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From the London Vision Clinic, London, United Kingdom (DZR, MG, LG, TJA, GIC); Department of Ophthalmology, Columbia University Medical Center, New York, New York (DZR); and Centre Hospitalier National d'Ophtalmologie, Paris, France (DZR).
Dr. Reinstein is a consultant for Carl Zeiss Meditec AG, Jena, Germany, and has a proprietary interest in the Artemis technology (ArcScan Inc., Morrison, Colorado) through patents administered by the Cornell Research Foundation, Ithaca, New York. The remaining authors have no proprietary or financial interest in the materials presented herein.
In corneal refractive surgery, correct alignment of the corneal ablation is paramount to achieving good visual outcomes because decentered treatments can lead to a significant increase in visually disturbing higher-order aberrations 1 with decrease in quality of vision, diplopia, 2 decreased contrast sensitivity, and night vision disturbances. 3 Because small incision lenticule extraction (SMILE) does not involve the use of an eye tracking system, it has been suggested that this is a potential weakness of the procedure. 4
In LASIK, although the advances in eye tracking systems 5 have significantly reduced the occurrence of decentered treatments, it has not been completely eliminated and the problem of topographical decentration still exists. 3,6,7 In SMILE, the alignment of the refractive lenticule is effectively auto-centered by the fact that the patient fixates coaxially on a fixation light when suction is applied, resulting in lenticule formation centered on the corneal vertex of the coaxially fixating eye. Optical zone centration in myopic SMILE has been the subject of two recent studies, which have both shown that the achieved centration of SMILE was good. Li et al. 8 reported that the optical zone on topography was offset on average by 0.17 mm from the corneal vertex, and within 0.50 mm of the corneal vertex in all eyes. Lazaridis et al. 9 found a mean offset of 0.32 mm from the corneal vertex in the SMILE group using pachymetry difference maps, compared to a mean offset of 0.45 mm from the entrance pupil center (the intended centration point) in the femtosecond LASIK group.
The aim of the current study was to compare optical zone centration between matched myopic eyes treated by fixation-based SMILE (the SMILE group) or eye tracker-based LASIK (the LASIK group) in a large sample of...