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. The different components of the optical system of the eye form a certain refractive power which is measured in diopters (D).

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).

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 laser surgery procedures have been developed and have proven to provide excellent vision correction.