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Vision is the learned ability to see for information and performance; 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 means that at a 20 ft. distance a person is able 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 judge distances, to identify colors and to coordinate your eyes with hand and body movements. About four in ten people have 'perfect' vision.
There are also various eye disorders 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, causing light images to focus 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 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 lenses. 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 clearly 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 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. Nearsightedness affects nearly 30% percent of the population and can also be caused by heredity or the strain of too much close work. The signs and symptoms are blurred vision or squinting when trying to see distant objects, eyestrain, and headaches. This condition is usually diagnosed before a person reaches the age of 20. There are many alternatives that one can turn to in order to have clearer vision, such as contact lenses, laser eye surgery, and eyeglasses.
Contact lenses are delicately crafted, very thin optical discs about the diameter of a shirt button. They are comfortably held in place by the eye's own natural tears, which are always present between the lens and the eye. Recent advances in contact lenses include astigmatism correcting lenses (toric), bifocals, color contacts, daily disposables, and even contacts that can be slept in. Contact lens wear can begin as soon as the need for vision correction is identified. Contact lenses have even been frequently been used in premature infants, who sometimes have vision problems. The cost of contact lenses can vary greatly.
If you have a difficult prescription or need correction for problems like astigmatism, your lenses will be more expensive. If you have no special requirements, your options will range from daily disposables, which are more affordable to gas permeable (GP) contacts which are a fairly higher cost. Another alternative for clearer vision is laser eye surgery. -There are two different types of laser eye surgery: Precision Surgery (PRK) and LASIK. PRK is a procedure generally performed with local anesthetic eye drops. This procedure gently reshapes the cornea by removing microscopic amounts of tissue from the outer surface with a cool, computer-controlled ultraviolet beam of light.
The beam is so precise it can cut notches in a strand of human hair without breaking it, and each pulse can remove 39 millionths of an inch of tissue in 12 billionths of a second. The procedure itself takes only a few minutes, and patients typically return to daily routine in one to three days. LASIK is a more complex procedure than PRK. It is performed for all degrees of nearsightedness. The surgeon uses a knife called a microkeratome to cut a flap of corneal tissue, removes the targeted tissue beneath it with the laser, and then replaces the flap. There is generally a faster recovery time after LASIK than after PRK. LASIK patients can see well enough to drive immediately and have good vision within a week.
There is little if any discomfort during surgery because the cornea and eye are anesthetized by drops. After the anesthetic wears off, the amount of discomfort varies with each individual, but any irritation is minor and usually disappears within a few hours. Recovery is minimal, and usually the patient can be driven home after about 30 minutes. One may be sensitive to light for a few of days. The most common side effects are a halo effect and some glare at night around lights. Laser treatment itself takes only about 15 to 40 seconds, based on the degree of correction necessary.
Improved sight occurs in 3 to 5 days following treatment. The cost of laser eye surgery is generally $1,800 to $2,600 per eye. Eyeglasses are a very common and safe alternative to achieving clearer vision. They have been around since the 19th century. Eyeglasses are now thin, sleek and available in various styles, shapes, and designer names. They are now 100% safe, and healthier for your eyes. For many people, perfect vision is achievable with eyeglasses.
Eyeglasses range from very affordable to very expensive depending on the brand name and prescription. Vitamins play a beneficial and necessary role in maintaining healthy eyesight. Vitamins A, C, E, lutein and other antioxidants promote healthy eyes. These vitamins can be found in carrots, oranges, and nuts. Lutein is an antioxidant that has benefits for eye, skin and cardiovascular health. It is found in dark green leafy vegetables, fruit, corn, tomatoes, and egg yolks. These vitamins and antioxidants do very little for advanced diseases, but certain eye problems can be slowed or prevented if one consumes these supplements throughout their lifetime. Works Cited Kavner, Richard S., and Lorraine Dusky.
Total Vision. New York: A& W Publishers, Inc., 1978. Miller, David. The Wisdom of the Eye. San Diego: Academic Press, 2000. Wertenbaker, Lael. The Eye: Window to the World.
Washington, D.C.: U.S. News Books, 1990..
Research essay sample on Eyesight