The sclera is made of a tough material and has the important job of covering most of the eyeball. Think of the sclera as your eyeball's outer coat.
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Look very closely at the white of the eye, and you'll see lines that look like tiny pink threads. These are blood vessels, the tiny tubes that deliver blood, to the sclera. KOR-nee-uh , a transparent dome, sits in front of the colored part of the eye.
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The cornea helps the eye focus as light makes its way through. It is a very important part of the eye, but you can hardly see it because it's made of clear tissue. Like clear glass, the cornea gives your eye a clear window to view the world through. Behind the cornea are the iris, the pupil, and the anterior chamber. EYE-riss is the colorful part of the eye. When we say a person has blue eyes, we really mean the person has blue irises! The iris has muscles attached to it that change its shape. This allows the iris to control how much light goes through the pupil say: The pupil is the black circle in the center of the iris, which is really an opening in the iris, and it lets light enter the eye.
To see how this works, use a small flashlight to see how your eyes or a friend's eyes respond to changes in brightness. The pupils will get smaller when the light shines near them and they'll open wider when the light is gone.
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AN-teer-ee-ur chamber is the space between the cornea and the iris. This space is filled with a special transparent fluid that nourishes the eye and keeps it healthy. These next parts are really cool, but you can't see them with just your own eyes! Doctors use special microscopes to look at these inner parts of the eye, such as the lens.
After light enters the pupil, it hits the lens. The lens sits behind the iris and is clear and colorless. The lens' job is to focus light rays on the back of the eyeball — a part called the retina say: The lens works much like the lens of a movie projector at the movies. Next time you sit in the dark theater, look behind you at the stream of light coming from the projection booth. This light goes through a powerful lens, which is focusing the images onto the screen, so you can see the movie clearly.
In the eye's case, however, the film screen is your retina. Your retina is in the very back of the eye. It holds millions of cells that are sensitive to light. The retina takes the light the eye receives and changes it into nerve signals so the brain can understand what the eye is seeing. The lens is suspended in the eye by a bunch of fibers. These fibers are attached to a muscle called the ciliary say: The ciliary muscle has the amazing job of changing the shape of the lens.
That's right — the lens actually changes shape right inside your eye! Try looking away from your computer and focusing on something way across the room. Even though you didn't feel a thing, the shape of your lenses changed.
When you look at things up close, the lens becomes thicker to focus the correct image onto the retina. When you look at things far away, the lens becomes thinner. The biggest part of the eye sits behind the lens and is called the vitreous say: The vitreous body forms two thirds of the eye's volume and gives the eye its shape.
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It's filled with a clear, jelly-like material called the vitreous humor. Ever touch toy eyeballs in a store? Sometimes they're kind of squishy — that's because they're made to feel like they're filled with vitreous humor. In a real eye, after light passes through the lens, it shines straight through the vitreous humor to the back of the eye.
The retina uses special cells called rods and cones to process light. Just how many rods and cones does your retina have? How about million rods and 7 million cones — in each eye! Rods see in black, white, and shades of gray and tell us the form or shape that something has. Rods can't tell the difference between colors, but they are super-sensitive, allowing us to see when it's very dark.
Cones sense color and they need more light than rods to work well. Cones are most helpful in normal or bright light. The retina has three types of cones. Each cone type is sensitive to one of three different colors — red, green, or blue — to help you see different ranges of color.
These five surprising foods will help keep your eyes healthy and your vision sharp. Redness, itching, watering, g Redness, itching, watering, grittiness Dry eye is a condition in which inadequate tear production leads to eyes th Dry eye is a condition in which inadequate tear production leads to eyes that burn, sting, or feel gritty, among other symptoms. While there are multiple causes, one to consider is medication. A surprising number of over-the-counter and prescription meds can cause dry eye. More on Eye Health.
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