19.4 The Eye and Vision

Have you ever stopped to appreciate how remarkable your eyes are? They play a very important role in your perception of the world around you. Your eyes, like the one shown in Figure 16, are optical instruments that perform the same tasks of bending and focusing light as telescopes, cameras, and microscopes.

Your eyes form images every moment they are exposed to light. They receive and focus visible light from objects near and far. Your brain then interprets the images of the objects formed by your eyes.

Structure of the Eye

You can read this page because light reflected from the page enters your eye. But how does this light get transformed into images of objects you recognize? Various parts of the eye, each one having its own specific function, work to make your sense of vision possible. Figure 17 shows the structure of the human eye. The main parts of the eye are the cornea, the pupil and iris, the lens, and the retina.

Cornea

Light rays enter your eyes through the transparent outer coating of the eye, called the cornea. The cornea's curved surface helps to focus light entering your eye.

Figure 16 The lens of the eye focuses incoming light rays onto light-sensitive nerve endings located inside and at the back of your eye.

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