Ultraviolet radiation is virtually imperceptible to the human eye, but with intense exposure it causes a typical radiation injury (retinal burn). Soft ultraviolet (300–380 nm) is perceived by the retina as a faint violet or grayish-blue light, but is almost completely absorbed by the lens, especially in middle-aged and elderly people.
To protect the eyes from the harmful effects of ultraviolet radiation, special protective glasses are used that block up to 100% of ultraviolet radiation while remaining transparent in the visible spectrum. Typically, the lenses of such glasses are made from special plastics or polycarbonate, into which colorless additives are introduced.
UV protection is enhanced by the glasses' design — giving the models a close-fitting shape — to limit the flow of rays not only passing through the lenses but also reaching the eyes around the frames.