Download LASIK - Operation

In-depth Explanation of how LASIK works.
Summary
LASIK is the most commonly performed refractive surgery procedure, and it stands for LaserASsisted In situ Keratomileusis. LASIK has advantages over other forms of refractive surgery
due to the relative lack of pain, good vision is achieved quickly, and the ability to resolve a
variety of vision problems, such as myopia (solved by flattening the cornea), hyperopia (solved
by making the cornea steeper), and even astigmatism, which can be corrected with an excimer
laser.
An instrument called a microkeratome is used in LASIK eye surgery to create a thin, circular
flap in the cornea, but not removing the strip; the flap is still connected to the cornea by a
“hinge”. This can also be done with a laser. The surgeon folds the hinged flap back out of the
way, and removes some corneal tissue underneath using an excimer laser. The excimer laser
uses a cool ultraviolet light beam to precisely remove very tiny bits of tissue from the cornea
to reshape it in a desired way depending on the visual problem of the patient in question.
When the cornea is reshaped in the right way, it refracts light differently from before, now
focusing the incoming light rays onto the fovea of the retina, providing clearer vision. In
myopic patients, the cornea is too thick, causing the light rays from faraway objects to be
refracted too much such that the image is formed in front of the retina. When the cornea is
flattened, the light rays from faraway objects are reflected less such that they fall onto the
retina. In hyperopic patients, the cornea is not steep enough, causing light rays from near
objects to be insufficiently refracted such that the image is formed behind the retina. When
the cornea is made steeper, the incoming light rays are refracted more so that the image is
formed onto the retina.
The flap is then laid back in place, covering the area where the corneal tissue was removed. It
is then left to heal.
Before LASIK
After choosing your LASIK surgeon, your eye doctor will perform a series to tests to see
whether you are suitable for LASIK, what kind of vision correction is necessary and how much
correction is necessary. Unsuitable but possible candidates include the elderly.
Additionally, corneal topography usually is used; this measures the curvature of your eye and
creates a kind of "map" of your cornea. With new wavefront technology associated with
custom LASIK, you also are likely to undergo a wavefront analysis that sends light waves
through the eye to provide an even more precise map of aberrations affecting your vision.
Finally, the doctor will ask you about any health problems you have or medications you take.
Some health conditions will disqualify you altogether for LASIK, but others may just postpone
the procedure until a later date. For example, people with glaucoma or blepharitis should
avoid LASIK. Dry eyes is also an important issue when performing LASIK, as the laser may
damage the eyes if a tear film is not present. LASIK also aggravates dry eyes, so it is not advised
to perform LASIK if one has dry eyes.
During LASIK
LASIK is an ambulatory procedure, that is, you walk into the surgery centre, have the surgery
and walk out on the spot. The actual surgery takes only 5 minutes and only the eye being
operated on is anesthetized. Sometimes the surgeon will also give you a mild sedative
beforehand.
Despite the surgery being quick for a surgery, LASIK is very delicate procedure; it is important
for it to be performed by a highly skilled surgeon with proper equipment. It is also advised to
have someone to bring you to the surgery centre and back home after the surgery.
Before your LASIK begins, numbing eye drops will be applied to your eyes so you don't feel any
discomfort during the procedure. The doctor will have you lie down, and then make sure your
eye is positioned directly under the laser. (One eye is operated on at a time.) A kind of retainer
is placed under your eyelids to keep them open. This is not uncomfortable.
The surgeon will use an ink marker to mark the cornea before the flap is created. The flap is
then created with either a microkeratome or a femtosecond laser. Whichever device is used, it
is securely attached to your cornea with a suction ring to prevent eye movements or loss of
contact that could affect flap quality. During the procedure you won't actually see the creation
of the flap, which is very thin.
An ultra-thin flap is created on the eye's surface during LASIK corrective eye surgery. After
laser energy is applied to reshape the eye, the flap is replaced to serve as a type of natural
bandage.
The surgeon uses a computer to adjust the excimer laser for your particular prescription. You
will be asked to look at a target light for a short time while he or she watches your eye through
a microscope as the laser sends pulses of light to your cornea.
The laser light pulses painlessly reshape the cornea. You'll hear a steady clicking sound while
the laser is operating. You also may smell a mild odor during the laser treatment; this is normal.
The higher your prescription, the more time the surgery will take. The surgeon has full control
of the laser and can turn it off at any time.
After the procedure is finished, you will rest for a little while. If you're having both eyes done
the same day, the surgeon typically will begin working on your second eye immediately after
treatment of the first eye is finished. Some people choose to have their second eye done a
week later. Your surgeon may prescribe medication for any postoperative pain, but many
people feel no more than mild discomfort after LASIK.
After LASIK
It is recommended to rest after LASIK, and refrain from activities which are straining on the
eyes, as well as refrain from rubbing the eyes since there is a chance of dislodging the corneal
flap. Strenuous exercise should be reframed from because it may traumatize the eye and
affect healing.
While most people’s vision improves immediately, some find that their vision will improve
slowly over days or even weeks. Some patients still need glasses or contact lenses following
laser vision correction, though their prescription level typically will be much lower than before.
Post-operative LASIK complications can include infection or night glare (starbursts or halos that
are most noticeable when you're viewing lights at night, such as while you're driving). Rarely,
people will experience clear vision after LASIK, then notice a gradual worsening of their
eyesight over time (called "regression"). If this happens, discuss it with your surgeon to
determine if more surgery (called an enhancement or "touch-up") will be necessary.