Refractive Surgery
What is Refractive Surgery?
"Refractive surgery" is a term for several procedures designed to treat "refractive errors," such as nearsightedness, farsightedness and astigmatism. These procedures attempt to alter refractive errors by changing the shape of the cornea.
How does the Eye Work?
Clear vision in the normal eye is the result of light rays passing through the cornea, pupil and lens and focusing directly upon the retina.
Nearsightedness occurs when the cornea is too curved or the eye is too long. This causes light to focus in front of the retina, resulting in blurry distance vision.
Farsightedness occurs when the cornea is too flat in relation to the length of the eye. This causes light to focus at a point beyond the retina, resulting in blurry close vision and sometimes distance vision as well.
Astigmatism occurs when the cornea is shaped like a football, more curved in one direction than the other, and often occurs with nearsightedness and farsightedness. This causes light not to focus on any point, resulting in blurry and distorted vision.
The goal of refractive surgery is to reduce or eliminate dependence on corrective lenses. Although the vast majority of patients see 20/40 or better post-operatively, individual results cannot be guaranteed. Patients over 40 years old who have surgery to treat nearsightedness may find they need reading glasses for close work after surgery. Refractive surgery is performed on an outpatient basis, and most people return to work within one to three days.
The Excimer Laser
In the early 1980s, researchers found that IBM's new Excimer laser, used initially for etching computer chips, had refractive surgery applications as well. Unlike other lasers that tend to damage surrounding tissue, the "cool" light from the Excimer laser created no thermal damage to surrounding tissue and left a very clean margin.