# Laser Vision Correction for Regular Myopia and Supracor Presbyopia: A Comparison Study
## 2 Materials and Methods  
Our study population included two groups of eyes, 40 eyes of 20 study patients (female: 14, male: 6, age: 30 \(\pm\) 9 years) were treated with regular myopic LASIK correction, and 50 eyes of 25 study patients (female: 14, male: 11, age: 52 \(\pm\) 3.8 years) were treated for presbyopia with the PresbyLASIK Supracor treatment (B&L Technolas, Munich, Germany). All surgery procedures were performed by an experienced surgeon (BP) at the Eye Clinic ORASIS between January 2014 and February 2015.  
The LDV femtosecond laser (Ziemer Ophthalmology, Port, Switzerland) was used to make the LASIK flaps, whereby the hinge was superior in all cases. The flap diameter depended on the corneal curvature and was between 8.5 and 9.0 mm. The Munnerlyn formula [12] along with the B&L-Technolas proprietary transition zone algorithm was used to calculate the ablation patterns for the regular myopia corrections. In a two-step approach a 2.0 mm laser spot diameter was first used to apply the basic correction, followed by the fine-tuning step with a 1.0 mm laser spot. An eye tracker system was active during all interventions. The cyclorotation is automatically compensated which is especially important for cases where astigmatism correction was included. Whenever the angle kappa was smaller or equal 6\({}^{\circ}\) the laser spot was placed in the pupil center, otherwise it was placed at the point of the arithmetic mean between the pupil center and the Purkinje reflex. After the laser correction, the flap was carefully placed back onto the stromal bed, making sure no visible wrinkles are left.  
The same approach as for the myopia ablation patterns is also employed to calculate the Supracor PresbyLASIK ablation patterns, however, the target refraction is chosen such that the dominant eye was at 0.0D and the follow-eye was at \(-\)0.5D. The goal of a first application phase is to obtain a perfect mono-focal correction, and only in the second phase the central cornea is steepened by the multifocal curvature addition in the 3.0 to 6.0 mm zone. Considering that such an ablation could potentially induced spherical aberration, the Supracor procedure was performed wavefront-guided for all cases.  
Corneal shape was assessed one week before and then 3 months after the LASIK treatment, with the Galilei G4 tomographer (Ziemer Ophthalmic Systems, Port, Switzerland). Thereby, each individual measurement was repeated three times in a row. So, only one measurement with the median astigmatism cylinder value is selected for further data evaluation.  
The statistical methods used in this study were straightforward calculations of average and standard deviation, as described in any textbook of statistics. Excel software package (Microsoft, Redmond, WA, USA) was used to import and process data, as well as, to obtain the functional dependence of the selected parameters and their visualization. Two-tailed Student \(t\)-test was used for calculating the parametric datas and for the nonparametric test the Wilcoxon signed rank test was used. The level of significance was set at \(p<0.05\).