UV protection. You’ve probably heard it advertised as a selling point for sunglasses, and with just cause; UV protection is the most critical defensive attribute a pair of sunglasses can provide.
Sunglasses with UV Protection
You may select your sunglasses based on style and looks, your lenses based on the options or tints they feature… but UV protection is what guards your eyes against harmful light. It’s the least glamorous but most important feature sunglasses offer you.
UV stands for ultraviolet, meaning ultraviolet light. UV light is invisible to the naked eye, so it’s not to be confused with visible sunlight; the rays of the sun that activate the pain receptors in our eyes and cause us to look away from direct sunlight. Ultraviolet light cannot be seen or felt and does its damage silently, over time. It’s the ultraviolet light of the sun that causes suntans and sunburns.
We select our sunglass tints to escape the bright light of the sun, to make it more comfortable, to dull its effect on our eyes – but it’s the radiation of ultraviolet light that can inflict vision damage over the long term. Molecules in our eyes called chromophores absorb UV light to protect us from our environment. But if the chromophores become saturated due to overexposure of long-term build up, damage can occur to the eye lens, the cornea, and the retina.
Ultraviolet light is categorized by its wavelength and exists in the following ranges:
- Ultraviolet (UV) – wavelength of 400-100nm
- Ultraviolet A (UVA) – wavelength of 400-315nm
- Ultraviolet B (UVB) – wavelength of 315-280nm
- Ultraviolet C (UVC) – wavelength of 280-100nm
- Near Ultraviolet (NUV) – wavelength of 400-300nm
- Middle Ultraviolet (MUV) – wavelength of 300-200nm
- Far Ultraviolet (FUV) – wavelength of 200-122nm
- Hydrogen Lyman-alpha – wavelength of 122-121nm
- Extreme Ultraviolet (EUV) – wavelength of 121-10nm
- Vacuum Ultraviolet (VUV) – wavelength of 200-10nm
The sun emits all wavelengths of UV light, but the Earth’s ozone layer filters out the stronger wavelengths. The UV that penetrates and causes damage to human skin and eye tissue is in the UVA, UVB, and UVC range. This is why it’s important, especially for those who spend a lot of time outdoors or exposed to the sun, to select sunglasses with the highest percentage of UV protection. Many lens tints innately provide coverage, and for those that do not, coatings are typically available to block UVA, UVB, and UVC light.