There are many kinds of lenses for myopia glasses, which one is better, in fact, it varies from person to person, you can follow the following classification method:
One, according to the material
Common lens materials are common resin sheet, PC resin sheet, glass lens, crystal lens, etc., the common resin sheet accounts for the majority of the market, with a good transmittance of light, PC cosmic lenses are stronger, lighter, UV resistant, more expensive and better quality than resin; glass lenses are more wear-resistant and have a higher refractive index but are too heavy and easy to break; crystal lenses are too expensive and have poor protection against harmful rays and are not suitable for daily use.
Two, according to the design points
Divided into spherical lenses and aspheric lenses, spherical lenses to see the object will be distorted, aspheric will be clearer and more realistic, the weight is also lighter. Basically buy lenses will choose aspheric, of course, spherical lenses also have a market, there are people buy.
Three, according to the treatment of points
Surface treatment has no film; add hard film, can protect the lens, enhance the resistance, abrasion resistance, etc.; anti-reflection film, to improve the visual effect, but also has a certain protective effect; anti-fouling film, so that the lens is not easy to dirty, oil, water stains, etc. can be. Specifically which kind of coating, according to their own needs to choose.
Four, according to the color
Can be divided into white, colorless lenses; dyed film, adding chemicals to dye; color change film, adding silver halide, strong light stimulation under the decomposition of silver and halogens, so that the color of the lens becomes darker, the light becomes weaker and then combined with the silver halide, the color becomes lighter; polarized lenses, only allow a certain direction of light to pass, so it can filter out some of the stray light to pass through, thus filtering out some of the stray light. Most myopic lenses are white, with good light transmission, and there are also yellowish anti-blue light lenses.
Fifth, according to the thickness
The thickness of the lenses have ordinary, ultra-thin and other classifications, here to introduce a concept called the refractive index, the higher the refractive index of the lenses, the more thin and light, the price is also higher. However, you can't blindly choose a high refractive index, you have to choose a reasonable refractive index according to the degree of myopia, you can refer to:
1, 100 degrees of myopia or plano, it is recommended to choose 1.50 refractive index lenses;
2, 100 to 300 degrees of myopia, it is recommended to choose 1.56 refractive index lenses;
3, 300 to 600 degrees of myopia, it is recommended to choose 1.60 refractive index lenses;
4, 300 to 600 degrees of myopia, it is recommended to choose 1.60 refractive index lenses. 1.60 refractive index lenses;
4. 600-800 degrees of myopia, it is recommended to choose 1.67 refractive index lenses;
5. 800 degrees of myopia, it is recommended to choose 1.74 refractive index lenses.
The above is only for reference, subject to the actual. Lens thickness is also related to myopia, lens material, frame size and other factors, must not be the thinner the better. 1.74 and above refractive index, basically foreign imports, domestic technology is not mature.
Summary:
Nearsightedness lenses should be comfortable and suitable for you in the end. If the requirements of the lens is very high, you can configure it in this way: the material selection of PC sheet, aspheric design, according to the actual situation plus the film, the function to increase the anti-blue light, anti-fatigue, etc., the refractive index in the appropriate range of choice of higher.