Histologic Evaluation of in vivo Femtosecond Laser–Generated Capsulotomies Reveals a Potential Cause for Radial Capsular Tears

Abstract

Purpose: To compare histologically the size and appearance of capsule disks after femtosecond laser–assisted cataract surgery and conventional cataract surgery. Methods: In 100 eyes of 100 patients with visually significant cataracts, a femtosecond laser capsulotomy or a capsulorhexis with an aimed diameter of 5.0 mm was performed by one experienced surgeon. The diameter, area, circularity, and cut quality was histologically examined with light microscopy and scanning electron microscopy. Results: The mean diameter of the manual and the femtosecond laser capsule disk group were not statistically significantly different (manual 4.91 ± 0.34; femtosecond: 4.93 ± 0.03; p = 0.58). The mean area of the capsule disks was 18.85 ± 2.69 mm² in the manual and 19.03 ± 0.26 mm² in the femtosecond group (p = 0.64). The capsules of the femtosecond group (0.95 ± 0.02) were significantly more circular than the ones of the manual group (0.81 ± 0.07; p<0.0001). The femtosecond laser capsule disks displayed a more saw blade–like structure created through the single laser spots. The histologic examination combined with prospective video analysis revealed respiratory movement of the eye during the capsulotomy as a potential risk factor for redial tears. Conclusions: Femtosecond laser can perform a capsulotomy with high reliability. In comparison to a highly experienced cataract surgeon, the achieved results in size are similar. In terms of circularity, the femtosecond laser was superior the manual procedure. Better refractive outcomes based on a 360°-degree optic overlap seem to be possible, especially for less experienced surgeons.