Statistical package for the social sciences spss statistics for windows version 22

The main outcome measurements of the study included central corneal epithelial thickness (CCET), SD cet , visual acuity (VA; logMAR), and spherical equivalent refraction at baseline and several postoperative time points (1 week, 1 month, 3 months, and 6 months from day 0) after t-PRK surgery. Unless stated otherwise, all parameters were assumed to be at the specific time point. The Kolmogorov-Smirnov test was used to test the normality of all variables. Categorical variables are reported as numbers and percentages, and continuous variables are reported as mean ± SD. Continuous variables were compared using an independent Student's t-test; Pearson's chi-squared and Fisher's exact tests were used to evaluate the differences in categorical variables.
A generalised estimating equation was used to calculate the parameters. Correlation analyses between CCET, SD cet , and haze with refraction, UDVA, and OCT pachymetry parameters were expressed as Spearman's rank correlation coefficient. Statistical significance was defined as a p-value<0.05. All statistical analyses were performed using the IBM Statistical Package for the Social Sciences (SPSS) Statistics for Windows, Version 22.0. (IBM Corp., Armonk, NY, USA).