Only with an accurate prescription for optometry can we proceed with the selection of lenses and frames. Discount eyeglasses online matching generally requires providing the degree of the spherical lens, the degree of the cylindrical lens, the axial position, and the distance between the left and right pupils.

The degree of the spherical lens, the degree of the cylindrical lens, and the axial position determine the choice of the lens, while the distance between the left and right pupils determines the choice of the frame. However, the selection of the lens and frame is not completely independent, and their mutual influence and comprehensive consideration are necessary to make the final configuration of the discount prescription glasses most suitable for oneself.

The first step in selecting discountglasses lenses is to choose the refractive index of the lens based on its combined luminosity, which is the power of the spherical lens and the power of the cylindrical lens. Generally, the lens conversion rate can be chosen.

The refractive index of a lens mainly affects its thickness (aesthetic level), Abbe number, and price. Generally speaking, the higher the conversion rate, the lower the Abbe number, and the higher the price. The higher the refractive index, the thinner and lighter the lens, and the better the toughness of the lens.

The so-called Abbe number is the "dispersion coefficient" used to measure the degree of light dispersion in transparent media. The Abbe number of general optical lens materials is between 30 and 60, with glass lenses having a high Abbe number. The most commonly used resin lenses generally have an Abbe number between 30-40, and the Abbe number of lenses should not be lower than 30, otherwise obvious dispersion phenomena will make the wearer's vision blurry.

The higher the Abbe number, the closer it is to the human eye. When selecting lenses, try to choose high Abbe numbers.