Eyesight :: essays research papers fc

EyesightVision is the knowledgecapable ability to view for information and performance it wholeows us to understand things that we cannot touch, taste, smelling or hear. 20/20 vision does not mean perfect(a) eyesight. 20/20 vision simply means that at a 20 ft. distance a person is able to travel to a certain letter than an average eye should be able to see at that distance. You can have 20/20 vision and insufficiency the abilities to use your two eyes together as a team, to attempt distances, to identify colors and to coordinate your eyes with hand and body movements. active four in ten people have "perfect" vision. there are also various eye sicknesss associated with eyesight such as astigmatism, farsightedness, and nearsightedness. Astigmatism is a condition in which vision at all distances may be blurred or distorted. An irregularly shaped cornea, create light images to focalization on two separate points in the eye, characterizes this condition. When the front of the eye is more oval than round, light does not focus powerful on the back of the eye, also known as the retina. Astigmatism is not a disease, but is actually a vision condition that is kind of common--only moderate to highly astigmatic eyes need corrective lenses. The signs and symptoms of exacting astigmatism are blurred or distorted vision. For mild astigmatism the symptoms are headaches, eyestrain, jade, and blurred vision at certain angles. The causes of astigmatism are unclear. It may be genetically inherited or may outcome from various environmental factors such as poor lighting, incorrect posture, or an increased use of the eyes for close work.      Another eye put out is farsightedness, also known as hyperopia. With this disorder, objects are seen clearly far apart but are blurry close up. The eyeball is too shortsighted for the lens to focus a clear image on the retina. to a greater extent than half of all people who wear glasses are f arsighted. 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 neural after prolonged concentration, and difficulty 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.