Keratokeratosis is a localized keratoconus caused by long-term local pressure and friction of foot skin. Commonly known as "meat thorn". The main inducement is that people who stand and walk for a long time are more prone to friction and oppression. Too tight shoes or deformed foot bones will thicken the corner layer of the foot that is rubbed or oppressed, push it inward, and become a cone-shaped horny thing with an inward tip. As shown in the figure below: