Successful cataract surgery can follow removal of posterior chamber phakic IOL
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Phakic lens implants are useful for the treatment of high degrees of myopia, which are beyond the capabilities of keratorefractive laser treatment.
Typically, these phakic lens are used to treat about –10 D or more of myopia in patients who are younger and still have accommodation via their crystalline lens. Posterior chamber phakic IOLs are placed in the ciliary sulcus, behind the iris, and may have the benefit of being farther away from the cornea, which may help to limit endothelial cell loss. These patients do well with the phakic lens implants for many years, but with age, the crystalline lens loses accommodation, begins cataract formation, and increases in thickness, which leaves less room for the phakic IOL. When these issues progress, removing the phakic IOL and performing cataract surgery is often the best approach.
Source: Uday Devgan, MD
At the consultation, take note of the position of the phakic IOL and determine if there is narrowing of the angle, examine the corneal endothelial surface carefully, and check the peripheral retina for areas of weakness. Biometry can be done normally because optical methods of measurement will go right through the phakic lens. Because these patients are typically very myopic with long axial lengths, the choice of IOL for the cataract surgery may be limited. In particular, patients who require IOL powers of 5 D or less may be relegated to a meniscus-design monofocal three-piece IOL. Lens calculations should be done with more modern approaches, and a goal of mild myopia can be more useful than plano while reducing the risk for a hyperopic postop surprise.
Even though we usually perform cataract surgery through 2.2-mm wide incisions, in order to remove the phakic lens, we will need a slightly larger 2.8-mm phaco incision (Figure 1). Dispersive viscoelastic is injected behind the phakic lens and in front of the anterior lens capsule to create space and facilitate removal. A small hook or other instrument can be placed through the small holes of the phakic lens to help elevate it partially into the anterior chamber, while care is taken not to inadvertently damage the anterior lens capsule. Forceps are used to grasp the edge of the phakic lens and then gently pull it out of the eye (Figure 2). Because this lens is thin and flexible, it will readily roll onto itself and come right out of the incision. Note that smaller incisions, such as the typical 2.2-mm phaco incision, will make it challenging to remove. Once the Visian ICL (STAAR Surgical) is removed from the eye, it is examined to ensure that it is intact and that no remnants are left inside the anterior segment (Figure 3).
Cataract surgery can now be performed in a relatively routine manner. The silicone phaco tip sleeve should be the larger one that will fill up the 2.8-mm incision to prevent excessive leakage. If the standard 2.2-mm silicone sleeve is used with this larger incision, there will be excessive fluidic outflow, which will lead to chamber instability and a higher risk for posterior capsule rupture. In these highly myopic eyes, posterior capsule rupture can lead to an increase in the risk for retinal detachment.
This patient desired a slight myopic refractive outcome paired with an extended depth of focus (EDOF) IOL to improve computer range vision for her profession. A toric version of the EDOF IOL was chosen to help address the preexisting corneal astigmatism. The greater flattening effect of the larger 2.8-mm incision was taken into account to ensure accurate astigmatic calculations. The toric EDOF IOL was placed in the capsular bag, centered with the visual axis, and rotated to the appropriate astigmatic meridian (Figure 4). The patient achieved an excellent postoperative outcome and was very pleased with her new vision. Patients with posterior chamber phakic lens implants who, decades later, develop cataracts can have a successful surgery to have their sight restored.
A video of this surgery can be found at https://cataractcoach.com/?s=phakic.
- For more information:
- Uday Devgan, MD, in private practice at Devgan Eye Surgery and a partner at Specialty Surgical Center in Beverly Hills, California, can be reached at devgan@gmail.com; website: www.CataractCoach.com.
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