Technology uses the
"physics" of light to aid humans in increasing vision. Many
students are curious about exactly how they see. It is understanding the
eye and how it works, that allows technology to improve our sight by
improving glasses and contact lens.
The human eye sees images upside down
and backward. Your brain is sent the image and then turns it the way it
really is. The optic nerves take the image from the retina to the brain.
The inner layer of the eye is called
the retina and is sensitive to light. The retina has layers of tightly
packed cells called rods and cones. Rods are very sensitive to light and
help you see at night. Cones need more intense light to work and allow
you to see color.
Light passes into the eye through
a clear, protective shield called the cornea. Behind the shield is the
iris which gives the eye its color. The opening in the center is called
the pupil. The lens is behind the pupil and is about the size of a pea.
The rest of the eye is called the vitreous humor with is a clear,
jelly-like substance. This prevents the eye from collapsing. At the back
of the eye is the retina, which is where the image is projected. It
contains nerve cells which sends messages to the brain through the optic
nerve. The fovea is where the image is focused the sharpest.
Have the students label the retina, fovea,
optic nerve, cornea, lens, and iris after you discuss what each of them.
Look at the worksheet and have students trace
the path of light through the lens of our eyes. The optic nerve
transmits the information to the retina; and the brain inverts the
inverted image, so we see the image the way it actually is.