Statistical analysis In the first step of the statistical analyses, Chi-square test (or Fisher exact test, if n<5) and Kruskal-Wallis test, followed by the Mann-Whitney U test were used to analyze each variant individually for univariate analysis. In the second step, multivariate regression models were used for elucidating the independent influence of each morphological change on postoperative visual outcome. Levels of statistical significance were set at P<0.05.