Caring for Your Eyes and Ears In this lesson, you will Learn About… Keeping your eyes healthy. Why people wear glasses or contact lenses. Caring for your ears.

Caring for Your Eyes and Ears The Vocabulary terms for this lesson are : Optometrist. Optometrist Ophthalmologist. Ophthalmologist Astigmatism. Astigmatism Decibel. Decibel

Your Eyes Your eyes tell you about the world—about light, colors, shapes, and movements. The data that your eyes gather is interpreted by your brain, for example, to help you recognize a friend or the words on a page.

Structure of the Eye The optic nerve is a bundle of nerve fibers that sends messages to the brain, which interprets them. The sclera is the white of the eye. It covers and protects the whole eye, except for the front. The cornea is the clear section that lets in light at the front of the eye. The iris is the colored part of the eye. It controls the size of the pupil. The pupil is the dark opening in the center of the iris. It grows larger in dim light and smaller in bright light, so that the right amount of light enters the eye. The lens focuses the light on the retina. The retina is the light-sensing part of the inner eye.

Eye Care Your sense of sight is important, so you need to take care of your eyes. Make sure you have enough light. Avoid light that is too bright. Avoid rubbing your eyes. Protect your eyes from injury.

Eye Examinations To make sure that your eyes are healthy, visit an eye care professional for regular examinations. Eye care professionals include an optometrist and an ophthalmologist.optometrist ophthalmologist If you wear glasses or contact lenses, have your eyes checked once a year. Otherwise, have them checked every two years.

Eye Examinations (cont’d.) Some of the most common vision problems include the following: Nearsightedness – A vision problem in which a person can clearly see only objects close to his or her eyes. Farsightedness – A condition in which a person can see only distant objects clearly. Astigmatism – An eye condition in which images are distorted, causing objects to appear wavy or blurry.

Vision Correction Many vision problems can be corrected with either eyeglasses or contact lenses. Contacts are available in several basic types: Hard lenses – Made of slightly flexible plastic. Soft lenses – Made of soft, flexible plastic. Disposable lenses – Can be either hard or soft; worn for a set period of time and then replaced with a new pair.

Your Ears In the inner ear, the fluid in the cochlea moves. Tiny hair cells lining the cochlea vibrate in response, sending electronic messages to the auditory nerve. These messages travel to the brain, which identifies the sound. C In the middle ear, sound waves make the eardrum vibrate. The vibrations move the hammer, the anvil, and the stirrup. These bones carry the vibrations to the inner ear. B The outer ear is shaped like a cup to pick up sound waves, which travel through the external auditory canal. A

Ear Care Protect your ears from loud sounds. Sounds over 125 decibels are loud enough to be painful. Exposure to loud noises can cause loss of hearing or tinnitus.decibels Prolonged exposure to lower levels of sounds can also harm the ears.

Ear Care (cont’d.) To protect your ears from noise and to prevent other problems: Keep the volume fairly low on your radio, CD player, cassette player, and television. Wear earplugs and other hearing protection devices when exposed to loud and prolonged noises. Have periodic hearing tests administered. Hearing tests can be administered by the school nurse, speech therapist, or an audiologist.

Ear Care (cont’d.) It is important to clean and protect your ears. Clean the outside of your ears with a wet washcloth. On cold days, wear earmuffs or a hat that covers your ears. Cold air can irritate the middle ear and cause frostbite on the outer ear. If you think you have an ear infection, are experiencing pain in one or both ears, or have trouble hearing, tell your parents or guardians right away.

Reviewing Terms and Facts 1.Define astigmatism. Astigmatism is an eye condition in which images are distorted, causing objects to appear wavy or blurry.

Reviewing Terms and Facts 2.What is a decibel? A decibel is the unit for measuring the loudness of sound.

3.What activities or situations in your life could be harmful to your hearing? What can you do to protect your hearing? Thinking Critically

Vocabulary Review An optometrist is a health care professional who is trained to examine the eyes for vision problems and to prescribe corrective lenses.

Vocabulary Review An ophthalmologist is a physician who specializes in the structure, functions, and diseases of the eye.

Vocabulary Review Astigmatism is an eye condition in which images are distorted, causing objects to appear wavy or blurry.

Vocabulary Review A decibel is the unit for measuring the loudness of sound.