Many times when we are looking at sunglasses we see in the description that the lenses protect your eyes from UVA and UVB rays. While this seems like a good thing what exactly does it mean and what are the differences between the two?
UVA or Ultraviolet A rays are long wave rays. In contrast UVB or Ultraviolet B rays are short wave rays. Essentially UVA rays can age our eyes while UVB rays can burn our eyes. While both types of rays cannot be seen with the naked eye, they both can do damage to it.
UVA is ultraviolet radiation between 400-320nanometers in wavelength and UVB is between 320-290nanometers in wavelength. The shorter the wavelength, the higher the energy of radiation. UVA rays account for 90 to 95% of UV radiation that reaches the earth.
UVB makes up only 5-10% of solar radiation, its high energy damages surface epidermal layers and can cause your eyes to burn. UVB is strongest between 10AM and 4PM, from April to October and do not significantly penetrate glass.
In contrast, UVA is present equally throughout the daylight hours and throughout the seasons, and can penetrate through clouds and glass.
Luckily all of Optx 20/20 sunglasses come with UVA and UVB protection, some with as much as 99.9% which should assist in preventing burning of the eyes, aging of the eyes and most importantly damage to the eyes.
Happy sunglass wearing!