Descripción: “...Some other investigators have proven that the invasive technique breakup time (BUT) does not have a significant value because of its low reproducibility\h 4,\h 5 also, due to fluorescein induced biochemical tear film alteration. This study has been made in order to evaluate a non invasive beak-up-time technique (NIBUT), based on physical principles of interferometry through interferometric colors generated by the various wave- length, by means of Tearscope® from Keeler U.K....”