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Purpose To evaluate the effect of age, size, position, and species on the strength of minicapsulorhexes. Setting Surgical Suite and Laser Laboratory, Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, USA. Methods Capsulorhexes 0.7 to 2.3 mm in diameter were made centrally or peripherally in 35 eye-bank eyes and 32 rabbit eyes. A custom-made instrument stretched the capsulorhexes until rupture. Load and stretch at rupture were recorded. Results Maximum load and stretch were 26.3 mN ± 20.3 (SD) and 50% ± 18% for central and 50.8 ± 20.5 mN and 69% ± 17% for peripheral capsulorhexes in eye-bank eyes and 19.8 ± 15.2 mN and 38% ± 13% for central and 13.5 ± 9.5 mN and 30% ± 7% for peripheral capsulorhexes in rabbit eyes. Peripheral capsulorhexes were stronger and more elastic than central capsulorhexes in eye-bank eyes, and maximum load and stretch increased statistically with the capsulorhexis diameter. Conclusions Peripheral minicapsulorhexes were more resistant to rupture than central capsulorhexes in eye-bank eyes, probably because of increased lens capsule thickness at the periphery. An increase in capsulorhexis diameter increased the resistance to rupture.

Purpose To quantify the cut quality of lamellar dissections made with the femtosecond laser using atomic force microscopy (AFM). Setting Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, USA. Design Experimental study. Methods Experiments were performed on 3 pairs of human cadaver eyes. The cornea was thinned to physiologic levels by placing the globe, cornea side down, in 25% dextran for 24 hours. The eyes were reinflated to normal pressures by injecting a balanced salt solution into the vitreous cavity. The eyes were placed in a holder, the epithelium was removed, and the eyes were cut with a Visumax femtosecond laser. The energy level was 180 nJ for the right eye and 340 nJ for the left eye of each pair. The cut depths were 200 μm, 300 μm, and 400 μm, with the cut depth maintained for both eyes of each pair. A 12.0 mm trephination was then performed. The anterior portion of the lamellar surface was placed in a balanced salt solution and imaged with AFM. As a control, the posterior surface was placed in 2% formalin and imaged with environmental scanning electron microscopy (SEM). Four quantitative parameters (root-mean-square deviation, average deviation, skewness, kurtosis) were calculated from the AFM images. Results From AFM, the 300 μm low-energy cuts were the smoothest. Similar results were seen qualitatively in the environmental SEM images. Conclusion Atomic force microscopy provided quantitative information on the quality of lamellar dissections made using a femtosecond laser, which is useful in optimizing patient outcomes in refractive and lamellar keratoplasty surgeries. Financial Disclosure No author has a financial or proprietary interest in any material or method mentioned.