Carbon bursts inside a small aperture intraocular lens after Nd:YAG laser capsulotomy

Abstract

PurposeThe IC-8® Apthera™ (AcuFocus Inc.™, Irvine, California, USA) is the first small aperture intraocular lens (IOL) to receive FDA approval for presbyopia correction in the summer of 2022. It is a single-piece hydrophobic acrylic monofocal lens, which is placed in the capsular bag. In its center it carries a black circular mask (FilterRing™) with a diameter of 3.23 mm consisting of polyvinylidene fluoride and carbon black nanoparticles. In the center of this mask sits a 1.36 mm wide aperture. Thanks to this pinhole effect the IC-8® serves as an extended-depth-of-focus (EDOF) IOL and can be used in presbyopia correction.This report describes the case of a patient with an IC-8® implant who underwent Nd:YAG laser capsulotomy for posterior capsule opacification (PCO). The post laser checkup showed a dark central optical change within the IOL and the patient described optical phenomena as well as blurred central vision, which is why he received IOL exchange. The explanted IC-8® was sent to the Intermountain Ocular Research Center at the University of Utah for further analysis. ObservationsA 56-year-old male underwent cataract surgery with implantation of a non-diffractive EDOF-IOL on the right and the IC-8® small aperture IOL on the left eye. On the left eye, the patient had received penetrating keratoplasty seven years prior to the cataract operation due to posttraumatic corneal scarring. The early checkups after cataract surgery showed a corrected distance visual acuity (CDVA) in the left eye of +0.1 logMAR in the first month. About 5 months after the operation, PCO was first described on the left eye leading to a decrease in visual acuity to +0.4 logMAR (CDVA). Due to PCO, Nd:YAG laser capsulotomy was conducted 5 months after the cataract operation on the left eye. 12 shots were applied at 2.7 mJ. The following appointments showed a continuously reduced visual acuity of +1.3 logMAR (uncorrected) on the left eye and the patient described blurry and ‘swirled’ central vision. By slightly tilting his head and thus not using the center of his optic axis, he would be able to see sharper. Slit lamp examination showed a small optical change inside the IC-8® IOL not resembling a pit but believed to be a small pocket of air. Due to the ongoing symptoms as well as the reduced VA, the seemingly damaged small aperture IOL was exchanged for a three-piece hydrophobic acrylic monofocal lens, which was also placed in the posterior chamber. The explanted IC-8® was sent to the Intermountain Ocular Research Center at the University of Utah for further analysis. Results from gross and light microscopic analysis showed that the change caused by the Nd:YAG laser application consisted of a localized optical area containing carbon black nanoparticles used for the circular mask within the IOL. Conclusions and importanceWhen dealing with PCO and performing Nd:YAG laser capsulotomy in eyes with an IC-8® IOL implant, the laser shots should be applied either inside the aperture or outside of the black circular mask of the IOL. Otherwise, the Nd:YAG laser can lead to bursts of carbon nanoparticles within the IOL which may cause optical phenomena as well as decreased visual acuity possibly resulting in an IOL exchange.