Diagram of the human eye http://220.127.116.11/images/Senior%20Site/Section%201/eye-diagram.jpg
Eye parts Iris Round, colored part of the eye ball Helps control the amount of light that enters the eye Lens Clear structure in the eye Focuses light rays to the retina http://www.medterms.com/script/main/art.asp?articlekey=4044
Eye Parts Pupil Dark hole of the eye Controls how much light goes in the eye Retina Nerve layer Lines back of eye Creates urges that travel through the optic nerve to the brain http://www.medterms.com/script/main/art.asp?articlekey=4044
Eye parts Cornea Clear outer layer of the eye Focuses light in the eye Optic Nerve The nerve that connects the eye to the brain Carries impulses formed by the retina to the visual cortex of the brain http://www.medterms.com/script/main/art.asp?articlekey=4044
What is needed to see? If you guessed light, you are correct. The human eye can not see without some sort of light source.
Are all parts of the eye important for seeing? The answer: Yes. Each part of the eye plays a different role, and each are equally important. For example: The optic nerve connects to the brain so you can remember things you see. The lens focuses the light rays to the retina. The pupil controls the amount of light that enters the eye. All are very important for seeing clearly.
What does it mean to be blind? People who are blind can not see. Some blind people can see only shapes, bright lights, and dull lights. One is considered blind if their vision is no better than 20/200.
What does it meanto be blindcontinued Some are born blind Some become blind Causes of blindness is if the optic nerve is not functioning or is damaged. When the cornea or the lens gets clouded over, it does not let light in. This also causes blindness.
Rods and cones Both are parts of the retina Rods work in dim light Cones are used in bright light Both are used for seeing colors
Cones Cones are sensitive to color They are less sensitive to light The cones are accountable for high resolution vision.
Rods Not sensitive to color Responsible for dark-adapted vision Rods are good motion sensor.
What is 20/20 vision? “Normal vision” Can see at twenty feet what most people can see at twenty feet Does not mean perfect vision, it only means the clarity of vision at a specific distance.
Work CitedInformation Adler, Irving, and Ruth Adler. Your Eyes. New York: The John Day Company, 1962. Print. 2. "Definition of Iris." MedicineNet.com. MedicineNet, 2011. Web. 10 Oct 2011. <http://www.medterms.com/script/main/art.asp?art iclekey=4044>. "Visual Acuity: What is 20/20 Vision?." American Optometric Association . American Optometric Association, 2011. Web. 10 Oct 2011. <http://www.aoa.org/x4695.xml>. 4. http://hyperphysics.phy- astr.gsu.edu/hbase/vision/rodcone.html#c4