Orthokeratology mirror originated in the United States. After 50 years of development, it has been applied in 34 countries around the world. It is a kind of orthokeratology lens designed with special reverse geometry, and its inner surface is composed of several arc segments. The lens and tear layer are unevenly distributed, and the resulting hydrodynamic effect changes the geometry of the cornea. When worn in front of the cornea during sleep, the corneal curvature gradually flattens and the axial length of the eye is shortened, thus effectively preventing the development of myopia. Known as "the technology that can control and correct myopia while sleeping".