The Human Eye and How It Works

Features that Protect the Eyes

The eyeballs are protected, in part, by their location-they are embedded in sockets, which are strongholds of bone, fat, and muscle. Other protective features of the eye are:

Eyelashes, which protect your eyes from dust, contaminants, and other small particles.

Eyebrows, which trap liquids (such as perspiration) and particles that might otherwise find their way into your eyes.

Tears, which supply moisture that not only keeps your eyes from drying out but also contain substances that fight bacteria. If a foreign object gets into your eye, tear production increases to flush it out. When perspiration drips into your eyes, the high salt content makes your eyes sting, and the stinging stimulates tear production. The tears dilute the salty perspiration (or other liquid Cataract Surgery The lens is clear in this normal eye, allowing light to pass through. that might accidentally enter your eye) and cleanse the eye.

Eyelids, which work like windshield wipers when you blink, to spread tears across the cornea. Blinking is usually automatic-you seldom have to remember to blink-but it is also a protective reflex that goes into action when your eyes perceive an object moving toward them or are assaulted by extremely bright light.

How Vision Occurs »