Comparison of the mechanical properties of the anterior lens capsule following manual capsulorhexis and femtosecond laser capsulotomy.

ABSTRACT

PURPOSE: 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. METHODS: 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). RESULTS: 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. CONCLUSIONS: 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.