Sheep Eye Dissection Analysis

The structure of the eye is composed of spherical layers that transmit light and allow our brains to understand our environment and provides vision.

Externally, the eye is covered in fatty and muscle tissue that cushions the eyeball and keeps it in place during bodily movements. Extrinsic muscle also covers the eyeball, contracting and releasing to allow eyes to navigate and move around in up/down, side/side directions and movements in between. In the picture below on the left, you can see the fatty tissue covering the eye, including the eyelids which frame the opening to the sclera. Underneath the tissue, you will find the sclera, which is hard and difficult to puncture- allowing proper protection for the eye overall and keeping the internal parts intact. In the photo below on the right, you can spot the optic nerve, which is located in the back of the eye. This structure is hard and transmits the sensory neurons from the retina to the brain.

Light enters the eye primarily through the cornea, which then passes through the aqueous humor. It then reaches the pupil, located in the center of the iris. Light pass through the small opening, goes through the lens and vitreous humor and lands in the retina. Inside the retina are rods and cones. Rods allow us to see various shades of light or tones of grey and Cones give us color vision. After landing in the retina, light goes to the optic nerve which transmits the neurons to our brain.


This picture on the right shows the ciliary bodies on the left/black side of the eye, which contract and release to help the eye move around. On the right side, you can see the lens and the gelatinous vitreous humor attached to it.

In this next photo, you can see the choroid, which is the white layer that was spread across the internal sclera. The choroid only attaches to the retina in one spot, and this spot is the eye's blindspot. After scraping away the choroid, it is clear where the blindspot is located. The picture also shows the lens/vitreous humor slipping out, which exposes the ciliary bodies that surround the lens. Since we dissected a sheep's eye, there is a reflective surface behind the choroid which increases the reflection of light and allows animals to see better in the night. Humans do not have this feature.







After removing the lens and the pupil, and cutting off the cornea, we are able to see the opening of the pupil-- which is the hollow area seen below, and the back of the iris which is the gray area surrounding the opening.