Eye See You: Cow Eye Dissection

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Hands down - dissection is one of the most requested in my science classroom.  The kids want to experience it and it is listed as a favorite activity year after year.  My favorite dissection that I do with kids is a cow eye!  I have used this lesson as a part of a unit on the ye in a medical science class, and now with the implementation of OpenSciEd I use it as a part of 6.1 - Light and Matter.


Material Notes - 

  • Cow Eye: I get these from the butcher; they charge me $1 each. You can also get them from a science supplier (such as Carolina), but I do not prefer it because they remove so much of the fat and muscle.

  • Dissection Tools: Students will need tweezers, dissection scissors and a scalpel (used VERY briefly).

  • Tray:  Just about anything will do to perform the dissection on - dissection tray, meat tray, even a thicker paper plate will do.

  • Personal Safety: Students should wear gloves and goggles at the minimum.  I also highly recommend lab coats or aprons; I have seen my fair share of eyes squirt out some of the vitreous humor.


Introducing the Lesson - 

Prior to doing the dissection I have the students complete the 3D paper model from Getting Nerdy with Mel and Gerdy on Teachers Pay Teachers.  I don’t know them personally but I love their dissection model products and they really prepare the students for dissections.


The number one thing that I stress when introducing this lesson is safety.  My safety notes are in both my booklet and powerpoint version.  I created my original booklet version in Publisher, which has kind of gone by the wayside, so here it is in PDF form.  Good news, you get a copy; bad news, it has my name in a few places. For the booklet version, I printed back to back, laminated and put a velobind spine on them.  If you do have publisher, here is the file that you can edit if you choose.  During the dissection, students use wet erase markers which allows me to use the books over and over.  The slides version is able to be edited by you as needed, just make a copy for yourself.


The other thing that I stress with students is that for many of them that this is the first time they are doing this - ask questions, work together and don’t be afraid to make a mistake!


Procedure - 

The following procedure is also outlined in both of the linked documents above along with pictures and questions for students to answer as they work.


  • Step #1: Using the scissors, carefully remove the fat and muscle from around the eye. 

  • Step #2: Using the scalpel to make an incision in the cornea, as shown in the picture below.  Continue cutting downward until the clear liquid, aqueous humor, is released.  This is made mostly of water. Slide your scalpel under the cornea to gauge its thickness.


  • Step #3: Use your scalpel to make an incision in the side of the sclera in the middle of the eye.  Use the scissors to cut around the center of the eye so that you have two halves—one that has the cornea and one that does not. Inside the eye is a think jelly like  fluid called vitreous humor, and is made of proteins and water.


  • Step #4: The next step is to pull out the iris. The iris is between the cornea and the lens. It may be stuck to the cornea or it may have stayed with the back of the eye. Find the iris and pull it out. It should come out in one piece and looks like a black ring.


  • Step #5: Now you want to remove the lens. It’s a clear lump about the size and shape of a squashed marble.


  • Step #6: Use your finger to push the retina around. The retina is attached to the back of the eye at just one spot. That’s the place where nerves from all the cells in the retina come together.

Under the retina, the back of the eye is covered with the tapetum. It reflects light from the back of the eye. Turn your eye inside out.

Clean-up - 

The eyes and gloves can be thrown away.  If using a disposable tray that can be thrown away as well.  You are going to want to remove these items from the room immediately, so I have everyone use one garbage can for all dissection garbage. I have students set their tools in a tray with a bleach water solution.  They wipe down their goggles and put their apron/lab coat in the laundry.  Wipe down tables as you would for any other lab experience.


e your finger to push the retina around. The retina is attached to the back of

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