Laser vision correction (LASIK and PRK) is a relatively
new procedure used to reduce or eliminate a person's dependence on glasses
and contact lenses. The procedure is performed on an outpatient basis and
is effective for treating nearsightedness, farsightedness, and astigmatism.
To date, over two million procedures have been performed worldwide.
How
Does the Laser Work?
The goal of excimer laser LASIK and PRK is to reshape
the cornea so that the rays of light that enter the eye are focused clearly
onto the retina. The laser produces an ultraviolet beam of light that meticulously
removes tissue. Tissue is removed in a precise fashion on a microscopic
level, without harming or heating adjacent corneal tissue. This process
of tissue removal is called photoablation.
The excimer laser
is unique amongst the many types of lasers used in eye surgery. There are
three basic categories of medical lasers— thermal
(heats tissue),
mechanical
(cuts tissue), and photochemical (interacts
directly with molecules). For example, argon lasers heat tissue and have
been used for years to treat disorders such as glaucoma and diabetic eye
disease. YAG lasers break tissue bonds by creating a shock wave and are
generally used following cataract surgery and to treat certain types of
glaucoma. The excimer laser is the only laser properly suited to the task
of refractive corneal surgery since it does not heat or mechanically damage
tissue. Rather, it directly interacts with chemical bonds, neither heating
nor disrupting the tissue, thus minimizing possible scarring.
