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What if LASIK is
not the best procedure for me?Can I wear contact lenses
after surgery if I want to?
What causes nighttime side effects?
And what can be done to help it they occur?
What if these effects occur? What
can be done?
How long will the results of surgery
last?
What keeps the flap in position?
Can I lose my corneal
flap?
One Eye or Two at a Time?
What is the percentage chance of
certain complications occurring?
LASIK FREQUENTLY ASKED QUESTIONS
 A:During
your examination, we gather important information
regarding the health of your eye, including various
measurements regarding your prescription, your
pupil size and the shape and thickness of your
cornea. Our goal is to help you select the procedure
which will have the highest chance of getting
you to your goal of clear vision without glasses,
while at the same time having the least risk possible
of any complications.
Some patients have corneas that are thinner than
average, and, depending on the amount of correction
needed in these cases, a LASIK procedure could
be riskier than in a patient with a cornea of
normal thickness. With LASIK, a flap is created
and lifted aside, and the laser is used to sculpt
the exposed corneal bed, which is usually 130-180
microns deeper into the cornea from the surface.
The laser sculpts the cornea by vaporizing corneal
tissue. So, the laser will make the cornea thinner
than it was. If the thickness of the corneal bed
is reduced too much with LASIK, a complication
known as "ectasia" can occur, which
is a destabilization of the cornea, causing high
levels of nearsightedness, astigmatism and possibly
cornea irregular curvatures to result. This is
something which needs to be avoided. The amount
of corneal tissue vaporized with the laser depends
on the degree of correction being attempted, and
the treatment zone diameter programmed into the
laser. Bigger treatment zones are helpful in reducing
nighttime side effects, but they do go deeper
into the cornea.
 Patients
with thinner corneas might be better off with
a procedure other than LASIK. A procedure which
does not create a flap would give us more cornea
to work with, to enable a more complete correction
and/or a bigger treatment zone diameter. There
are surface treatments available, known as LASEK
or PRK. These techniques are extremely similar.
They involve removing the very surface layer of
the cornea, known as epithelium (usually about
50 microns thick), then lasering the exposed corneal
bed. This way, the laser is not vaporizing tissue
as deep in the cornea as with LASIK, and the risk
of ectasia is lowered. With LASEK, a form of alcohol
is applied to the cornea, which loosens (and kills)
the surface epithelium. After the laser part of
the procedure, the layer of dead and dying epithelial
cells is replaced over the treated area to act
as a bandage, and a contact lens is placed over
that. Much of the healing involves the regeneration
of new epithelium cells, over the course of a
week. With PRK, no alcohol is used, and the surface
epithelial cells are removed with a soft brush.
After the laser treatment, as with LASEK, a disposable
contact lens is placed on the eye, without replacing
the damaged epithelial cells. New epithelium regenerates
naturally, over two to three days. Both techniques
are effective, however I have found that the alcohol
used with LASEK causes significant inflammation
and delayed recovery of vision. In other words,
patients seem to see and recover more quickly
with PRK, without trying to salvage the surface
epithelium cells.
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 A:
It is very uncommon that someone would want
or need to wear contacts after surgery. Most patients
do not need any correction, and those who do usually
just need part-time correction for things like
night driving. Rarely will someone want to wear
contacts versus glasses for activities like this.
If full-time glasses or contacts is needed after
surgery, usually a retreatment can be done to
improve the vision and reduce the need for use
of glasses. In the rare case that someone wants
to wear contacts after surgery, usually they can
without any trouble (assuring they could wear
contacts prior to surgery). There is always the
outside possibility that a contact would not fit
well, but this is rare.
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A: Nighttime side effects include blurring
at night, glare, and starburst and halos around
lights. There are several things that can cause
these effects. Residual nearsightedness, farsightedness,
and astigmatism can cause these problems. If this
is the case, glasses at night, or more surgery
may help.
Another possible cause has to do with the size
of the pupil and the shape of the treated cornea.
In low light, the pupil inside the eye dilates
to allow more light into the eye. When the pupil
dilates, the light coming into the eye is focused
by a larger area of the cornea than when the pupil
is small. If light is being focused by more peripheral
areas of the cornea that have not been reshaped
by the laser, optical aberrations can cause these
night effects. The best bet is to reduce the risk
of this occurring by using a laser which can reshape
a large area of cornea, or to avoid treating patients
with very large pupils if a large treatment zone
cannot be done.
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A: There are medication eyedrops that can
be used to constrict the pupil at night. These
will reduce glare, starburst and halos, but they
will also cause less light to be allowed into
the eye, usually giving murky or washed out night
vision. One problem is traded for another, and
usually this is not a viable solution. In some
patients, though, it may be helpful. Similarly,
some patients find that turning on the light inside
the car causes just enough pupillary constriction
to eliminate annoying night effects.
 Treatments
which are not centered properly over the cornea
can also lead to severe nighttime side effects.
This is usually easily avoided by a skilled surgeon.
This trouble, if it occurs, is extremely difficult
to fix. Future techniques like custom corneal
sculpting (custom LASIK) may be the best solution.
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A: LASIK has been done since 1991, with
generally stable results. Beyond this length of
time, we do not know. It is important to realize
that your eyes still can change as you age, causing
a need for glasses or contacts. Some people may
become nearsighted or farsighted again over time,
though most seem not to. If your eyes are very
unstable (i.e. still changing rapidly) prior to
surgery, this may continue after surgery. You
may decide to wait until your eyes are more stable
to have the surgery, if this is the case. If there
are changes down the road after you do have LASIK,
it is usually easy to have more surgery to adjust
the vision. In some cases, this will not be an
option.
We do know that as people reach their early 40's
they develop presbyopia, and begin to need reading
glasses.
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A: There are several things occurring that
keep the flap in position without stitches. Initially,
there is a vacuum effect created by the cells
lining the inner surface of the cornea. These
cells, known as endothelial cells, function as
a pump to move fluid (water) from within the substance
of the cornea into the inner part of the eye.
This suction type of force initially holds the
flap in position. As the eye heals over the first
day or two, the outer surface of the cornea, known
as the epithelium, seals the edges of the flap.
Over weeks to months, natural substances in the
cornea help bond the flap to the underlying cornea.
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A: With a flap there is a hinge, which
attaches the flap to the rest of the cornea. There
is no chance of losing a corneal flap. A corneal
flap can be DISPLACED if the eye is rubbed shortly
after surgery. This would require repositioning
of the flap in the operating room. Rarely (roughly
1 in 1,500 cases), there will be no hinge and
the microkeratome will cut a free cap. A free
cap CAN be lost, if you rub your eye too hard
shortly after surgery. If a free cap is created
at the time of surgery, the laser part of the
procedure will be done, the cap will be replaced
on the eye, and you will be notified of this occurrence
so that you can be sure to take extra precautions
in the postoperative healing period to reduce
the risk of losing the free cap. Please note that,
as recently as 1994, this type of surgery was
done without any hinge-ALL cases had free caps.
It was extremely rare for any of these patients,
in those days, to lose their corneal cap.
Even if the corneal cap were to be lost, this
would probably not be as disastrous as it sounds.
The cornea would overall be somewhat thinner,
and there would be a chance of scarring, but overall
the vision would likely be quite good. It is possible,
but unlikely, that a corneal transplant would
be needed. Nevertheless, this is a complication
we wish to avoid.
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A: Ultimately this choice is up to you,
the patient. There are theoretical advantages
and disadvantages each way. Basically, two issues
arise. One, is there a MORE ACCURATE RESULT when
the eyes are done separately? In other words,
do we learn something from the outcome of the
first eye which we can apply to the second eye
to increase the chance of a perfect result? And
secondly, is it SAFER to do the eyes separately?
In answering the first question regarding accuracy,
a study done at Emory University in Atlanta a
few years ago demonstrated NO increase in accuracy
if the eyes are done separately. Each eye can
respond slightly differently, and any over or
undercorrection in the first eye does not predict
a similar response in the second eye.
 With
regard to the second question concerning safety,
what we are worried about is a complication occurring
which is not apparent at the time of the surgery,
but which appears a few hours or days later, and
which can occur in both eyes at once if both eyes
were treated. An infection is one such complication.
If an infection occurs, it usually will occur
within the first two or so days postoperatively.
An infection in both eyes, if severe, can lead
to scarring, loss of vision, and even a need for
a corneal transplant. Obviously, this is a situation
we wish to avoid. Fortunately, the risk of an
infection occurring in even just one eye is remote,
but not zero. The risk is on the order of one
in 5,000 to one in 10,000 cases. Additionally,
most (but not all) infections are treatable and
do not cause visually significant scarring. An
analogy can be made with contact lenses. Contact
lenses can cause corneal infections, scarring
and loss of vision, especially extended wear contacts.
The risk is fairly low. People generally wear
contact lenses in both eyes, and they do take
an extremely small risk of getting infections
in both eyes at once, which can cause some loss
of vision. They take this risk because it is astronomically
small.
The advantage of doing both eyes at once is several
fold. First, you will only be taking the medications
used before, during, and after surgery just once.
Any medication has some degree of risk of side
effects and, generally speaking, if we can minimize
your use of medications, that is beneficial. A
second advantage is minimizing the number of office
visits necessary for surgery and follow up care.
This is certainly a convenience issue, and bear
in mind that the decision to have one eye at a
time or both at once should not be made simply
out of convenience. There may be more to minimizing
visits than simply convenience. A statistical
analysis of risk presented in 1999 at one of our
annual eye surgery meetings showed a higher risk
of being injured or killed in a car accident while
traveling to or from the doctor's office than
risk of loss of vision in both eyes from infection
caused by surgery. The point here is that there
is risk inherent in almost anything we do. If
the risk is acceptably small, then it makes sense
to accept that risk. Most of our patients choose
to have both eyes treated at once and I, as a
surgeon, am very comfortable with that. Some of
my patients elect to do the two eyes separately,
and that is perfectly acceptable. Ultimately,
it is up to each person to decide which way they
would like to have the surgery done.
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A: Various complications have different
risk frequencies associated with them. Below is
a list of certain complications and their corresponding
risk frequencies.
Free corneal cap - 1 case in 1,500 (note:
a free cap does NOT mean a lost cap)
Thin, short or irregular flap - 1 case
in 1,000. If this occurs, the proper way to proceed
is to stop the surgery and NOT perform any laser
treatment. The flap is replaced into position,
the eye is allowed to heal and the surgery is
repeated a few months later. Proceeding with the
laser part of the treatment in a case where the
flap is not of perfect quality can lead to disastrous
results.
Epithelial ingrowth - 1 case in 300. This
occurs when the surface layer of the corneal flap,
composed of cells called epithelium, sneak under
the edge of the flap and grow in the interface
underneath the flap. They are normal cells growing
in a place they shouldn't be. Treatment is observation
if mild and, for more severe cases, surgically
lifting the flap, removing the cells, and replacing
the flap.
Diffuse interface inflammation (a.k.a. "Sands
of the Sahara") - 1 case in 500-1,000.
This is an inflammatory reaction in the interface,
underneath the flap, which typically occurs one
to three days postop. It can cause blurring, redness,
and discomfort. It is NOT an infection. Cause
is unknown, and treatment is with frequent use
of steroid eyedrops. Most cases resolve without
incident. Severe cases, which are even more rare,
can cause corneal scarring.
Irregular astigmatism - 3 cases in 1,000,
for average levels of correction. May increase
to 3 cases in 100 for very high levels of correction
(above 9 diopters). This is an irregularity in
the curvature of the cornea which can cause blurriness.
This blurring can NOT be corrected with glasses,
or with current laser technology. It nearly always
CAN be corrected with a contact lens, and hopefully
with future laser technologies like "custom-LASIK."
The blurring is usually, but not always, subtle.
Most patients with irregular astigmatism still
see 20/40 or better in the eye with the irregularity.
The irregularities in curvature are microscopic,
and can occur even in perfectly executed surgery.
The risk of irregular astigmatism increases with
novice surgeons, and can be increased with improperly
assembled equipment, microkeratome blade irregularities,
reused microkeratome blades, improperly calibrated
lasers, poorly centered treatments, and generally
poor surgical technique.
Flap wrinkles or striations - 1 case in
1,000. Can cause irregular astigmatism. Poor surgical
technique can increase the chance of this occurring.
Can occur if flap is not repositioned properly
at the time of surgery, or can occur if you rub
your eye too hard during the initial healing period
(first few weeks to one month). Treatment is to
lift the flap, smooth out, and reposition. This
is usually done only if the striations are affecting
the vision. It is possible to have wrinkles or
striations which are not affecting vision -- these
are best left alone.
Dry eye - Unclear what the exact risk
is. The majority of patients do experience dryness
after LASIK, which tends to resolve in most but
not all patients over several weeks to months.
I estimate the risk of permanently drier eyes
to be in the 5% range. Treatment is with artificial
teardrops. Risk is lower with a nasel flap compared
to a superior hinge.
Glare, halos and starburst - Risk depends
on many factors, but overall estimate is 5-10%.
As with dryness, most patients experience these
nighttime side effects and they tend to resolve
in most but not all patients over a period of
weeks to months. In some cases, they can continue
to improve over a year postoperatively. The risk
of these side effects depends on the amount of
correction being done (larger corrections have
higher risk), pupil size (larger pupils have higher
risk), treatment zone size used (smaller treatment
zone diameters have higher risk), surgeon skill
in centering the treatment (better centered treatments
will have less risk), and patient cooperation
(it seems that patients who focus on the light
better tend to have less risk). Most patients
who experience permanent increase in nighttime
side effects report them as mild, and usually
are not impaired by the side effects.
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