Causes of Explantation of Phakic Intraocular Lenses.

Causes of Explantation of Phakic Intraocular Lenses We read with interest the article by Alió et al.1 on phakic intraocular lens (PIOL) explantation in the January issue. There is an ongoing debate about the long-term safety of PIOLs, especially angle-supported lenses.2 In late 2014, Alcon Laboratories, Inc. discontinued production of the AcrySof CACHET Phakic Lens (Alcon Laboratories, Inc., Fort Worth, TX),3 the ophthalmic industry’s latest attempt of many with this approach (all of them unsuccessful). The numbers are impressive in this clinical series, by far the largest published, and only comparable to those reported in 2006 by Alió et al.4 Our first question is why the authors did not perform endothelial keratoplasty instead of penetrating keratoplasty, when the case required bilensectomy followed by corneal transplantation.5 When analyzing the explantations due to cataract, knowing the age of this subgroup of patients would have helped to make a better analysis of the influence of surgical trauma and presence of PIOL versus senile cataract. It is not really correct to state that the reasons for endothelial cell loss are related to inadequate anatomy of the anterior chamber, as the authors did. Regardless of their anatomy, if those eyes had not undergone the lens implantation, none of them would have presented endothelial damage. There were cases of corneal decompensation in all three groups of PIOLs (angle-supported, iris-fixated, and posterior chamber). Although information on incidence is lacking, because three to seven times more cases of corneal decompensation presented in the angle-supported group (15 eyes versus 5 eyes in the iris-fixated group and 2 eyes in the posterior chamber group), it appears that this anatomical site has an increased risk of severely altering the corneal endothelium. The same trend was evident in the eyes with endothelial cell loss without corneal decompensation (11 to 23 times more cases in the anglesupported group). It would have been helpful to have the data available on the density of the population of endothelial cells in these eyes, because the clinical implications of having approximately 1,500 cells/mm2 are not the same as having approximately 600 cells/mm2. Although it is probable, at least for earlier models of posterior chamber PIOLs, and is in concordance with other studies cited by the authors, because they did not establish incidence it is not possible to affirm that the incidence of cataract formation was significantly higher with those lenses, as they did. The authors emphasized that the aim of the study was not the evaluation of the explantation ratio and recognized that this was a limitation of their study. We believe it would have been useful to have those data to put the findings in context. Having such a large group of patients, we strongly believe that calculating incidence of explantation (at least for one of the participating centers) or estimating an approximate incidence measure if the exact number of lenses of each model implanted in each is definitely not known will provide valuable information to the scientific community.