Evaluation of Size and Shape of Anterior Lens Capsules after Photodisruption Laser Capsulotomy and Continuous Curvilinear Capsulorrhexis

Abstract

Purpose: : The manual continuous curvilinear capsulorrhexis (CCC) is currently the most frequently used technique for capsulorrhexis in routine cataract surgery. Computer controlled photodissruption laser capsulotomy may provide a more accurate capsule size and/or shape and is the subject of this study.

Methods: : 12 anterior capsules after photodisruption laser capsulotomy and 11 anterior capsules after continuous curvilinear capsulorrhexis (CCC) were removed undamaged during a single day of cataract surgery at the APEC Luis Sanchez Bulnes Hospital in Mexico City, MX. Intended CCC diameter varied between 5.0 and 7.0mm while intended laser capsules varied between 5.0 and 5.75mm. All removed capsules were placed in BSS in individual small containers and were processed within 48 hours of removal. A blue stain was used to enhance the photographic contrast. All capsules were digitally photographed with a surgical microscope with a mm scale in the image. Post processing was performed using custom image processing software to measure the photographed capsules: vertical and horizontal diameters were measured for standard and oblique orientations, as well as RMS deviation from fit to a perfect circle. Size and shape comparisons between the laser cut capsules and CCC capsules were generated and analyzed as intended versus achieved.

Results: : The mean difference between the attempted versus achieved capsule diameter for the laser cuts was 82um (+/- 110um), and was 445um (+/- 596 um) for the CCC (p<0.05.) The RMS deviation from a perfect circle for the laser capsulotomies was 141um (+/- 104um) compared to the CCC at 346um (+/-99um) (p<0.01.)

Conclusions: : The laser capsulotomy size (attempted vs achieved diameter) and shape (RMS error from circle) were found to be statistically significant more accurate than the CCC capsules. Laser capsulotomy may improve the achieved geometry of the capsular bag in cataract surgery compared to conventional CCC.

Keywords: laser • cataract • anterior segment