The definition of cheapest eyeglasses online refractive index is the ratio of the propagation speed of light in a vacuum to the propagation speed of light in that medium.

Simply put, this is a numerical parameter calculated through a formula. As for why it must be this value. The higher the refractive index of a material, the stronger its ability to refract incident light.

The edges of cheapest eyeglasses online lenses with the same refractive index and material are thinner than those with lower refractive index. Refractive index is the first parameter that many people first come into contact with lenses.

Its intuitive manifestation on the lens is that the higher the refractive index, the thinner the lens. For those who have requirements for aesthetics and weight, thin lenses are a good choice.

After discussing the refractive index, we need to talk about the Abbe number, which is closely related to it. The Abbe number refers to the dispersion coefficient and is an important indicator for measuring the clarity of lens imaging.

The higher the value, the clearer the imaging of the lens. The lower its value, the more blurry the imaging of the lens. It is also closely related to the refractive index of the lens itself.

Generally speaking, the higher the refractive index of a cheapest eyeglasses online lens, the lower its Abbe number. So high thinness and high definition are something that cannot be achieved simultaneously. At this point, you need to choose the most suitable lens for yourself, rather than considering a single indicator.

When choosing lenses, it is not necessarily better to have a higher refractive index or a thinner lens. On the contrary, the higher the refractive index of the lens, the lower the Abbe number, and the less clear it is to see through the lens.