The recently published study by Benito-Llopis and associates is described as a case series; however, this is incorrect. A case series study would involve following a group of patients who have a similar diagnosis or are undergoing the same procedure over a certain period without the use of controls. In the current study, the author selected 2 groups of participants based on an exposure, or risk factor, of interest: 1 with eyes that underwent laser-assisted subepithelial keratocyte (LASEK) and the other with nonoperated eyes. As such, this study design is better described as a cohort study. Unfortunately, this is not merely a semantic issue as it has implications for the appropriate statistical analysis and, therefore, the proper interpretation of the observed results. None of the analyses the authors mention use paired statistics, which are needed to account for the clustering effect when comparing the same unit of observation (in this case, eyes) between different time points. Additionally, the authors report using the Bonferroni test to test the normality of the data, concluding that the data are normally distributed. However, we are unaware of any Bonferroni test used to measure normality, and given the nature of the data, it is unlikely that the data are normally distributed. If they wrongly concluded that the data are normally distributed, then the use of parametric statistical tests is also incorrect. The authors are strongly urged to conduct a reanalysis of their study data and provide readers with the appropriate measures of association and P values, amending their interpretation as warranted.
Keratocyte Density 3 Months, 15 Months, and 3 Years After Corneal Surface Ablation With Mitomycin C
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