LASIK Candidacy

1/9 | http://www.docshop.com/education/vision/refractive/lasik/candidacy
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BY
Francis Clark, MD
SENIOR SECTIONAL EDITOR
updated March 12, 2015
Source:
http://www.docshop.com/education/vision/refractive/lasik/candidacy
Generally speaking, candidates for LASIK (laser-assisted in situ
keratomileusis) surgery are those who:
Are nearsighted, farsighted, or have astigmatism
Wish to reduce or eliminate the need for corrective eyewear
Are at least 18 years of age
LASIK Candidacy

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Are in good overall health
Have adequate corneal thickness
Have a stable corrective eyewear prescription
Are not pregnant or breastfeeding
Do not have glaucoma, or have highly controlled glaucoma
Are taking aggressive measures to control dry eye syndrome, or have
been rehabilitated following a diagnosis of dry eye syndrome.
However, as with any medical procedure, there are no absolutes, and
the only way to accurately determine whether a patient is an
appropriate candidate for LASIK is to undergo an in-depth evaluation by
an eye care professional. Today, we are all well aware of the life-
changing benefits that many have experienced as a result of this
sophisticated refractive surgery. As anyone who has worn glasses or
contacts can tell you, the idea of being able to depend on your own eyes
is appealing, to say the least.
For the right patient, LASIK can make freedom from corrective eyewear
a reality. During initial consultations, my staff will spend at least 90
minutes or more asking and answering questions, and getting an idea of
their expectations to make certain that they are candidates for the
procedure.
Of course, a LASIK candidate also must feel confident undergoing the
procedure. My colleague Jon Peet, M.D. says advancements in LASIK
technology have been the single greatest factor in helping to make more
patients comfortable with undergoing refractive surgery.
"Wavefront measurements (digital mapping of the cornea) and eye
tracking (a safety measure that immediately deactivates the excimer
laser if the eye moves to the slightest degree) have contributed to more
predictable outcomes, which improves patient confidence and therefore
encourages more people to seek treatment," Dr. Peet said. "Meanwhile,

this potentially drives down cost to some extent, further broadening
access."
Patient education plays a crucial role in the success of LASIK eye
surgery. If you are considering taking steps toward permanently
correcting refractive errors, it pays to become as familiar as possible
with the principles of LASIK, as well as the distinguishing
characteristics of a suitable candidate. This knowledge will allow you to
ask informed questions and play a more active role in determining if
LASIK or another procedure is the appropriate way for you to achieve
improved vision.
The LASIK Procedure
The cornea is the dome-shaped front surface of your eye. It is the point
at which light enters the eye and becomes refracted. Tiny irregularities
in the corneal surface can have a profound effect on how light is
refracted, which can result in nearsightedness (having difficulties
focusing on far objects), farsightedness (having difficulties focusing on
close objects), or astigmatism (vision at every distance is distorted).
Your glasses or contact lenses have specific contours, or correction,
that are intended to compensate for corneal irregularities, resulting in
clearer vision.
LASIK surgery is a process of using an excimer laser to vaporize small
portions of the cornea in order to refine its shape. This requires using a
special laser to create a small hinged flap in the outermost layer of the
cornea (epithelium) to expose the stroma. After reshaping the cornea,
the flap is replaced.
Because LASIK involves refining the stroma, and depends on the
corneal flap to facilitate healing, having especially thin corneas can
preclude some patients from undergoing the procedure.
Corneal Thickness
In the evolution of laser refractive eye surgery, LASIK is preceded by

photorefractive keratectomy, or PRK. PRK involves the removal of the
epithelium, rather than the creation of a flap, to access the underlying
tissue. As such, it requires a longer and less comfortable recovery
period, which prompted doctors to begin researching and developing
modern LASIK surgery. However, PRK is still commonly used to treat
some patients whose corneas are too thin to accommodate a flap.
Fortunately, technology is continuing to evolve, making it possible for
some patients with borderline corneal thickness to undergo LASIK.
Many practices, such as mine, have adopted the femtosecond laser, a
precise tool that replaces the keratome blade in creating the corneal
flap. This increased precision makes creating the corneal flap much less
invasive, so those who are not candidates for traditional LASIK may be
candidates for all-laser LASIK (sometimes called iLASIK). However, in
addition to thickness, several other characteristics of the cornea are
crucial distinguishing characteristics of a LASIK surgery candidate.
Prescription Stability
If you have had to change your corrective eyewear prescription in the
last two years, you probably should not undergo LASIK surgery at this
time. Any changes could indicate that your corneas are in a state of
flux, and that the results of LASIK surgery could potentially be short
lived. I require that patients have a stable prescription for at least two
years before moving ahead with refractive surgery.
Although vision can fluctuate at
any age, we find that patients are
most likely to have achieved
stable vision by around age 22.
While many 18-year-old patients
are anxious to achieve freedom
from glasses and contact lenses,
it is often recommended that they
wait until their mid-20s,
increasing their chances of experiencing the greatest long-term benefits
of LASIK.
Pregnancy can also cause vision to fluctuate because of the dramatic
We find that patients are
most likely to have
achieved stable vision by
around age 22

hormonal changes that take place. This is true even among patients who
have 20/20 vision. That is why I always recommend that any patient
who is pregnant, or planning to become pregnant, wait until a year after
pregnancy to undergo LASIK. By that time, the hormones have usually
returned to a normal balance that will no longer affect vision.
Meanwhile, I recommend that women who undergo LASIK avoid
becoming pregnant for at least 6 months following surgery.
While prescription stability is a major issue among younger patients
considering LASIK, patients beyond age 40 have their own unique risks
and characteristics that must be considered before moving ahead with
laser refractive surgery.
Cataracts
The crystalline lens lies behind the cornea, the colored ring of tissue
that surrounds the pupil. It focuses light upon the retina, which
generates nerve impulses that the brain eventually perceives as visual
images. The lens is composed of water and protein. For reasons that
are not entirely understood, the protein within the lens can begin to
clump, obstructing vision.
This chronic and progressive condition is called cataracts, and it
eventually requires the surgical replacement of the lens with a synthetic
intraocular lens (IOL). Your risk of developing cataracts increases
dramatically past age 40. Patients diagnosed with cataracts are not
necessarily precluded from undergoing LASIK. After a thorough
evaluation, the doctor can determine your options.
The advent of all-laser LASIK surgery has made it possible for those
who have undergone cataract surgery in the past to undergo LASIK
surgery. IOLs contain correction, and can help those who are
nearsighted, farsighted, or have astigmatism to see more clearly.
However, some patients with IOLs still require glasses. In these cases,
if a patient wishes to achieve 20/20 vision, LASIK can help them
achieve their goals.

Conversely, if a patient who has undergone LASIK eventually begins to
develop cataracts, modern cataract surgery makes it possible to replace
the crystalline lens without affecting the corneal refinements created
during LASIK.
Monovision LASIK
Monovision LASIK is a treatment that was developed to help patients
with presbyopia, a condition that usually presents after age 40, in which
the crystalline lens begins losing its ability to focus on close objects.
I often receive inquiries from professionals age 40 or older who must
spend considerable time at work reading, including educators,
attorneys, and clergy. LASIK is most effective for correcting distance
vision, but there are ways to use this treatment to help those who want
better close-up vision.
True monovision involves correcting the dominant eye for distance
vision, and correcting the other for close vision. Patients can gain an
understanding of the effects of monovision by wearing two different
prescriptions of contact lenses during a trial period. If a patient does not
find this imbalance agreeable, I may recommend modified monovision.
In this instance, I will back off a little and just preserve some reading
power in one eye, which usually satisfies the patient's desire to reduce
their need for reading glasses, but with a less pronounced difference in
focusing ability from one eye to the other.
Dry Eye Syndrome
If you do not produce enough tears to keep the eye adequately
lubricated, or if one of the layers of your tears - water, mucus, or oil - is
out of balance, it can result in constant irritation, redness, excessive
tear production, and other symptoms. Dry eye syndrome is fairly
common - in fact, more than half of the patients who approach my
practice about LASIK are unaware that they have dry eye syndrome.
They just know that wearing contact lenses is very uncomfortable.

This condition must be controlled before a patient can safely undergo
LASIK, because dry eyes can seriously impede the healing process. I
pursue dry eye diagnosis very aggressively during pre-LASIK
consultations to make certain dry eye is not missed. In some cases, the
eye can be rehabilitated through procedures that close the tear ducts.
Meanwhile, if a patient is aggressively taking care of dry eyes with
treatments like prescription eye drops, artificial tears or punctual plugs,
they may be able to safely undergo LASIK.
It should be noted that all patients will experience some degree of dry
eye following LASIK surgery. It usually corrects after a couple of
months.
Glaucoma
Aqueous humor is a fluid that maintains pressure within the anterior
chamber, the space between the lens and the cornea, which is also
occupied by the iris. Glaucoma occurs when this fluid cannot properly
drain, causing pressure to build within the eye. This pressure can
damage the optic nerve, leading to compromised vision or blindness.
Patients with controlled glaucoma may be able to safely undergo LASIK.
Occupation
Virtually anyone who wears glasses or contact lenses would probably
choose to have 20/20 vision using their own eyes. However, those in
certain professional occupations can be especially suited for LASIK eye
surgery because their jobs are easier to perform when unencumbered
by corrective eyewear. This can include technicians of all stripes, as
well as physicians and other medical professionals. LASIK can also
offer tremendous benefits for those who love to take part in outdoor
All patients will experience some degree
of dry eye following LASIK surgery

activities such as skiing and diving.
In Her Own Words: Julia's LASIK Pre-
screening
Julia is a patient of mine who recently underwent LASIK surgery. She
wasn't very familiar with the details of the procedure, so we had a lot to
review during her consultation.
"I knew nothing about LASIK prior to my consultation, so I guess you
could say I went in blind, no pun intended," she said. "All I was sure of
was that I was tired of not being able to see well, and feeling like I was
missing out on life. The consultation was informative and exciting."
As always, we conducted a battery of tests to make certain that she
was a candidate for surgery.
"Prior to meeting with Dr. Clark, I
had not considered conditions
like glaucoma or dry eye to be a
factor in candidacy," Julia said.
"The consultation was helpful in
fully explaining every aspect of
LASIK, from general procedure
information to specific details
regarding both of my eyes."
Julia was fortunate to have no issues with glaucoma or dry eye that
would preclude her from undergoing surgery.
"Preparation was easy," she said. "There were some appointments prior
to surgery in order to get proper measurements and readings. The staff
was so knowledgeable, and that made me feel comfortable. You are
given eye drops and specific instructions for their use before and after
the procedure. Dr. Clark and his staff are very clear on the entire
process, so you know exactly what to expect every step of the way."
Prior to meeting with Dr.
Clark, I had not
considered conditions like
glaucoma or dry eye to be
a factor in candidacy

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Make Sure LASIK is Right for You
LASIK has helped millions to experience a better quality of life, but it is
not suitable for everybody. If you suffer with nearsightedness,
farsightedness, or astigmatism, and would like to reduce or eliminate
your dependency on glasses or contact lenses, consult with an eye
professional. Your refractive surgeon and his staff should spend ample
time examining your medical history, asking plenty of questions about
your health and goals, and, of course, listening to your concerns and
answering all of your questions.
Advancements in medical technology have made it possible for more
men and women than ever before to safely undergo LASIK surgery.
However, if your surgeon determines that you are not a candidate, there
are alternatives that can help you reduce your need for corrective eye
wear. There is no better way to determine your candidacy for LASIK
than to select a reputable, credentialed ophthalmologist. Listen to
friends' recommendations, conduct extensive online research, and don't
be afraid to consult with more than one surgeon to determine if LASIK
is the right way to reach your goals.
References & Resources
Source:
http://www.docshop.com/education/vision/refractive/lasik/candidacy
Author: Francis Clark, MD
Publisher: DocShop

LASIK Candidacy

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