Why do mountaineers wear sunglasses?

Sunglasses are an indispensable tool to protect the eyes of mountaineers. Most of the places they climbed were high mountains above four or five thousand meters, where the air was thin, dust was less, and the light was strong. In addition, thick white snow accumulates on the slopes and peaks, which strongly reflects the sun. We know that the stronger the sunlight, the greater the content of infrared and ultraviolet rays in it. If it shines directly on the retina of the eye, it will burn the viewing angle cells and even cause blindness. The sunglasses worn by mountaineers contain chemical drugs iron oxide and cobalt oxide that can absorb infrared and ultraviolet rays in the lens glass. These two compounds are added to the glass raw materials to become special glass specially made for the sunglasses used by mountaineers.