1. Essilor

Essilor lenses have an invisible anti-counterfeiting logo (fogged mark - Crizal). When the protective film of Essilor lenses is not wiped off, He breathed a sigh of relief, and the lens displayed "Crizal" (except blue crystal).

2. Carl Zeiss

All Carl Zeiss lenses will have laser anti-counterfeiting marks, which are shaped like two small flags put together. Laser anti-counterfeiting marks are difficult to imitate. , and each lens has an original warranty card.

3. Tag Heuer lenses

Different series of Tag Heuer lenses have different anti-counterfeiting marks. At a certain angle, we can see a set of code numbers.

Things to note when purchasing lenses

1. Select lens material

Lens materials are mainly divided into glass, resin and PC. Although glass lenses have good optical properties, It is fragile and poses a hidden danger to eye health. Nowadays, very few people wear glass lenses. More and more people are choosing lenses made of resin. Whether in terms of performance or health, resin lenses are good. Resin lenses are more expensive than glass and PC lenses, but resin lenses are also divided into grades, and they can be bought for as cheap as a hundred or ten yuan.

2. Choose the sphericity of the lens

As people deepen their understanding of the eyes, they find that our eyes themselves are not a perfect sphere. Therefore, it is necessary to adapt to such non-spherical eyes. The lenses are called aspherical lenses. Aspherical lenses can help us obtain better visual quality. Aspherical lenses are also lighter, thinner and clearer than spherical lenses of equal power, making them suitable for people of high altitude.

3. Select the refractive index of the lens

The 1.56, 1.61, 1.67, 1.70, 1.74 and other values ????marked on the lens refer to the refractive index. The higher the refractive index, the lens with the same power will be matched. The thinner. Prices will also rise significantly. Moreover, the higher the refractive index, the greater the dispersion, which means that the visual effect will be reduced.

The higher the refractive index of the material, the stronger its ability to refract incident light, and the thinner the lens thickness. That is, the center thickness of the lens is the same, the same power and the same material, the lens with a high refractive index is thinner at the edge than the lens with a low refractive index. Thinner lenses are relatively lighter and generally more expensive.

4. Pay attention to the interpupillary distance problem

There is another data that is necessary when we wear glasses, and that is the interpupillary distance. Interpupillary distance is the distance between the centers of the pupils of our eyes when we look straight ahead. Because the principle of wearing glasses is that the center of each lens must exactly correspond to the center of our pupils. If the degree is off, it will be wrong. Once the interpupillary distance is known, the optician can use a machine to grind the lenses.