LASIK : Refractive Problems
Do Any One of These Conditions Describe Your Eyesight?
It may sound like Greek, but the words myopia, hyperopia, astigmatism, and presbyopia describe vision problems that afflict countless millions of people of all ages.
In recent years, ophthalmologists, researchers, and technological wizards have devised increasingly effective ways to overcome or minimize most of these conditions--most notably, the development of the LASIK surgical procedure.
All of these terms come together to describe what are known as "refractive problems." Refraction refers to the ability of the eye to focus light. The shape of the cornea, the strength of the lens and of the eye, and the length of the eyeball determine how clearly you see. If even one of these factors is not coordinating properly with the others, light will not focus correctly and your vision will not be clear.
Myopia
An elongated eye (or steeper cornea) causes a condition known as Myopia in which visual images come into focus in front of the retina. |
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Myopia (commonly called nearsightedness) is the most common refractive problem. People with myopia can see objects closer to them, but have difficulty focusing on distant objects. The condition is caused by a cornea that has more curvature than normal, or an eyeball that is too long. In either case, light is focused at a point in front of the retina, causing a blurred image. About one in four American adults are myopic. The condition usually begins in childhood, and stabilizes in the late teen years.
Hyperopia
A shortened eye (or flatter cornea) causes a condition known as Hyperopia in which visual images come into focus behind the retina. |
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Hyperopia ( commonly called farsightedness) is the opposite of myopia. For people with hyperopia, objects at a distance are clear, while objects up close are blurry with uncorrected vision. This is caused by a flatter-than-normal cornea, or an eyeball that is too short--causing light to focus on a position behind the retina.
Astigmatism
Astigmatism is a condition caused by a corneal irregularity that prevents light rays from focusing properly on the retina. It can occur with or without nearsightedness or farsightedness. |
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Astigmatism, or ovalness of the cornea, is another refractive problem. With this condition, there is a distortion that tilts or bends the image due to an unequal bending of light as it attempt to focus. People with a high degree of astigmatism have difficulty focusing properly at any distance, and experience a "ghosting" or "doubling" effect with the images they view. Nearsighted and farsighted people may also have some degree of astigmatism.
Presbyopia
Presbyopia is the loss of elasticity in the lens of the eyes in older adults and impairs the ability to focus sharply for near vision. |
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Presbyopia is a very common condition that is simply part of the normal aging process. It cannot be corrected with refractive surgery. Presbyopia develops as the lens of the eye loses flexibility, typically between the ages of 40 and 50. Those who are nearsighted find they need to wear bifocals, and those with normal vision will need to wear reading glasses. After having corrective laser surgery for either myopia or hyperopia, patients with presbyopia will probably need to wear corrective lenses for reading.
