The refractive index not only determines the thickness of the lens, but also affects the Abbe number. The larger the Abbe number, the smaller the dispersion. Conversely, the smaller the Abbe number, the greater the dispersion and the worse the image definition. The higher the refractive index, the greater the dispersion, so it is often impossible to give consideration to the thinness and sharpness of the lens. When choosing a lens, the first thing to observe is the clarity of the lens.

2. Light transmittance

You can't see anything until the light comes in, so the light transmittance is also one of the factors that affect the quality of the lens. If the light is too dim, looking at things for too long will cause visual fatigue, which is not conducive to eye health. Good materials can effectively reduce the loss of light, have good light transmission effect, are clear and transparent, and provide you with bright vision.

3. Ultraviolet protection

Ultraviolet light is light with a wavelength of 10nm-380nm. Excessive ultraviolet rays will do harm to human body, especially to eyes, and even lead to blindness in severe cases. At this time, the anti-ultraviolet function of the lens is particularly important, which can effectively isolate ultraviolet rays without affecting the passage of visible light, and protect vision without affecting visual effects.

4, thin and light

Many people who wear glasses always need to hold their glasses from time to time to prevent them from falling off. There are still many people who wear glasses at work. What they can do is to change a pair of lighter lenses. The material determines the refractive index of the lens, and the common refractive indexes are: 1.56, 1.60, 1.67, 1.7 1, 1.74.

Under the same degree, the higher the refractive index of the lens, the stronger the ability to refract incident light, the thinner and lighter the lens, and the more comfortable it will be to wear.

5. Lens brand

Brand differences lead to differences in quality and price. The quality of lenses is directly reflected in the brand of lenses. Famous brand lenses are of good quality and stable performance. Because the lens is processed in the background, whether it is genuine or not, consumers can't track it, mainly relying on the integrity of the operator.