Transition zone design and smoothing in custom laser-assisted subepithelial keratectomy

Purpose: To evaluate the results of custom laser-assisted subepithelial keratectomy (LASEK) with a specially designed transition zone and smoothing for the treatment of refractive errors. Setting: Department of Ophthalmology, Istituto Clinico Humanitas, Rozzano-Milan, Italy. Methods: This prospective study involved myopic eyes having refractive surgery with the butterfly LASEK technique and the Nidek EC-5000 excimer laser. The treatment was based on the surgeon's analysis of topographic and aberrometric data provided by Final Fit ablation software, which features the Custom Aspheric Transition Zone software algorithm. After the ablation, smoothing was performed to remove corneal microirregularities. Results: Fifty-five eyes of 38 patients were treated. The mean preoperative spherical equivalent (SE) refraction was -6.58 diopters (D) ± 2.24 (SD) (range -12.13 to -1.75 D). At 1 year, the mean SE refraction was -0.26 ± 0.79 D (range -4.00 to +0.75 D). Conclusion: The surface ablation technique provided satisfactory results and took into account strategies to reduce unpredictability factors such as corneal biomechanical forces, haze induced by an irregular postoperative surface, and a high curvature gradient in the transition zone.