Ultra violet translates to beyond violet in Latin. This reference is to its comparison of wavelength to the visible light spectrum, violet being the shortest wavelength of the visible light spectrum. Ultra Violet rays are shorter than violet rays, but longer than X-rays which have electromagnetic radiation characteristics that may be extremely dangerous.
Ultra Violet rays are also known as deoxidizing rays and chemical rays for its electro magnetic radiation properties.
There are many form of UV light, UVA and UVB are both common in ouratmosphere.
UV's Damaging effects to the eye
Excessive ultra violet light exposure to the eyes' intraocular lens, which protects the retina, can cause severe damage to the eye.
UVB light is the more harmful light to the eye. Excessive UVB light can cause photokeratitis (also known as Welder's flash, Arc eye, Arc flash, Flash Burns, and/or Corneal Flash Burns) and may also induce cataracts, pterygium, and pinguecula.
UV protective coatings
Glass lenses are transparent to UVA.
Besides glass, most lens materials used on eyewear have a natural composition that filters out most UV light. Added protection may be applied to achieve 100% protection from UVA and UVB light.
UV coating can be applied to clear lenses, providing 100% UV coating without any color applied to the lens.
Added UV protection may be added with a chemically baked on technique. However, with technological advances UV protection is most commonly applied by submerging the lens into a clear chemical agent heated to approximately 200˚ Fahrenheit for a set time, usually only a few minutes at most.
However, even though a lens has 100% UV protection, the lens cannot filter UV light that is exposed around the lens. For maximum protection from UV light, eyewear lens frames that completely cover the eye are optimum.