Ultra-thin lenses are lenses with high refractive index, which are more beautiful and are the choice of many people with high myopia. Compared with ordinary lenses, ultra-thin lenses are naturally more expensive. Let's take a look at how about ultra-thin lenses? Most of the lenses with high refractive index on the market are resin lenses. The ultra-thin resin lens adopts a special processing technology. The ultra-thin lens is thinner than the ordinary lens and has a higher refractive index. Under the same material and power, the higher the refractive index, the thinner the center thickness of the lens. In the market, you can see lenses with refractive indices of 1.60, 1.61, 1.67, and 1.74. And generally ultra-thin lenses are aspherical lenses. Ultra-thin resin lenses with high refractive index will also be lighter. The use of high refractive index materials can reduce the curvature of the lens. Get a concave lens with a thinner edge or a convex lens with a thinner center for the same power. For some people with high myopia and hyperopia, because the degree is too high, if the edge of the lens is particularly thick, it is easy to produce prismatic effect and off-axis aberration when wearing it, and the wearer is prone to dizziness. Therefore, if they wear glasses, they need to choose ultra-thin lenses with high refractive index. It will be more comfortable to wear. Ultra-thin lenses include not only resin lenses but also glass lenses. Glass lenses are made by adding lead-containing heavy metal oxides to increase the refractive index of the lenses. When the refractive index of the glass lens increases, the degree remains unchanged, and the weight of the lens also increases. Resin lenses improve the refractive index of the lens by changing the molecular structure of the material. The higher the refractive index of the lens, the thinner the lens will be at the same degree. However, the refractive index of resin lenses is generally lower than that of glass lenses.