Purpose: To evaluate cell death and ultrastructural effects on capsulotomy specimens derived from femtosecond laser-assisted cataract surgery.
Methods: In 26 eyes, an anterior capsulotomy was performed using a femtosecond laser. In 10 eyes (group 1), the laser-pulse energy was set to 15 μJ using a rigid curved interface and in another 10 eyes (group 2) to 5 μJ using a curved interface combined with a soft contact lens. The control group (6 eyes, group 3) underwent manual anterior capsulorhexis using forceps. All extracted capsule specimens underwent cell death analysis using the TUNEL kit, ultrastructural analyses using atomic force microscopy (AFM), and scanning electron microscopy (SEM). Counterstaining was performed with 4',6-diamidino-2-phenylindol (DAPI) and hematoxylin-eosin (HE).
Results: Cell death was found in all capsule specimens along the cutting edge but was significantly more pronounced in group 1. DAPI and HE staining showed regular epithelial cell distribution with a demarcation line along the cutting edge of both laser groups, which was more pronounced in group 1. In AFM analysis, laser spot size in the femtosecond laser groups were in accordance with the preoperative planned size (P < 0.01). Cutting edges in SEM observations were smoother and more roundly shaped using 5 μJ (group 2).
Conclusions: Cutting edges of femtosecond laser-performed capsulotomies are precise and laser spot lesions are within planned size. Cell death reaction depends on the laser pulse energy settings and can be reduced to the level observed in a manual capsulorhexis.
Keywords: apoptosis; atomic force microscopy; capsulorhexis; capsulotomy; cell death; femtosecond laser; laser energy; scanning electron microscopy.