Keil Kunzer
Mr. Wirth
Physics R
4 March 2008
The Human Eye

The human eye is a very complex structure of our body. Our eye gives a person the sense of sight and vision. The eye helps us decipher objects, colors, and shapes; it also can detect the difference between dim and bright light. There are many different parts to the human eye but the main ones are the iris, pupil, cornea, lens, and retina. Light waves enter the eye first through the cornea which is the clear part in the center of the eye. Then all the light gets processed in the pupil which is part of the iris. There are also many muscles in the eye that allow it to move and allow for our pupils to get bigger or smaller depending on the brightness of light rays. The human eye consists of many different complex parts, without these we would not have the ability of one of our most important senses (Montgomery).
Human vision is an extremely complex and interesting subject. The basic light sensing structure of the eye is the retina, which consists of both rods and cones. The rods and cones process the light through a chemical reaction, which then creates electrical impulses to the eye’s nerve. After the electrical impulses are sent to the nerve, this information is then sent to the brain where it is processed and then interpreted as light. In the cones are three different color sensing pigments. These colors include red, green, and blue color sensitive pigments. The eye can sense any combination of these colors unless a person has a color blindness disorder. Colorblindness occurs when one of the color pigments in the cones are not functioning properly. Colorblindness occurs in females in less than one percent of the population, but in males it occurs in eight percent of the population. The ability to see light and color is an extremely special feature of the human body, and it is something that many people take for granted.
Just because most everyone have the same eye structure, does not mean every human has the same vision. If someone is considered to have normal vision their vision is 20/20. That means the majority of the human population can see what you see at twenty feet. 20/10 vision is better than normal vision because it means you can see twenty feet of what a normal person can see when standing ten feet away from a vision chart. In the United States a person is legally blind when their vision is 20/200. A few vision problems a person might have are nearsightedness or farsightedness. When a person is nearsighted they have difficulty seeing objects that are close to them, which is caused by an elongated eyeball. The opposite is true for farsighted people, which is when people have trouble seeing objects farther away from them caused by a shorter eyeball. Another vision problem a person might develop is an astigmatism. An astigmatism is when the cornea is uneven or curved. This causes distortion to a person’s vision, yet this can be corrected with a lens that is fitted to correct the uneven cornea. The human vision system is an extremely complex structure of the human body (Bianco).
The human eye is an amazing organ, and gives people the great sense of vision. There are many people who are unable to see the everyday occurrences in their lives due to vision problems. It would be extremely difficult to live not being able to comprehend colors and frequencies of light.



Works Cited

Bianco, Carl. "How Vision Works." How Stuff Works. 4 March 2008
<http://health.howstuffworks.com/eye.htm>

Montgomery, Ted. "Anatomy, Physiology and Pathology of the Human
Eye." 4 March 2008 <http://health.howstuffworks.com/eye.htm>