Corneal curvature power before and after corneal refractive therapy with contact Lenses, standard LASIK and custom LASIK Queirós A. 1, González-Méijome J.M. 1, Villa-Collar C. 2, Gutiérrez AR. 3, Jorge J. 1 Department of Physics (Optometry), School of Sciences, University of Minho,Braga, Portugal. Clínica Oftalmológica Novovision, Paseo de la Castellana, Madrid,Spain. 3 Department of Ophthalmology, University of Murcia, Murcia, Spain 1 2
Purpose: The purpose of this study was to evaluate the changes in power of the anterior corneal surface after refractive surgery (LASIK) and corneal refractive therapy (CRT). Methods: One hundred and twenty two eyes of 122 patients, mean age of 30.6±7.5 years, of which 70 were female (57.4%), were retrospectively analyzed in this study. Of those, 43 were submitted to standard LASIK ablation, 40 to customized LASIK and 39 to corneal refractive therapy (CRT) with orthokeratology. Topographical data along the horizontal meridian using the tangential power map. Results: Average refractive error expressed as spherical equivalent was -2.98±0.89D for standard LASIK, -2.94±0.90D for custom LASIK and -2.56±0.82D for CRT (p=0.040, K-Wallis). Pre-treatment corneal topography was not significantly different among groups. A myopic shift was observed at the nasal and temporal locations at 3 and 4 mm from center. In the CRT group, a sharper, narrower and bilaterally symmetrical myopic shift was observed compared with surgical interventions presenting wider optic zone and less symmetric changes between nasal and temporal regions. Contrary to surgery, peripheral corneal after CRT shows a slight flattening, probably as a result of the interaction with the landing zone of the contact lens. Conclusions: Both, surgical and non-surgical interventions show a mid-peripheral myopic shift, which is surprising after surgery. However, CRT seems to provide the most appropriate optics to create an effect of sharp myopic shift in the mid-peripheral area with implications in aberration induction by refractive treatments, depth of focus and potential to slow down myopia progression.
Published on Mar 11, 2011
Proceedings for the International Conference of Optometry and Visual Science 2009 (CIOCV'09). University of Minho, Braga, Portugal