Carbon Bursts Inside A Small Aperture Intraocular Lens After Nd:Yag Laser Capsulotomy

The IC-8® Apthera™ (AcuFocus Inc.™, Irvine, California, USA) is a single-piece hydrophobic acrylic monofocal lens, placed in the capsular bag. It carries a central black circular mask (FilterRing™) with a diameter of 3.23 mm consisting of 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 partial-range of field IOL and can be used in presbyopia correction.

This report describes the case of a patient with an IC-8® implant who described optical phenoma and blurred vision after undergoing Nd:YAG laser capsulotomy for posterior capsule opacification (PCO). Due to a dark central optical change within the IOL, he ultimately underwent IOL exchange.

The examinations as well as the initial IC-8® implantation, the Nd:YAG laser capsulotomy and the IOL exchange were performed at Goethe-University in Frankfurt, Germany. The explanted IC-8® was sent to the Intermountain Ocular Research Center at the University of Utah for further analysis.

A 56-year-old male underwent cataract surgery with implantation of a non-diffractive, extended partial-range of field (RoF) 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 central vision. Slit lamp examination showed a small optical change inside the IC-8® believed to be a small pocket of air. Due to the ongoing symptoms and reduced VA, the seemingly damaged IOL was exchanged. 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.

When performing Nd:YAG laser capsulotomy in patients with an IC-8® implant and PCO, one of two laser techniques are advised: either staying inside the central aperture or outside of the circular carbon mask incorporated within the IOL. Bausch & Lomb recommends placing laser shots approximately 1.0 mm outside of the carbon mask and following a capsulotomy pattern with an inferior hinge (Figure 1). Higher proximity of laser shots to the circular mask may cause intra-optic carbon bursts, which may require lens exchange due to subjective visual disturbances noticed by the patient.