When you buy glasses, how to choose the lens ? (2)

5. Anti-fouling ability

In recent years, many brand lenses has shifted their direction of research from increasing hardness and increasing light transmittance to increasing the smoothness of the lens to improve its ability of water and grease resistance.

The most representative lens is the Zeiss lotus film series.

Test Method - We can wipe the lens clean and drop a drop of water and move it back and forth on the lens. If the lens is always a water droplet, it proves that it is good waterproof. If the water droplets are all spread out on the surface of the lens, the function is relatively poor.

6. Anti-UV ability, anti-radiation ability, anti-blue light ability

Let me talk about anti-UV first.

Anti-UV lenses are UV resistant lenses. It can completely absorb or reflect the most harmful ultraviolet rays to the human eye to protect the eyes. The UV resistance coefficient is expressed by the UV value: the most preferred is UV400, which is generally UV375. Optical shops generally have instrument to test it.

However, it should be noted that the optical lenses of regular lens manufacturers all contain UV protection (more than or equal to UV375), and should not be blinded by many market gimmicks.

Look at the radiation resistance.

Nowadays, almost all lenses on the market have anti-radiation film layers. However, the radiation protection effect of the lens is limited to the range of the lens covering, and the electromagnetic wave is not completely linear. Therefore, the lens used as a gimmick should be treated with caution.
 
Finally talk about anti-blue light.

Most of the glasses maker are go for the function of anti Blue-ray in recent years.

For those who use computers or electronic devices for a long time, the role of anti-blue lenses can certainly prevent some harmful blue light from harming the eyes, and making the eyes more comfortable when working in front of the computer screen. However, there is no further evidence that anti-blue lenses can effectively improve eye soreness, dry eyes, decreased vision, and fundus lesions.

At present, many merchants have taken this as a great business opportunity to sanctify anti-blue lenses and boost it can treat various eye diseases. However, customers should be cautious about marketing ads that are exaggerated its functions.

In addition to these functions, there are many functional lenses on the market. Due to the processing technology is different and the materials are different, the price varies greatly. Remember, it is blind to buy the glasses which is more expensive and have more functions. It may be just a gimmick and also be that the eye is not suitable for such a lens. Therefore, it is better to listen to the optometrist's suggestion. The best is the suitable one.

7. How to identify lenses?

The lens manufacturing technology is extremely precise, and it is impossible to determine the authenticity of the lens without the professional instrument inspection provided by the lens manufacturer. As a consumer, it can only be identified by the lens anti-counterfeiting logo, original packaging bag, and verification code. Some large brand lenses (such as Essilor) also have a brand-specific fog display, which can be seen by blowing a breath on the lens.

However, it should be noted that the above anti-counterfeiting measures can be faked by manufacturers in theory.

The identification threshold of the lens itself is very high, which causes a lot of optical shops to mix the bad products with good. In this case, the best way to avoid encountering fakes is to choose the glasses though the introduction of friends and  reliable recommendations on the internet.