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 What is Vision?
Simple
Eyes
The
Brain and Eye
The
Single-Lens Eye
Anatomy
of a Single-Lens Eye
The
Compound Eye
Anatomy
of a Compound Eye
The Eyes Have
It
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The Single-Lens Eye
 All vertebrate animals have single-lens eyes. The single-lens eye, unlike the compound eye, can be focused. This allows an animal to see a detailed image of an object, whether it is up close or at a distance.
Only a small part of the eye is visible from the outside. The rest of the eye sits in the skull in a protective cup called the orbit. The front of the eye is covered by a transparent layer called the cornea. Just behind the cornea is the iris, the pupil, and the lens. The eye is filled with a clear, jelly-like substance called the vitreous humor. At the back of the eye is the retina, a layer of photoreceptive cells called rods and cones. The rods work best in dim light, and allow an animal to see in black and white. The cones work best in bright light, and allow animal to see color and fine details.
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