Corneal Functional Optical Zone after LASIK for Myopia and Myopic Astigmatism
Kramann, C.1, Krummenauer, F.2, Dick, H. B.1
1University Eye Hospital, Johannes Gutenberg University of Mainz; 2Department of Medical Biometry, Epidemiology and Informatics, Johannes Gutenberg University of Mainz
Purpose: To evaluate the corneal functional optical zone (FOZ) after LASIK for myopia and myopic astigmatism using a flying spot excimer laser (ESIRIS, Schwind eye-tech-solutions, Germany) and to identify determinants of changes in the FOZ .
Method: This cohort study comprised 76 eyes with myopia and/or myopic astigmatism. Preoperative refraction, attempted correction and achieved correction, ablation zone diameter, preoperative pupil size, corneal pachymetry, intraocular pressure and corneal keratometry were correlated with the intraindividual FOZ reduction via Spearman correlation coefficients. Intraindividual FOZ changes were analysed using the sign tests to assess statistical significance, data description was based on medians and quartiles. Risk factors of clinically relevant FOZ reductions were identified using a multiple logistic regression model (Wald test). p values < 0.05 indicate local statistical significance.
Results: After LASIK, a median FOZ decrease to 87% (interquartile range 77% - 101%) was observed (sign test p<0.001), corresponding to an absolute reduction of -0.8 mm (-1.4 mm - +0.08 mm). None of the clinical parameters showed an absolute correlation larger than 30% (attempted correction 25%, ablat
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