| Good vision
has its origin in the accurate focusing of sharp images on the retina
of the eye.
With normal vision the optical system of the eye
refracts light rays (images, which we see) in a way that they come to
focus on the retina, normally in the fovea, the area of highest resolution.
If refractive power is correct, images which we see are focused accurately
on the retina of the eye.
If light is not focused directly on the retina but in front of or behind
it, the result is blurry vision. This is called a refractive error.
Common refractive errors include nearsightedness
(or myopia), farsightedness (or hyperopia),
astigmatism and presbyopia
(loss of accommodation in the eye).
FreeVis has developed a simulator to demonstrate the difference
in refractive errors. Please use the red slider to enter your
refractive error.
The most common form of vision correction is the use of eyeglasses.
Except for the fact that a nearsighted person is dependent on his/her
glasses for focused vision, there are no disadvantages for those persons
with moderate nearsightedness wearing eyeglasses.
Contact lenses also provide good visual correction for nearsightedness
and are tolerated by most people. The use of soft contact lenses, especially
if not properly taken care of, may result in corneal infection or a
growth of blood vessels in the cornea. However, these side effects occur
very infrequently.
Within the last decade, several surgical
procedures have been developed and have proven to provide excellent
vision correction |