Comparison of the Mechanical Properties of the Anterior Lens Capsule Following Manual Capsulorhexis and Femtosecond Laser Capsulotomy

Abstract

Original Article Gábor L. Sándor, MD; Zoltán Kiss, PhD; Zoltán I. Bocskai; Krasimir Kolev, MD, PhD, DSc; Ágnes I. Takács, MD; Éva Juhász, MD; Kinga Kránitz, MD; Gábor Tóth, MD; Andrea Gyenes, MD; Imre Bojtár, PhD, CSc; Tibor Juhász, PhD; Zoltán Z. Nagy, MD, PhD, DSC To evaluate and compare the mechanical properties of anterior capsule openings performed with the continuous curvilinear capsulorhexis (CCC) technique and femtosecond laser capsulotomy (FLC) in ex vivo porcine lens capsule specimens. Fresh porcine eyes were included in the study (CCC group, n = 50; FLC group, n = 30). The capsule openings were stretched with universal testing equipment until they ruptured. The rupture force and circumference stretching ratio were evaluated. The morphologic profile of the cut capsule edges was evaluated using scanning electron microscopy (SEM). The average rupture force was higher in the CCC group (median: 155 mN; interquartile range [IQR]: 129 to 201 mN; range: 71 to 294 mN) than in the FLC group (median: 119 mN; IQR: 108 to 128 mN; range: 91 to 142 mN) (P < .01, Mann–Whitney U test). The average circumference stretching ratio in the CCC group was greater (median: 150%; IQR: 146% to 156%; range: 136% to 161%) than in the FLC group (median: 148%; IQR: 145% to 150%; range: 141% to 154%) (P = .0468, Mann–Whitney U test). When less than 71 mN, no capsular tear occurred in either group. When less than 91 mN, no capsular tear occurred in the FLC group, whereas at 91 mN, the probability of capsular tears was 9% for the CCC group. SEM examination found that the CCC group had smooth edges, whereas those of the FLC group were gently serrated. According to the current results in a porcine eye model, FLC had less average resistance to capsule tear than CCC, but the weakest openings were seen in the CCC group. [J Refract Surg. 2014;30(10):660–664.] From the Departments of Ophthalmology (GLS, ÁIT, ÉJ, KKránitz, GT, AG, ZZN) and Medical Biochemistry (KKolev), Semmelweis University, Budapest, Hungary; the Departments of Polymer Engineering (ZK) and Structural Mechanics (ZIB, IB), Budapest University of Technology and Economics, Budapest, Hungary; and the Departments of Ophthalmology and Biomedical Engineering, University of California, Irvine, California (TJ). Supported by the Hungarian Scientific Research Fund (OTKA 83023). Drs. Nagy and T. Juhász are consultants for Alcon Laboratories, Inc. The remaining authors have no financial or proprietary interest in the materials presented herein. The authors thank Evan Johnson for revising grammar and Györgyi Oravecz for technical assistance. AUTHOR CONTRIBUTIONS Study concept and design (ZIB, IB, TJ, ZK, KKolev, ZZN, GLS); data collection (ZIB, AG, ÉJ, ZK, KKránitz, GLS, ÁIT, GT); analysis and interpretation of data (GLS); drafting of the manuscript (ZIB, AG, ÉJ, ZK, ÉJ, KKránitz, GLS, ÁIT, GT); critical revision of the manuscript (IB, TJ, KKolev, ZZN); administrative, technical, or material support (ZK, KKolev, ÁIT); supervision (IB, TJ, KKolev, ZZN) Correspondence: Gábor L. Sándor, MD, Mária Street 39, Budapest H-1085, Hungary. E-mail: sandorgaborlaszlo@gmail.com 10.3928/1081597X-20140903-08