Carolina Mammal Eye Dissection Guide

Sclera

Retina

Optic nerve

Blind spot

Choroid

Zonula ciliaris

Lens

Aqueous humor

Pupil

Cornea

Iris

Hyaloid fossa

Vitreous
humor

CarolinaTMMammal Ey

e

Dissection Guide

C80130

CarolinaTMMammal Eye Dissection Guide

Overview

The Carolina Mammal Eye Dissection Guide is a general set of instructions for dissecting mammal eyes. With
each type of eye, there will be differences in the size of the structures and in the thickness and coloration of
the tissue, but the general structures and their relative location are the same.

Safety

Follow safe laboratory practices when performing any dissection. Wear splashproof safety goggles, gloves, and
lab aprons at all times. Be careful when using sharp tools, such as scalpels, forceps, teasing needles, and
scissors. Perform dissections on a dissecting tray to contain specimens and fluids.

Procedure

Review the glossary provided at the end of this dissection guide. Refer to the diagram of the eye as a general
reference as you observe and identify external and internal structures.

1. Observe the outer structure of the eye. Identify the following: optic nerve, sclera, cornea.

2. Trim away excess tissue surrounding the eyeball on the sclera.

3. Hold the eyeball gently with your thumb and forefinger at the

cornea and near the optic nerve.

4. Begin a cross-section of the eye by making an incision slightly
behind the middle of the eyeball through the sclera. Do not
cut deep into the eyeball or squeeze it too tightly
damage the interior structures. You may begin the cut with a
scalpel and finish with small scissors, or you may use a scalpel
for the entire cut. If some of the vitreous humor begins to
come out of the eyeball as you cut through the sclera, let it come out slowly.

5. Once you have made a cut around the eyeball, separate the eye into halves. Let the vitreous humor—
gelatinous, transparent material found inside the eye behind the lens—and any associated structures slowly
slide out of the eye. You may need to tease the vitreous humor gently away from the lining of the eye.

6. Look at the inside front portion of the eyeball. The lens may still be suspended in the middle of the pupil.

ip the front portion over and let the lens and associated structures fall out. Again, depending on the

T
viscosity of the vitreous humor, you may need to tease the material loose from the inside of the eye.

7. Observe the vitreous body, lens, and associated structures. The hyaloid fossa is an indention in the center
of the vitreous body that supports the lens. Surrounding the hyaloid fossa is the zonula ciliaris, made up of
suspensory ligaments that suspend the lens and stretch it to focus. You will also notice dark lines around
the hyaloid fossa. These lines are pigment from the iris.

8. Pick up the lens with a pair of forceps. Pat it dry with a paper towel. Note: You may want to place the
lens on some printed text on paper and observe its ability to magnify. This works best if you allow the lens
to dry overnight.

9. Turn the front half of the eyeball over so that you are looking at the cornea. Cut the front of the eye
around the outside of the cornea (where the cornea meets the sclera) to remove the cornea. This cut
works best if you mak

e the initial incision with a scalpel but then use scissors to finish.

, so as not to

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