Decentration and Dislocation

The reported incidence of symptomatic decentration or dislocation of an IOL after uncomplicated cataract surgery is 0.19%–3.00%. The decentered or dislocated IOL may be either inside the capsule (intracapsular) or outside it (extracapsular) (Fig 11-4). The most common cause of intracapsular IOL malposition is zonular degradation associated with pseudoexfoliation syndrome. Insufficient zonular support may also be associated with trauma, previous vitreoretinal surgery, capsular contraction, retinitis pigmentosa, high myopia, uveitis, or congenital conditions that affect zonular integrity. Asymmetric bag/sulcus haptic positions (ie, 1 haptic in the capsular bag and 1 in the sulcus) aggravated by capsular fibrosis and contraction may also tilt or decenter an IOL. The most common cause of extracapsular IOL malposition is sulcus placement of an inadequately sized IOL, such as a smaller 3-piece IOL designed for intracapsular placement. Additional causes include a decentered or oversized capsulorrhexis, localized zonular defects, capsular defects, and IOL haptic damage.

Decentration of an IOL can cause unwanted glare and reflections or multiple images if the edge of the lens is within the pupillary space. When an aspheric, multifocal, or accommodating lens is decentered, the effect of the lens is diminished. Decentration of an aspheric lens with negative spherical aberration (used to counteract the positive spherical aberration of the cornea) results in greater higher orders of aberration (eg, coma) than decentration of a spherical lens. However, a decentered aspheric lens with zero spherical aberration correction causes less coma than a decentered spherical lens. Therefore, when postoperative IOL decentration is a significant concern, the surgeon may consider implanting an aspheric IOL with zero spherical aberration correction. Decentration of any posterior chamber intraocular lens (PCIOL) may lead to pupillary capture or uveitis-glaucoma-hyphema (UGH) syndrome owing to contact with uveal tissue.

Minor decentration may be treated with miotics to constrict the pupil over the IOL optic; in cases of pigment dispersion or recurrent hyphema, treatment with cycloplegic agents can reduce iris chafing by the IOL optic or haptics. Laser pupilloplasty may be used to realign the pupillary aperture with the IOL optical center. This procedure may be particularly useful with multifocal lenses. Severe cases of IOL decentration or dislocation are managed with IOL repositioning, stabilization with sutures, or exchange.

An extracapsular decentered IOL may be rotated and repositioned into a stable axis if there is sufficient support. Many extracapsular and selected intracapsular 3-piece IOL dislocations can be managed with peripheral iris suture fixation using a McCannel suture or Siepser sliding knot technique with a nonabsorbable monofilament suture, such as 9-0 or 10-0 polypropylene (Video 11-1; Fig 11-5). Iris fixation has some advantages over scleral fixation, including decreased risks of late suture erosion or breakage, IOL tilting, intraocular hemorrhage, and endophthalmitis. Disadvantages include possible posterior iris pigment chafing, pupil distortion, pseudophacodonesis, and hyphema. One-piece uniplanar acrylic IOLs are not suitable for secondary sulcus or iris fixation because of chafing of the iris pigment (Fig 11-6) and possible development of UGH syndrome.

VIDEO 11-1 Iris fixation of IOL. Courtesy of Charles Cole, MD. Go to www.aao.org/bcscvideo_section11 to access all videos in Section 11.

When irregular capsular fibrosis decenters an IOL placed in the capsular bag, deformation of the haptics may limit rotation for surgical recentering of the IOL. In such cases, the IOL haptics may need to be moved into the ciliary sulcus or the lens replaced. When the optic is removed before implantation of a new IOL, haptics fixated in the capsular bag or sulcus can be either amputated and left in place or slipped out of a fibrous cocoon.

Severe pseudophacodonesis or intracapsular (in-the-bag) dislocation of an IOL due to zonular loss may be managed with haptic fixation to the sclera. There are many ab externo (Fig 11-7) and ab interno (Fig 11-8) approaches and suture configurations, including scleral suture fixation (Video 11-2), intrascleral haptic fixation in Scharioth tunnels, also called “glued IOL” technique (Fig 11-9; Video 11-3), and intrascleral flanged haptic fixation, also referred to as Yamane technique (Fig 11-10; Videos 11-4, 11-5). For sutureless techniques, IOLs with haptics made of material such as polyvinylidene fluoride are preferable, as the polymethyl methacrylate (PMMA) haptics of a 3-piece foldable IOL can be brittle and prone to kinking or breaking with manipulation. A concurrent anterior vitrectomy is often necessary. Iris retractors may be used for better visualization or to stabilize the haptics during suturing. To prevent erosion through the conjunctiva, sutures through the scleral wall can be buried in a partial-thickness scleral groove or covered by a scleral flap. The scleral flap can be created through a conjunctival incision or a tunnel incision dissected posteriorly from the limbus (eg, Hoffman pockets; Video 11-6).

When dislocation of the IOL is complete, pars plana vitrectomy techniques are required to retrieve the lens or lens–capsule complex and elevate it safely into the anterior segment for fixation to the iris or sclera by a variety of techniques. In some cases, the implant may be removed altogether and replaced with either an ACIOL (see Chapter 8) or an iris- or scleral-fixated PCIOL.

Suture breakage and subluxation of scleral-fixated sutured IOLs occurring 3–9 years after implantation with 10-0 polypropylene fixation sutures have been reported. Double-fixation techniques and thicker 9-0 polypropylene or CV-8 Gore-Tex sutures (off-label use; W.L. Gore & Associates) are currently recommended for scleral fixation of IOLs. Other complications of sutured IOLs include vitreous or suprachoroidal hemorrhage, lens tilting, CME, retinal tears or detachment, suture erosion, and endophthalmitis. (See also BCSC Section 12, Retina and Vitreous.)

An ACIOL may be associated with decentration, iris tucking, UGH syndrome, corneal edema, or pseudophacodonesis, which will prompt repositioning of the lens or IOL exchange with either a differently sized flexible ACIOL or, preferably, a PCIOL. An ACIOL associated with pseudophakic bullous keratopathy is treated by endothelial keratoplasty, usually in combination with IOL exchange.

When an iris-supported lens becomes dislocated or associated with corneal edema or UGH syndrome, IOL exchange is warranted, if possible.

VIDEO 11-2 Ab externo IOL fixation (sutured). Courtesy of The University of Iowa; Jesse Vislisel, MD; and Kenneth M. Goins, MD.

• Agarwal A, Jacob S, Kumar DA, Agarwal A, Narasimhan S, Agarwal A. Handshake technique for glued intrascleral haptic fixation of a posterior chamber intraocular lens. J Cataract Refract Surg. 2013;39(3):317–322.

• Jacob S. Management of late lens implant and capsule dislocation. Focal Points: Clinical Practice Perspectives. American Academy of Ophthalmology; 2017, module 3.

• Yamane S, Sato S, Maruyama-Inoue M, Kadonosono K. Flanged intrascleral intraocular lens fixation with double-needle technique. Ophthalmology. 2017;124(8):1136–1142.

Excerpted from BCSC 2020-2021 series: Section 11 - Lens and Cataract. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.