HBS 2.4.1 EYE REVIEW

When the cow was alive, the cornea was clear. Describe the membrane now.

Clear so that you can see through the eye

Hold the lens up in the direction of your partner and look through it. What do you notice about the image you see? NOTE: If the eye is not fresh, you may have trouble seeing through the lens

I can see my partner through the lens except her image was reflected

Note that the retina is the sensory layer of the eyeball which contains receptors for sight, called rods and cones. The eye uses light coming in to make an image, a picture which lands on the retina. Seeing the state of the retina after removing the fluid, what do you think would happen to the retina if this fluid was not present? How would this affect vision?

If the fluid was not present, the eye would have trouble perceiving light which would make it harder for the vision to be clear

Locate the optic nerve. You may find this spot by locating a patch of white goop. This goop is the myelin around the neurons of the optic nerve. What is the function of this myelin?

Increase the speed the signal travels down the axon to transmit information

If the eyelid is still present, note its structure and the presence of eyelashes. What is the function of the eyelid and eyelashes?

Protect the eye from bacteria and debris

Observe the fat attached to the outside of the eye. Remember the fat pads you built behind the eye of your Maniken® . What purpose do you think this fat serves?

Protection and cushion for the eye

Find muscle attached to the side of the eye. Why do you think the human eye is surrounded by six different muscles? What roles do these muscles play?

Six muscles in the human eye allow it to move in all sorts of directions instead of manually moving our head. Roles the muscles play include blinking, crying, opening and closing eyelids, etc.

Feel the sclera. Do you think this structure is designed for strength or clarity? Why?

Strength, because it has to be strong in order to attach muscle to the eye

Note that the cornea does not have any blood vessels. Given the function of the cornea, why do you think it is important that the cornea is clear and free of blood vessels?

The cornea covers and protects the eye. If there were blood vessels in the eye, it would block the cornea's ability to bend light into images.

Put the lens down on your paper and look through it to words on the page. If you are using a preserved eye, you may need to shine a light on the lens to see the words. What do you notice?

The lens acts as a magnifier

hyperopia

a.k.a far sighted, when image lands beyond retina because eye shape is to short.

myopia

a.k.a near sighted, when image lands in front of retina because eye shape is to long.

hyperopia correction

convergent lens to bring light together with convex lens. (BEHIND RETINA)

myopia correction

divergent lens to spread light with concave lens. (INFRONT OF RETINA)