This is an auxiliary substance. Widely used in the operation of medical beauty instruments. The light guide gel has the functions of heat insulation and light guide, and is especially suitable for beauty instruments that generate heat energy from light. Using light-guiding gel can better guide the light source into the skin, and at the same time, it can prevent the skin surface from being burned by heat energy. Light-guiding gel also has the function of physical cooling, which is helpful to improve the symptoms such as redness and fever of eyes. Light-guiding gel is a commonly used auxiliary substance and a water-soluble substance in cosmetic treatment projects such as photon rejuvenation, which can be washed off after treatment.