HOW THE EYE WORKS When you look at an object around you, what you are actually seeing are beams of light bouncing off of the object and into your eyes. Light rays enter the eye through the cornea. The cornea is a thick, transparent protective layer on the surface of your eye. Then the light rays passes through the pupil and into the lens. Your lens in your eyes change size all the time. When you look at objects real close up, the lens gets thicker. If you look at objects far away, it gets thinner. It does this to help you focus the correct image on the retina. After light passes through the lens it shines through the vitreous humor to the back of the eye where it hits the retina. The retina takes the light and changes it into nerve impulse so the brain can understand what the eye sees. It sends the message to the brain by way of the optic nerve.
Cornea: The cornea is a clear white covering over the outside of the eye. It helps the eye focus like a lens on a camera. Iris: The iris is the part of your eye that has color. It gets bigger and smaller to let in different amounts of light. Pupil: Black opening in the middle of the eye. Light comes through this opening. Aqueous humor: The aqueous humor is clear water-like substance that keeps your eye clean. It also provides nutrition. Lens: The lens bends light. This helps the eye see close up and far away things. Vitreous Humor: The vitreous humor is clear water-like substance in the back of your eye. Retina: The retina has nerve cells called rods and cones that detect light. It is in the back of your eye. Optic Nerve: The optic nerve carries electrical signals from your retina to your brain so you can see. Sclera- is made of a tough material and has the important job of covering most of the eyeball.
RODS AND CONES Rods and cones are special cells that process light. Rods and cones are extremely small. In fact, there are about 120 million rods and 7 million cones in each eye! Rods help us see black and white and shades of grey. Cones help us see color. You have three kinds of cones are - red, green, and blue. These cones work together to help us see millions of colors.
FLIPPED IMAGE When you see images, they turn upside down when they hit the retina. So your brain sees everything in the world upside down. Your brain basically flips everything around so it is right side up again.
EYE MOVEMENT There are the six small muscles that move each eye from side to side, up and down and on the slant. When these muscles don't work together, it can affect vision. One condition that can arise when these muscles don't work together is “lazy eye”, a condition that affects about 5% of children and arises when the eye muscles don't work together properly. This leads to "lazy eye," in which one eye takes over all the vision duties. A defining characteristic of these tiny muscles is that they are nearly always moving, even during sleep. In fact, even when "staring" at a fixed object, the eyes keep moving over the image. Although these muscles are very small, they use a lot of energy because they are always on the go.
PROTECTING YOUR EYES The eyebrows are the strips of hair above your eyes which prevent sweat from running into them. Eyelashes help keep the eye clean by collecting small dirt and dust particles floating through the air. The eyelashes also protect the eye from the sun's and other light's glare. The eyelids sweep dirt from the surface of the eye. The eyelid also protects the eye from injury. Tears are sterile drops of clean water which constantly bathe the front of the eye, keeping it clean and moist.
FUN FACTS Most people blink every 2 to 10 seconds One in every twelve males is color blind If you had only one eyes, everything would appear two-dimensional A newborn baby sees the world upside down because it takes time for the brain to learn to turn the picture The color of your eyes is controlled by how much melanin in your iris, for example brown eyes have more melanin in their iris If you wore glasses which flipped images upside down, your brain would correct your vision You say ‘in the blink of an eye’ because it’s the fastest muscle in your body It is impossible to blink 5 times in a single second Your eyeballs stay the same size from birth to death The pupil of an eye expands as much as 45 percent when a person looks at something plesant