Anatomy of the Eye

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Slide 20

Eye Glasses

To correct this fuzzy vision, many people, including many kids, wear glasses. Glasses help the eyes focus images correctly on the retina and allow someone to see clearly. As adults get older, their eyes change shape and they often need glasses to see things up close or far away. Most older people you know - like your grandparents - probably wear glasses.

Slide 21

To the Brain

Think of the optic nerve as the great messenger in the back of your eye. The rods and cones of the retina change the colors and shapes you see into millions of nerve messages. Then, the optic nerve carries those messages from the eye to the brain! The optic nerve serves as a high-speed telephone line connecting the eye to the brain.

Slide 22

Reflected light

Reaches the retina where it falls onto the cones and rods.

The critical part of the imaging process is the lens.

The lens gives the detailed information about the size, shape, and color of an object.

Slide 23

The lens is transparent with spherical surfaces.

It is convex which means thicker in the center.

Slide 24

Fovea

The area near the center of the retina is called the fovea.

The detectors are packed tightly and details of the image are distinguished easily.

Slide 25

Peripheral vision

Light that enters your eye from the side does not fall on the fovea, but on the part of the retinal where there are fewer detectors.

This explains why peripheral vision is limited.

Slide 26

The placement and number of cones in your retina limit how well you see colors in your peripheral vision.

Slide 27

The placement of rods and cones differ in people which accounts for the diversity of vision.

Slide 28

Myopia

An eye that is too long or a cornea that is too steep causes myopia (or nearsightedness). In nearsighted eyes, the image isn't focused precisely inside the eye, causing blurring in the distance. The more nearsighted you are, the more blurred the distant object appears, and the thicker your glasses need to be. Most nearsighted people feel that their condition is severe, due to their dependence on glasses and contact lenses. In fact, only one in ten nearsighted individuals are actually in the "severe" or "extreme" categories.