How the Eye Works

The key to understanding refractive surgery (LASIK) is to understand how the eye works. Much like a camera, light rays passing through the cornea, pupil and lens to focus directly upon the retina which results in sharp and clear vision. If the cornea is not round, or if it is too steep or too flat in relation to the length of the eye, the light rays may not focus directly on the retina resulting in "refractive errors" such as nearsightedness, farsightedness and astigmatism.

Images Via National Institutes of Health


Nearsightedness, or myopia, occurs when the curvature of the cornea is too steep. With nearsightedness, the eye's refractive power is too strong, forcing the image to be focused in front of the retina of the eye, rather than upon it as would be with normal vision. When light focuses in front of the retina, near objects can be seen more clearly, while far objects appear blurry.

Farsightedness, or hyperopia, is caused when the curvature of the cornea is too flat and hence causes light to focus behind the retina. With farsightedness, the eye's refractive power is too weak forcing the image to be focused behind the retina of the eye, causing far objects to be seen relatively more clearly while near objects appear more blurred.

Astigmatism is caused when the cornea is shaped irregularly - like a football or a spoon as compared to a ball or sphere, preventing light from converging on the retina. Some parts of the image may focus on the retina, while other parts are focused behind or in front of it. This has the effect of bending light inconsistently and causes blurred images. Astigmatism can occur with either nearsightedness or farsightedness.

Laser Vision Correction is a term for two separate procedures (LASIK and PRK) designed to treat these "refractive errors." The cornea is the clear dome on the front of the eye. Many people who are nearsighted place contact lenses on their corneas to improve the way light is focused for clearer vision. Instead of using a contact lens, laser vision correction reshapes the cornea so that it can focus the light clearly. Laser vision correction is performed at our Laser Surgery Suite on-site in Dalton and is a straightforward, same day, outpatient procedure. And most patients are able to return to their normal activities the following day. Your Professional Eye Associates laser vision specialist will help you decide which procedure or combination of procedures is best suited for you.

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