Endothelial cell loss after pIOL implantation for high myopia

Abstract

Coullet et al.1 report 2 cases of severe endothelial cell loss 2 years after angle-supported phakic intraocular lens (pIOL) implantation. The first patient was 47 years old at the time of implantation and the second, 52 years old. Furthermore, in the second case, the preoperative endothelial cell count (ECC) was 2000 cells/mm2, which is the lower limit for implantation with most types of pIOLs. The proportion of refractive surgery peformed by lenticular methods is increasing. The surgeon must advise the patient about the risks and benefits of preserving the crystalline lens by implanting a pIOL versus the alternative of refractive lens exchange (RLE) and placement of an IOL. In the second scenario, a further discussion ensues regarding the various IOL options with respect to pseudoaccommodation, multifocality, and adverse visual effects. The advantage of pIOL surgery over RLE is preservation of accommodation. In presbyopic patients, or those approaching presbyopia, this advantage is lost or markedly reduced and RLE rises in the ranking of surgical options. In the report by Coullet et al.,1 the patients were of presbyopic (or near presbyopic) age and 1 patient had a borderline ECC for pIOL surgery. Given these circumstances, we suggest that RLE may be preferable to pIOL implantation. It is important to note that lens extraction is associated with a loss of endothelial cells on the order of 2.6%.2 This compares with the loss of endothelial cells following pIOL surgery of 2.3% to 5.5% at 6 months, 3.5% to 7.21% at 12 months, 4.7% to 9.1 % at 24 months, and 6.7% to 10.9 % at 36 months.3,4 Superimposed on this is the physiological mean cell loss of 0.6% ± 0.5% per year. The accepted minimum density of endothelial cells required for normal function is 700 cells/mm2. Coullet et al. state that severe endothelial decompensation is rarely reported. However, Alió et al.5 performed a retrospective review of 100 eyes that had angle-supported pIOL explantation. There were 24 cases (24%) of progressive endothelial cell loss requiring explantation. The mean interval between implantation and secondary intervention was 8.97 years ± 2.21 (SD) (range 2 to 14 years). The patients presented by Coullet et al. were referred from another center and received contemporary management. Having said that, refractive surgery is usually elective in nature and patients present a diverse range of expectations and ocular examination findings. Lenticular solutions are well established, and we suggest they should be given greater consideration in the presbyopic (and prepresbyopic) age group.