The human eye is responsible for the sense of sight. The process of seeing requires the eyes to perceive external properties, such as color and movement, and then share the information with the brain. People may have eyes that differ in color, size and shape, but all eyes need the same parts to help them function.
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Features of the Eye
Each eyeball sits in a hollow opening in the skull called the eye socket. A flexible piece of skin called the eyelid covers and protects the front of the eyeball, and the white area known as the sclera covers a large portion of the eyeball. The round, colored iris at the front of the eyeball contains a small, black, circular area known as the pupil. Explain to your child how the pupil changes in size in response to light. The iris is just behind a round, transparent piece of tissue called the cornea and just in front of the clear spherical tissue called the lens. Out of view at the back of the eyeball is a very important thin membrane called the retina. Show your child pictures of various animals and ask her how each animal's eyes are different than hers. Explain how some animals have different placement of their eyes. Some, for example, have eyes that are closer together, which gives them improved depth perception.
Function of Your Eyes
The human eye works like a camera during the process of seeing to capture images of external objects and events. Light enters the eye through the cornea, which adjusts to focus the eye on items in the line of sight. The iris controls muscles that alter the size of the pupil in order to adjust the amount of light entering the eye. After passing through the pupil, light reaches the lens, which focuses the light on the film-like retina. The retina contains thousands of cells that are sensitive to light, and they help transform the light into a neural message for the brain to interpret as an image. Have your child cover one eye, then the other eye. Ask her how things look different as she does this.
Purpose of Tears
Tears are an essential part of the human eye that help protect the eyes and ensure they perform as best as they can. Each eye contains a lacrimal gland at the outer edge. These glands produce tears that help clean and lubricate the outer portion of the eyes each time you blink. The bathing process removes all kinds of dirt and irritants, including dust and germs.
Some people's eyes do not function perfectly or properly. When the eyes have such problems, you may need to get contact lenses or glasses to correct inadequate vision. Sometimes a medical procedure, such as laser surgery, can correct eyesight problems also. Common vision problems include farsightedness, which happens when you can see distant objects clearly and close objects not clearly enough; and nearsightedness, which happens when you can see close objects clearly and distant objects not clearly enough. Astigmatism occurs when the cornea is not evenly shaped, which makes objects look blurry.
Keeping Eyes Healthy
To keep eyes healthy, it is important to get regular vision checkups, especially since many eye diseases and problems are treatable when detected early. Eye care professionals can test your eyes to see if they are working properly. Indications of a problem with your eyes include abnormal sensitivity to light, constant redness or tearing, frequent rubbing, inability to see faraway objects, problems reading, squinting and white pupils. Tell your child that sunglasses are worn to protect her eyes from UV rays that can be harmful to her vision.