Evaluation of the mechanical properties of the anterior lens capsule following femtosecond laser capsulotomy at different pulse energy settings.
OBJECTIVE
To evaluate and compare the mechanical properties of anterior capsule opening performed with femtosecond laser capsulotomy at different energy settings in ex vivo porcine anterior lens capsule specimens.


METHODS
Twenty-five fresh porcine eyes per group were included in the study. Femtosecond laser capsulotomy was performed with three different pulse energy levels: 2 µJ (low energy group), 5 µJ (intermediate energy group), and 10 µJ (high energy group). The capsule openings were stretched with universal testing equipment until they ruptured. The morphologic profile of the cut capsule edges was evaluated using scanning electron microscopy.


RESULTS
The high energy group had significantly lower rupture force (108 ± 14 mN) compared to the intermediate energy group (118 ± 10 mN) (P < .05) and low energy group (119 ± 11 mN) (P < .05), but the difference between the intermediate energy and low energy groups was not significant (P = .9479). The high energy group had significantly lower circumference stretching ratio (144% ± 3%) compared to the intermediate energy group (148% ± 3%) (P < .05) and low energy group (148% ± 3%) (P < .05), but the difference between the intermediate energy group and low energy group was not significant (P = .9985). Scanning electron microscopy images showed that the edge was only serrated with low and intermediate energy, but additional signs of collagen melting and denaturation were observed at high energy.


CONCLUSIONS
Anterior capsule openings created at a high energy level were slightly weaker and less extensible than those created at low or intermediate levels, possibly due to the increased thermal effect of photo-disruption.
Gábor L
GL
Sándor
Zoltán
Z
Kiss
Zoltán I
ZI
Bocskai
Krasimir
K
Kolev
Ágnes I
ÁI
Takács
Éva
É
Juhász
Kinga
K
Kránitz
Gábor
G
Tóth
Andrea
A
Gyenes
Imre
I
Bojtár
Tibor
T
Juhász
Zoltán Z
ZZ
Nagy
D000818:Animals; D057866:Anterior Capsule of the Lens / Q000502:physiology* / Q000601:surgery / Q000648:ultrastructure; D001696:Biomechanical Phenomena; D004548:Elasticity / Q000502:physiology*; D008855:Microscopy, Electron, Scanning; D064727:Posterior Capsulotomy / Q000379:methods*; D013552:Swine