The eye is an
It helps us take
This is how!
• Can you see :
• the optic
• Spinal cord?
What are the parts of the eye?
• Let’s use a diagram to help us get familiar with
the parts and pronounce them correctly!
Cornea- transparent membrane that covers iris and
pupil. Focuses light on the retina.
Pupil, Iris, Sclera
Pupil- hole passes different amounts of light
Iris- colored part of the eye that controls the size of
Sclera- “whites” of the eye that forms outer covering
Aqueous Humor, Ciliary Muscle, Lens
Aqueous Humor- nutritious fluid between the iris and
the cornea. As we age, it breaks down and we begin
to see “floaters”
Ciliary Muscles- produces aqueous humor and
controls lens shape
Lens- Bends light rays to the back of the eye –retina.
Elastic so change in shape allows for focus on
objects close up or far away
• Full of light
• Rods- Light
neededThis is Ms. Vikingson’s retina!!
Blind Spot- site of
Vitreous Humor, Blind Spot, Optic Nerve,
Vitreous Humor- transparent jelly-like fluid that fills
the eye and refracts light
Blind Spot- area where optic
nerve attaches. No retina is
located there so information
cannot be picked up; “Blind”
Optic Nerve- sends messages
picked up by retina to the brain
Choroid Layer, Tapetum lucidum
Choroid Layer- lies between the
sclera and the retina it provides
the blood supply to the eye.
Tapetum lucidum- iridescent film
under the retina that provides
animals with “night vision”
• Select a place to make an incision of the sclera midway
between the cornea and optic nerve. Use the point of a
surgical scissors to make a small cut through the sclera.
Fluid should ooze out of the eyeball when you have cut
• Arrange the two hemispheres of the eye as you see in
• Observe the semi-fluid vitreous humor that fills the
central cavity of the eye. It is transparent in the living
eye but might be cloudy in the preserved specimen
• The retina lines the the posterior cavity of the eye and
extends forward to the ciliary body. Use your probe to lift and
pull the retina back from the underlying choroid layer.
• Notice that the retina is only firmly attached to the choroid at
one place. This region is the optic disc or blind spot.
Remove the lens and place against
newspaper to see that it is a magnifier!
• When the lens is removed, an opening, allowing light to enter
the eye is seen. This opening, the pupil is located in the
center of the iris. Note the oblong shape of the sheep pupil,
in humans the pupil is circular.
• The back side of the iris can be seen just above the pointer in
Can you identify the parts? You will need
to so you can get credit during the lab
3. Optic Nerve
6. Ora Serrata (you do not
have to know this
7. Ciliary Body
9. Tapetum Lucidum
12. Vitreous Humor
• Once all eye parts have been located and signed off
by your teacher, it is time to clean up!
• Clean off all instruments on your paper towel and
put them away
• Wrap up eye and all eye parts inside your paper
• Remove gloves around paper towel for easy
• Place items into garbage can
Let’s take a peek at this interactive eye and see
how many you can get correct!