Laser In-situ Keratomileusis (LASIK)
History
In 1991, Ioannis Pallikaris, MD, in Heraklion, Crete, was
probably the first to use a microkeratome to cut a thin flap of cornea and then apply the excimer laser to remove tissue from
within the cornea. (The microkeratome had been used successfully
in South America for about 30 years previously, but it was
not used in conjunction with the laser.) Pallikaris suggested
the name laser in-situ keratomileusis ( LASIK ) for this procedure. "Keratomileusis" is derived from
two Greek words that literally mean "to shape the cornea."
"In-situ" means "in place." Therefore, the term LASIK means "to reshape the cornea in place using laser."
The technique has been further developed by Stephen Slade,
MD, in Houston; Steve Brint, MD, in New Orleans; Luis Ruiz,
MD, in Bogota; and by Tarek Salah, MD, Akef El-Maghraby, MD,
and George O. Waring, MD, in Jeddah, Saudi Arabia. Since its
introduction, LASIK has become increasingly popular around the world, replacing
other forms of refractive surgery such as RK and PRK in many refractive surgery centers. Currently, InView
physicians are among a small number of ophthalmologists in
the United States taking part in clinical investigations of
the LASIK technique.
Technique
 The LASIK procedure combines two sophisticated techniques of surgery
to correct refractive
errors . The first technique involves the use of
an automated instrument, the microkeratome , to create a thin protective layer of corneal tissue
that covers the area to be sculpted by the laser. This flap allows for rapid recovery of vision and reduces discomfort
after surgery. The second technique uses a computer-controlled
excimer laser -- a cold, invisible, ultraviolet laser -- to
sculpt the underlying cornea, correcting the refractive error.
This is the same laser that is used in PRK . The protective layer of tissue is repositioned without
sutures and is secure after a few minutes so that a patch
is not required. Visual recovery is typically rapid, and there
is little or no post-operative pain. Eye drops need only to
be taken for a week. For a detailed pictorial
display of how the surgery works, click
here.
Discussing LASIK
Almost everyone who is considering refractive surgery wants
to know what his/her chances are for obtaining a satisfactory
outcome. Patients want to know what the "track record"
has been for the procedure and surgeon he/she is considering.
Unfortunately, this is not as easy to do as it may seem.
We are prohibited by law from advertising procedures that
are not approved by the FDA, from making claims as to the
efficacy of experimental procedures, and from making efficacy
claims regarding any medical procedure unless those claims
can be proven. On the other hand, we are required by Georgia
State law to inform patients fully about the risks and benefits
of any surgical procedure we may recommend, as well as alternative
forms of treatment. Therefore, we are in danger of violating
FDA and FTC regulations if we discuss the results of LASIK.
On the other hand, we are in danger of failing to obtain informed
consent if we fail to discuss them with patients considering
any form of refractive surgery.
In an effort to inform our patients about refractive surgical
alternatives without violating FDA and FTC requirements, we
present below general information about the outcomes of LASIK-potential
complications, advantages, and disadvantages of the procedure.
This information is generally available in the professional
literature, and selected references are listed are shown below.
Results of LASIK
The results of LASIK have been reported by several groups
using a variety of lasers.
For low and moderate myopia (up to about 7 diopters), about
95% of eyes typically achieve 20/40 or better vision while
about 85% of eyes achieve 20/25 or better vision. About
1% of eyes cannot see as well with glasses after surgery as
they could with glasses before surgery.
For high myopia (over 7 diopters), the results are not quite
so good, with about 90% of eyes achieving 20/40 or better
vision and 70% of eyes achieving 20/25 or better vision.
Up to about 5% of eyes cannot see as well with glasses after
surgery as they could with glasses before surgery.
Complications
As with any surgical procedure, complications can occur
with LASIK . These include undercorrections, overcorrections, and
loss of best-corrected vision. Undercorrections occur when
insufficient tissue has been removed to correct the vision
completely. Overcorrections occur when too much tissue
has been removed. Undercorrections can be treated by
an enhancement . Overcorrections are more difficult to treat.
Problems can occur during preparation of the flap . These can include failure to prepare a flap of the
correct diameter, thickness, or shape; slippage or dislocation
of the flap after surgery; and infections of the flap.
With the exception of infections, flap complications can typically
be treated without significant visual loss, and the risk of
infection has been estimated to be approximately 1/5000.
Possible Side Effects
Even though the refractive
error may be corrected and the visual acuity may be good after LASIK , some patients experience one or more of the following
side effects of the procedure:
Optical Aberrations : As
with any refractive procedure, it is common for patients to
notice halos, ghost images, shadows, and slight distortions
for the first months after surgery. In unusual circumstances,
these optical aberrations may interfere with normal visual
activities.
Night myopia : Because only the central portion of the cornea is reshaped, eyes may become more nearsighted when the pupil dilates and allows light to enter through the peripheral
cornea that had not been reshaped. Even if excellent unaided
vision is obtained during the daytime, a thin pair of glasses
may be required at night for optimum vision.
Dry Eye : During the healing
process, your eye may feel dry, and you may need to use artificial
tear replacement for comfort temporarily.
Discomfort : Most of the
discomfort following LASIK occurs within the first 24 hours and can easily be controlled
with Tylenol or similar mild pain relievers. The eyes may
be transiently more sensitive to sunlight following surgery.
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