The shorter the wave length the more dangerous. The dangerousness of electromagnetic radiation is linked to its capability to interact with the organic molecules which, in our case, make up the visual apparatus. Although it is the solar spectrum component that is present in the smallest quantity, it is the most dangerous component since it has sufficient energy to break chemical bonds, thus causing irreversible damage. As ultraviolet radiation is a dangerous but not necessary component for vision, the objective of sun filters is its total elimination. The damage caused by ultraviolet radiation mainly affect the cornea and crystalline, since the retina is screened almost totally by crystalline.
Cataract is among the commonest pathologies affecting the crystalline.
Obviously, this is the most important component for vision, and it ranges from violet to red. So far, no evidence has been found of direct damage to the eye at the normal amounts present in solar light, however there is substantial scientific evidence of cumulative damage to retina, commensurate to the exposure time and intensity of radiation. Although they eliminate all Blue light, the so-called Blue Blocker filters are characterised by a very strong colour distortion which makes it difficult for people to wear sunglasses for a long time, thus annihilating the advantages of protection. The damage caused by blue light is cumulative, therefore the limited use annihilates the effectiveness of protection. Infrared radiation It is the lowest energy radiation, therefore the less dangerous.