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General Anatomy
In order to understand how refractive procedures will help to
correct your vision, it is important to understand how the eye
functions.
The cornea of the eye is composed of transparent tissue. The
cornea functions as a window through which light travels to the
retina in the back of the eye. The retina sends the "picture"
of the viewed object to the brain where the object is seen. In
the normal eye with perfect vision, the light rays enter the eye
and are focused directly on the retina. In this situation, the
image is sent to the brain.
 The
cornea provides about 75 percent of the eye's focusing power.
The shape, or curvature of the cornea determines how well you
see and how in focus an object is. The natural lens inside the
eye provides the remaining focusing power, therefore, the cornea
and the lens of the eye are the two areas that are used in correcting
your vision.
What is nearsightedness?
If you are nearsighted, distant objects are blurry, close
objects are clear. This occurs when light rays are focused in
front of the retina instead of directly on the retina.
What is farsightedness?
If you are farsighted, distant objects and up close objects are
blurry. This occurs when the light rays
are not bent to focus on the retina.
What is astigmatism?
Astigmatism occurs when light rays are focused at more than one
point on the retina.
What is presbyopia?
If you are presbyopic, you will have blurred vision of near
objects. This occurs around the age of 40, and is due to the natural
lens of the eye losing it's flexibility and power to accommodate.
Can refractive surgery correct presbyopia?
No, however some people choose refractive surgery to achieve monovision,
where laser surgery corrects one eye for distance and the other
eye for near vision; otherwise, reading glasses will be required.
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