Sheep Eye Dissection

Here's a picture of the eye before we dissected it! The oval shaped structure in the center is the cornea, which helps focus the light entering the eye. Surrounding the cornea is the sclera, also known as the white of the eye. The sclera is a tough outer coat that protects the eye. It was very hard to cut into it. On top of the sclera is fatty tissue and external eye muscle remnants that we cut off later.

Cornea and sclera seen from the outside of the eye.

Cornea and sclera seen from the inside of the eye.

The small bump on the top of the eye is the optic nerve which sends the visual information from the retina to the brain. 

Here is the eye cut into two hemispheres. On the left, there is the retina and tapetum lucidum. The retina, bunched up at the top on the left, contains the photoreceptors for vision. The blue part under the retina is the tapetum lucidum. It's part of the choroid layer and reflects light onto the retina. The choroid is the black layer that  nourishes the back of the eye. The tapetum lucidum isn't found in humans, but it is in the eyes of many nocturnal animals to help them see at night. The ciliary body is in the right side of the eye. It is made up of muscles and controls and shapes the lens.

The round structure at the bottom of the picture is the lens. The lens changes shape to focus light on the retina. I thought that it would be squishy because it changes shape; however, the lens was hard like a marble. The liquid, which had the consistency of a gel, around the lens is the vitreous humor. It fills the central cavity of the eye. The suspensory ligament can be seen around the lens and connects the lens to the ciliary body.

This is the iris, or the colored portion of the eye. The hole in the center is the pupil. This is where light passes through into the eye.