Why do sunglasses have dark lenses?

Answer

Sunglasses serve to absorb part of the incident sunlight. In addition, good sunglasses protect your eyes against the invisible but harmful UV rays of the sun. This UV protection is obtained by a special layer that is applied to the lenses, a UV filter.

Brown, yellow, grey, green, pink, … By tinting the lenses of sunglasses, the light is absorbed. Which color you choose depends on your personal taste, but each color has different properties. Gray tinted lenses reduce the intensity of the sunlight and show the different colors. So you see everything a little darker because a little of all colors are blocked. Green tinted lenses transmit the green light and absorb the other colors (including the red). This characteristic has important consequences: with sunglasses with green lenses you will not see the red traffic light well.

The color of the lenses therefore has nothing to do with protection, but with comfort. Conclusion: Sunglasses have dark lenses to block the light as much as possible and to prevent glare.

Sunglasses date back to the twelfth century. For example, Chinese judges used smoke-colored quartz in flat frames to hide their facial expressions when questioning witnesses. The actual invention of sunglasses happened around 1900 by, among others, the American Sam Foster.