1, the higher the refraction, the better. Generally, the higher the refractive index, the thinner the lens. At least 1.67 refractive index lenses are recommended for high myopia, and thinner lenses are 1.74 and 1.76.

There are also 1.80 and 1.90 glass lenses, but they are more fragile than resin lenses, so attention should be paid to daily protection. In addition, it should be emphasized that people with high myopia have too high a degree, so they have to choose high refractive index lenses to slow down the weight of the lenses and improve the wearing comfort. However, the higher the refractive index of the lens, the greater the dispersion, the worse the transmittance and the slower the adaptation.

Therefore, if the lens weight and edge thickness are acceptable, it is better to choose a lens with a relatively low refractive index, such as 1.67.

2. Aspheric lenses should be preferred for high myopia. Aspheric lens has a specific eccentric position, that is, the lens gradually flattens from the center to the edge, and the curvature gradually decreases to reduce excessive diopter and astigmatism at the edge.

Therefore, under the same refractive power, aspheric lens is thinner than ordinary lens by 10%-30%, and the aberration of aspheric lens is only 1/5 of that of spherical lens. Therefore, the aspheric lens sees things naturally, and the magnification is uniform and does not deform.

3. The lens materials of resin and PC mainly include glass, resin and PC (polycarbonate). The main disadvantage of glass lenses is that they are heavy, especially high myopia lenses, which leads to a significant increase in the pressure on the patient's nasal root and behind the ear, which is often unbearable for the wearer.

The latter two are widely used in recent years because of their light weight and strong plasticity, occupying an absolute share of the lens market.