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Guang-ming George Dai, Dimitri Chernyak, Daniel R Neal, Steven C Schallhorn; Comparison of Centration between Pupil Center and Corneal Vertex for LASIK Surgeries. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):3913.
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© ARVO (1962-2015); The Authors (2016-present)
To compare and contrast two LASIK treatment centration methods (pupil centration and corneal vertex centration) in terms of optical effects and visual outcomes. The treatments considered are based on wavefront, corneal topography and Munnerlyn equation.
Two types of analysis methods are used for determining effects of centration method: optical modeling and clinical data evaluation. With optical modeling, induction of low-order and high-order aberrations (HOAs) is examined for both centration methods. Wavefront diameter of 6 mm is used for the analysis. With clinical data, post-operative high-order aberrations (in particular coma and spherical aberration) and visual acuities are correlated with pre-operative decentration parameters, such as the angle kappa. Wavefront analysis was done over 6 mm and 5 mm diameter, respectively.<br /> <br />
Optical modeling shows a significant induction of coma with corneal vertex centration, because of the incorrect placement of the ablation profile. Likewise, a significant induction of cylinder error is present. No such induction of coma and cylinder is seen with pupil centration. With clinical data analysis, no correlation can be found between 6-month post-operative uncorrected and best corrected acuities, HOAs, with pre-operative angle kappa. Between two sub-groups with large (>= 0.55 mm) and small (<= 0.25 mm) angle kappa, no statistically significant difference in terms of coma, spherical aberration, and high order RMS can be found. In addition, LASIK with pupil centration has the following advantages: easier to perform, utilizing all of the light going through the pupil aperture, does not impact the vision of patients with large angle kappa, does not induce higher order aberrations, and is optimal for wavefront-guided procedures.<br />
The study shows the centration method over the entrance pupil has more advantages compared to the corneal vertex centration for all types of LASIK surgeries.
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