to open the eye and to remove the lens using a second instrument as a ramp and removing all vitreous adhesions with a mechanical cutter. Significant vitreous entanglement or more posteriorly dislocated iris supported IOLs are best managed with primary vitrectomy techniques as described for dislocated posterior chamber lenses in a subsequent section. Following removal of a dislocated iris-supported lens, either anterior chamber lens implantation or posterior chamber lens implantation with scleral or iris suture support can be performed at the surgeon's discretion (Figure 46-3).
|
Figure 46-3 Removal of the dislocated iris-fixated lens from the anterior vitreous cavity by a limbal approach using a C-hook. |
Posterior-chamber intraocular lenses
Repositioning
Repositioning a lens should always be considered as an alternative to an exchange procedure. Repositioning a PC IOL that is decentered secondary to asymmetric haptic fixation may be accomplished by several different methods. If the capsular bag is intact, it is usually possible to inject a less retentive OVD into the bag just beneath the anterior capsule. Unless there is a tear in the capsule, or a previous can-opener capsulotomy, the capsular bag can generally be re-opened. The IOL can be either rotated into the bag or into the sulcus where symmetric haptic fixation will result in centration of the lens. A useful trick is to engage the displaced haptic in the crotch of an Osher curved Y-hook (Bausch & Lomb Y hook STORZ E577), (Duckworth & Kent Y hook, P2443A6-471) while the right hand dials the lens clockwise. The curved Y-hook compresses and lowers the haptic, repositioning it into the bag. Alternatively, the IOL haptics can be rotated into the sulcus (Figure 46-4) with an option of capturing the optic within the anterior capsulorrhexis.
|
Figure 46-4 Two-hook rotation of a malpositioned posterior-chamber intraocular lens in the ciliary sulcus. |
There are many situations where the IOL can be repositioned. The single-piece acrylic IOL that has been inadvertently placed into the ciliary sulcus can be repositioned by reopening the bag with OVD then manipulating the soft, highly flexible haptics. Any IOL captured by the pupil can also be repositioned. An IOL inadvertently inserted backwards can be “summersaulted” using the protection of a retentive OVD to fill the chamber and bag. A small IOL that has decentered in a gigantic capsular bag can be repositioned by creating either an anterior or posterior optic capture. A slight power shift will occur when prolapsing an optic backwards into the bag or forward, creating an anterior capture through the capsulorrhexis.
If the posterior capsule is open, the capsular bag cannot be reopened since injected OVD will enter the vitreous cavity. Still it is often possible to reposition an IOL. For example, if a single-piece lens is decentered within the torn capsular bag, the optic may be prolapsed forward and captured within an intact capsulorrhexis. An acute central tear may in some cases be converted to a primary posterior capsulorrhexis and the optic may be captured posteriorly. Even when the tear has extended peripherally, it is sometimes possible to snag the optic between two flaps of capsule or a three-piece lens can be repositioned into the ciliary sulcus. A single-piece AcrySof lens should not be placed into the ciliary sulcus because of its thick, square-edged haptics and small overall diameter. A long-standing capsular tear may allow a new capsulotomy to be created in the fused anterior and posterior capsules, presenting another opportunity for optic capture.
Repositioning a decentered PC IOL can also be accomplished by a Lasso Suture, first described by Osher in a Video Symposium on Malpositioned IOLs at the annual meeting of the AAO in 1997.[24] A double-armed 10-0 prolene suture is passed through a stab incision, the first needle going behind the optic and exiting through the ciliary sulcus out through the sclera. The second needle is passed through the same stab incision but the needle is directed above the haptic before exiting through the ciliary sulcus adjacent to the first pass. The externalized arms of the sutures are cinched up ensnaring the haptic, which is tied to the scleral wall. This knot is trimmed and rotated into the sclera. Alternatively, the sutures can be passed beneath a scleral flap.
Subsequently, Steinert modified the lasso suture for the specific case of suture stabilizing a fully in-the-bag IOL. This scenario can occur after trauma, but is most common in the presence of pseudoexfoliation. The IOL-capsule complex may dislocate many years after uncomplicated surgery. In the Steinert technique, a 10-0 polypropylene suture on a long, gently curved needle is inserted ab externo through the ciliary sulcus and directed behind the haptic, up through the capsule between haptic and optic, and then exits through a paracentesis. The needle is then reversed and passed back ab interno through the ciliary sulcus approximately 1.5mm lateral to the first pass. The suture is tied with four square single throws and then rotated beneath the sclera, so that only a conjunctival flap is needed to cover the suture securely. This maneuver is repeated for the second haptic.
There are many other variations of suturing the loop or plate haptics of a decentered PC IOL through the ciliary sulcus to the scleral wall.[25–31] A haptic can be externalized through a stab incision where a knot can secure the haptic to the sclera before repositioning the lens. Other elegant suturing techniques for repositioning a subluxed IOL within the capsular bag secondary to pseudoexfoliation syndrome have been described by Steinert and others.[32–34] A clever technique avoiding conjunctival dissection has been described by Hoffman,[34A]while Agarwal has published a technique of fixating a PC IOL beneath scleral flaps with fibrin glue.[34B] Osher described using a CTR to stabilize an IOL by creating artificial zonules[35]and Fine has described repositioning a subluxed IOL/bag/CTR complex by suturing the ring back to the scleral wall.[34]
The technique of repositioning a PC IOL by fixating the haptics to iris first described by Stark has become very popular.[36–38] The optic of the PC IOL is captured through the pupil and a retentive OVD like Healon 5 is injected into the anterior chamber. The haptics behind the iris become visibile as the OVD deepens the chamber compressing the iris against the haptics. Using a modification of the Siepser suture technique each haptic is secured to the mid peripheral iris (too proximal a pass will result in a “cat's eye” pupil).[39] Finally, the optic is dunked through the pupil and centered in the posterior chamber while the iris provides suture support.
A final word of caution is necessary when the surgeon is attempting to use the ciliary sulcus when the capsular bag has been torn. Most contemporary posterior chamber IOLs have a shorter overall length than the older style lenses which were often 13.5mm or 14mm. To ensure that the lens is centered and well supported, the Osher “bounce test” (Figure 46-5) is performed by gently and deliberately decentering the optic toward each haptic which should result in spontaneous recentration. Failure to recenter indicates either a serious problem with the capsular support, permanent deformation of the lens haptic, or inadequate sizing, each of which may indicate the need for suture fixation, explantation, or exchange depending on the nature of the problem. Alternatively, optic capture can be considered.
|
Figure 46-5 The “bounce” test used to ensure that a repositioned posterior-chamber intraocular lens spontaneously recenters. |
Explantation/exchange
In many instances, repositioning a dislocated PC IOL may not be possible or desirable. This may be related either to structural abnormalities of the implant or to co-existing ocular conditions that necessitate removal and/or exchange. The dislocated lens may have pre-existing structural damage to the haptic, as a result of haptic distortion or breakage precluding adequate refixation. When repositioning is not possible, exchange of the PCIOL for another posterior chamber lens is our strong preference when adequate residual peripheral capsulozonular support is present. This can best be determined when the pupil is widely dilated and after all posterior synechiae between iris and capsule are separated intraoperatively to reconstruct a full-sized posterior chamber. Direct inspection of the peripheral retroiridal anatomy indicates the best axis for implantation and where best fixation of the IOL may be achieved. Provided there is sufficient residual capsular support, three-piece acrylic foldable or a single-piece all-PMMA IOL with a large optic (6–6.5mm) with a large diameter (12.5–13.5mm) is preferable to either an anterior chamber lens or a sutured posterior chamber lens. However, there is recent evidence to support the safety of using anterior chamber lenses in these challenging cases.[40] Today it would be rare to explant a lens without also performing an exchange.
Exchange of the posterior-chamber intraocular lens when the bag is intact
The most common reason necessitating exchange is inadvertent IOL power miscalculation with either anisometropia or patient dissatisfaction. Although some surgeons prefer implanting a piggy back IOL to compensate for the power error this may lead to interface opacification, and undesired optical phenomena especially with a multifocal IOL (MIOL). Sometimes, a monofocal in-the-bag PCIOL will be exchanged for an MIOL based upon a patient's strong desire for presbyopic IOL correction. Preservation of the capsular bag integrity is of utmost importance. Reopening the capsular bag can be performed by pressurizing the anterior chamber with an OVD, then viscodissecting the capsular bag open. A variety of OVDs will perform this task suitably and it may be left to surgeon's discretion. Occasionally, the anterior capsulorrhexis is difficult to elevate from the anterior optic surface of an acrylic PCIOL. Slipping a thin spatula under the edge can achieve a separation. When the adherence seems too tight for this, the capsulorrhexis margin can be gently lifted off the optic using the non-beveled side of the end of a 25- or 30-gauge needle. The OVD cannula can then be slipped under the capsular edge and the bag is expanded. Viscodissection is frequently required in all quadrants and may be accessed by multiple paracenteses or by using different cannula configurations.
Once the capsular bag has been opened, the method of removing the optic depends on whether it is foldable or not. The PMMA optic requires an incision of similar size as the diameter of the optic. Several options exist for the removal of the foldable optics through a smaller incision. Transection with either a scissors or a snare can be achieved under viscoelastic protection before removing each half. Jack Dodick popularized the Hinge technique in which the optic is partially transected leaving the distal fifth intact. When one half of the optic is grasped and ushered into the incision, the other half hinges open and follows.[41]
Paul Ernest developed a clever method for intraocular folding of the IOL.[42] Using OVD protection the lens is maneuvered into the anterior chamber where the superior haptic is prolapsed out of the incision. Next, a spatula is passed under the optic from a side port incision placed across from the primary incision, and a lens insertion forceps is introduced through the main incision over the optic. Upward force of the spatula combined with the downward force of the forceps results in re-folding of the optic, which can then be rotated 90° and explanted.
Another innovative technique was developed by Shuichiro Eguchi. After prolapsing the proximal haptic into the anterior chamber, a radial scissors cut is made in the optic. The lens is then rotated, and a second radial cut is made in the optic 90° away. One-quarter of the lens is explanted and the remaining three-quarters of the lens is rotated out through the small incision.[43]
Crisscross lensectomy is a technique for explanting a silicone plate lens through a small incision developed by Robert Osher utilizing the Eguchi principle.[44] The surgeon makes a radial incision along the longitudinal axis of the lens, rotates the lens 90°, and makes a second radial incision which intersects with the first, freeing a rectangle of the IOL which can be removed. The lens is rotated another 90° and a third radial incision is made along the longitudinal axis. A final 90° rotation allows the last radial incision to intersect and a second rectangle is explanted. The remaining segment of the lens can be maneuvered out through the small incision. The authors have found that the Osher IOL serrated cutting scissors (Duckworth & Kent P1870B) is very effective in cutting either silicone or acrylic material. The serrated blade reduces the tendency of the lens to tilt during the cut.
Exchange of the posterior-chamber intraocular lens when the bag is torn
The intraoperative findings and the behavior of the IOL will determine whether it can be repositioned or must be explanted. If a lens with a known C or J-loop haptic fails to easily rotate, it is likely that the haptic is either snagged within the zonules or protruding through a tear in the zonules or the capsular bag. Reverse rotation followed by decentration toward the ensnared haptic and then re-rotation can sometimes free it. The lens can then be rotated 90° and a “bounce test” can be performed to confirm centration and fixation. If the haptic has an eyelet or bulbous tip, removal may be more difficult. Continued resistance to rotation indicates that haptic amputation is necessary and the piecemeal removal of the lens may be required. When the severed haptic is stuck within an intact bag, an attempt should be made to inject viscoelastic material under an edge, which often opens the bag, allowing retrieval. Gentle perseverance under the protection of an OVD may enable successful removal, although leaving the amputated haptic behind is preferable to causing additional damage to the capsular bag.[44A]
Regardless of how the IOL is going to be removed, the surgeon must be prepared to deal with vitreous. If minimal vitreous prolapse is present, a dry vitrectomy using a limbal approach can be performed by filling the chamber with an OVD, through which the vitrectomy handpiece is inserted. This vitrectomy technique produces a more limited vitrectomy, with less of a tendency toward collapse of the globe. If vitreous fills the anterior chamber, a limbal bimanual vitrectomy with low-flow irrigation through a second stab incision can be performed.[45] Alternatively, the surgeon may perform the vitrectomy through the pars plana 3.5mm posterior to the limbus. The surgeon should set the automated vitrector on “cut/IA” and utilize a high cutting rate with moderate vacuum settings. If the posterior capsule is open and vitreous has been removed, maintaining a pressurized anterior chamber is crucial to preventing further vitreous prolapse at the end of the case. OVD can be removed manually in small aliquots and exchanged for BSS or by bimanual irrigation and aspiration through paracenteses after the primary incision has been closed. Instillation of intraocular carbachol and topical medications can provide prophylaxis against an IOP spike following surgery.
Recently, Burk and colleagues described the use of Kenalog suspension (triamcinolone acetonide) to highlight vitreous present in the anterior chamber.[46] (See Chapter 45 for detailed discussion.)
Management of the posteriorly luxated intraocular lens
Previous sections of this chapter have described many elegant and efficient techniques for the management of the malpositioned IOL when this subluxation is in the realm of the anterior segment – the anterior chamber, the iris plane, the ciliary sulcus, the level of the capsular bag, or at the level of the very anterior vitreous. In these instances, an anterior segment surgeon is well within her/his scope of practice when applying the principles and techniques described earlier in this chapter. When the pseudophakos is completely luxed posteriorly, is entangled in the vitreous, and/or is in contact with the retina, surgical techniques are required which fall into the scope of practice of the subspecialty trained vitreoretinal surgeon – alone or in combination with an anterior segment surgeon. Prior to proceeding with a brief description of these techniques, we will offer some of the considerations involved in deciding on how to manage the more posteriorly dislocated but not yet completely luxed lens implant. Today, a vast majority of the implants in this scenario are PC IOLs.
The individual attending surgeon bears the sole responsibility for deciding which surgical techniques to employ and which surgical cases to attempt. Each patient presents with his/her own unique fact pattern and requires an individualized approach for management. Each surgeon has their own surgical skill set and their own level of comfort with each of the surgical techniques which make up that skill set. Certainly a luxed PC IOL lying on the surface of the macula is best managed by prompt referral to a vitreoretinal surgeon. On the other hand, some anterior segment surgeons would (and should) feel confident managing a severely subluxed PC IOL dangling into the mid-vitreous cavity by one haptic in a patient in whom a previous complete PPVx had been performed and in whom both IOL haptics are easily visualized as not being engaged in vitreous (or residual vitreous skirt). The issue becomes more muddled when surgical management requires vitrectomy techniques. The key question is to determine how much vitrectomy needs to be performed.
The two predominant vitrectomy techniques available for the anterior segment surgeon are the limbal anterior vitrectomy and the limited pars plana anterior vitrectomy. With limbal anterior vitrectomy, the vitreous cutter is inserted into the anterior segment through a limbal incision, most often with the infusion “split”, supplied via a separate limbal incision or paracentesis. With limited pars plana anterior vitrectomy, the vitreous cutter enters the eye through a single pars plana sclerotomy or trocar created 3mm posterior to the surgical limbus. Irrigation is achieved with a cannula inserted into the anterior segment through a separate anterior segment wound. We suggest that purely anterior vitrectomy techniques be limited to the most basic anterior maneuvers and that strong consideration be given to using the limited pars plana anterior vitrectomy techniques in any case requiring manipulation of the anterior vitreous within the vitreous cavity. It is important to stress that neither of these two surgical techniques allow for a complete vitrectomy or for ANY amount of peripheral or posterior vitreous dissection. These limitations relate to the fluidics and the limited visualization inherent to these surgical techniques.
The most important consideration here is the position of the IOL and haptics relative to the vitreous. Careful attention should be paid to identifying if either of the IOL haptics is entangled in the vitreous base with meticulous scleral depressed peripheral retinal examination. If so, freeing the optic from vitreous with a limited anterior vitrectomy is not sufficient and manipulating the IOL without a more complete peripheral vitreous dissection can have disastrous consequences, including retinal detachment with giant retinal tear. Prompt referral to a vitreoretinal surgeon is appropriate.
The decision to proceed with anterior surgical techniques vs. involving a retinal surgeon rests on having the observational skills to accurately and reproducibly identify these and other important anatomical relationships preoperatively, intraoperatively and postoperatively. A simple mental experiment is useful in deciding how to proceed. Imagine a 65-year-old loved one who presents with a mild-to-moderate vitreous hemorrhage in the setting of an acute PVD. You examine the patient and find no retinal tears. How do you feel about this scenario? If you lose sleep and seriously think about a referral to a retinal surgeon, serious consideration should be given to deferring any pars plana vitrectomy in the setting of a subluxed IOL to that same retinal surgeon. If, on the other hand, you feel comfortable discussing the signs and symptoms of a retinal detachment and seeing your loved one back again in a few weeks, and are confident in your negative exam (even when you know that published series have long documented a 50–82% incidence of retinal tear in this scenario),[47–51] then considering limited pars plana anterior vitrectomy techniques may not be so unreasonable.
Special mention should be made of the recent development of 25- and 23-gauge pars plana vitrectomy techniques.[52–57] These technologies allow for transconjunctival trocar placement and allow for microincisional sutureless vitrectomy techniques and have already been employed for limited anterior pars plana vitrectomy.[58,][59] The advantages and disadvantages of these new microincisional techniques remain to be elucidated.
If a luxed IOL is to be addressed using three port pars plana vitrectomy techniques, the first step is of course, a complete and meticulous core and peripheral vitrectomy. This, by definition includes peeling of the posterior hyaloid. A very careful peripheral dissection is then performed trimming the vitreous base and carefully disengaging the IOL optic and both IOL haptics from all vitreous attachments. The IOL is then mobilized anteriorly by the placement of a bubble of perfuoro-n-octane, allowing the bubble to float the IOL anteriorly[62](Figure 46-6), or with a combination of aspiration from the vitreous cutter, or with an extrusion cannula and manipulation with forceps. Once the IOL has been retrieved, it is either repositioned (with or without suture fixation), or explanted and exchanged for a primarily sutured PCIOL or ACIOL.
|
Figure 46-6 Perfluorocarbon liquid flotation of dislocated posterior-chamber intraocular lens into anterior vitreous cavity. |
Whether IOL repositioning or replacement is initially planned, the preoperative planning should include appropriate measurements and calculations for a replacement IOL, in the event that repositioning cannot be successfully achieved. The precise lens type and dioptric power of the luxed IOL should also be ascertained. Considerations in the decision to reposition or replace a lens include the structural stability of the lens, the size, and the haptic design. For example, foldable silicone lenses are less amenable to repositioning than all-PMMA lenses because of their greater inherent structural instability. Lenses with smaller optical zones and interhaptic distances are more likely to produce optical edge effects and to be less stable when suspended by scleral sutures than other styles. Similarly, very thin or shortened haptics, particularly older-style J-loops, as well as single piece acrylic lenses are less amenable to primary suture fixation than other styles.
A variety of techniques have been described for repositioning lenses that are displaced into the vitreous.[60–73] Fixation options have been described previously in this chapter including; iris fixation, scleral suture fixation or residual capsular fixation.
In cases of progressive zonulopathy, such as pseudoexfoliation syndrome, a subluxation of the implant lens contained within the capsular bag complex may occur. This can occur, even when the capsular bag contains a capsular tension ring. If the subluxation is mild, a suture can be passed through the capsular bag periphery around the apex of the haptic or around any point of the CTR, then passed transclerally. The other end of the double-armed suture is passed through the sclera and then tied externally. A number of differing suture-passing techniques through the bag and around the haptic/CTR can be equally effective, including some ab externo approaches and suture-docking procedures. When the zonular damage is profound, it is sometimes more facile to remove the entire IOL/bag complex, either in toto or in pieces and exchange the IOL/bag complex for a sutured PC IOL.
The results of several published surgical series on primary positioning by a pars plana route are summarized in Table 46-1. Of 282 eyes with dislocated IOLs, treated by either exchange or repositioning with either scleral or iris fixation to supplement sulcus repositioning, 165 (58%) achieved 20/40 or better final vision. Fifty-seven of 282 (20%) developed CME, which was usually transient and responsive to medical therapy, and 19 (6.7%) developed a retinal detachment postoperatively. Postoperative retinal detachments developed between 10 days and 2 years after surgery, although most occurred within the 2 months of IOL repositioning or exchange. Other reported complications of ciliary sulcus repositioning by a pars plana route with scleral fixation sutures include lens tilt, redislocation, suture erosion, retinal phototoxicity, persistent intraocular pressure elevation, corneal opacification, iris capture, epiretinal membrane formation, suture exposure, persistent uveitis, wound leak with hypotony, choroidal effusions, and vitreous hemorrhage.
Table 46-1 -- Results of vitrectomy and repositioning for posteriorly dislocated IOLs
|
Authors |
Patients (n) |
Method |
VA ≥20/40 |
Comments |
|
Sternberg and Michels (1986) |
5 |
Iris/haptic fixation |
5/5 |
|
|
Smiddy and Flynn (1991) |
4 |
Sclera/haptic fixation |
3/4 |
|
|
Maguire et al (1991) |
6 |
Sclera/haptic fixation |
4/6 |
Prior retinal damage in 2/6 eyes |
|
Chan (1992) |
12 |
Sclera/haptic fixation |
11/12 |
CME in 3/12 eyes |
|
Lewis and Sanchez (1993) |
8 |
Sclera/positioning hole fixation; temporary perfluorocarbon |
6/8 |
|
|
Mello et al. (2000) |
110 (72 in posterior segment) |
Sclera or capsule/haptic fixation |
63/110 |
Postoperative RD in 7/110 eyes CME 19/110 eyes |
|
Thach et al. (2000) |
78 |
Sclera/haptic fixation after temporary externalization of haptic |
Postoperative RD in 5/78 eyes CME in 20/78 eyes |
|
|
Sarrafizadeh et al. (2001) |
59 |
Repositioned with (16) or without(13) sutures with scleral or capsule/haptic fixation Exchanged for sutured PC IOL (13) or AC IOL (17) |
12/29 repositioned 19/30 exchanged |
Nonrandomized case series comparing repositioning versus exchange of dislocated PC IOL; similar complication rates |
|
CME, Cystoid macular edema; RD, retinal detachment; VA, visual acuity. |
Discussion
Surgical treatment of malpositioned and dislocated IOLs remains an important and challenging clinical problem. Several previous publications have summarized the reasons for IOL removal. Although there are many common themes the details are notably affected by the date of the study, and the type of IOL used.
Solomon et al. evaluated 2500 explant cases at the Center for Intraocular Lens Research between 1982 and 1988. Anterior chamber lenses accounted for 59% and were usually explanted because of pseudophakic bullous keratopathy or inflammatory complications. Iris-fixated lenses represented 21%, whereas posterior-chamber lenses accounted for 20%. The latter were most frequently explanted because of decentration, malposition, or inflammation.[74]
Apple et al. showed that many anterior chamber lenses were explanted because of poor manufacturing, characterized by rough optic and haptic edges, which resulted in chronic iris chafing.[75]
Kraff et al. reported their results of explantation surgery in 1986, at which time anterior chamber lenses were most often removed as a result of corneal decompensation and chronic inflammation. Posterior chamber lenses, which represented only 20% of those explanted in the survey by Kraff et al., were removed because of dislocation, decentration, or incorrect power.[76]
Mamalis et al. reviewed 102 explanted lenses between 1982 and 1989. Anterior chamber lenses, which represented 66.7% of the series, were removed because of pseudophakic bullous keratopathy, UGH syndrome, and CME. Iris-supported lenses made up 17.6%, with pseudophakic bullous keratopathy representing the most frequent reason for removal. PC IOLs represented 15.7% of the explanted lenses, and the underlying cause was most often lens dislocation or decentration. Although approximately 70% of these patients underwent IOL exchange, the overall visual outcome showed that 39% experienced improvement, 46% were unchanged, and 15% showed a worsening of vision following surgery. The most common cause of further visual deterioration was corneal decompensation followed by glaucoma and CME. It was noteworthy that 90% of patients who underwent exchange with a PC IOL had a successful clinical outcome.[77]
In a series of 1400 implant cases published in 1980, Kline and Yang found a 1.7% incidence of lens removal. Corneal edema, CME, uveitis, and iris erosion were the most common causes for explantation.[78]
Smiddy and Flynn reviewed 32 cases of posterior dislocation of posterior chamber lenses. Management consisted of conservative observation without surgery in two eyes, repositioning in 19 eyes, exchange in eight eyes, and explantation without exchange in three eyes. The visual acuity of 20/40 or better was achieved in 69% of eyes in their study.[79]
Doren, Stern, and Driebe reviewed 101 consecutive explantations performed between 1983 and 1987. The majority of lenses removed were anterior chamber styles (53.9%) and iris-fixated lenses (33.7%). Pseudophakic bullous keratopathy was the main reason for explantation (69%) followed by UGH syndrome (9%) and IOL instability (7%). The best visual outcome was attained in eyes with an unstable IOL, half of which attained visual acuity of 20/40 or better. The poorest visual outcome was seen in eyes with UGH syndrome. Although 83% of the eyes in the latter group failed to attain acuity better than 20/200, even these patients benefited by the resolution of pain and better control of the intraocular pressure.[80]
Sinskey, Amin, and Stoppel conducted a retrospective review of 79 patients who underwent IOL exchange. Sixty-one percent were posterior chamber lenses, and 39% were anterior chamber lenses; these were replaced by posterior chamber (76%) and anterior chamber (24%) lenses. Indications for lens exchange included eccentric or displaced IOL (42%), endothelial decompensation (28%), incorrect IOL power (13%), and UGH syndrome (10%). The postoperative visual acuity was better than or equal to 20/30 in 72%, whereas 8% had a loss of one or more lines of visual acuity. Complications encountered following lens exchange included retinal detachment in four eyes, glaucoma in 14 eyes, corneal decompensation in three eyes, and anisometropia in one eye.[81]
Lyle and Jin published a series of eyes undergoing IOL exchange with and without penetrating keratoplasty in 1992. Of the 56 eyes that underwent IOL exchange without penetrating keratoplasty, the type of lens explanted was an AC IOL in 41%, an iris-supported IOL in 14%, and a PC IOL in 45%. The most frequent indications were dislocation of the lens in 20 eyes (36%), incorrect power in 14 eyes (25%), and CME in 11 eyes (20%). The geometric mean visual acuity improved from 20/61 preoperatively to 20/43 postoperatively. A visual acuity of 20/40 or better was attained in 69%, and 46% of eyes gained two or more lines. The main reason for a visual acuity of less than 20/200 was CME (four eyes). The authors noted a better prognosis if either the original lens was a PC IOL or if the original lens was exchanged for a PC IOL. The most frequent complications following explantation included hyphema (23%), CME (18%), posterior capsule opacification (13%), and glaucoma (9%). Isolated cases of choroidal detachment, endophthalmitis, retinal detachment, and lens dislocation also occurred.[82]
Marques et al. studied 49 eyes which had had IOL exchange between 1986 and 2002 performed by the same surgeon. The mean interval between surgeries was 53.8 months and the mean follow-up, 35.6 months. There were 15 eyes with an AC IOL and 34 eyes with a PC IOL originally. The mean interval between the primary surgery and IOL explantation was 82.3 months in the AC IOL group and 37.9 months in the PC IOL group. The main reason for IOL exchange was inflammation (53.3%) in the AC IOL group, and dislocation/decentration (85.3%) in the PC IOL group. The preoperative best corrected visual acuity was similar in both groups, and visual acuity was maintained or improved in 80%. Vitreous prolapse was the main intraoperative complication. The primary indication for IOL exchange was intraocular inflammation in patients with an AC IOL and IOL malposition in patients with a PC IOL.[83]
Dislocation of an IOL with the capsular bag is a late complication of cataract surgery, reported with increasing frequency in recent years. Gimbel et al. reported an identified predisposing condition in 90% of reviewed cases. Pseudoexfoliation was the most common cause, accounting for more than 50% of cases. Other common conditions were uveitis, myopia, and other diseases associated with progressive zonular weakening and capsular contraction. Capsular tension rings probably help but do not prevent this complication. An AC IOL was implanted in 48% of the cases and sutured PC IOL in 26% of the eyes included in this review.[84]
Gross et al. carried out a multicenter analysis of 25 eyes of 22 patients with dislocation of the PC-IOL encased within the capsular bag, secondary to dehiscence of the zonules supporting the capsular bag. They concluded that in-the-bag PC-IOL dislocations are an unusual, sometimes bilateral, late complication of cataract surgery and the most common associated condition was pseudoexfoliation. The dislocated in-the-bag PC-IOL was replaced with an anterior chamber intraocular lens in 60% or repositioned/exchanged and scleral fixated in 40% of eyes. Associated conditions included pseudoexfoliation syndrome 44%, uveitis 16%, and trauma 16%. There was no identifiable cause in 24% of eyes.[85]
Dick et al. reported on a survey of the German Society of Ophthalmic Surgeons which determined that the most common reasons for the exchange of foldable monofocal IOLs were lens opacification in 2000, and incorrect IOL power in 2001. In addition to incorrect IOL power and decentration, IOL opacification of hydrophilic IOLs accounted for a very high percentage of the explantations (46%).[86]
The results of a 2001 and a 2003 survey of the American Society of Cataract and Refractive Surgery members and the European Society of Cataract and Refractive Surgeons were reported by Mamalis. The most common complications associated with foldable IOLs that required explantation or secondary intervention were residual ametropia followed by malpositioning and lens opacification.[87,][88]
This increased importance of incorrect refractive error as a reason for IOL exchange was corroborated by Jin et al. who evaluated 51 eyes that underwent IOL exchange between January 1998 and December 2004. The overall rate of IOL exchange was 0.77% for all cataract surgeries. Incorrect IOL power (41.2%), decentration/dislocation (37.3%), and glare (7.8%) were the most common indications for IOL exchange. An AC-IOL was used in 14 eyes (27.5%) and a PC-IOL in 37 eyes (72.5%) for IOL exchange. None of the PC-IOLs were sutured to the sclera or iris. Overall, 90.2% of patients obtained a best-spectacle corrected visual acuity (BSCVA) of 20/40 or better. All eyes in the AC-IOL group and 94.6% of eyes in PC-IOL group achieved a visual acuity of between −1 and + 5 lines of the pre-exchange vision. The authors suggest that an open-loop flexible AC-IOL poses no greater risk than PC-IOL with respect to visual outcome and safety for IOL exchange.[89]
More recently, Jin et al. evaluated patients who underwent IOL exchange for unexpected postoperative refractive errors. Of 22 cases, the identifiable reasons included: keratometry errors in 5 (23%) and incorrect axial length (AL) determination in 3 (14%). Three other postoperative refractive surprises occurred because the wrong IOL was implanted. After IOL exchange, 82% (18/22) of eyes were within ±0.50 diopters (D) and 86% (19/22) within ±1.00 D of emmetropia. Uncorrected visual acuity was 20/40 or better in 82% of eyes, and BSCVA was 20/40 or better in 95% (21/22) of eyes.[90]
Copyright © 2010 Elsevier Inc. All rights reserved. Read our Terms and Conditions of Use and our Privacy Policy.
For problems or suggestions concerning this service, please contact: online.help@elsevier.com
Conclusions
As ophthalmic surgical practice continues to evolve, a gradual shift has been seen in the frequency and reasons for repositioning or exchanging IOLs. Fortunately, the incidence of pseudophakic bullous keratopathy, UGH syndrome, chronic CME, and even “incorrect” IOL power continues to decline. That said, patient expectations are higher than ever, especially with the advent of presbyopic correcting IOLs. Patients expect excellent uncorrected visual acuity, and in the absence of pathology other than cataract, we are better equipped than ever to fulfill those expectations. Given this, it is incumbent upon surgeons to recognize the etiologies that may require IOL exchange, and make every possible effort to prevent its necessity. Furthermore, surgeons must rectify IOL problems, that are symptomatic, or that may create the potential for other ophthalmic pathology. Explantation of an IOL is always challenging, yet armed with knowledgeable preparation and meticulous operative technique the results are generally satisfying to both the patient and the surgeon.
Copyright © 2010 Elsevier Inc. All rights reserved. Read our Terms and Conditions of Use and our Privacy Policy.
For problems or suggestions concerning this service, please contact: online.help@elsevier.com
References
[1]. Brown D.C., Swead J.W.: Intraocular lens implant exchanges. J Am Intraocul Implant Soc 1985; 11:376-379.
[2]. Werner L., Apple D.J., Crema A.S., et al: Permanent blue discoloration of a hydrogel intraocular lens by intraoperative trypan blue. J Cataract Refract Surg 2002; 28:1279-1286.
[3]. Flynn Jr H.W.: Management and repositioning of posteriorly dislocated intraocular lenses. In: Stark W.J., Terry A.C., Maumenee A.E., ed. Anterior segment surgery: oils, lasers, and refractive keratoplasty, Baltimore: William & Wilkins; 1987:321-329.
[4]. Blumenkranz M., Maguire A.: Modern management considerations in dislocation of crystalline and intraocular lenses. In: Stirpe M., ed. Advances in vitroretinal surgery, Rome: Fondazione GB Bietti/Ophthalmic Communications Society; 1992:39-46.
[5]. Percival S.P., Das S.K.J.: UGH syndrome after posterior chamber lens implantation. Am Intraocul Implant Soc 1983; 9:200-201.
[6]. Insler M., Benefield D., Ross V.: Topical hyperosmolar solution in the reduction of corneal edema. LAO J 1987; 13:149.
[7]. Osher R.H.: Surgical management of the malpositioned posterior chamber lens. Audiovisual J Cataract Implant Surg 1991; VII:
[8]. Ellington F.R.: The uveitis-glaucoma-hyphema syndrome associated with the Mark VIII anterior chamber lens implant. Am Intracellular Implant Soc J 1978; 4:50.
[9]. Keates R.H., Ehrlich D.R.: “Lenses of change”: complications of anterior chamber implants. Ophthalmology 1978; 85:408.
[10]. Percival S.P.K., Das S.K.: UGH syndrome after posterior chamber lens implantation. J Am Intraocul Implant Soc 1983; 9:200.
[11]. Koch D.D.: Scleral fixation of posterior chamber implants. Audiovisual J Cataract Implant Surg 1990; VI:
[12]. Lubniewski A.J., Holland E.J., Van Meter W.S., et al: Histologic study of eyes with transsclerally sutured posterior chamber intraocular lens. Am J Ophthalmol 1990; 110:237-243.
[13]. Ozdal P.C., Mansour M., Deschenes J.: Ultrasound biomicroscopy of pseudophakic eyes with chronic postoperative inflammation. J Cataract Refract Surg 2003; 29:1185-1191.
[14]. Loya N., Lichter H., Barash D., et al: Posterior chamber intraocular lens implantation after capsular tear: ultrasound biomicroscopy evaluation. J Cataract Refract Surg 2001; 27:1423-1427.
[15]. Fry L.: Pupil stretching. VJCRS 1995; XI:
[16]. Marques F.F., Marques D.M., Smith C.M., Osher R.H.: Intraocular lens exchange assisted by preoperative neodymium:YAG laser haptic fracture. J Cataract Refract Surg 2004; 30:247-249.
[17]. Koch D.D.: Scleral fixation of posterior chamber implants. Audiovisual J Cataract Implant Surg 1990; VI:
[17A]. Chang D.F.: Use of Malyugin pupil expansion device for intraoperative floppy-iris syndrome: results in 30 consecutive cases. J Cataract Refract Surg 2008; 34:835-841.
[18]. Price F.W.: Iris fixation of posterior chamber implants. Audiovisual J Cataract Implant Surg 1990; VI:
[19]. Moretsky S.L.: Suture fixation technique for subluxated posterior chamber IOL through stab wound incision. J Am Intraocular Implant Soc 1984; 10:455-480.
[20]. Girard L.J., Nino N., Wesson M., et al: Scleral fixation of subluxed posterior chamber intraocular lens. J Cataract Refract Surg 1986; 14:326-337.
[21]. Anand R., Bowman R.W.: Simplified technique for suturing dislocated posterior chamber intraocular lens to the ciliary sulcus. Arch Ophthalmol 1990; 108:1205-1206.letter
[22]. Lubniewski A.J., Holland E.J., Van Meter W.S., et al: Histologic study of eyes with transsclerally sutured posterior chamber intraocular lens. Am J Ophthalmol 1990; 110:237-243.
[23]. Gimbel H.C., DeBroff B.M.: Intraocular lens optic capture. J Cataract Refract Surg 2004; 30:200-206.
[24]. Osher R.H.: Sewing through the capsular bag: a brief history. Cataract & Refract Surgery Today 2004; 4:72-73.
[25]. Hoffman R.S., Fine I.H., Packer M., Rozenberg I.: Scleral fixation using suture retrieval through a scleral tunnel. J Cataract Refract Surg 2006; 32:1259-1263.
[26]. Hoffman R.S., Fine I.H., Packer M.: Scleral fixation without conjunctival dissection. J Cataract Refract Surg 2006; 32:1907-1912.
[27]. Epley K.D., Levine E.S., Katz H.R.: A simplified technique for stable transscleral suture fixation of posterior chamber intraocular lenses. Ophthalmic Surg Lasers 1999; 30:398-402.
[28]. Chan C.K., Agarwal A., Agarwal S., Agarwal A.: Management of dislocated intraocular implants. Ophthalmol Clin North Am 2001; 14:681-693.
[29]. Hannush S.B.: Sutured posterior chamber intraocular lenses: indications and procedure. Curr Opin Ophthalmol 2000; 11:233-240.
[30]. Kulkarni K., Zarbin M., Del Priore L.V., Tezel T.H.: Ab externo technique for accurate haptic placement of transscleral sutured posterior chamber intraocular lenses. Ophthalmic Surg Lasers Imaging 2007; 38:72-75.
[31]. Leon J.A., Leon C.S., Aron-Rosa D.: Endoscopic technique for suturing posterior chamber intraocular lenses. J Cataract Refract Surg 2000; 26:644-649.
[32]. Arkin M.S., Steinert R.F.: Sutured posterior chamber intraocular lenses. Int Ophthalmol Clin 1994; 34:67-85.
[33]. Gimbel H.V., Condon G.P., Kohnen T.: Late in-the-bag intraocular lens dislocation: incidence, prevention, and management. J Cataract Refract Surg 2005; 31:2193-2204.
[34]. Fine I.H., Hoffman R.S.: Phacoemulsification in the presence of pseudoexfoliation: challenges and options. J Cataract Refract Surg 1997; 23:160-165.
[34A]. Hoffman R.S., Fine I.H., Packer M.: Scleral fixation without conjunctival dissection. J Cataract Refract Surg 2006; 32:1907-1912.
[34B]. Agarwal A., Kumar D.A., Jacob S., et al: Fibrin glue-assisted sutureless posterior chamber intraocualr lens implantation in eyes with deficient posterior capsules. J Cataract Refract Surg 2008; 34:1433-1438.
[35]. Osher R.H.: Synthetic zonules. Ophthalmology Times 1997; 15:
[36]. Stark W.J., Goodman G., Goodman D., Gottsch J.: Posterior chamber intraocular lens implantation in the absence of posterior capsular support. Ophthalmic Surg 1988; 19:240-243.
[37]. Stark W.J., Goodman G., Goodman D., Gottsch J.: Posterior chamber intraocular lens implantation in the absence of posterior capsular support. Yan Ke Xue Bao 1989; 5:19-23.
[38]. Stark W.J., Gottsch J.D., Goodman D.F.: Posterior chamber intraocular lens implantation in the absence of capsular support. Arch Ophthalmol 1989; 107:1078-1083.
[39]. Osher R.H., Snyder M.E., Cionni R.J.: Modification of the Siepser slip-knot technique. J Cataract Refract Surg 2005; 31:1098-1100.
[40]. Kwong Y.Y., Yuen H.K., Lam R.F., et al: Comparison of outcomes of primary scleral-fixated versus primary anterior chamber intraocular lens implantation in complicated cataract surgeries. Ophthalmology 2007; 114:80-85.E Pub 2006, Oct 27
[41]. Batlan S.J., Dodick J.M.: Explantation of foldable silicone intraocular lens. Am J Ophthalmol 1996; 122:270-272.
[42]. Ernst P.: Intraocular refolding. Video J Cataract Refractive Surg 1996; XII:
[43]. Eguchi S.: Quadrantotomy. VJCRS 2000; XVI:
[44]. Osher R.H.: Criss-cross lensectomy. VJCRS 2005; XXI:
[44A]. Trindade FC.: Haptic-induced recurrent vitreous hemorrhage and increased intraocular pressure with a hydrophobic acrylic intraocular lens. J Cataract Refract Surg 2009; 35:399-402.
[45]. Snyder M.E., Foster R.E.: Anterior vitrectomy. Comp Ophthalmol Update 2001; 2:149-158.
[46]. Burk S.E., Da Mata A.P., Snyder M.E.: Visualizing vitreous using Kenalog suspension. J Cataract Refract Surg 2003; 29:645-651.
[47]. Winslow R.L., Taylor B.C.: Spontaneous vitreous hemorrhage: etiology and management. South Med J 1980; 73:1450-1452.
[48]. Butner R.W., McPherson A.R.: Spontaneous vitreous hemorrhage. Ann Ophthalmol 1982; 14:268-270.
[49]. Dana M.R., Werner M.S., Viana M.A., Shapiro M.J.: Spontaneous and traumatic vitreous hemorrhage. Ophthalmology 1993; 100:1377-1383.
[50]. Lindgren G., Sjodell L., Lindblom B.: A prospective study of dense spontaneous vitreous hemorrhage. Am J Ophthalmol 1995; 119:458-465.
[51]. Hasenfratz G.: Acute vitreous hemorrhage – possibilities for differential diagnostic, echographic assessment. Fortschr Ophthalmol 1990; 87:641-645.
[52]. De Juan Jr E., Hickingbotham D.: Refinements in microinstrumentation for vitreous surgery. Am J Ophthalmol 1990; 109:218-220.
[53]. Fujii G.Y., De Juan Jr E., Humayun M.S., Chang T.S., Pieramici D.J., Barnes A., et al: Initial experience using the transconjunctival sutureless vitrectomy system for vitreoretinal surgery. Ophthalmology 2002; 109:1814-1820.
[54]. Fujii G.Y., De Juan Jr E., Humayun M.S., et al: A new 25-gauge instrument system for transconjunctival sutureless vitrectomy surgery. Ophthalmology 2002; 109:1807-1812.
[55]. Lakhanpal R.R., Humayun M.S., de Juan Jr E., et al: Outcomes of 140 consecutive cases of 25-gauge transconjunctival surgery for posterior segment disease. Ophthalmology 2005; 112:817-824.
[56]. Ibarra M.S., Hermel M., Prenner J.L., Hassan T.S.: Longer-term outcomes of transconjunctival sutureless 25-gauge vitrectomy. Am J Ophthalmol 2005; 139:831-836.
[57]. Eckardt C.: Transconjunctival sutureless 23-gauge vitrectomy. Retina 2005; 25:208-211.
[58]. Chalam K.V., Shah V.A.: Successful management of cataract surgery associated vitreous loss with sutureless small-gauge pars plana vitrectomy. Am J Ophthalmol 2004; 138:79-84.
[59]. Shah V.A., Gupta S.K., Chalam K.V.: Management of vitreous loss during cataract surgery under topical anesthesia with transconjunctival vitrectomy system. Eur J Ophthalmol 2003; 13:693-696.
[60]. Lewis H., Sanchez G.: The use of liquid perfluorocarbon in the repositioning of posteriorly dislocated intraocular lenses. Ophthalmology 1993; 100:1055-1059.
[61]. Sternberg P., Michels R.G.: Treatment of dislocated posterior chamber intraocular lenses. Arch Ophthalmol 1986; 104:1391-1393.
[62]. Flynn H.W., Buus D., Culbertson W.W.: Management of subluxated and dislocated intraocular lenses using pars plana vitrectomy instrumentation. Cataract Refract Surg 1990; 16:51-56.
[63]. Smiddy W.E., Flynn H.W.: Needle assisted scleral fixation technique for relocating posteriorly dislocated IOLs. Arch Ophthalmol 1993; 111:161-162.
[64]. Smiddy W., Flynn H.: Management of dislocated posterior chamber intraocular lenses. Ophthalmology 1991; 98:889-894.
[65]. Maguire A.M., Blumenkranz M.S., Ward T.G., et al: Scleral loop fixation for posteriorly dislocated intraocular lenses. Arch Ophthalmol 1991; 109:1754-1758.
[66]. Chan C.K.: An improved technique for management of dislocated posterior chamber implants. Ophthalmology 1992; 99:51-57.
[67]. Smiddy W.E., Ibanez G.V., Alfonso E., et al: Surgical management of dislocated intraocular lenses. J Cataract Refract Surg 1995; 21:64-69.
[68]. Mello M.O., Scott I.U., Smiddy W.E., et al: Surgical management and outcomes of dislocated intraocular lenses. Ophthalmology 2000; 107:62-67.
[69]. Thach A.B., Dugel P.U., Sipperley J.O., et al: Outcome of sulcus fixation of dislocated posterior chamber intraocular lenses using temporary externalization of the haptics. Ophthalmology 2000; 107:480-484.
[70]. Sarrafizadeh R., Ruby A.J., Hassan T.S., et al: A comparison of visual results and complications in eyes with posterior chamber intraocular lens dislocation treated with pars plana vitrectomy and lens repositioning or lens exchange. Ophthalmology 2001; 108:82-89.
[71]. Wong K.L., Grabow H.B.: Simplified technique to remove posteriorly dislocated lens implants. Arch Ophthalmol 2001; 119:273-274.
[72]. Kokame G.T., Atebara N.H., Bennett M.D.: Modified technique of haptic externalization for scleral fixation of dislocated posterior chamber lens implants. Am J Ophthalmol 2001; 131:129-131.
[73]. Johnson M.W., Schneiderman T.E.: Surgical management of posteriorly dislocated silicone plate intraocular lenses. Curr Opin Ophthalmol 1998; 9:11-15.
[74]. Solomon K., Apple D., Mamalis N., et al: Complications of intraocular lenses with special reference to an analysis of 2500 explanted intraocular lenses (IOLs). Eur J Implant Ref Surg 1991; 3:195-200.
[75]. Apple D.J., Brems R.N., Park R.D., et al: Anterior chamber lenses. Part I. Complications and pathology and a review of designs. J Cataract Refract Surg 1987; 13:157-173.
[76]. Kraff M., Sanders D.R., Lieberman H.L., et al: Secondary intraocular lens implantation. Ophthalmology 1983; 90:324-326.
[77]. Mamalis N., Crandall A., Pulsipher M., et al: Intraocular lens explantation and exchange: a review of lens styles, clinical indications, clinical results, and visual outcome. J Cataract Refract Surg 1991; 17:810-818.
[78]. Kline O.R., Yang H.K.: A review of 1400 intraocular lens implant cases. Contact Lens 1981; 7:262-278.
[79]. Smiddy W., Flynn H.: Management of dislocated posterior chamber intraocular lenses. Ophthalmology 1991; 98:889-894.
[80]. Doren G., Stern G., Driebe W.: Indications for and results of intraocular lens exchanges. J Cataract Refract Surg 1992; 18:79-85.
[81]. Sinskey R.M., Amin P., Stoppel J.O.: Indications for and results of a large series of intraocular lens exchanges. J Cataract Refract Surg 1993; 19:68-71.
[82]. Lyle W., Jin J.C.: An analysis of intraocular lens exchange. Ophthalmic Surg 1992; 23:453-458.
[83]. Marques F.F., Marques D.M., Osher R.H., et al: Longitudinal study of intraocular lens exchange. J Cataract Refract Surg 2007; 33:254-257.
[84]. Gimbel H.V., Condon G.P., Kohnen T., et al: Late in-the-bag intraocular lens dislocation: incidence, prevention, and management. J Cataract Refract Surg 2005; 31:2193-2204.
[85]. Gross J.G., Kokame G.T., Weinberg D.V.: In-the-bag intraocular lens dislocation. Am J Ophthalmol 2004; 137:630-635.
[86]. Dick H.B., Tehrani M., Brauweiler P., et al: Complications of foldable intraocular lenses requiring explantation. Results of the 2000 and 2001 survey in Germany. Ophthalmologe 2003; 100:465-470.
[87]. Mamalis N.: Complications of foldable intraocular lenses requiring explantation or secondary intervention – 2001 survey update. J Cataract Refract Surg 2002; 28:2193-2201.
[88]. Mamalis N., David B., Nislon C.D., et al: Complications of foldable intraocular lenses requiring explantation or secondary intervention – 2003 survey update. J Cataract Refract Surg 2004; 30:2209-2218.
[89]. Jin G.J., Crandall A.S., Jones J.J.: Changing indications for and improving outcomes of intraocular lens exchange. Am J Ophthalmol 2005; 140:688-694.
[90]. Jin G.J., Crandall A.S., Jones J.J.: Intraocular lens exchange due to incorrect lens power. Ophthalmology 2007; 114:417-424.Epub 2006 Nov 21