Ultraviolet
(UV) light can damage eye tissue increasing the risk of
cataracts and eye cancer. It is important to protect the eyes
against this hazard with good sunglasses.
Ultraviolet light is not visible to the human eye. It has a
wavelength shorter than the color violet, which we can see.
Ultraviolet light is divided into categories according to its
wavelength: A (long wave or black light), B (medium wave), and C
(short wave or germicidal). Ordinary window glass blocks most of
the UVB and UVC rays, but is transparent to UVA.
When selecting sunglasses, look for lenses that are rated to
block ultraviolet light. The American Optometric Association
recommends sunglasses that block at least 99% of both UVA and
UVB.
1 This is especially important for people who
spend much time outdoors. UVC from the sun is blocked by the
atmosphere, so people typically need protection from UVC only in
areas with welding equipment or artificial lighting designed to
kill germs. Swimmers, boaters, and beach-goers need to remember
that the water can reflect UV rays into your eyes even when your
eyes are shielded from the sun directly by a hat or canopy.
Winter sports enthusiasts also need to consider the fact that
snow and ice reflect UVA and UVB, which can increase their
exposure.
So, when shopping for your next pair of sunglasses, ensure it is
rated to block UVA and UVB to help ensure your eyes remain
healthy for a long time.
1.
www.aoa.org/uv-protection.xml, 4/27/10.
