How to choose sunglasses?

1.UV Protection

Excessive exposure to ultraviolet light can lead to cataracts, burns, and even cancer. It is important to choose a pair of sunglasses with high UV protection. Good sunglasses, at least block out 99% of the UVB rays and 95% of UVA rays. If there is no label on the glasses, tell you how much UV protection the pair is.

2.Color

By filtering the color of the sunglasses, the eyes see a different color contrast. If you choose colored lenses, it's ok, but you have to get the traffic light when you're driving. 

Gray lenses can be very effective in reducing the intensity of light without affecting the contrast of the color.

Brown glasses can enhance some color contrast and block the blue light, so the brighter the day, the better the brown, such as the snow day.

Yellow/amber color is more yellow than brown color, can largely enhance the color contrast, almost block all blue light, separately when the traffic lights, don't choose the color.

Red and orange are more suitable for cloudy days in winter.

Purple is suitable for people hunting on green grass.
Copper can blend the colors of the sky and grass, and is suitable for golf.

Blue and green can strengthen the contrast of yellow, suit to play tennis.