Features

Dislocated lenses, including both crystalline lenses and intraocular lens implants (IOL), can prove to be interesting cases for which there are a variety of options for surgical management. They are typically caused by weakening of capsular support, especially zonular weakness/loss or posterior capsule defects. Lens dislocation can occur due to insufficient capsular-zonular support after cataract surgery or following traumatic injury. Other predisposing factors include prior retinal surgery, high myopia, pseudoexfoliation syndrome, hypermature cataracts, and uveitis (▶ Fig. 79.1). Subluxed lenses can also be due to hereditary causes with systemic associations (e.g., Marfan syndrome, homocystinuria, Weill-Marchesani syndrome, Ehlers-Danlos syndrome) and those without systemic associations (familial ectopia lentis, ectopia lentis et pupillae, and aniridia; ▶ Fig. 79.2, ▶ Fig. 79.3). Defects in genes causing microfibril assembly are thought to underlie a majority of these syndromes associated with subluxed lenses and ectopia lentis.

79.1.1 Common Symptoms

Impact on vision depends on the severity of the dislocation; possible decreased vision, monocular diplopia, glare, and seeing the edge of the lens implant. Symptoms may be intermittent depending on the mobility of the lens or IOL.

79.1.2 Exam Findings

In the setting of lens subluxation and dislocation, it is important to assess capsular support and structures as this can help guide surgical management. Key questions to address that impact decisions for surgical approach include the following: (1) Where is the lens or IOL located? (2) What type of IOL is present and what material is it made of? (3) Is the anterior or posterior capsule intact? The presence of phacodonesis should be noted. Phacodonesis can be detected by having the patient look from side to side or jarring the slit lamp. Presence of vitreous in the anterior chamber or to any surgical wounds should also be noted.

Dislocated lenses can also be associated with other ocular complications: pupillary block glaucoma, uveitis, lens-corneal touch leading to corneal decompensation, vitreous hemorrhage, retinal breaks, and amblyopia in children. These should be evaluated at the time of exam.

79.2 Key Diagnostic Tests and Findings

79.2.1 Ultrasonography

B-scan can be helpful to evaluate for retinal pathology if vitreous hemorrhage, cataract, corneal edema, or other pathology is present. In some cases, the dislocated IOL obstructs the visual axis and impairs view of the fundus.

79.2.2 Keratometry

If surgical management is planned, it is critical to get good quality IOL measurements, including corneal keratometry and A-scan.

79.3 Critical Work-up

In addition to those mentioned earlier, it is imperative to consider systemic associations particularly if a hereditary cause is suspected. Connective tissue disorders such as Marfan syndrome can be associated with life-threatening complications including aortic root aneurysms. These patients should be referred to appropriate specialists for further evaluation and monitoring.

79.4 Management

79.4.1 Treatment Options

There are many surgical approaches available for the management of dislocated lenses. The surgical risk profile should be considered when weighing which approach to use for a specific patient.

Nonsurgical Management

If the lens dislocation is minimal or minimally symptomatic, one could observe so long as there are no associated complications including glaucoma or corneal edema. If the lens is dislocated outside of the visual axis, nonsurgical management with aphakic correction (often with a contact lens) could be considered. This may be a preferable option in pediatric patients or those for whom vitreoretinal surgery would have increased risks of complications, like Marfan patients.

Removal of Lens

If surgical removal is necessitated, care must be taken to avoid vitreous traction through performing an anterior or posterior vitrectomy. For patients with minimal lens instability, traditional phacoemulsification techniques can be used with care taken to avoid stressing the zonules and using adjuvants such as a capsular tension ring. If there is enough capsular support, a sulcus IOL could be considered. Similarly, hooks, scissors, or forceps can be used to remove minimally dislocated IOLs through a clear corneal wound. A pars plana approach to lens removal enables more complete vitrectomy and reduces the vitreoretinal risks associated with limbal extraction. Care should first be taken to remove vitreous traction and zonules if needed using a vitrector and possibly dislocating the lens posteriorly before attempting removal. In children and young adults, the vitrector can be used to perform the lensectomy, but denser lenses will require phacofragmentation. Dislocated IOLs can be brought anteriorly using forceps before removal through a corneal wound.

Anterior Chamber Intraocular Lens

If there is not enough capsular-zonular support for a secondary sulcus IOL, one could consider an anterior chamber intraocular lens (ACIOL). Traditional closed-loop ACIOLs were associated with a high incidence of pseudophakic bullous keratopathy, pigment dispersion, and chronic iritis. However, open-loop newer-generation ACIOLs have decreased contact with ocular tissues with lower haptic erosion into the angle with less damage to the corneal endothelium. A review by the American Academy of Ophthalmology supported them as safe and effective, finding insufficient evidence to demonstrate the superiority of scleral-sutured or iris-sutured IOLs compared to them. The relative ease of inserting them compared with scleral-fixated IOLs make them an attractive option.

Iris-Fixated Intraocular Lens

Sutureless iris-claw lenses are fixated by a small knuckle of iris tissues on either side of the iris. They can be used with an anterior or retropupillary implantation. Sutured iris fixation has also been described and involves directly suturing an IOL to the iris with one of a variety of strategies, including the McCannel suture, Siepser knot, and girth-hitch knot. Potential complications of iris fixation include pupillary distortion, synechia, pigment dispersion, and chronic iritis.

Scleral-Sutured Intraocular Lens

Scleral-sutured intraocular lens (SSIOL) is a widely used option in the management of dislocated lenses. They can be used in eyes that have abnormal anterior segment structures or insufficient capsular support and are placed in the correct anatomic location reducing optical aberrations and complications related to pigment dispersion and abnormal pupillary movement. Vitreous management during IOL placement can be performed from either an anterior or posterior approach. Potential complications from SSIOL include suture breakage, erosion, and exposure potentially leading to bleeding or endophthalmitis. Different techniques have been described to minimize these complications, including the creation of triangular scleral flaps or pockets as well as suture knot rotation into the eye.

More recently, the use of expandable polytetrafluoroethylene (Gore-Tex; WL Gore & Associates, Inc. Elkton, MD) suture has been described for the scleral fixation of Bausch and Lomb Akreos AO60 or Alcon CZ7OBD IOLs, as these sutures may have less risk of degrading or breaking with time. Outcomes have been promising. The foldable nature of the AO60 lens, simplified surgical technique, and often excellent surgical results provide significant appeal (▶ Fig. 79.4). However, the AO60 lens is hydrophilic and IOL opacification has been described with the use of an air or gas tamponade (▶ Fig. 79.5). Use of the Bausch and Lomb EnVista MX60 hydrophobic acrylic lens in conjunction with Gore-Tex sutures has been described without opacification with air or gas tamponade, though long-term data have not yet been gathered (▶ Fig. 79.6).

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