What Is LASIK?
Laser-Assisted
In-Situ Keratomileusis (LASIK) is a medical procedure where
an extremely precise laser is used to gently reshape the cornea, the exterior
or watch crystal of the eye, in order to change a person's refractive error.
When
light enters the eye, it is bent by the cornea and the lens in order to focus
the light rays on the retina which is like the film in a camera. The cornea
does two-thirds of the light bending, the lens the other third.
In
the normal eye, the light rays come to a sharp focus in the center of the retina,
known as the fovea. In the near-sighted, or myopic eye below, the light rays
are focused inside of the eye, and by the time they reach the retina, they are
out of focus again. Typically near-sighted eyes are too large, which is the
cause of this poor focus.
Far-sighted
eyes (hyperopia), on the other hand, are a little too short. The light rays
haven't yet focused when they reach the retina. They would focus somewhere behind
the eye, if given the chance.
Astigmatism,
is a condition where either the lens, but more commonly the cornea is a little
oblong or football-shaped. This results in light rays being bent more in one
plane than the opposite plane. The bottom line is that the light rays are split
into TWO focus points inside of the eye.
In
the LASIK procedure, eyedrops are placed to numb the eye. The eyelids are opened
with an instrument in order to alleviate any blinking. The patient is instructed
to fix his eye on a light during the procedure. Next a suction ring is placed
over the eye so that the surgeon has a steady grip on the eye. The patient will
feel a "pressure" sensation and occasionally some mild discomfort.
While the suction is engaged, the vision will darken or dim and it is during
this time that the flap is created. The suction is removed, and the vision returns--the
fixation light is visible again. Next, the flap is flipped back and vision smears.
It is at this time that the laser is directed at the eye and is very important
to continue looking at the fixation light. Your surgeon will direct you if you
are not keeping good focus. Following the laser application, the flap is replaced,
some water is placed on the eye and some eye drops are placed into the eye.
The instrument is removed from the eyelids, and the procedure is complete. This
takes a total of 4-5 minutes per eye.
The
eye is prepped for LASIK. The microkeratome creates a flap (not pictured).
The
flap is flipped backwards for laser application.
The
laser is applied to the cornea, gently reshaping it.
The
flap is replaced, water and eye drops are placed onto the eye.
