Material analysis of spontaneously subluxated iris-fixated phakic intraocular lenses

PURPOSE: To conduct a material analysis of spontaneously subluxated iris-fixated phakic intraocular lenses (IOLs) using light and scanning electron microscopy. METHODS: Six explanted Artisan/Verisyse and Artiflex/Veriflex IOLs (Ophtec, Groningen, Netherlands/AMO, Santa Ana, CA) were analyzed in a laboratory using light and scanning electron microscopy. Four of the IOLs had been explanted after spontaneous subluxation leading to a decrease in visual acuity, whereas the remaining two IOLs did not demonstrate signs of disenclavation but had been explanted in the course of planned cataract surgery and thus served as the control in this study. RESULTS: Light microscopy enabled the detection of clear deformations of the fixation arms on one or both haptics of the lens that had subluxated, and scanning electron microscopy revealed micro-cracks in the material. The deformations, which appeared to have been caused by some form of manipulation of the fixation arms, meant that adequate closure of the fixation arms was no longer possible and a reliable fixation in the iris stroma was unattainable. At least three of the lenses had been implanted with the use of an IOL haptic expander for enclavation, which may have contributed to the malformation of the haptics. The two control lenses exhibited no signs of material deformation or subsequent disenclavation. CONCLUSIONS: Deformations of the haptics of iris-fixated phakic IOLs can cause irreversible damage leading to disenclavation and inadequate re-enclavation. In such cases, explantation appears to be the only therapeutic option. It is important to adhere to an appropriate implantation technique to reduce the risk of spontaneous subluxation.