Plastic lenses do not protect your eyes. You need to have UV
protection from UV rays, which are not inherent in a plastic
lens. You can have a UV protective coating applied to a plastic
lens, but polycarbonate lenses have built-in UV protection.
Glass lenses protect your eyes from harmful UVB rays but not
from UVA. Some experts think UVA rays might have long-term,
damaging effects to your eyes and skin.
The light we see with our eyes is really a very
small portion of what is called the "Electromagnetic Spectrum." The
Electromagnetic Spectrum includes all types of radiation - from the X-rays
used at hospitals, to radio waves used for communication, and even the
microwaves you cook food with.
Radiation in the Electromagnetic Spectrum is often categorized by wavelength.
Short wavelength radiation is of the highest energy and can be very
dangerous - Gamma, X-rays and ultraviolet are examples of short wavelength
radiation. Longer wavelength radiation is of lower energy and is usually
less harmful - examples include radio, microwaves and infrared. A rainbow
shows the optical (visible) part of the Electromagnetic Spectrum and
infrared (if you could see it) would be located just beyond the red side of
Ultraviolet light (UV) is an invisible light that is part of the sun's radiant
spectrum. Exposure to ultraviolet light can cause the lenses of the eye to
become cloudy, causing cataracts among many other conditions. Ultraviolet
light causes the eye to age faster, thus can also cause macular
degeneration. You can't see ultraviolet light. It affects the eye without
your awareness to its being there, and the effects are cumulative. Almost
everything in nature is affected by UV light, and almost everything
deteriorates because of it. Not all sunglass lenses block all of the UV
light, but the lens we recommend most is a polarized sunglass lens for
sunglasses and polycarbonate lenses for dress wear.
Infrared (IR) is an invisible electromagnetic radiation that has a longer
wavelength than visible light and is detected most often by its heating
effect. Part of the discomfort you feel in your eyes after being out in the
sun for a while is caused by IR light. Not all sunglass lenses block all of
the UV light, but the lens we recommend most is a polarized sunglass lens
for sunglasses and polycarbonate lenses for dress wear. Although infrared
radiation is not visible, humans can sense it - as heat. Put your hand next
to a hot oven if you want to experience infrared radiation "first-hand!