The potential for blindness is from misuse of applicators such as dropping it on a dirty bathroom floor and still using it. You can get bacterial keratitis from putting in dirty contacts, using infected eyeliner pencils and makeup brushes, and a number of other things. The formula itself doesn't cause blindness, but the brown pigmentation thing is scary. If I didn't already have brown eyes, no way in hell would I risk having them become permanently brown just for longer lashes.