Transcript The Science Behind Glasses - mrs

Glasses correct and improve vision
 The Lenses on the glasses increase the focusing
power of the cornea of the eye.
 They correct nearsightedness, which is when
people cannot see things clearly when they are far
away.
 They also correct Farsightedness, which is a person
cannot see things when they are
Close up.
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 The lenses are the part of the glasses that help
correct the vision.
 They are often made of glass or clear plastic.
 The frame is the part of the glasses that holds the
lenses and also helps to keep the glasses on your
head. They are curved so it can be attached to your
ears to hold it on your face.
 Frames are made of a wide variety of materials. They
are most commonly made of Monel Metal, Zyl, or
Nylon Based Plastics.
Glass Lens
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Pros
It can be made in any color imaginable
It is extremely scratch resistant
It is extremely inexpensive
Cons
It is very heavy
Plastic Lens
 Lighter than the glass lens
 Cons
 Are more likely to scratch than a glass lens
Glass Lens
They are often made of a mixture of
several metals called Monel.
o It is corrosion resistant
o Malleability: the ability to be
permanently shaped or bent without
cracking or breaking.
o They are hypoallergenic.
o
Zyl
• Can be made in any color desired
• extremely lightweight
 Nylon based plastics are also strong and
flexible, but cannot be made in a wide
variety of colors.

 There is no known inventor, but glasses were created some
time between 1268 and 1289.
 They were first seen in Italy.
 They originally were very tightly attached to people’s noses
or held by hand instead of ear held/hanging glasses.
 The Lenses were made out of quartz and the frames were
made of bone, metal or leather.
 We now use more clear, lighter materials for the lenses such
as plastic because they are more convenient.
 For the frames, we now use extremely light, colorful frames
made from materials like plastic and mixed metals, because
they look better and are more comfortable to wear.
Frame
Lens
Author Unknown. Children's Hospital Boston. Web. 21 Oct. 2010.
<http://www.childrenshospital.org/az/Site861/mainpageS8 61P0.html>.
Morgan, Erinn, and Gina White . All About Vision. Web. 22 Oct. 2010.
<http://www.allaboutvision.com/eyeglasses/eyeglass_frame_materials.htm>.
Gorman, Tim. Ezine Articles. Web. 21 Oct. 2010.
<http://ezinearticles.com/?What-Are-Prescription-Eyeglasses-MadeOf?&id=41490>.
Glass, Don. Moment of Science. Web. 24 Oct. 2010.
<http://indianapublicmedia.org/amomentofscience/a-brief-history-ofeyeglasses/>.