The eye is the organ used to see. It's sphere-shaped, hollow and filled with fluid.
The outer layer (sclera, or white, and cornea) is used for protection made of fibers.
The middle tunic layer (choroid, ciliary body and the iris) is made of many small blood vessels.
The innermost layer (the retina) is made of many nerves that sense light.
The fluids in the eye are divided by the lens into vitreous, which is behind the lens and the aqueous, which is in front of the lens.
The lens itself is flexible and held in place by ligaments that allow it to change shape to focus light on the retina, which is composed of sensory neurons.
Information provided by: MedlinePlus Medical Encyclopedia
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