& Lomb's Hansatome microkeratome
In preparation for Lasik, the eyelids
are swabbed with an antiseptic solution to reduce the
chance of infection. A mild sedative such as Valium
is taken orally to relax the patient. The patient needs
to be awake and able to follow commands during the procedure.
First, the eyelids are draped to keep
the lashes out of the surgical field. A device called
a speculum is inserted to keep the lids and the eye
in an open position. Anesthetic eyedrops are dripped
onto the eye to numb it. A ring is placed onto the eye
to secure it. Vacuum is applied to make the eye firm.
The vision usually dims or goes dark at this point.
A flap-making device called a microkeratome
is then attached to the ring and activated, to create
a flap of corneal tissue.
This flap of tissue is thin, approximately
160-180 microns (the center of the cornea averages about
550 microns), and remains attached to the rest of the
cornea by a hinge. The location of the hinge depends
on the type of microkeratome used. The ring and microkeratome
are removed from the eye.
The corneal flap is then flipped, opened
like the cover of a book. Again, the flap remains attached
at the hinge. The patient is directed to look at the
red blinking fixation light of the laser. The red light
is not the laser but is used for centering the laser
treatment. The surgeon then begins the laser treatment
by depressing a foot pedal. The total treatment time
depends on the amount of prescription, but in most cases
is less than a minute. There is no pain during the laser
Once the laser treatment has been completed,
the corneal flap is replaced, closed like the cover
of a book. The surgeon then squirts some irrigating
fluid under the flap to clean the under- surface of
debris. The flap is gently stroked with a tiny sponge
to "squeegee" the remaining fluid out from
under the flap. The flap is then allowed to dry into
place. Proper positioning is verified by looking at
inked alignment marks placed before the flap was made.
Additional eyedrops, usually an antibiotic and a non-steroidal
anti-inflammatory, are dripped onto the eye, before
the drapes and speculum are removed.