The keratoplasty lens is divided into 4 areas with a total of 7 arc segments, which are the base arc region, the reversed arc region, the positioning arc region, and the peripheral arc region. Base arc area: The base arc area is also known as the central optical area or treatment area, usually the width of the base arc area is 6.00mm-6.50mm most common. Generally, the curvature of the base arc area is flatter than the central curvature of the cornea, and the difference is generally the sum of the desired reduction and the overcorrection. The maximum reduction is currently -6.00D for FDA (U.S. Food and Drug Administration approved) and SFDA (China State Food and Drug Administration approved) in the United States. Reversed arc region: The curvature of the reversed arc region is related to the corneal curvature of the central zone and the positioning arc region, and the difference between the curvature of the central zone and the central zone ranges from 3.00D-15.00D. Oppcon Vision Technology Co. The keratoconus reversal arc is designed in two different radii of curvature to improve the link between the reversal arc and the central arc area and the positioning arc. Positioning arc area: the positioning arc is designed mainly to improve the stability of the lens, so that the lens is parallel to the cornea in this area. Peripheral arc area: This area creates a side warp at the outer edge of the lens to facilitate the exchange of tears. The peripheral curve of a keratoplasty lens is between 60um and 70um. The hydrodynamic force generated between the inner surface of the lens, the tear fluid, and the corneal epithelium, along with the combined force generated by the blinking action, changes the shape of the central surface of the cornea to reduce myopia. It achieves a good myopia control effect that cannot be achieved with ordinary frames and soft contact eyes.