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I. Introduction
Laser in-situ keratomileusis, or
LASIK, the most commonly performed type of laser surgery,
is generally a safe and effective treatment for a wide
range of common vision problems. Specifically, LASIK
involves the use of a laser to permanently change the
shape of the cornea, the clear covering of the front
of the eye. LASIK is a quick and often painless procedure,
and for the majority of patients, the surgery improves
vision and reduces the need for corrective eyewear.
However, as LASIK is a surgical procedure conducted
on a delicate part of the eye, it is crucial that potential
candidates are well educated on the benefits and risks
of the procedure, understand the importance of a thorough
screening by their physician, and maintain realistic
expectations about the procedure’s outcome.
II. Patient
Profiles:
Who is Right for Laser Eye Surgery?
While many individuals are considered
good candidates for LASIK, there are some who do not
meet the generally accepted medical criteria to ensure
a successful laser vision procedure. Individuals that
are not deemed good candidates with conventional LASIK
may be able to have the surgery in the future, as technology
advances and new techniques are refined. Anyone considering
laser eye surgery must have a thorough examination by
an ophthalmologist that will help determine whether
or not LASIK is right for them. Recently, an important
new "wavefront" technology has been approved
by the U.S. Food and Drug Administration. It is helping
physicians to determine more accurately the appropriate
course of treatment during the prescreening phase by
providing comprehensive diagnostic information about
each individual eye.
Based on various conditions and
circumstances, all LASIK candidates will fall into one
of the following three broad categories.
The Ideal LASIK Candidate
The ideal candidate includes those who:
• Are over 18 years of age and have had a stable
glasses or contact lens prescription for
at least two years.
• Have sufficient corneal thickness (the cornea
is the transparent front part of the eye).
A LASIK patient should have a cornea that
is thick enough to allow the surgeon to safely
create a clean corneal flap of appropriate depth.
• Are affected by one of the common types of vision
problems or refractive error – myopia
(nearsightedness), astigmatism (blurred
vision caused by an irregular shaped cornea),
hyperopia (farsightedness), or a combination
thereof (e.g., myopia with astigmatism). Several lasers
are now approved by the U.S. Food and Drug Administration
(FDA) as safe and effective for use in LASIK, but the
scope of each laser’s approved indication
and treatment range is limited to specified
degrees of refractive error.
• Do not suffer from any disease, vision-related
or otherwise, that may reduce the effectiveness
of the surgery or the patient’s ability
to heal properly and quickly.
• Are adequately informed about the benefits and
risks of the procedure. Candidates should
thoroughly discuss the procedure with their
physicians and understand that for most
people, the goal of refractive surgery should be
the reduction of dependency on glasses and contact lenses,
not their complete elimination.
The ‘Less Than Ideal’
LASIK Candidate Sometimes, factors exist
that preclude a candidate from being ideal
for LASIK surgery. In many cases, a surgeon
may still be able to perform the procedure safely, given
that the candidate and physician have adequately discussed
the benefits and risks, and set realistic expectations
for the results. Candidates in this category include
those who:
• Have a history of dry eyes, as they may find
that the condition worsens following surgery.
• Are being treated with medications such as steroids
or immunosuppressants, which can prevent
healing, or are suffering from diseases
that slow healing, such as autoimmune disorders.
• Have scarring of the cornea.
More often, factors exist that may keep an individual
from being a candidate immediately, but do not preclude
the individual from being a candidate entirely. Candidates
in this category include those who:
• Are under age 18.
• Have unstable vision, which usually occurs in
young people. Doctors recommend that, prior
to undergoing LASIK, candidates’ vision
has stabilized with a consistent glasses
or contact lens prescription for at least two
years.
• Are pregnant or nursing.
• Have a history of ocular herpes within one year
prior to having the surgery. Once a year
has passed from initial diagnosis of the
disease, surgery can be considered.
• Have refractive errors too severe for treatment
with current technology. Although FDA-approved
lasers are available to treat each of the
three major types of refractive error –
myopia, hyperopia and astigmatism – current
FDA-approved indications define appropriate
candidates as those with myopia up to -12 D, astigmatism
up to 6 D and hyperopia up to +6 D. However, laser
eye surgery technology is evolving rapidly, and doctors
may be able to treat more severe errors in the future.
The Non-LASIK Candidate
Certain conditions and circumstances completely preclude
individuals from being candidates for LASIK surgery.
Non-candidates include individuals who:
• Have diseases such as cataracts, advanced glaucoma,
corneal diseases, corneal thinning disorders (keratoconus
or pellucid marginal degeneration), or certain other
preexisting eye diseases that affect or
threaten vision.
• Do not give informed consent. It is absolutely
necessary that candidates adequately discuss
the procedure and its benefits and risks
with their surgeon, and provide the appropriate
consent prior to undergoing the surgery.
• Have unrealistic expectations. It is critical
for candidates to understand that laser eye surgery,
as all surgical procedures, involves some
risk. In addition, both the final outcome
of surgery and the rate of healing vary from person
to person and even from eye to eye in each individual.
III. Pre-LASIK
Testing: What Types of Exams Should
Patients Expect?
Anyone considering LASIK should undergo a thorough
examination by an eye care professional. The exam, and
a follow-up consultation with the physician, can also
identify ongoing health concerns that may affect the
candidate’s vision in the future,
inform the candidate of potential outcomes
of LASIK, frame expectations for what the
procedure can do, and inform the candidate of his or
her vision health status.
Listed below are the tests that should be routinely
performed before a final decision is made to proceed
with surgery. Additional testing, depending on the special
needs of the candidate, may also be appropriate. For
example, some physicians may opt to use wavefront technology,
which is described in more detail on this Web site.
If, after an evaluation, a patient has
questions about why a test was included
or omitted, he/she should discuss the matter
with the eye care professional in question. Certainly
a patient can and should question why a
test was omitted. The patient should be
satisfied with the explanation before proceeding.
Assessment of Eye Health History
• History of wearing glasses: It is important to
determine if a candidate’s vision
has stabilized or is changing. If it is
unstable, LASIK may not be appropriate at this time.
The ideal candidate is at least 18 years
of age with a stable glasses or contact
lens prescription for at least 2 years.
• History of contact lens wear: Contact lenses
may change the shape of the cornea (the
clear front surface of the eye) or act
in such a way as to prevent the ophthalmologist
from determining a candidate’s correct prescription.
Most ophthalmologists require that soft
contact lenses be discontinued at least
3 days and rigid contact lenses 2 to 3
weeks prior to the evaluation. If concern arises about
contact lens-induced changes in the cornea, it may be
necessary for a candidate to stop wearing contacts for
as long as several months to allow the
cornea to return to its natural contour, so that a surgical
evaluation can be made.
• History of ocular or systemic diseases and medications:
Some eye diseases and medications can affect the suitability
of a candidate for LASIK.
• History of previous ocular problems such as lazy
eyes, strabismus (eye misalignment caused
by muscle imbalance), or the need for special
glasses to prevent double vision.
• History of previous eye injury.
• Assessing vocational and lifestyle needs: The
LASIK candidate’s work or recreational
activities and needs can influence vision
correction strategies. For example, different
strategies can affect depth perception and the ability
to see near or far.
A Comprehensive Examination of the Eye
• Determination of uncorrected vision and vision
as corrected by glasses or contacts.
• Determination of the magnitude of visual error
in each eye to establish the amount of
surgical correction that is needed and
develop the appropriate surgical strategy.
• Assessment of the surface of the cornea by “mapping”
its topography (corneal curvature or shape), to correlate
its shape to errors in focusing (correlate corneal shape
to refractive astigmatism), to find irregularities,
if any, and to screen for disease states
that may produce poor outcomes with LASIK.
• Measurement of pupil size in dim and room light.
Pupil size is an important factor in counseling
a candidate about night vision and planning
the appropriate laser vision correction
strategy.
• Assessment of motility to measure the ability
of the muscles to align the eyes.
• Examination of the eyelids to see if they turn
inward (possibly scratching the cornea)
or outward and redirect tear flow away
from the eye, and other conditions.
• Examination of the conjunctiva, the transparent
membrane that covers the outer surface
of the eye and lines the inner surface
of the eyelids, to see whether there are irritations,
redness, irregular blood vessels or other abnormalities.
• Examination of the cornea to determine if there
are any abnormalities that could affect
the outcome of surgery.
• Examination of the crystalline lens to determine
if clouding of the lens (cataract) or other
abnormalities are present.
• Measurement of corneal thickness (pachymetry).
The amount of LASIK correction may be determined
in part by corneal thickness.
• Measurement of intraocular pressure to detect
glaucoma or pre-glaucomatous conditions.
Glaucoma is a visual loss caused by damage
to the optic nerve from excessively high
pressures in the eye. It is a common cause of preventable
vision loss.
• Assessment of the back (posterior segment) of
the eye: The dilated fundus exam is used
to assess the health of the inside back
surface of the eye (retina), with the pupil
fully open. Examination of the retina, optic nerve,
and blood vessels screens for a number
of eye and systemic disorders.
• Follow-up should include review of examination
results by an ophthalmologist, discussion
with the candidate, additional testing
as necessary, and adoption of a plan for
managing the candidate’s eye-care needs.
IV. Realistic
Expectations: Why Are They Central to Patient Satisfaction?
The overwhelming majority of patients who have had
LASIK surgery are fully satisfied with their results
– having experienced the significant
benefits of improved vision. However, as
with any medical or surgical procedure,
for certain patients the outcome of the procedure
may not seem “ideal” or meet all of his/her
expectations. A small minority of patients
may also experience complications. Therefore,
it is crucial that LASIK surgery candidates
thoroughly discuss the procedure — its benefits,
risks and probable outcomes — with their physician
prior to undergoing the surgery. Each patient
should be fully informed and feel comfortable
that they are making an educated decision
based upon facts. Candidates should be
aware that:
• LASIK cannot provide perfect vision every time
for every patient. However, for the majority
of LASIK candidates, the surgery improves
vision and reduces the need for corrective
eyewear. In fact, the vast majority of patients with
low to moderate nearsightedness achieve 20/40 vision
or better, and many can expect to achieve 20/20 vision
or better.
• Re-treatments (enhancements) may be required
to achieve optimal outcomes. Fortunately, it is possible
to repeat the laser treatment by lifting
the flap, typically about three months
after the original procedure. Even after
enhancements, vision after LASIK may not be as
good as it was with glasses or contact lenses before
the procedure.
• There may be visual aberrations after LASIK—most
commonly, glare and halos under dim lighting
conditions. Usually, these are not significant,
and resolve within several months of surgery.
Occasionally, they are severe enough to
interfere with normal activities.
• Those who undergo wavefront-quided LASIK should
be aware that, while the ability to customize LASIK
to each individual's eye offers the potential for improved
vision quality, it does not guarantee "super vision."
Wavefront technology adds a new level of precision to
an already safe and effective procedure, but just as
with conventional LASIK, complications are possible.
• Monovision is a technique in which one eye is
corrected for distance vision and the other
is left nearsighted to focus on near objects
without glasses. Today, it is the only
way that LASIK candidates older than about 45 years
can avoid reading glasses. LASIK will not
cure presbyopia, the aging changes that
prevent older people from seeing near objects
through the same glasses that they use for viewing
distant objects.
• LASIK surgery, as all surgical procedures, has
the risk of complications. Fortunately,
the likelihood of visual loss with LASIK
is very small. In the many millions of LASIK
procedures done so far, less than one percent of patients
have experienced serious, vision-threatening problems
(defined as the loss of two or more lines of best spectacle
corrected visual acuity on the Snellen Eye Chart for
six months or more). Most complications
represent delays in full recovery and resolve
within several months of surgery.
V.
Initiating A Dialogue: What Should I Ask My Doctor?
The decision to have LASIK should be an informed one,
made in close consultation with an eye care professional.
In order to understand whether LASIK is right for them,
patients considering the procedure should ask the following
questions:
• What type of testing will you do in order to
determine whether or not I’m a candidate
for LASIK?
• Has my glasses or contact lens prescription been
consistent for at least two years?
• Does my nearsightedness, farsightedness or astigmatism
fall within the accepted levels established for surgery
by the FDA?
• Are my corneas thick enough to perform LASIK
surgery?
• Do I have cataracts, glaucoma or other corneal
diseases?
• Are my corneas scarred?
• Do I have any diseases that would affect the
outcome of the surgery or my ability to
heal properly?
• Are there any other reasons why I may not be
a candidate for LASIK surgery?
• Will you be using wavefront technology during
my prescreening and treatment? Why or why not?
• Am I at risk for complications?
• What can I expect during the procedure?
• What outcome can I expect from the surgery?
The
Eye Surgery Education Council
The Eye Surgery Education Council (ESEC) is an initiative
established by the American Society of Cataract and
Refractive Surgery (ASCRS), a professional society of
ophthalmologists dedicated to raising the
standards and skills of surgeons who operate
on the anterior (front) segment of the
eye through clinical education. ASCRS also works with
patients, government, and the medical community to
promote delivery of quality eye care.
The ESEC, which is committed to helping
patients make informed decisions about
undergoing eye surgery, has two missions --
to provide patients with accurate, accessible information,
and to promote active physician/patient discussion
about the benefits and risks of eye surgery procedures.
The information provided in these patient guidelines
is intended to provide educational information and is
not intended to establish a particular
standard of care, provide an exhaustive discussion
of the subject of laser eye surgery, or serve as a
substitute for the application of the individual physician’s
medical judgment in the particular circumstances presented
by each patient care situation.
Candidates and prospective candidates for laser eye
surgery should likewise understand that the information
provided in these guidelines is educational in nature
and is not intended to serve as a substitute
for medical advice. The decision whether
to undergo laser eye surgery must be made
by each individual based on the relevant facts
and circumstances acting in consultation with a qualified
eye care professional.
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