Eyesight :: essays research papers fc

EyesightVision is the learned ability to see for information and process it allows us to understand things that we cannot touch, taste, smell or hear. 20/20 vision does not mean perfect eyesight. 20/20 vision simply way of life that at a 20 ft. distance a person is cap fit to see a certain letter than an average eye should be able to see at that distance. You can have 20/20 vision and lack the abilities to use your two eyes together as a team, to justness distances, to identify colors and to coordinate your eyes with hand and body movements. About four in ten people have "perfect" vision. There be also various eye bothers associated with eyesight such as astigmatism, farsightedness, and nearsightedness. Astigmatism is a condition in which vision at all distances whitethorn be blurred or deformed. An irregularly shaped cornea, causing light images to focus on two separate points in the eye, characterizes this condition. When the front of the eye is more ellipse than rou nd, light does not focus properly on the back of the eye, also known as the retina. Astigmatism is not a disease, but is actually a vision condition that is quite common--only moderate to highly astigmatic eyes need corrective lens systemes. The signs and symptoms of severe astigmatism are blurred or distorted vision. For mild astigmatism the symptoms are headaches, eyestrain, fatigue, and blurred vision at certain angles. The causes of astigmatism are unclear. It may be genetically inherited or may result from various environmental factors such as poor lighting, incorrect posture, or an increased use of the eyes for close work.      Another eye disorder is farsightedness, also known as hyperopia. With this disorder, objects are seen understandably far away but are blurry close up. The eyeball is too short for the lens to focus a clear image on the retina. More than half of all people who wear glasses are farsighted. The signs and symptoms of farsightedness are aching or burning eyes, suffering from eyestrain, general tension, fatigue or headaches after close work, becoming irritable or nervous after prolonged concentration, and trouble concentrating and maintaining a clear focus on near objects.      Nearsightedness also known as myopia, is a disorder where one can see clearly close up, but see blurry at a distance (for example, not being able to read the blackboard but being able to read a book). This occurs when the eyeball is too long or the cornea is too curved to focus on the retina.