Comparison of the maximum applicable stretch force after femtosecond laser–assisted and manual anterior capsulotomy

PURPOSE: To objectively measure the strength of the capsulotomy performed with a femtosecond laser-assisted technique or performed manually in a pig-eye laboratory study. SETTING: International Vision Correction Research Centre, Department of Ophthalmology, University of Heidelberg, Heidelberg, Germany. DESIGN: Experimental study. METHODS: Ten fresh pig eyes were randomly assigned to femtosecond laser-assisted capsulotomy or manual capsulotomy. The capsule was immersed in hyaluronic acid, and retractors were fixed in the capsule opening with a pull-force measuring device. The force necessary to break the capsulotomy was measured in millinewtons (mN); the maximum stretching ratio was also assessed. RESULTS: The observed mean rupture force (ie, maximum amount of force measured immediately before tissue rupture) was 113 mN ± 12 (SD) in the laser-assisted procedure and 73 ± 22 mN in the manual procedure (P<.05). The stretching ratios were 1.60 ± 0.10 (femtosecond) and 1.35 ± 0.04 (manual) (P<.05). CONCLUSION: In this laboratory pig-eye study, femtosecond laser-assisted capsulotomy resulted in a significantly stronger anterior capsule opening than the standard manually performed capsulotomy.