18 Bilensectomy (Phakic IOL Explantation with Coincidental Cataract Surgery and IOL Implantation) Abstract Phakic intraocular lenses (IOLs) are a useful tool in the armamentarium of a refractive surgeon, especially in those patients in which corneal refractive surgery cannot be performed. Although an excellent visual outcome is achieved after the implantation of phakic IOLs, they need to be explanted at some point of time due to the development of cataract (in most of the cases). There are three types of phakic IOLs: angle supported, iris fixated, and posterior chamber IOLs. Angle-supported IOLs are no longer used due to the complications that they are associated with (severe endothelial cell loss, pupil ovalization). Before performing bilensectomy, a careful examination must be done to manage possible complications during and after surgery; for example, the presence of posterior synechiae, a low endothelial cell count, severe pupil ovalization, or a poor mydriasis. A fundus examination in these patients is also very important because many of them are high myopes with long axial lengths that are susceptible to retinal detachments. The aim of this chapter is to discuss the main uses of bilensectomy and describe the surgical technique (which is going to be different depending on the type of phakic IOL) and the visual outcomes. Keywords: bilensectomy, phakic intraocular lens, cataract, micro-incisional cataract surgery (MICS), endothelial cell loss, posterior synechiae The term bilensectomy was first introduced by Joseph Collins and refers to the explantation of a phakic intraocular lens (IOL), followed by phacoemulsification and implantation of a posterior chamber IOL.1 Placement of phakic IOL can lead to corneal endothelial decompensation along with cataract formation. Although the removal of phakic IOL becomes mandatory in such cases, the potential outcomes can be limited or restricted in nature due to associated clinical features and decompensation. These cases need a particular mention that the decompensated endothelium needs to be protected at all stages of surgical maneuver and in advanced cases it may also be essential to perform an endothelial keratoplasty procedure. There are three types of phakic IOLs: • Angle supported. • Iris fixated. • Posterior chamber IOLs. Phakic IOLs have many advantages: they preserve accommodation, they can correct high refractive errors, and they achieve a good visual outcome and optical quality,2,3 but it is essential to mention that all of them eventually need to be explanted because of the natural development of cataract.4 In fact, cataract is the main cause of phakic IOL explantation in all types of phakic IOLs,5 with posterior chamber phakic IOLs reporting the highest rate of cataract formation,5 which may be due to an improper vaulting, chronic inflammation secondary to friction between the IOL and iris, and/or inadequate aqueous perfusion to the lens.3 Also, the use of steroids, trauma during surgery, and high myopia are important causes of cataract formation independent of the type of phakic IOL implanted.5 • When the corrected distance visual acuity (CDVA) has decreased at least two lines from the CDVA measured after phakic IOL implantation and the loss of vision is related to cataract formation. • When there is a functional loss of endothelial cell count (< 1,500 cells/mm2). • Significant pupil ovalization in patients older than 45 years ( Anterior chamber depth measurement, the position of the IOL in relation to the corneal endothelium, iris, and lens, and the presence of synechiae (
18.1 Introduction
18.1.1 Phakic Intraocular Lenses
18.1.2 Indications of Bilensectomy
Fig. 18.1).1,5
Table 18.1 lists the main causes of phakic IOL explantation according to a multicentric study.5
18.1.3 Preoperative Evaluation
Fig. 18.2) has to be evaluated before surgery, as well as the endothelial cell count to prevent corneal decompensation after surgery, and a fundus examination.
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