2007 CBCJ Class Item
Purpose of Sunglasses
• Protection from UV light rays
• Comfort to eyes in constant sun
• Keep eyes from tiring out
• Protection from dust particles
• Ultraviolet light (UV) – short wavelengths
of light that can cause harm to our eyes
• Two categories of UV light – UVA (longer
wavelengths) & UVB (shorter wavelengths)
• UVB rays have been found to cause more
eye damage than UVA. However, a good
pair of sunglasses should protect against
both types of UV light.
Recommended UV Standards
• Sunglasses must block 99% of UVB rays.
• FDA recommendation: 99-100% of UVA
and UVB radiation. The label should read
either UV 400 or 100% UV protection.
• UV-blocking: term refers to sunglasses
that block 99% of UVA and UVB rays
• Check the label on the sunglasses; it
should state the protection percentage.
Background Info on Lenses
The darkness does not
affect the ability of the
lenses to protect
against UV light.
However, darkness will
determine how mush
visible light gets seen.
Types of Lenses
• Plain Lenses – uniformly tinted throughout; come in a
variety of colors
• Blue Blockers – usually amber colored; block blue light;
• Single Gradient Lenses – tinted darker at the top than
the bottom; driving
• Double Gradient Lenses – tinted darker at the top and
bottom and lighter in the center; sailing, skiing, &
• Polarized and Anti-Reflective Lenses – designed to
reduce reflected glare; water sports, biking, & driving
• Photo-chromatic Lenses – darken and lighten in
response to amount of light available
• Flash and Mirror-Coated Lenses – have mirror-like
finish (silver, colored, iridescent); coating adds
appearance; scratches easily
• Polycarbonate – durable, lightweight
plastic; super-strong and impact-
resistant; composes most sport
• CR-39 – plastic used mostly in
• Glass – durable; heavy; breaks easily
• The FDA requires all sunglasses to within
an impact test.
Background Info on Color
The color of the lenses does not affect the
blocking of UV light, either. Color only
determines which colors will be seen by
the viewer. Color coated lenses tend to
scratch easier and loose their color than
lenses that are dyed. Some color coated
lenses have a scratch-resistant layer
added on them by the manufacturers.
• Gray – reduce brightness; don’t distort color
• Brown/Amber – reduce glare; distort color
• Yellow – reduce haze from blue light; sharpen up
the view; cause more color distortion
• Green – reduce glare; filter out some blue light;
provide good contrast between objects
• Orange – have best contrast enhancement at
depth perception; distort color
• Rose – good for water sports or outdoor activities;
provide good contrast for objects against blue and
• Blue - offer no real benefits; mainly cosmetic
• Some models have polarized lenses.
• The purpose of polarized lenses is to
reduce the glare caused by light
reflected from polarizing surfaces (such
as water) and skylight.
• Polarization can be especially useful
when fishing, as the ability to see
beneath the surface of the water is
• Frames need to be both sturdy and
• When purchasing sunglasses, check to
ensure that the frames are not bent or
• They should be wide enough not to press
on the temples and long enough to rest
on the ears.
• Price has little to do with the
performance of a pair of sunglasses.
• Sunglasses that are effective and
reliable can be inexpensive to
• For the contest, read the situation
carefully. Check to see of cost is a factor
in ranking the class.
• UV radiation (block UVA and UVB)
• Types of lenses
• Materials that compose lenses
• Colors of lenses
• Frame composition