16.1 Introduction

With modern phacoemulsification, continuous curvilinear capsulorhexis (CCC), and foldable intraocular lenses (IOLs), it is uncommon to see IOL complications, decentrations, or lens malposition. However, whether due to underlying pathology, trauma, prior or subsequent ocular surgery, iatrogenic causes, or IOL design-related issues, repositioning of a previously implanted IOL is sometimes required. The following are indications for IOL repositioning:

• 
  

  IOL subluxation resulting in vision loss.

  
  
• 
  

  Impending dislocation of IOL into posterior vitreous cavity.

  
  
• 
  

  Dysphotopsia, including arcs, halos, IOL edge effect, and glare.

  
  
• 
  

  Uveitis-glaucoma-hyphema (UGH) syndrome.

  
  
• 
  

  Suboptimal refractive outcome caused by IOL position; toric IOL misalignment, multifocal IOL decentration, accommodating IOL with Z-syndrome.

IOL subluxation has been reported from 0.2 to 1.7% after cataract surgery. ^{1 ,​ 2 ,​ 3 ,​ 4} The most common associations with IOL subluxation are pseudoexfoliation syndrome, trauma, and surgical complications. This may be associated with visual loss or dysphotopsia, or UGH syndrome.

IOL repositioning is a reasonable option if the IOL design is amenable to the fixation strategy, is not damaged or opacified, and of appropriate refractive power for the eye. If these conditions are not met, IOL exchange should be considered (see Chapter 17).

Surgical techniques will vary depending on whether the IOL is in the anterior chamber (AC), sulcus, bag-sulcus, capsular bag, or vitreous. Repositioning strategies typically involve movement or fixation of an IOL to a stable position within the eye. Possible fixation locations for IOL repositioning include the following:

• 
  

  Capsular bag.

  
  
• 
  

  Ciliary sulcus.

  
  
• 
  

  Optic capture (OC) within the AC and/or posterior capsule (PC).

  
  
• 
  

  Iris sutured.

  
  
• 
  

  Scleral sutured.

  
  
• 
  

  Intrascleral haptic fixation.

  
  
• 
  

  Anterior chamber angle supported.

  
  
• 
  

  Iris enclavation.

The following are some of the important surgical tools used:

• 
  

  Microinstrumentation, including microforceps, microtyers, and microscissors.

  
  
• 
  

  Kuglen or equivalent hook.

  
  
• 
  

  Sinskey hook.

  
  
• 
  

  Cohesive and dispersive ophthalmic viscosurgical devices.

  
  
• 
  

  For iris suture fixation, 10–0 polypropylene on CIF-4 needles (Ethicon).

  
  
• 
  

  For scleral suture fixation, double-armed 7–0 polytetrafluoroethylene or 9–0 polypropylene.

  
  
• 
  

  25- or 27-gauge half-inch hypodermic needle.

  
  
• 
  

  23- or 25-gauge vitrectomy setup, with or without trocar if needed.

  
  
• 
  

  Triamcinolone for staining vitreous if needed.

  
  
• 
  

  Intracameral miotic agent.

In some cases the subluxed IOL may be incarcerated in vitreous, so it is critical that vitreous be handled carefully and completely to avoid vitreoretinal traction and reduce the risk of retinal complications. The use of triamcinolone can be helpful to stain vitreous, ⁵ and small-gauge vitreous cutters with high cut rates are preferred. The use of pars plana incisions with microvitreoretinal trocars can provide better access for more posteriorly subluxed IOLs. In some cases the IOL may be suspended and held in position by entangled vitreous, hence releasing vitreous may result in the IOL subsequently dropping farther posteriorly into the vitreous cavity. For this reason, the use of an AC maintainer or posterior infusion line while grasping the IOL with a microforceps in one hand and using the vitreous cutter in the other permits bimanual manipulation of the IOL and excision of vitreous around it (Fig. 16.1).

16.2 IOL Repositioning within the Capsular Bag

To reposition an IOL either within the capsular bag or to the capsular bag (from the sulcus) requires intact zonular support, and ideally an intact PC with sufficient anterior capsule present to overlap the IOL optic. Excessive capsular contracture or phimosis is a relative contraindication to endocapsular repositioning. Common scenarios for IOL repositioning into or within the capsular bag include inadvertent bag-sulcus or sulcus implantation of an IOL (especially a single-piece foldable design), decentration of a multifocal IOL, Z-syndrome subluxation of an accommodating IOL, or misalignment of a toric IOL. Repositioning within the capsular bag includes several benefits: the well-known safety and physiological fixation within the eye, the fact that any PCIOL is amenable to this position, and the fact that no IOL calculation adjustments are required.

16.2.1 Surgical Technique

Reopening the capsular bag is the key first step in this approach. The presence of anterior capsule overlap onto part or all of the IOL optic provides an avenue to separate the anterior and PC leaflets. Once a portion of the anterior capsule leaflet is dissected open, a cohesive ophthalmic viscosurgical device (OVD) is injected to viscodissect the capsular bag open. Many approaches have been described to reopen the capsular bag, including the use of a needle, a hook, or microforceps (Fig. 16.2). In most cases, the capsulorhexis margin can be lifted, and both viscodissection and manual dissection—typically with a blunt cannula—are used to separate the AC and PC (Fig. 16.3). Care should be taken to ensure the entire capsular bag is reopened and all fibrotic adhesions are released. This may necessitate removal of some residual sheets of lens epithelial cells and/or Soemmering’s ring. The most challenging area to release is around the haptic, particularly the bulbous end of some single-piece foldable IOLs. This often requires visco- and manual dissection along the long axis of the haptic.

In the case of an inadvertent bag-sulcus or sulcus-placed IOL, once the capsular bag has been reopened, the IOL can be reposited or rotated into the bag with microinstruments or hooks (Fig. 16.4).

An in-the-bag multifocal IOL (MFIOL) that is decentered from the visual axis may result in suboptimal visual quality and thus may require repositioning within the capsular bag. This typically involves nudging the IOL slightly nasal to the visual axis, which can be confirmed using the first Purkinje image from the microscope light, or with the use of a fixation light or a digital overlay. Once the capsular bag has been reopened and the lens mobilized, the IOL is nudged toward the intended position. If possible, it is preferred to align the IOL haptic along the “6 and 12 o’clock” position, which makes it easier to nudge the IOL along the horizontal meridian. It may not be possible to use this alignment in some scenarios, for example, with a toric MFIOL correcting against-the-rule corneal astigmatism. Nevertheless, by reopening the capsular bag, removing all of the OVD from behind and around the IOL, nudging the IOL nasally and then seating it into position, a mildly decentered MFIOL can be repositioned in the bag (Fig. 16.5).

Repositioning an accommodating IOL that has undergone Z-syndrome misalignment often involves managing the capsular contracture around the IOL, which may prove to be difficult. In severe cases, IOL exchange should be considered. Often there are fibrotic bands and fixed folds present on either or both the AC and PC, which require release or lysing. Mobilizing an accommodating IOL’s haptics can be challenging, but it is important to prevent Z-syndrome from recurring (Fig. 16.6). The IOL should be rotated to an axis of greatest laxity within the capsular bag. Furthermore, implantation of a capsular tension ring (CTR) during the repositioning surgery is important to keep the capsular bag on stretch. CTRs are covered in greater detail in Chapter 20.

The approach, surgical options, and calculation methods of managing a patient with residual astigmatism are covered in detail in Chapter 11. In the event of a misaligned toric IOL that has either been positioned on the incorrect axis or rotated off the axis, the IOL is carefully rotated within the capsular bag after 360° reopening of the capsular bag as described earlier (Fig. 16.7). After removal of the OVD, the IOL is then seated in position. For larger capsular bags and longer eyes (i.e., axial length > 27 mm), the use of a CTR may provide enhanced stability and can be placed into the capsular bag after reopening and mobilization of the IOL. A CTR, by stretching the capsular bag, can promote AC and PC apposition, thus promoting fibrosis and reducing the risk of postoperative IOL rotation.

Removal of the OVD is important to ensure that the repositioned IOL maintains its position postoperatively. This can be done using an automated irrigation and aspiration hand piece, or manually using a 27-gauge cannula on a syringe with balanced salt solution (BSS).

If IOL centration or alignment is suboptimal after repositioning within the capsular bag is attempted, alternative options include optic capture (OC) techniques or suturing of the haptics through the capsular bag.

16.3 IOL Repositioning to Capsule with Optic Capture

OC, covered in detail in Chapter 19, is a useful alternative to the capsular bag if the bag is not stable for an IOL—typically when the PC is deficient or if the AC and PC leaflets are fused together and unable to be reopened. ⁶ Additionally, in eyes with megalocornea, where the capsular bag is excessively larger and the IOL has decentered within the bag itself, OC is a reasonable option. Reverse optic capture (ROC) has been used successfully to treat negative dysphotopsia. ⁷ Optic capturing techniques require adequate zonular support and a capsulotomy that is centered and smaller than the optic of the IOL. The advantage of OC is a well-secured IOL that avoids contact with surrounding structures and is unlikely to be mobile or at risk for chafing against intraocular tissues. Furthermore, IOL power selection changes minimally when in an OC position compared to in-the-bag. ^{8 ,​ 9} The use of microforceps and hooks can assist in the manipulation of the IOL into an OC position.

Although there are many variations of OC, the most common OC techniques are listed in Table 16-1.

OC is ideally performed with a three-piece PCIOL, which can be used for all OC techniques (Fig. 16.8). It is important to avoid placing single-piece IOL haptics in the sulcus. A single-piece foldable IOL should not be placed in a standard OC due to concerns with their bulky haptics making contact with the posterior iris and the risk for UGH syndrome. They may be placed in a ROC position, or in a posterior optic buttonhole (POBH) position if the haptics are behind the anterior capsule (Fig. 16.9, Fig. 16.10). However, in those situations, it is important that the capsulotomy not be too small, or this may risk excessive torsion of the flexible haptic optic junction of the single-piece lens, resulting in IOL tilt. Plate IOLs are not amenable to OC (see Chapter 2).

In the event that an anterior capsulotomy is not ideally sized or positioned for OC or ROC, the PC should be evaluated for possible POBH capture. This may be through a preexisting posterior opening, or it may be created with a posterior capsulorhexis (Fig. 16.11). This may also be a reasonable option if the AC and PC are fused.