Comparison between groups of the outcomes modeled; Kruskall-Wallis test (with p values) and effect size, (ES)1.

Sample was stratified according to the Amsler– Krumeich grading system according to the severity of the disease.1Comparing each stage of the disease versus normal eyes, effects size was estimated as follows: , calculating for the normal eyes group, for each stage of the keratoconus group, and being a pooled standard deviation of compared data.Comparison between groups of the outcomes modeled; Kruskall-Wallis test (with p values) and effect size, (ES)1.