Evaluation of femtosecond laser clear corneal incision: an experimental study.

PURPOSE: To evaluate the changes of corneal topography following femtosecond laser and manual clear corneal incision (CCI). METHODS: Inflation testing was performed in 14 human eye globes to evaluate the topographic response of the cornea to CCIs. In seven samples (femtosecond laser group), a 2.75-mm three-plane CCI was created using the iFS femtosecond laser (Abbott Medical Optics, Inc., Santa Ana, CA); the remaining seven samples (control group) received a 2.75-mm manual CCI using disposable angled knives. Topographic maps of the anterior and posterior cornea were acquired using a Scheimpflug topographer Pentacam HR (Oculus Optikgerate GmbH, Wetzlar, Germany). Keratometric data were used to analyze the curvature changes of the cornea. The changes of corneal astigmatism were analyzed by vector analysis. RESULTS: After CCI, the mean change of the anterior keratometric power was 0.04 +/- 0.39 and 0.05 +/- 0.51 diopters (D) (analysis of variance, P > .05) in the femtosecond laser and control groups, respectively. The mean change (P > .05) of the posterior corneal keratometric power was 0.16 +/- 0.19 and 0.15 +/- 0.18 D, respectively. The average change of the anterior and posterior corneal astigmatism vector magnitude was 0.17 D or less in both groups (P > .05). A slight against-the-rule astigmatic change of the anterior and posterior corneal interfaces was found after both CCI techniques. CONCLUSION: The 2.75-mm three-plane CCI created with femtosecond laser showed minimal changes of the anterior and posterior corneal topography, comparable with those of single-plane angled manual incision.