LASIK
(Laser Assisted In-Situ Keratomileusis)
LASIK (Laser assisted
in-situ keratomileusis) is a refractive surgical procedure that results in rapid
recovery of vision and has the capability to benefit patients with nearsightedness,
farsightedness, and astigmatism by reducing dependence on eyeglasses and contact
lenses. Millions of people worldwide have already undergone this exciting and
marvelous procedure. Nearly a million people in the U.S. underwent LASIK in 1999
and approximately 1.3 million underwent the procedure in 2000. The great majority
of individuals who wear glasses or contacts may now benefit from LASIK. Candidates
must be at least 18 years of age.
LASIK is a procedure
in which the eye surgeon creates a thin surface flap of the cornea using a microkeratome
to expose underlying tissues (stromal bed). It is within the deeper layers of
the cornea that the surgeon then applies the Excimer laser beam to create the
refractive ablation. This reshapes the cornea using the extraordinary precision
of the Excimer laser. The laser is programmed prior to
each procedure for the ablative "cut" based on the patient's pre-operative
refractive error (nearsightedness, farsightedness, and astigmatism). Once the
laser ablation is completed, the surgeon gently replaces the corneal surface flap
to restore surface integrity of the eye. It's as if the refraction is "ground
in" to the middle layers of the cornea! The results are often dramatic and
very rapid, with most patients seeing well enough to drive a car without correction
the very next day. However, the best post-operative visual acuity may not be obtained
until 2 to 3 weeks, or in some cases, even a few months, after the procedure. Visual
Results with LASIK LASIK nearly always
results in improved vision without correction. However, LASIK is an imperfect
procedure, and does not always result in 20/20, or even 20/40 visual acuity. The
large majority of patients can expect to see well without glasses or contact lenses,
however, those patients with the highest degrees of refractive error (above -7.0
D myopia and 3 to 4 D astigmatism) should reduce their expectations for the procedure.
The CRS-USA LASIK Study results, presented at the April
1999 American Society of Cataract and Refractive Surgery Annual Meeting, give
us substantial data on which to rely for outcomes with LASIK patients. In this
study, distinguished refractive surgeons J. Charles Casebeer, M.D. and Guy M.
Kezirian, M.D. presented results from 1,736 eyes with myopia and myopic-astigmatism
that underwent LASIK. They showed that approximately 87% of eyes that had LASIK
had 20/40 or better visual acuity one month postoperatively. That figure rose
to 89% at 3 months and 93% at 6 months postoperatively. The study showed that
45% of patients were 20/20 or better just one month postoperatively, with that
figure rising to 50% by 6 months following surgery. It
is very important to note that patients with extreme degrees of myopia (up to
-14.0 diopters) and astigmatism (up to 6 diopters) were included in this study,
as patients in the extreme range of myopia generally have less favorable outcomes
with LASIK. To put these levels of refractive error into perspective, one need
only realize that 54% of the nearsighted population has only -3.0 diopters of
myopia or less. CRS-USA
LASIK Study Results | | Post-Op | 1
month | 3 months | 6 months | | 20/20
or better | 45% | 46%
| 50% | | 20/40
or better | 87% | 89%
| 93% |
Indications
for the LASIK Procedure
1. Appropriate Levels of Nearsightedness, Farsightedness,
or Astigmatism
2. Relative Intolerance of Glasses or Contact Lenses
3.
Properly Motivated and Realistic Patient LASIK may
be used to treat nearsightedness (myopia), farsightedness (hyperopia), and astigmatism.
However, not all Excimer lasers are presently FDA approved to treat all three
types of refractive errors. For example, some Excimer lasers are not yet FDA approved
to treat farsightedness. Your surgeon can provide this information to you at your
request. LASIK is an elective procedure which, like
any procedure, has potential risks and benefits. In general, indications for surgery
must include an appropriate level of nearsightedness, farsightedness, or astigmatism,
as well as an educated and properly motivated patient with realistic expectations.
The best candidate for LASIK is an individual who desires to be less dependent
on glasses or contact lenses, is willing to accept the risks of the procedure,
and understands that an enhancement procedure may sometimes be required. The
primary potential risks include postoperative glare, halos or starburst around
lights at night, and infection in the cornea with loss of best corrected visual
acuity. Fortunately, risks that threaten vision in the eye, such as infection
in the cornea, are very rare. LASIK
Pre-Operative Evaluation Patients who wear soft
contact lenses or rigid gas-permeable contact lenses should discontinue their
contact lens wear at least 3 days or 3 weeks prior to the evaluation, respectively.
Prior to the LASIK procedure, one or more careful refractions (determinations
of eyeglass correction needed) will be completed. Contact
lens wearing patients who are believed to have an unstable refraction will be
asked to discontinue contact lens wear and return for a repeat refraction in one
to three weeks. When back-to-back refractions are stable (equivalent), the procedure
may be scheduled. Corneal topography, or a detailed surface map of the cornea,
will also be completed to rule-out keratoconus and irregular astigmatism of the
cornea. A complete and thorough eye examination including determination of eye
pressure, slit-lamp examination, and dilated retinal evaluation will be completed.
The LASIK Procedure The
LASIK procedure is completed under topical (eye drop) anesthesia and is typically
entirely painless during and after the procedure. A few minutes prior to the procedure,
anesthetic eye drops will be applied to numb the eye and prevent discomfort during
the procedure. A speculum is placed to hold the lids apart, thereby preventing
blinking during the procedure. The surgeon places a ring on the surface of the
eye designed to hold the eye steady and increase the pressure in the eye. A microkeratome
is utilized to create a thin flap of the corneal surface. The surface flap is
gently folded to one side in preparation for the laser refractive "cut."
The laser, being computer driven for accuracy and precision, is programmed based
on the patient's refractive error (nearsightedness, farsightedness, astigmatism).
The laser delivery is completed next, and takes less than
one minute for most patients. Laser delivery may take slightly longer for patients
with hyperopia (farsightedness). Finally, the surface flap is returned to its
original position restoring the surface integrity of the eye. The surgeon will
often observe the eye under the laser microscope for up to 5 minutes to be certain
the flap is securely in position. The speculum is removed and the patient may
typically leave the laser center within the hour. Many patients now have both
eyes treated with LASIK on the same day.
The
surgeon uses a microkeratome to create the flap. The flap is then positioned to
one side of the corneal "bed" as the Excimer laser beam (left) is applied.
The broad beam Excimer laser widens the treatment
zone as the procedure progresses.
The laser beam ablation nearing completion as the edge of the laser beam
approaches the borders of the flap.
The laser ablation is complete and the flap is being replaced. Once The flap
is returned to preoperative position, the surgeon carefully checks and rechecks
the flap to be certain it is secure and well-positioned.
Postoperative
Management Post-operatively, most patients will
be instructed to use antibiotic and anti-inflammatory eye drop medications for
3 to 7 days. A shield is usually worn over the operated eye while sleeping for
the first few days or week following surgery. The patient is also typically instructed
to avoid rubbing the eye for the first few weeks following surgery. Post-operative
visits are typically minimal, but vary widely from one surgeon to another. Most
patients will only require one to three post-operative evaluations, which take
place in the first six months following surgery. Patients who are over-corrected,
or under-corrected, may require an "enhancement," utilizing a procedure
similar to the initial LASIK. Depending on the chosen time frame for an enhancement
(when necessary), the surgeon may elect to lift the original flap or create a
new flap with the microkeratome. Q. What to Expect After
LASIK Surgery A. Your eye or eyes (if both are
treated) will likely be quite blurry immediately after your LASIK surgery. Do
not be alarmed. This is natural and expected. You will likely awaken the next
morning after your LASIK surgery with much improved vision. Your vision should
also improve over the first two to three weeks following surgery. It is best to
carefully protect your operated eyes with shields or goggles while sleeping during
the first week or as your surgeon advises. Also, be sure to use the eye drop medications
in the manner that your surgeon prescribes. Be very cautious not to rub your operated
eyes for the first month after surgery, as this may cause the flap to dislocate.
In general, after the first few days, it is very unlikely that you could dislocate
your flap by rubbing your eye, but be cautious nevertheless.
LASIK patients do not generally have any postoperative
discomfort. If your eye begins to hurt or your vision deteriorates
rather than improves, contact your surgeon immediately. We now
know that dry eye syndrome commonly follows LASIK procedures,
at least transiently. This may make your eyes burn, sting, feel
dry or gritty, or even blur your vision. Many surgeons advise
using non-preserved artificial tears for the first few weeks after
LASIK. Other surgeons are now recommending placement of tiny tear
duct plugs preoperatively to help prevent the complications of
dry eyes following LASIK. Tear duct (punctal) plugs are tiny silicone
plugs that may be simply and conveniently placed in one or more
of the tear drainage ducts to prevent drainage of tears out of
the eye via that duct. The plug can just as easily be removed
at a later date if too many tears seem to be present or if for
any other reason the plug is not desirable.
Type
of the Refractive Surgery | 
