2022.1.16 改訂

LASIK・PRK：Patient InformationLASIK is a refractive surgery that reshapes the cornea to improve vision. LASIK is the acronym for
Laser in situ Keratomileusis, and it is used to correct myopia, hyperopia, and astigmatism. It is an
outpatient procedure performed by ophthalmologists.
LASIK is performed by creating a flap in the cornea and exposing the underlying cornea to a laser
beam. The cornea is then reshaped, and the flap is replaced. The procedure is generally completed
in about 15 minutes.
As with any surgery, there are risks associated with LASIK. For instance, there is the possibility ofunder- and overcorrection, necessitating additional treatments, glasses, or contact lenses after
surgery. In addition, there is also the risk of developing dry eyes and that of experiencing glare or
halos in dim light. Therefore, it is crucial that you understand the pros and cons of the procedure.

How do the Eyes Work?
As light enters the eye, it first passes through the cornea—the clear “window” of the eye. Because
the cornea is curved, the light rays are refracted. The light then passes through the pupil to the lens.
The iris—the colored portion of the eye—regulates the amount of light that enters the eye. The irismuscles contract and dilate the pupil according to the amount of light. When the light hits the curved
surface of the lens, it is refracted or bent even more so that it focuses properly on the retina. The
retina then converts the light into electrical energy that passes through the optic nerve to the brain.
This sequence may be summarized as follows:⚫

The cornea is the clear surface of the eye. Light rays are refracted as they pass through thecornea to the pupil.

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The Iris is the colored portion of the eye. It regulates the amountof light that passes through the pupil.

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The pupil is the opening at the center of the iris. Light passes
through the pupil to the lens.

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The lens refracts light to focus it correctly on the retina.

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The retina converts light energy into electrical energy, passed⚫

to the optic nerve.
The optic nerve serves as a pathway to the brain stem, whichtransfers the electrical power to the occipital lobe.

This entire process works perfectly in people with 20/20 vision. Impaired vision occurs when the
shape of the eye is irregular or when the light rays do not focus directly on the retina; theseimperfections are known as refractive errors.
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Refractive Errors
LASIK can surgically correct the most common refractive errors; nearsightedness, farsightedness,
and astigmatism.

Nearsightedness (Myopia)
The eyeball is too long for the lens and the cornea to focus
light on the retina. Hence, light rays from distant objects arefocused in front of the retina. Myopia blurs distance vision.

Farsightedness (Hyperopia)
The eyeball is too short for the lens and the cornea to focus
light on the retina. Light rays from close objects are thus
focused behind the retina. Hyperopia blurs near vision.

Astigmatism
Astigmatism occurs when the eyeball is shaped more like afootball than a basketball. This odd shape causes the light tofocus on two points on the retina rather than one. Astigmatism isoften accompanied by either nearsightedness or farsightedness.
In such cases, LASIK treats both refractive errors simultaneously.

LASIK, PRK, and other refractive procedures correct nearsightedness, farsightedness, andastigmatism by reshaping the cornea so that the focal point of the light rays entering the eye is righton the retina.

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Cornea
The corneal tissue is arranged in five essential layers, each critical function. The thickness of the cornea
is approximately 0.53 mm.

－3－Examination: Preparing for LASIK Surgery
Before LASIK surgery, you will have to go through a series of eye tests. Your doctor will perform
complete eye examinations and obtain a detailed eye history. The examinations should include thefollowing:⚫

Discussion of medical history, lifestyle, and expectations
from the surgery⚫

Corneal topography and eye aberration⚫

Refractive error⚫

Visual acuity⚫

Intraocular pressure⚫

Pupil and corneal thickness⚫

Tear function analysis⚫

Dilated eye examination to check for ocular irregularities

Corneal Topography Map

Indication: Am I a LASIK Candidate?
During these examinations, the doctor will determine whether you are a good candidate for LASIK.
There are a few general requirements for being a LASIK candidate:⚫

You should be at least 18 years old.

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Your spectacle-corrected visual acuity should be more than 20/20.

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You must not suffer from optical conditions, such as cataracts or retinal diseases.

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You must not suffer from general diseases, such as uncontrolled diabetes or autoimmune
disorders.

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You should not be pregnant.

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Some jobs prohibit specific refractive procedures. Be sure to check with your employer or
professional society before undergoing LASIK surgery.

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You must understand the risks involved in LASIK surgery and have realistic expectations
regarding the outcome.

If you have been taking any medication for an extended period, please consult your doctor because
it may affect the safety and effectiveness of LASIK.
－4－LASIK Surgery
Excimer Laser
LASIK is accomplished by using an excimer laser. Each pulse of the excimer laser removes a
microscopically thin section of tissue (usually less than 1 µm) from the cornea. Multiple pulses of theexcimer laser are applied to the cornea in a computer-controlled manner to remove a precise
amount of stromal tissue. As a result, the corneal surface is reshaped, and the distance vision is
improved.

Femtosecond Laser
In LASIK, a thin flap is created using a device known as a femtosecond laser. However, in somecases, when the femtosecond laser does not work, we resort to PRK surgery.

QuestTM M2

AMO IntraLese FS Laser

LASIK Surgery: The Procedure

At the beginning of the procedure,
the eye is anesthetized with topicaleye drops.

After the flap has been created,
an excimer laser is used toreshape the cornea.

The surgeon then uses a device called a femtosecond laser to create a corneal
flap on the outer layer of the eye.

The corneal flap is replaced.

The eye will heal by itself, andno stitches are needed.

The actual surgery is usually completed in about 15 minutes, but preoperative preparation may extend
the duration of the surgery to 1 hour. Both eyes can be operated on at the same time.
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PRK Surgery
PRK is performed by removing the corneal surface layer, called the epithelium, by employing an
excimer laser. The laser then gently reshapes the underlying corneal stroma. The procedure is
generally completed in less than 10 minutes. After the process is over, these corneal epithelial cells
regenerate in about one week.

PRK Surgery

At the beginning of the procedure,
the eye is anaesthetized with
topical eye drops.

First, the epithelial cells are
removed by an excimer laser.
The laser then gently
reshapes the underlying corneaｌ
surface.

The eye is fitted with a bandage
contact lens to increase comfort
during healing.

Custom LASIK, Custom PRK
Custom LASIK is order-made LASIK that provides laser ablation tailored to the shape and degree ofdistortion unique to each eye. LASIK procedures slightly increase distortions; however, thisincrease in distortion is minor in custom LASIK procedures, thus providing better vision.
There are two types of custom LASIK: topography-guided LASIK and wavefront-guided LASIK.
They differ according to whether the distortions mentioned above are restricted to the cornea or theentire eye. In topography-guided LASIK procedures, laser ablation is tailored to distortions of thecorneal topography. Topography-guided LASIK will be performed if the distortions are primarily
restricted to the cornea. In wavefront-guided LASIK procedures, on the other hand, laser ablation is
tailored to the overall distortions of the eye determined using an aberrometer. Laser ablation
patterns are custom-tailored to each eye to offer clearer vision.
Most patients who are eligible for LASIK will achieve better vision with custom LASIK treatment.

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Topography-guided LASIK procedures are particularly suitable for the following candidates:・those who have significant asymmetry in corneal shape; and・those who have substantial corneal distortion.
Wavefront-guided LASIK procedures are particularly suitable for the following candidates:・those who have significant distortion of the eye; and・those who have a large pupil diameter after dark adaptation.・Custom PRK is also possible in the sameidea of order made with custom LASIK.

Advantages
Custom LASIK procedures have the following advantages:•

Achieve a higher quality of vision;•

Improve low-contrast vision or night vision after surgery;•Can correct irregular corneas resulting from previous surgery or injury;•

Decrease the chances of complications, such as experiencing glare and halos in dim light andloss of best-corrected vision.

Disadvantages
More cornea needs to be removed in custom LASIK procedures, and the amount of the additional
corneal tissue removed depends on the degree of corneal or optic distortions.

Risks
Risks associated with LASIK and PRK
As with any surgical procedure, there are certain risks associated with LASIK. The following is a list of
possible risks.
⚫

Foreign body sensation or pain: Most patients experience slight discomfort or pain, particularly
during the first 24 hours after LASIK surgery. Occasionally, the use of painkillers may be necessary.
PRK may cause some discomfort and pain, especially for a couple of days after the surgery. In
some cases, the use of painkillers may be necessary.

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Blurred vision: Vision may be somewhat blurred during the early postoperative period.

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Subconjunctival bleeding: Bleeding sometimes occurs from the subconjunctiva (white part of theeye) when the femtosecond laser is fixed on the eye to create the flap. In this case, about 2 weeks－7－are required for the blood to be completely absorbed. However, this will not affect your visual acuity.
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Night vision problems, such as halos, glare, starbursts, and light sensitivity: Patients
commonly experience mild glare and haloes at night following LASIK. In most patients, these
symptoms are mild and dissipate over time. However, in rare cases, they may be severe andprolonged enough to require eye drops that constrict the size of the pupil.

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Dry eye: Dry eye commonly occurs after surgery. Dry eye causes discomfort and reduces thequality of vision due to intermittent blurring and other visual complications. Eye drops are necessary
to counter this problem during the first few weeks after surgery.

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Presbyopia: Presbyopia is a natural aging process of the lens inside the eye. Therefore, You may
require near vision correction by reducing myopia in the presbyopic age range.

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Undercorrection and regression: While introducing the excimer laser has improved the accuracyof refractive surgery for the correction of refractive errors, individual biology of wound healing andother factors vary from patient to patient; therefore, Surgery is not a 100% accurate procedure.
Moreover, it is impossible to predict how your eyes will respond to the treatment accurately.
Undercorrection is the most commonly noted inaccuracy and is generally very mild. If
undercorrection is significant, you may need to wear glasses or contact lenses or eventually haveadditional refractive surgery to achieve your best vision. Additionally, it has been observed thatsome patients have mild regression of correction following surgery. However, in most cases, thecorrection is relatively stable after surgery.

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Overcorrection: Following surgery for low-to-moderate degrees of myopia, overcorrection occurs
much less frequently than undercorrection. As with undercorrection, it is impossible to predict how
your eyes will respond to the treatment. A mild degree of overcorrection may be perfectly welltolerated. More severe overcorrection may necessitate wearing of glasses or contact lenses or may
require further refractive surgery.

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Loss of best-corrected visual acuity: A few patients lose lines of vision on the vision chart. This
loss cannot be corrected with glasses or contact lenses. It may be due to irregular astigmatism,
which occurs if the cornea heals in a wavy fashion.

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Infection: Infection is a potential complication that accompanies all surgical procedures. Following
LASIK, the risk of infection is less than 0.02%. To minimize the risk of postoperative infection, it iscritical to precisely follow the prescribed postoperative medication regimen.

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Retinal diseases: It is unknown whether refractive surgery affects the retina. However, thefrequency of retinal diseases, such as objects floating in the field of vision, retinal detachment, andretinal tears, maybe slightly more in myopic eyes.

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Keratectasia: Excessive corneal thinning (keratectasia) may result in weakness and abnormal
shape of the cornea. Although uncommon, it is a serious complication severely impacting thepatient’s vision.

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Elevated eye pressure: Steroid eye drops may result in elevated pressure inside the eye.
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Risks Associated with LASIK⚫

Incomplete flap: I If a flap is too small or too thin, the surgery will likely have to be postponed until
the cornea heals sufficiently before attempting to create the flap again.

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Epithelial defect: Rarely, epithelial defects may occur on the flap surface using the femtosecond
laser. In most cases, the epithelial defect will heal by a soft contact lens and eye drops. However,
several days may be required for complete healing and vision improvement.

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DLK (Diffuse lamellar keratitis): Mild inflammation at the interface between the flap andunderlying corneal tissue may occur after LASIK. In most cases, DLK generally disappears following
steroid eye drops. However, DLK can be significant in rare cases and require additional treatment.

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Displacement or wrinkling of the flap: Partial or complete corneal flap displacement can occur
during the early postoperative period, but it may also happen later due to trauma. Partial
displacement of the flap may result in striae or wrinkles, which reduce visual acuity. Most striae aretreatable, but some may be resistant to treatment. Complete displacement of the flap is often painful
and requires urgent replacement.

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Corneal epithelial ingrowth: Like all lamellar refractive surgeries, LASIK involves the creation of
an interface between two layers of corneal tissue. In all lamellar procedures, it has been observedthat surface epithelial cells can grow into this interface. Although it is not uncommon, epithelial
ingrowth into an interface is mild and not progressive. In most cases, it will not affect vision. In rarecases, these cells may continue to grow within the interface and can threaten vision and cause
irregularities. Under these conditions, the epithelial cells may need to be mechanically removed.

Risks Associated with PRK⚫

Delay in reepithelialization: In most patients, the corneal epithelium envelops the corneal surface
in 4 to 5 days. In rare cases, this process may be delayed.

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Haze (corneal cloudiness): In the postoperative period following PRK, inflammation of the cornea
may develop in some cases. This results in a white hazing of the cornea, which may spontaneously
resolve or require treatment with topical anti-inflammatory medications.

Precautions
Instructions for Patients Wearing Contact Lenses
Contact lenses alter the shape of the cornea. Therefore, people who wear contact lenses need to stop
wearing them before the surgery, depending on the type of contact lenses used.
⚫

Hard or gas permeable lenses (HCL) should not be used for four weeks before the final examination.
HCL should not be worn after the final examination.

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⚫

Soft contact lenses (SCL, Toric SCL) should not be used for three days before the final examination.
SCL may be used after the final examination but should not be worn one day before surgery.

Following the above instructions will ensure accurate measurement of refractive errors in patients.

On the Day of the Surgery⚫

Please do not wear makeup (except skin toner/emulsion).

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Please do not wear any sweater or garment made from mohair or similar yarn.

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Please avoid any outfit that exposes your shoulders or bring a jacket with you (the operating room ischilly).

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Please do not operate a vehicle.

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Please do not drink alcohol.

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Please do not put on any perfume, hair gel, or strongly scented cream when you come to the clinic forthe surgery.

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Please remove earrings before the surgery.

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If you have long hair, please tie it to the side before the surgery.

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Please bring the informed consent document with your signature. If you are less than 20 years old, yourparents' signature is necessary on the informed consent document.

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Please inform the doctor regarding any drug allergies that you have experienced.

Precautions after the Surgery
Significant improvement in vision will be noticeable approximately one day after LASIK surgery.
Although complications can occur with any surgery, there is usually little to no postoperative discomfort,
and some patients can return to daily activities the next day. Please follow the instructions mentioned
below to prevent postoperative infection.

On the Day of the Surgery⚫

Please do not touch your eyes or eyelids.

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Please do not take a bath, shampoo your hair, or wash your face. Instead, please wipe your facegently with a wet towel. You may take a shower, but please avoid wetting your face. After
examination by the physician on the day after the operation, if there are no complications, you may
take a bath, shampoo your hair, and wash your face.

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Please be sure to come to the clinic on the day following the surgery.

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Please use eye drops according to the instructions provided.

During the First Week after Surgery⚫

Please use protective sunglasses outdoors and protective eye patches while sleeping.

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Please do not participate in sports.

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Please do not wear eye makeup.
－10－During the First Month after the Surgery⚫ Please prevent water or sweat from entering your eyes and avoid vigorously rubbing your eyes.
Follow-up examinations will be conducted at one day (PRK:3 day), one week, one month (PRK:2
months), three months, six months, and every year after surgery. Please contact the clinic in case ofunusual symptoms or if your vision suddenly worsens.

－11－Instructions for the Postoperative Period
The next morning

1 day–1 week

* You may take ashower, but pleaseavoid wetting yourface.
* Please wipe your facegently with a wet
towel.
* Please do not touch
your eyes or eyelids.
* Please do not
shampoo your hair.

1 week–1 month

After 1 month

You may take a bath, shampoo your hair, andwash your face.
*Please prevent water from entering your eyes.
*Please avoid vigorously rubbing your eyes.
*PRK is please do not take a bath, shampoo yourhair, or wash your face for three days.
Instead, please wipe your face gently with a wet
towel.

Regular activities

Please use protective sunglasses outdoors.
Please use protective eye patches while sleeping.
(Please wash the eye patches before using them.)

Regular activities

You may participate
in sports, except for
swimming and diving.
Please consult yourdoctor for details.

Please do not participate in sports.

You may swim anddive with the eyes
protected by goggles
You may participate inboxing.

Please do not wear
makeup.

* You may wear makeup,
except in the areaaround your eyes.
* Please do not wear eye
makeup.

Regular activities

Please do not drink
alcohol.

You may drink a small
quantity of alcohol.

Regular activities

Regular activities

Please avoid dry sauna.

Postoperative
examination

1 day

3 Day
(PRK)

1 week2 months(PRK)
1 month 3 months 6 months

1 year, yearly after year 1－12－Frequently Asked Questions about LASIKWhat is the history of LASIK?
Q1: What is LASIK, and how is it performed?
Q2: What does LASIK stand for?
Q3: How long has LASIK been performed?

Will LASIK be suitable for me?
Q1: Who can benefit from LASIK?
Q2: Who is not eligible for LASIK?
Q3: If I am not eligible for LASIK, are there other options available?
Q4: I am happy with my contact lenses. Should I undergo LASIK?

What can I expect my vision to be like after LASIK?
Q1: What results can I expect from LASIK?
Q2: Will my vision after LASIK be as sharp as with glasses or contact lenses?
Q3: How many days after surgery will I see properly and have my best vision?
Q4: Will I require glasses or bifocals once my eyes have healed?
Q5: What will be the status of my vision at night or in low light after LASIK?
Q6: Will my eyes be dry after LASIK?
Q7: Are the results achieved from LASIK permanent?
Q8: If I undergo LASIK and my vision changes later in life, can LASIK be performed again?

Does the procedure hurt?
Q1: Is LASIK a painful procedure?
Q2: What type of anesthetic is used for LASIK?
Q3: How safe is LASIK?

Will undergoing LASIK inconvenience me?
Q1: Can LASIK be performed on both eyes at the same time?
Q2: If I choose to undergo LASIK in one eye at a time, what will be the status of my vision
between the first and second surgeries?
Q3: How long will I have to be away from work after undergoing LASIK?
Q4: Can I participate in sports after LASIK surgery?
Q5: Can I drive immediately after undergoing LASIK?
Q6: Will my eyes look different after LASIK?

What is the history of LASIK?
Q1: What is LASIK, and how is it performed?
A: LASIK is a surgical procedure capable of correcting a wide range of refractive errors, such asnearsightedness (myopia), farsightedness (hyperopia), and astigmatism.
Q2: What does LASIK stand for?
A: LASIK is an acronym for laser in situ keratomileusis, sometimes referred to as laser-assisted in situ
keratomileusis. The name refers to using a laser to reshape the cornea without invading theadjacent cell layers. "In situ" is a Greek phrase that means "in the natural or normal place."
Medically, "in situ" means confined to the site of origin without invasion of neighboring tissues.
"Kerato" and "mileusis" are Greek words for "cornea" and "to shape," respectively.
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Q3: How long has LASIK been performed?
A: LASIK has been performed worldwide for approximately thirty years. It was first performed in clinical
trials in the USA in 1995. It is important to note that the major components of the procedure have along history. For instance, ophthalmologists have been reshaping the cornea for over 60 years, andusing the excimer laser since the 1980s.

Will LASIK be suitable for me?
Q1: Who can benefit from LASIK?
A: LASIK can be beneficial for many people with myopia, hyperopia, and astigmatism. Candidates
should have a strong desire to be less dependent on corrective lenses, have realistic expectations,and understand the risks associated with the surgery.
Q2: Who is not eligible for LASIK?
A: Doctors need to evaluate many factors before determining the candidate's eligibility for LASIK.
Some doctors consider certain preexisting conditions as contraindications to the procedure and will
not perform the surgery on people with these conditions. Sometimes, certain factors preclude apatient from being an ideal candidate for LASIK surgery. However, a surgeon may still perform theprocedure safely in many cases, provided the patient and physician have adequately discussed therisks and benefits and set realistic expectations regarding the results.
Q3: If I am not eligible for LASIK, are there other options available?
A: LASIK is one type of refractive surgery available to patients. Although you may not be eligible for
LASIK, you may be eligible for a different procedure. It would be best if you discussed your options
with your doctor.
Q4: I am happy with my contact lenses. Should I undergo LASIK?
A: If you are comfortable wearing contact lenses and not inconvenienced by being dependent on them,
you should carefully evaluate the risks and benefits of LASIK before undergoing treatment.

What can I expect my vision to be like after LASIK?
Q1: What results can I expect from LASIK?
A: LASIK improves uncorrected vision—vision without wearing corrective lenses—in most patients
who have undergone the procedure. Over 90% of the patients with low-to-moderate myopia willachieve 20/40 vision. More than half of all patients can expect to achieve a vision of 20/20 or better.
However, there are no guarantees that you will have perfect vision, and patients with high myopia(more than –7 diopters) and high hyperopia (more than +4 diopters) should have a different set of
expectations. Those with realistic expectations regarding their vision after LASIK are primarily
satisfied with the results of the laser correction.
Q2: Will my vision after LASIK be as good as with corrective glasses or contact lenses?
A: Patients should understand that a 20/20 vision after LASIK might differ from a 20/20 vision withcorrective lenses. Some people report that the images they see postoperatively are not as "sharp"
as those seen through glasses.
Q3: How many days after surgery will I see properly and have my best vision?
A: Fast visual recovery characterizes this operation. Most patients achieve good vision on the day ofthe surgery and notice that their eyes feel relatively normal within a day. However, vision may－14－

continue to improve, and the best vision may be achieved after approximately 2–3 months.
Adjustments to the surgery—enhancements—can be made if required. Patients who undergo
hyperopic LASIK often need to wait longer to see clearly. Typically, patients cannot see extremely
clear images for 1–2 weeks, and the best vision is achieved several months postoperatively.
Q4: Will I require glasses or bifocals once my eyes have healed?
A: Most patients who undergo LASIK do not require glasses for their daily activities. However, patientsabove 40 years of age may need reading glasses. This is due to the eye's normal aging, known aspresbyopia. This condition occurs irrespective of whether or not the patient has undergone LASIK.
Some patients may require glasses with minimal correction for some activities. Patients whocurrently wear bifocals will still need reading glasses after the surgery unless they opt for atreatment plan called monovision, wherein one eye is corrected for distance and the other for nearvision.
Q5: What will be the status of my vision at night or in low light after LASIK?
A: Most patients do not notice a change; however, some may experience glare, halos, or starbursts
around objects under dim or low-light conditions. For the vast majority of patients, these symptoms
are temporary. However, others will continue to experience them for several months or longer.
Although these symptoms do not necessarily interfere with visual acuity as measured by an eye
chart, they can interfere with some activities.
Q6: Will my eyes be dry after LASIK?
A: Some patients who seek LASIK have an underlying dry eye syndrome that has not been diagnosed.
There appears to be a correlation between preoperative dry eye syndrome and the development of
more pronounced dry eye symptoms postoperatively. Therefore, many doctors test for dry eyes
before determining eligibility for LASIK.
Q7: Are the results achieved from LASIK permanent?
A: LASIK is a surgical procedure that permanently removes corneal tissue to reshape the eye toimprove refraction. The physical results are permanent. However, you should be aware that theeyes can change with time, and LASIK does not affect some visual conditions associated with age.
For example, LASIK does not prevent presbyopia or affect this condition once developed.
Q8: If I undergo LASIK and my vision changes later in life, can LASIK be performed again?
A: Retreatment may be a viable solution to vision changes later in life; however, other treatment
options exist. You would need to consult your ophthalmologist to determine the cause of the change
in vision and the treatment option best suited for you.

Does the procedure hurt?
Q1: Is LASIK a painful procedure?
A: Topical anesthetics (eye drops) are administered to numb the eye; therefore, patients do notexperience any pain during the procedure. When the surgeon applies the vacuum ring, the patient
experiences pressure just before their vision fades for a few seconds. The femtosecond laser—the
instrument used by the surgeon to create the flap—and the laser do not cause any pain or
discomfort. For several hours after the procedure, many patients describe a mild burning sensation,
which is similar to that experienced when eyes are opened while swimming in chlorinated water.
Therefore, taking a nap for the first 2 to 3 hours after LASIK is encouraged. After the first few hours,
this uncomfortable feeling usually subsides.
Q2: What type of anesthetic is used for LASIK?
A: Topical anesthetics (eye drops) are used in this procedure to numb the eye. Patients may be－15－administered a small amount of oral sedative to help them relax.
Q3: How safe is the LASIK procedure?
A: According to several extensive studies, there is approximately a 2% intraoperative and 3%–5%postoperative complication rate. Most of these complications do not result in loss of 2 or more lines
of best-corrected visual acuity or interfere with long-term vision. The rate of severe complications ismuch less than 1%. However, patients must understand that there is a small risk of complications
associated with LASIK as in other surgeries.

Will undergoing LASIK inconvenience me?
Q1: Can LASIK be performed on both eyes at the same time?
A: You can undergo bilateral, simultaneous LASIK (both eyes operated on simultaneously). BilateralLASIK is a common practice. However, in some circumstances, surgeons or patients will determinethat it is best to employ a waiting period between the operations on the two eyes to evaluate theresults. Patients should discuss their options with their ophthalmologist.
Q2: If I choose to undergo LASIK in one eye at a time, what will be the status of my vision
between the first and second surgeries?
A: There are several options to help patients see between procedures. Some patients who have notundergone bilateral surgery will begin wearing a contact lens in the eye that has not undergone
surgery. This practice provides an opportunity to use both eyes simultaneously. However, thecontact lens will have to be removed at least 3 days before second surgery. Other patients use theoperated eye immediately without using a contact lens in the unoperated eye. This option may beeffective in nearsighted patients with a moderate refractive error (less than 6 diopters). A patient witha refractive error greater than 6 diopters and who does not wear a contact lens may be unable touse both eyes together due to the significant difference in the refractive error between the eyes.
Removing one lens from a pair of glasses is usually not practical. Further, doing so could result indouble vision and eyestrain.
Q3: How long will I have to be away from work after undergoing LASIK?
A: This depends on your occupation. Patients may experience difficulty performing specific jobs that
require intense clarity of vision (for example, dentistry and surgery) for 1 or 2 days. Most patientscan resume work the next day, assuming that their vision is adequate for their job. However, somepeople may feel fatigued for a day following surgery.
Q4: Can I participate in sports after LASIK surgery?
A: You can resume almost all normal activities immediately after the surgery. However, you will have to
avoid strenuous activities for at least 1 month,which can cause sweat to run into your eyes. You
should wear protective glasses while participating in contact sports regardless of whether you haveundergone LASIK or not. However, if you do not routinely wear such glasses, your surgeon may
recommend them for at least 1 month after LASIK. You will have to avoid activities such as contact
sports and swimming for several weeks. It would help if you talked to your doctor specificallyregarding the limitations on activities after LASIK.
Q5: Can I drive immediately after undergoing LASIK?
A: Patients may experience some discomfort and blurred vision for a few hours after the surgery. In
addition, most patients receive a sedative before the surgery. Therefore, you cannot drive home
after undergoing this procedure; you should plan not to drive for at least 24 hours after surgery.
Q6: Will my eyes look different after LASIK?
A: No. Your eyes will look the same.
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Frequently Asked Questions about PRK
What is PRK?
Q1: How is PRK surgery performed?
Q2: What is the difference between LASIK and PRK?
Q3: Which is better, PRK or LASIK?

Will PRK be suitable for me?
Q1: Who can benefit from PRK?
Q2: Who is not eligible for PRK?
Q3: If I am not eligible for PRK, are there other options available?
Q4: I am happy with my contact lenses. Should I undergo PRK?

What can I expect my vision to be like after PRK?
Q1: What results can I expect from PRK?
Q2: Will my vision after PRK be as sharp as with glasses or contact lenses?
Q3: How many days after surgery will I be able to see clearly?
Q4: Will I require glasses or bifocals once my eyes have healed?
Q5: What will be the status of my vision at night or in low light after PRK?
Q6: Will my eyes be dry after PRK?
Q7: Are the results achieved from PRK permanent?
Q8: If I have PRK and my vision changes later in life, can PRK be performed again?

Does the procedure hurt?
Q1: Is PRK a painful procedure?
Q2: What type of anesthetic is used for PRK?

Will undergoing PRK inconvenience me?
Q1: Can PRK be performed on both eyes at the same time?
Q2: If I choose to undergo PRK in one eye at a time, what will be the status of my vision
between the first and second surgeries?
Q3: How long will I have to be away from work after undergoing PRK?
Q4: Can I participate in sports after PRK?
Q5: Can I drive immediately after undergoing PRK?

What is PRK?
Q1: How is PRK surgery performed?
A: The eye is anesthetized with eye drops. The outermost layer of the cornea is then removed with alaser. The amount of cornea removed depends on the amount of correction required. Following theprocedure, a bandage contact lens may be worn for 3–5 days.
Q2: What is the difference between LASIK and PRK?
A:In LASIK, first, a corneal flap is created using a femtosecond laser. Then the exposed corneal
surface is reshaped using an excimer laser. Finally, the corneal flap is replaced. In PRK, on the－17－other hand, the surface layer of the cornea (called the epithelium) is removed using an excimer
laser (no corneal flap is created). The underlying cornea is then reshaped. The epithelial cells
gradually regenerate. Both procedures can be used to correct nearsightedness, farsightedness, andastigmatism.
Q3: Which is better, PRK or LASIK?
A:
Generally speaking, both LASIK and PRK can yield excellent results for low corrections. LASIK
offers the advantages of quicker healing, less pain, less regression (more stable results), and lower
incidence of corneal scarring. Additionally, retreatments are generally easier to perform with LASIK.
Currently, most patients prefer LASIK. However, PRK may be the preferred technique in certain
special situations, such as patients with thin corneas.

Will PRK be suitable for me?
Q1: Who can benefit from PRK?
A: PRK may benefit many people with myopia, hyperopia, and astigmatism. Candidates should have astrong desire to be less dependent on corrective lenses, have realistic expectations, andunderstand the risks associated with the surgery.
Q2: Who is not eligible for PRK?
A: Doctors need to evaluate some factors before determining a candidate's eligibility for PRK. Some
doctors consider certain preexisting conditions as contraindications to the procedure and do not
perform the surgery on people with these conditions. Sometimes, certain factors preclude a patientfrom being ideal for PRK surgery. A surgeon performs the procedure safely in many cases, provided
the patient and physician have adequately discussed the risks and benefits and set realistic
expectations regarding the results.
Q3: If I am not eligible for PRK, are there other options available?
A: PRK is one type of refractive surgery available to patients. Although you may not be eligible for PRK,
you may qualify for a different procedure such as Phakic IOL（Intraocular Lens）. It would be best if
you discussed these options with your doctor.
Q4: I am happy with my contact lenses. Should I undergo PRK?
A: If you are comfortable wearing contact lenses and not inconvenienced by being dependent on them,
you should carefully evaluate the risks and benefits of PRK.

What can I expect my vision to be like after PRK?
Q1: What results can I expect from PRK?
A: PRK improves the uncorrected vision—vision without wearing corrective lenses—in most patients
who have undergone the procedure. Over 90% of the patients with low-to-moderate myopia willachieve 20/40 vision. More than half of all patients can expect to achieve a vision of 20/20 or better.
However, there is no guarantee that you will have a perfect vision. Patients with high myopia (morethan –7 diopters) and high hyperopia (more than +4 diopters) should have a different set of
expectations. Those with realistic expectations regarding their vision after PRK are primarily
satisfied with the results of the laser correction.
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Q2: Will my vision after PRK be as sharp as that with corrective glasses or contact lenses?
A: Patients should understand that a 20/20 vision after PRK might differ from a 20/20 vision withcorrective lenses. Some people report that the images they see postoperatively are not as "sharp"
as those seen through glasses.
Q3: How many days after surgery will I be able to see clearly?
A: Most patients achieve good vision one week after the surgery. However, vision may continue toimprove, and the best vision may be achieved after approximately 2–3 months. Adjustments to thesurgery—enhancements—can be performed if required.
Q4: Will I require glasses or bifocals once my eyes have healed?
A: Most patients who undergo PRK do not require glasses for their daily activities. However, patientsabove 40 years of age may need reading glasses. This is due to the eye's normal aging, which is
known as presbyopia. This condition occurs irrespective of whether the patient has undergone PRKor not. Some patients may require glasses with minimal correction for some activities. Patients whocurrently wear bifocals will still need reading glasses after the surgery unless they opt for atreatment plan called monovision, wherein one eye is corrected for distance and the other for nearvision.
Q5: What will be the status of my vision at night or in low light after PRK?
A: Most patients do not notice a change; however, some may experience glare, halos, or starbursts
around objects under dim or low-light conditions. For the vast majority, these symptoms aretemporary. However, others will continue to experience them for several months or longer. Althoughthese symptoms do not necessarily interfere with visual acuity as measured by an eye chart, they
can interfere with some activities.
Q6: Will my eyes be dry after PRK?
A: Some patients who seek PRK have an underlying dry eye syndrome that has not been diagnosed.
There appears to be a correlation between preoperative dry eye syndrome and the development of
more pronounced dry eye symptoms postoperatively. Therefore, many doctors test for dry eyes
before determining the eligibility for PRK.
Q7: Are the results achieved from PRK permanent?
A: PRK is a surgical procedure that permanently removes corneal tissue to reshape the eye to improverefraction. The physical results are permanent. However, you should be aware that the eyes canchange with time, and PRK does not affect some visual conditions that are associated with age. For
example, PRK does not prevent presbyopia or affect this condition once developed.
Q8: If I have PRK and my vision changes later in life, can PRK be performed again?
A:
Retreatment may be a viable solution to vision changes later in life; however, other treatment
options exist. You would need to consult your ophthalmologist to determine the cause of the change
in vision and the treatment option best suited for you.

Does the procedure hurt?
Q1: Is PRK a painful procedure?
A: Topical anesthetics (eye drops) are administered to numb the eye; therefore, patients do notexperience any pain during the procedure. After the surgery, there may be some mild to moderate
discomfort for 1 to 3 days, which may be relieved by oral medications and topical eye drops.
－19－Q2: What type of anesthetic is used for PRK?
A: Topical anesthetics (eye drops) are used in this procedure to numb the eye. Patients may take asmall amount of oral sedative to help them relax.

Will undergoing PRK inconvenience me?
Q1: Can PRK be performed on both eyes at the same time?
A: Usually, PRK is done separately for each eye.
Q2: If I choose to undergo PRK in one eye at a time, what will be the status of my vision between
the first and second surgeries?
A: Some options help patients deal with their vision in between procedures. Some patients who havenot undergone bilateral surgery will begin wearing a contact lens in the eye that has not undergone
surgery. This practice provides an opportunity to use both eyes simultaneously. However, thecontact lens will have to be removed at least three days before the second surgery. Others use theoperated eye without a contact lens in the unoperated eye. This option may be effective innearsighted patients with a moderate refractive error (less than 6 diopters). A patient with arefractive error greater than 6 diopters and who does not wear a contact lens may be unable to use
both eyes together due to the significant difference in refractive error between the eyes. Removing
one lens from a pair of glasses is usually not practical. Further, doing so could result in double visionand eyestrain.
Q3: How long will I have to be away from work after undergoing PRK?
A: After the PRK procedure, it is not advisable to return to work the next day. The visual results of PRK
surgery are not instantaneous; it may take several days for the vision to become clear enough for
you to be able to drive.
Q4: Can I participate in sports after PRK?
A: You will have to avoid activities such as contact sports and swimming for several weeks. It is crucial
for you to discuss with your doctor any limitations about participating in activities after PRK.
Q5: Can I drive immediately after undergoing PRK?
A: Patients may experience discomfort and blurred vision for a few days after the surgery. In addition,
most patients receive a sedative before the surgery. Therefore, you cannot drive home after
undergoing this procedure; you should plan not to drive until your vision improves.

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