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A Look Inside: The Mechanics Of The Human Eye

Posted Jul 29 2010 4:42am
Los Angeles Lasik To understand how Los Angeles Lasik surgery may help you see better and reduce or eliminate your need for glasses or contact lenses, it is helpful to understand how the eye works. In order to see clearly, the "normal" eye is designed to focus images clearly onto the retina. This focusing power is a combination of the front surface layer of the eye, the cornea, the lens of the eye, located inside the eye, and the length of the eye. If these three elements are not in perfect relationship to each other, then the eye may not focus images on the retina, leading to blurry vision. Los Angeles Lasik can correct irregularities in specific areas of the eye. The four main reasons that a healthy eye may have blurry vision are myopia, astigmatism, hyperopia, andpresbyopia.

Myopia, or nearsightedness, is the condition when the distance between the cornea and the retina is too long, and the image formed by a distant object falls into focus in front of the retina, causing blurred vision in the distance. According to Lasik surgery Los Angeles experts patients with myopia may be classified as mild (-1 to -4), moderate (-4 to -10), or severe (more than -10). Nearsightedness is most often caused by a natural change in the shape of the eyeball that makes the eyeball too long, so that it is egg-shaped instead of round. This causes light entering the eye to focus in front of the retina instead of directly on the retina, causing blurry vision. In a person with nearsightedness (myopia), a top Los Angeles Lasik surgeon explains that close objects can be seen more clearly than objects that are farther away. Nearsighted people may squint or frown to see things at a distance. They often hold books or other objects close to the face, sit at the front of a classroom or movie theater, and sit close to the television or computer.

Astigmatism occurs because the cornea is curved more in one direction than the other direction, so that it is shaped like the back of a teaspoon. With astigmatism, images at all distances will be blurry. A person's eye is naturally spherical in shape. Under normal circumstances, when light enters the eye, it refracts evenly, creating a clear view of the object. However, the eye of a person with astigmatism is shaped more like a football or the back of a spoon. For this person, when light enters the eye it is refracted more in one direction than the other, allowing only part of the object to be in focus at one time. Objects at any distance can appear blurry and wavy.

Astigmatism can be hereditary and is often present at birth. It can also result from pressure from the eyelids on the cornea, incorrect posture, or an increased use of the eyes for close work. Hyperopia, or farsightedness, is the condition when the distance between the cornea and the retina is too short, and the image formed falls into focus behind the retina, causing blurred vision. Because the youthful lens inside the eye can make up the additional power needed to focus images on the retina, many people who are farsighted do not have blurry vision until their lens ages.

Presbyopia is the normal aging change inside the eye whereby the lens inside the eye loses the ability to accommodate, or to change focus from the distance to close up. Presbyopia is the reason that people over the age of forty typically need reading glasses. This occurs because the light entering the eye is focused behind the retina instead of directly on it. Farsightedness occurs when an eye is too short lengthwise, the cornea is not curved enough, or the lens sits farther back in the eye than normal. Eyeglasses or contact lenses are used most often to correct farsightedness. In some cases laser eye surgery can improve vision.
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