Refractive errors occur when the shape of the eye prevents light from focusing directly on the retina. The length of the eyeball (longer or shorter), changes in the shape of the cornea which causes a refractive error.
Refractive errors include myopia (nearsightedness), hyperopia (farsightedness), or astigmatism, an irregularly shaped cornea.
If you have a refractive error, such as nearsightedness (myopia), farsightedness (hyperopia), or astigmatism, refractive surgery is a method for correcting or improving your vision.
Nearsightedness, or myopia, occurs when the curve at the front portion of the eye, the cornea, is too steep or the length of the eyeball is too long resulting in blurred images at a distance. Farsightedness, or hyperopia, occurs when the curvature of the cornea is too flat or the length of the eyeball is too short resulting in clearer vision at distance than at near. Astigmatism is blurred vision due to an irregular shaped cornea.
Presbyopia is a condition ocurring due to the natural age of the eye. Presbyopia is the decreased ability to focus at near, typically after age 40, and cannot be corrected by the LASIK procedure. Patients with myopia or hyperopia should realize that LASIK will not eliminate the potential need for reading glasses when reaching middle age.