Intereye comparison of femtosecond laser–assisted cataract surgery capsulotomy and manual capsulorhexis edge strength

Abstract

To compare the breaking force required to tear the explanted capsule after femtosecond laser-assisted cataract surgery in the worse eye and manual cataract surgery in the contralateral eye. Personaleyes, Sydney, Australia. Prospective nonrandomized case study. Patients with bilateral cataract had femtosecond laser-assisted cataract surgery with the Lensx laser in the eye with worse vision and manual cataract surgery in the contralateral eye. Each explanted capsule was stretched mechanically, and the breaking force and strain in grams (g) were compared. When a large contralateral difference in capsule strength was found, scanning electron microscopy (SEM) was applied to determine whether morphologic imperfections were present in a case with a weak capsule. Paired samples of 78 eyes of 39 patients were tested. The mean breaking force was not significantly different between manual capsulorhexes (2.3g±2.0 [SD]) and femtosecond laser capsulotomies (2.0±2.2g, P=.52). The breaking strain for the manual samples (33.8%±18.3%) and for the femtosecond laser samples (34.6%±18.6%) were also not significantly different (P=.81). In 5 patients, in the femtosecond group, the capsules required considerably less force to break than the capsules in the manual group. However, the SEM images of these samples did not show specific laser imperfections. In paired human eyes, the capsulotomies created by a femtosecond laser with a contact lens interface were as strong as manual capsulorhexes.